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A Dictionary

OF

Automobile Terms

BY

ALBERT L. CLOUGH

Associate Editor of THE HORSELESS AGE

Published by

THE HORSELESS AGE COMPANY

250 West 54th Street

New York

1913

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Copyrighted, 1013, by TUB HORSELESS AGE COMPANY

262593

PREFACE

This book represents a serious and painstaking, endeavor to
arrange alphabetically the mass of terms which current usage
applies to the motor car and its accessories, and to define these
terms clearly, concisely and in language as untechnical as the
nature of the subject permits.

So far as is known, this is the first Dictionary of Automobile
Terms to be compiled, and the author has thus not had the ad-
vantage of precedent to guide him, the work being of a pioneer
character and subject to all the limitations necessarily character-
izing a first attempt to systematize the vocabulary of a new art,
which is not yet entirely out of the formative stage.

Nearly all the material here presented originally appeared in
serial form in the columns of THE HORSELESS AGE, but it has
been thoroughly revised and corrected and considerably aug-
mented before being embodied in book form.

During the period covering the development of the motor car
industry in this country, a large body of terms has been coined,
borrowed from other languages or adapted, with new significa-
tions, from the vocabularies of other arts, and it has not only
proven a difficult matter for the general public and even the
users of motor cars to become conversant with the exact mean-
ings and uses of these terms, but it has been demonstrated that
many of these terms have come to be used with indefinite or even
contradictory significance by persons technically skilled in the art.

It is with the double purpose of informing the general public
and students of the automobile as to the commonly accepted
meanings of these terms, and with the hope that, in a general
way, the definitions herein suggested for them may be accepted
as suitable and standardized by a majority of those identified
with the industry, that this book has been brought out.

Many thousands of people each year enter the automobile mar-
ket with the intention of buying a motor car, or at least of in-
forming themselves concerning automobile technique. In the
course of their investigations they read masses of automobile
catalogues, couched in technical language, and converse with mi-

merous motor car users and salesmen. While so doing they are
constantly confronted with technical terms, the meanings of which
they do not understand, but which have a most important bearing
upon the problem in hand.

It is hoped that, by reference to this book, the meanings of
these terms may be made clear "not only to the intending pur-
chaser but to the student of automobile engineering and to all
others who take interest in the subject.

A word as to arrangement may not be amiss. Nearly every
important component part of an automobile is built in a wide
variety of "types" or forms, each one of them known by an
appropriate descriptive prefix. Thus there are "air cooled cylin-
ders," "water cooled cylinders," "block cast cylinders," etc. These
various types in which a certain component part figures in the
industry will, in general, be found grouped together under the
name of the part and not under the name of their respective
descriptive designations. Thus the types of cylinder mentioned
above will be found under "cylinder" and defined under the
titles of "cylinder, air cooled," "cylinder, water cooled" and "cylin-
der, block cast."

The author takes this occasion to express his appreciation- of
the assistance offered by P. M. Heldt and others of THE HORSE-
LESS AGE staff and by several prominent members of the Society
of Automobile Engineers, who have afforded useful hints and
suggestions. ALBERT L. CLOUGH.

MANCHESTER, N. H., December, 1912.

DICTIONARY

OF

AUTOMOBILE TERMS

Ability — A term sometimes employed to express the rela-
tionship between car weight and engine output, more partic-
ularly used in estimating the hill climbing and speed capa-
bility of cars. No unit of ability has been agreed upon, but
the output of the motor in horse power, or its piston displace-
ment, divided by the weight of the car in hundredweights has
been proposed. Thus, a car with a 30 horse power motor, and
weighing 3,000 pounds, would possess an ability of i.o, or would
possess one horse power per hundred pounds of weight. Quite
commonly the reciprocal of this unit is used by manufacturers,
viz., the car weight in pounds divided by the output of the motor
in horse power ; or, in other words, the car weight per horse power.

Accelerate — To increase in velocity or speed.

Acceleration — The rate of increase in the speed or velocity
of a moving body. Strictly speaking, the limiting ratio of
the gain in velocity during an infinitely short period of time
to the length of the period of time itself. In practice, ac-
celeration is generally measured in feet per second per sec-
ond. Example: If at a certain instant a car is moving at the
rate of 40 feet per second, and a second later is moving at the
rate of 45 feet per second, its acceleration is at the rate
of 5 feet per second per second.

Accelerator — A device for the direct and rapid control of
car speed by opening and closing the throttle. The term is
usually applied to the pedal and attached parts which perform
this function independently of the hand throttle (which can be
set for any desired degree of opening), and of the automatic
engine speed governor. Car speed is usually increased by the
action of the foot upon the accelerator pedal, and is automatic-
ally decreased, to a predetermined point, by the action of an
attached spring.

Syn. ; Foot throttle.

POSITIVE AND NEGATIVE

OF EDISON TYPE

ACCUMULATOR.

Accumulator — Edison type. An elec-
tric storage or secondary cell the positive
plates of which consist of nickel plated
steel frames containing steel tubes rilled
with nickel hydrate, the negative plates
consisting of similar frames containing
pockets filled with iron oxide. The two
sets of plates are immersed in a solution
of caustic potash contained in a nickel
plated steel jar. The method of use and
the applications of this cell are similar
to those of the lead cell.

Syn. : Secondary cell, storage cell.
Accumulator — Lead type. An elec-
tric cell consisting of two sets of plates
immersed in dilute sulphuric acid within
a containing jar, usually of glass or
hard rubber. The plates of one set are
known as positives, and consists of grids or frames of spe-
cially prepared lead, the interstices in which are rilled with
lead peroxide. The plates of the negative set are lead grids
filled with spongy lead.

When the positive plates of such a cell
are connected to the positive pole of a cir-
cuit carrying continuous current (and vice
versa), chemical changes take place and the
cell becomes charged. When so charged
the cell itself will furnish current to a cir-
cuit until its available chemical energy is
exhausted, when recharging becomes neces-
sary. A number of such cells electrically
connected constitute a storage battery or
secondary battery, which may be used to
drive an electric vehicle or to furnish light-
ing or ignition current.

Acetylene — A hydrocarbon (C2H2) used
as an iiluminant in automobile lamps. It
is produced by the reaction of water upon
calcium carbide. In automobile lighting it
may be produced, as consumed, in an auto-
matically regulated generator, or may be

ACCUMULATOR —

LEAD TYPE
(SECTIONAL VIEW)

A— Positive Plate;
B — Negative Plate;
C — Separator;
D— Hard Rubber Jar;
E — Bottom Rib;
!•'— Top Sealing;
G and I — Connectors;
H— Vent Hole;
J — Negative Strap.

drawn as desired from a storage tank in which the gas is carried
under pressure dissolved in acetone or some similar, absorbent.

Acetylene Torch — A torch used in heating the pilot light of a
steam car, which burns acetylene gas derived from a supply car-
ried upon the car.

Acid Cure — A method of curing rubber quickly, and without
the application of heat as required in true vulcanization. It is
employed in the securing of patches to inner tubes and in other
tire repairs. Chloride of sulphur is supposed to be the agent
employed to produce a sort of vulcanizing effect.

Active Material — The material which fills the spaces pro-
vided for it in the grids or frames that form the plates of storage
cells. This material is the seat of the chemical changes which
enable the cell to store and restore electrical energy, the grids
themselves acting only as conductors. (See Accumulator.)

Adapter — A device for attachment to a gas or oil lamp to
permit the use of an electric light therein, consisting of an
electric lamp socket and bulb, with
suitable electrical connections at-
tached to a fitting which may*be
substituted for the gas or oil
burner or clamped -upon the same.
In the latter case the fitting is
hinged so that the electric bulb
may be .swung out . of the way
when the gas or oil burner is to
be used.

Syn. : Converter.

Adhesion, Coefficient of— The ADAPTER.

ratio of the maximum tractive ef-
fort (q. v.), which can be applied by a driving wheel, without
causing the same to slip, to the weight acting at the point of
contact of the wheel with the roadway, both forces being ex-
pressed in the same unit, usually the pound. It varies with the
kind of tire used and the character and condition of the road
surface, having a value in the vicinity of 0.6 for a pneumatic tire
on dry, smooth macadam and as low as 0.05 or even lower for
such tires on wet snow, or very greasy mud ; e. g., a pneumatic
tired wheel carrying 800 pounds may be expected to slip on dry
macadam if a tractive effort greater than about 480 pounds is
exerted by it and to slip on soft snow if the tractive effort ex-
ceeds 40 pounds.

8

Advance — A term used with reference to the point in the
cycle of operations (q. v.) at which the igniting spark passes
within the fuel charge of an internal combustion engine.

v. To cause the spark to pass at a relatively earlier point in the
cycle of operations.

n. (Angle of) advance: The angle through which the crank
shaft of a motor turns between the point at which the spark pro-
ducing mechanism acts and the point at which the piston
reaches its extreme position on its compression stroke (its ex-
treme upward position in the case of a vertical motor).

Age (v.) — To lay aside a casting, for a period of time, after
it has been roughly machined, in order to permit any changes of
form caused by internal stresses in the metal to take place before
it is finished to its final form and thus to obviate the possibility
of distortion taking place later. Syn. : To season.

To lay aside a permanent magnet, after it has been charged,
so that any loss of magnetism may take place at that time,
rather than when the magnet is in service. Such ageing is some-
times artificially accomplished.

Air Bottle — A receptacle designed to be con-
veniently carried upon a car, containing highly com-
pressed air or liquified carbon dioxide, to be used
in the inflation of tires. Generally a strong steel
cylinder fitted with cock, rubber tubing and tire
valve connection.

Air Bound, Adj. — The condition created in a sys-
tem designed for the free flow of a liquid, occasioned
by the access of air or vapor
to certain portions thereof, by
which the flow is checked. Generally ap-
plied to the water or fuel feed systems of
automobiles.

Air Cooled, Adj.— Cooled by air. Gener-
ally applied to the cylinder of an internal
combustion motor, the temperature of
which is maintained at a point low enough
to enable lubrication to be maintained, and
the fuel charges to be efficiently expended,
by the direct application of a current of
relatively cool air to the external surfaces
of the cylinder from which heat is thereby
abstracted by convection and radiation.

AIR COOLED
CYLINDER.

A — Cooling Flange;
B — Valve Chamber.

9

Air Cooling — The practice of cooling a cylinder by the direct
application of air thereto.

Air Damper — A damper inserted in the air intake of a carbu-
retor which is normally kept open, but which, when closed, causes
the carburetor to deliver a very rich mixture in order to facilitate
starting the motor. Syn. : Starting shutter, primary air shut-off.
Also an adjustable valve in the main air intake of the carburetor
used in regulating the quality of the fuel mixture.

Air Gauge — A gauge which indicates the degree of pressure
which is acting upon the fuel, in a pressure feed system to cause
it to flow from the tank to the carburetor. Also
sometimes applied to a gauge for measuring the air
pressure in pneumatic tires. A tire gauge.

Air Intake, Auxiliary — The orifice through which
additional air is admitted to the carburetor to prevent
the mixture from becoming too rich under certain
conditions. This opening is usually controlled by a
valve regulated in some manner by the action of the carburetor
itself.

Syn. : Supplementary air intake.

Air Intake, Main — The orifice through which the main air
supply for the carburetor enters, and the
piping through which it passes. The air thus
entering generally passes in close proximity
to the fuel jet, and the size of the opening is
usually permanently adjusted. Syn. : Primary
air intake, initial air intake, fixed air intake.
Air Leak — The accidental entrance of air
into the fuel mixture after it leaves the
carburetor.

An aperture through which such air can
enter and thus weaken the mixture, in some AIR pUMP
cases interfering with the operation of the A— Cylinder;
motor. E. g., looseness between the intake c— Piston'

valve stems and their guides; lack of tight- Rod;

• . . , . ,. D— Delivery Ball

ness in intake pipe connections. Valve;

Air Pump— A pump operated either by
hand or by engine power to produce an F — Stirrup'.
air pressure upon the fuel in the supply tank to force it to the
carburetor in the case of a gasoline car, and to the burner in
the case of a steam car.

10

Air Resistance — The resistance offered to the motion of a
car by the air through which it moves and which is directly pro-
portional to the area it exposes to the air in the direction of
motion (projected area) and to the square of the car speed. This
resistance expressed in pounds may be taken as T = 0.0022 AV~
where A is the projected area in square feet and V the velocity
of the car in feet per second. To convert miles per hour into
feet per second, multiply the miles per hour by 1.466. The horse
power absorbed in- overcoming air resistance is

e. g. at 40 miles per hour, a car of 20 square feet projected
area moving against an air resistance of 152 pounds, calls for an
expenditure of 16 H. P.

The above formula applies to motion through still air. Under
other conditions the velocity of a head wind is to be added and
the velocity of a following wind subtracted from the car velocity
to obtain the air resistance and the power required to over-
come it.

Air Vent — A small aperture provided in a tank or other part
of a liquid-containing system to permit the entrance and exit
of air, so that the movement of the liquid may not be interfered
with. E. g., the small hole usually provided in the filling plug of
the fuel tank in a gravity feed system.

Alignment — The state of being perfectly in line. Applied, for
example, to the several bearings which support a shaft. When
these bearings are exactly in the same straight line they are
said to be in alignment, and the shaft can turn in them without
binding, and without excessive waste of power or undue wear.
Also applied to two connected shafts the bearings of which
are exactly in the same straight line, so that no motion between
their connected ends is required when the shafts turn. Also
applied to a condition of parallelism between the road wheels
of an automobile.

Alloy Steel — Steel which, in addition to its carbon content,
contains a certain intentional proportion of one or more other
elements, such as nickel, chromium, manganese, tungsten, vana-
dium, silicon, etc. The presence of certain proportions of these
elements greatly alters the physical properties of the metal in
numerous respects, such as hardness, strength, elastic limit,
ductility, ability to withstand repeated shocks, magnetic qualities,

11

etc. Alloy steels of appropriate qualities are very largely used
for the important parts of motor cars. (See steel.)

Alternating Current — An electric current which is produced
in a circuit by the action of an electromotive force that period-
ically alternates in direction. The direction of flow of such a
current reverses with each reversal of the electromotive force
producing it. The commercial alternating current generally em-
ployed for lighting and power alternates in direction 120 times
per second. The alternating current is, in general, not adapted
to the production of chemical changes, and is thus not directly
applicable to the charging of accumulators.

The term is used in contradistinction to the terms "continu-
ous" and "direct," which are applied to currents flowing in a
constant direction.

Aluminum Alloy — The following are specifications for alumi-
num alloys employed for crank and gear cases, housings, cover
plates and the like, because of their lightness.

No. i. Aluminum not less than 90.00%, copper 7.00% to 8.50%.
No. '2. Aluminum not less than 80.00%, zinc not over 15.00%,
copper from 2.00% to 3.00% and manganese not over 0.40%.

No. 3. Aluminum 65.00%, zinc 35.00% (a rather brittle, weak
metal, inferior to Nos, I and 2).

Ammeter — An instrument for the measurement of the rate
of flow of electricity in a circuit, or, in other words, for the
measurement of the volume of the elec-
tric current flowing. Ammeters are usually
constructed upon the electromagnetic prin-
ciple, the electromagnetic effect of the cur-
rent, and hence the indications of the in-
strument, increasing and decreasing with
the increase and decrease of the current
flowing through the circuit into which the
AMMETER. ammeter is connected. The readings of

such an instrument are in amperes.

Syn. : Amperemeter.

Ammeter, Coil Testing — A low reading ammeter, usually
calibrated to read to o.i ampere or lower, which is especially
adapted to be conveniently inserted in circuit with the primary
of a jump spark coil.' It is used to measure the current which
a coil passes and in adjusting the several units of a multiple
coil to equality in current consumption. It is also employed

12

to detect excessive demands upon the batteries for current on
the part of the coils.

Ampere — The practical unit of current volume. The unit
which is employed in measuring the rate of flow of electricity
in a circuit. The current which, steadily applied for one second,
will deposit 0.00113 grams of silver from a bath of silver nitrate.
Amperage — The volume of an electric current expressed in
amperes.

Ampere Hour — The quantity of electricity which passes in
an electric circuit when a current of one ampere flows for one
hour. The unit of quantity of electricity.

The term is principally used in connection with the charge
and discharge of storage batteries ; e. g. : A storage battery
which is 'charged for a period of seven hours at the rate of
10 amperes has received 70 ampere hours of electricity. Storage
batteries are commonly rated by their capacity in ampere hours ;
thus a 60 ampere hour (a. h.) ignition battery should be able to
deliver a current of 5 amperes for a period of twelve hours
when fully charged.

Ampere Hour Meter — An instrument for measuring and re-
cording the ampere hours of electricity which flow through a
circuit into which it is connected.

It consists of a small electric motor, the speed of which is
directly proportional to the current passing through the circuit.
This motor drives clockwork and an indicating dial, the reading
of which is in ampere hours.

Such an instrument is sometimes carried upon an electric ve-
hicle, being used to record the ampere hours of electricity sup-
plied in charging the battery and also the ampere hours given
out by the battery on discharge. By its use the state of charge
of the battery, at any time, may approximately be ascertained.

Angle Iron — A piece of metal in the form of an angle or
L, used as a brace for parts which are to be held in a definite
angular relation.

Angle Steel— A form of structural steel bars or beams, the
cross section of which is an angle or L, sometimes used in
automobile frame and sub-frame construction. This form of
cross section secures greater rigidity against transverse deflec-
tion than afforded by the same amount of metal in a circular
or square cross section.

13

Anneal (v.) — To soften a metal by heating. Annealing usually
increases the malleability and ductibility of a metal and reduces
its elastic limit. Steel may be annealed by heating it to an ap-
propriate degree and then allowing it to cool gradually.

Annealing is frequently resorted to in order to relieve internal
stresses set up in metal parts in the processes of rolling, forg-
ing, casting and hardening.

Syn. : To draw the temper.

Anti=Freeze Solution — A liquid used as a substitute for
water in the engine cooling system of a gasoline automobile,
which is capable of remaining fluid at the freezing temperature
met with in practice.

Solutions of certain neutral salts, alcohol and glycerine are
used for this purpose and also special mineral oils. Particular
solutions are treated later under their respective names.

Anti-freeze solutions are also used in acetylene generators, in-
stead of water, during cold weather.

Syn. : Non-freezing solution.

Anti=Skid Device — A device applied to the wheels of an
automobile, designed to enable them to obtain more secure foot-
ing upon the road surface than is realized by the use of ordinary
smooth rubber tires, and thus to decrease their liability of skid-
ding or slipping sidewise. Such devices usually consist of special
knobbed or metal studded tire treads or a series of cross
chains secured about the tire. (See tire chain, tire protector, tire
tread.)

Syn. : Non skid device, traction increasing device.

Apron — A term sometimes applied to extensions of metal,
fabric or leather attached to the fenders of a car to further
guard the car from road splash. Also sometimes applied to a
sort of boot placed under the mechanism to protect it from
road dirt.

Arc Flame — An electrical discharge which resembles the vol-
taic arc, in that it is not of an instantaneous, disruptive charac-
ter, but persists for an appreciable length of time, and is due
to the passage of a considerable quantity of electricity at a rela-
tively low pressure through a spark gap which has been rendered
conductive by the passage of a high tension, disruptive discharge.
The term is applied to the discharge of a high tension mag-
neto in which both primary and secondary windings are under
the influence of the same magnetic field.

14

Armature, Magnetic — A piece of magnetic material the func-
lion of which is to assist in conducting the magnetism from one
pole of a magnet to the other. In practice, a piece of soft iron
uiovably mounted in proximity to the pole or poles of an electro-
magnet and adapted to be moved by attraction thereof. E. g., the
iron portion of a coil vibrator which is attracted by the pull of
ihe core of the coil and returned to its initial position by a spring
Syn. ; Keeper. Also, the soft iron portion of a magneto
or dynamo which carries or is enclosed within the conductors
in which the current is generated. Usually but not always a
rotating part.

Armature Core — The soft iron portion of the armature of a
dynamo, magneto or electric motor, upon which are wound the
conductors which carry the currents developed by or utilized by
the machine. It is built up of appropriately shaped stampings of
thin, very soft iron or special steel, insulated from each other
and tightly clamped together upon a shaft, so as to form a solid
magnetic mass of a generally cylindrical form, slots usually being
provided in its surface to receive the conductors.
See core, magnetic, and cut of magneto armature.

A r ma t ure
Pi nion — A
small gear or
pinion fixed
upon the shaft
which carries
the armature or
rotating part
of an electric
vehicle motor
and which
transmits the
power to the rest of the driving mechanism.

Also, a small gear or pinion fixed upon the shaft that car-
ries the armature of a synchronous magneto. This pinion drives
the distributor shaft of the magneto.

Armature Shaft— The shaft upon which is mounted the
armature of a dynamo, magneto or electric motor.

Armature Winding— The electrical conductors upon an
armature in which are generated the currents produced by a
dynamo or magneto, and which, in an electric motor, receive the

MAGNETO ARMATURE.

A, Core; B, Winding; C, Shaft; D, Driving Gear;
E, Collector Ring; F, Binding Band.

15

current used in the machine. Highly insulated copper wire is
used.

Artillery Box — A box fitted to the rear deck of runabouts
to provide extra carrying space for tools, etc. So called be-
cause of its resemblance to the boxes used upon field gun
carriages.

Aspirating Stroke — The outward piston stroke of an in-
ternal combustion motor during which the explosive charge
is introduced into the cylinder from the carburetor through the
inlet valve, by the suction created by the piston movement.
Syn. : Suction stroke, charging stroke, intake stroke.
Assemble v. — To put together the various component parts
of a motor car in their correct relationship.

Assembled Car — A car the important parts of which, such
as the motor, gear box, axles, body, etc., are produced by several
different makers of these parts and are then brought together
at the factory of the manufacturer, whose name the car bears,
where they are assembled with other parts into a complete
vehicle. The term is employed in contradistinction to that
class of cars the chief parts of which are produced by the con-
cern whose name the car bears.

Autogenous Welding — A
method of welding or joining
metals without hammering or the
use of heavy pressures between
the parts to be joined. The parts
to be welded are correctly brought
together and an exceedingly hot,
non-oxidizing flame, produced by
a blowpipe burning acetylene in
an atmosphere of oxygen, is di-
rected upon the junction. The
abutting edges of the parts are
thus melted and flow together,
and a very intimate and strong
joint results. Any extra metal
which is required to make a
smooth weld is supplied from a
wire or rod of the same material
as the parts, the end of which is held in the flame. The process

AUTOGENOUS WELDING.

10

is very commonly applied to the joining of the edges of the
pressed steel parts of automobiles.

Automatic Cut=out — A device used in connection with a
battery charging circuit for the purpose of automatically dis-
connecting the storage battery from the charging circuit when
the current tends to flow back from the battery to the dynamo
on account of low dynamo speed or high battery voltage or
when the current flowing becomes excessive from any cause.

Syn. : Automatic circuit breaker,- reverse current circuit breaker,
low voltage release.

Automatic Fire Regulator — A device employed on steam cars

to regulate the fire under
the boiler, so as to main-
tain a constant pressure
therein, independent of
variations in the demand
for steam. It usually
consists of a flexible dia-
phragm acted upon by
the boiler pressure and
a suitable linkage com-
municating the motion of
this diaphragm to ; a

valve in the fuel supply
ELEVATION AND SECTION OF AUTO- of the burner When the

MATIC FIRE REGULATOR. steam pressure exceeds

A, Housing; C, Diaphragn; E, Valve; the desired amount, the

Ff Spring; H, Adjusting Screw; I, Connec- rUanVirso-m 0^fc m A'try,

tion to Water Space of Boiler; J, Gasoline QiaPnragm acts to dimm-

Feed; L, Needle Valve; N, Needle. ish the fire and vice

versa. In the case of

"flash" steam generator, the diaphragm is replaced by a thermo-
stat, which is sensitive to the temperature of the metal of the
generator. The thermostat acts to maintain the generator
at a constant temperature independent of the rate at
which water is supplied for steam raising. As the temperature
of the generator falls, the thermostat opens the fuel valve of the
burner, thus increasing the fire, and vice versa.
Syn.: Automatic fuel feed.

Automatic Spark Advance— See timer, automatically ad-
vanced.

17

SECTIONAL VIEW OF AUTOMATIC
WATER FEED.

Automatic Water Feed

— A device used upon
steam cars of the "flash"
generator type, which acts
to regulate the amount of
water pumped to the gen-
erator so that the pressure
therein is maintained at
nearly a constant amount,
independent of the rate of
demand for steam. A
flexible diaphragm, under

A, Connection to Generator; B, Copper the »fiu«lCC of the steam
Diaphragm; C, Connection to Steam Gauge; ^pressure, is usually em-
D, Diaphragm Pad; E, Housing; F, Spring; , . . ,

G, Adjusting Nut; H, Poppet Valve; I, ployed, which is mechani-
cally connected so as to
actuate a water pump by-
pass valve. As the steam pressure drops, the diaphragm partly
closes the by-pass, allowing the pump to feed water to the gen-
erator at an increased rate and vice versa.

Auxiliary — A term applied to those devices connected with
a gasoline engine, which are essential to its operation and driven
by it, but which are separate units distinct from the motor itself,
such as the circulating pump, the mechanical lubricator and the
magneto. The use of the term is sometimes broadened to in-
clude the carburetor, radiator, muffler, etc.

Auxiliary Air Valve — The valve which controls the ingress
of air through the auxiliary intake (see air intake, auxiliary) of
a carburetor. It may, for instance, be in the form of a butterfly
valve or shutter, which is mechanically connected to the throttle,
so that it is opened and closed correspondingly therewith. It may
be a poppet valve which is opened by the suction of the engine
against the action of a spring, or it may be a series of balls
which are lifted from their seats against gravity by the suc-
tion or some other equivalent arrangement.

Syn. : Supplementary air valve.

Auxiliary Exhaust — An arrangement for rapidly clearing the
cylinder of a gasoline engine of spent gases, used in addi-
tion to the regular exhaust valves. Slightly above the extreme

lowest position of the piston head, ports
are cut through the cylinder walls, and,
as the piston nearly reaches the end of
its power stroke, the piston head un-
covers these ports. A mechanically oper-
ated valve is sometimes used between
each auxiliary exhaust port and the ex-
haust manifold.

Auxiliary Fuel Tank — A tank ar-
AUXILIARY EXHAUST ranged to be carried upon a car and
A, Exhaust Port. adapted to hold a supply of fuel in addi-

B, Cylinder; C, Piston. . ,KFf

tion to that carried in the main tank, for

use in case the main supply has accidentally become exhausted.
Such a tank may be a portable one, the contents of which are
emptied into the main tank, or it may be a separate compart-
ment built into the main tank, which may be connected to the
carburetor supply piping by the opening of a valve, which is
normally kept closed.

Syn. : Emergency gasoline tank, reserve gasoline tank.
Auxiliary Oil Tank — A tank containing a supply of lubri-
cating oil in addition to that contained in the lubricating system
of a gasoline vehicle motor. It it connected to the engine lubri-
cating system by a pipe fitted with a valve, and when the oil
•supply in the engine becomes low or vitiated by long use, the
valve is opened and the requisite amount of fresh oil is fed to
it from the auxiliary tank.

Auxiliary Shaft — A shaft turned by the vehicle motor, which
drives the auxiliaries such as the circulating pump, the magneto
and the mechanical lubricator.

Auxiliary Spark Gap — A device employed
in connection with jump spark plug circuits,
which is intended to insure the passage of a
spark even though the plugs are sooted or
oily. It is merely a short gap or break, addi-
tional to that between the sparking points,
which is introduced into each plug circuit. Its
function is to prevent the gradual leakage of
the sparking current through the sooted spark-
plug ends or other electrical defects, and to
__ insure that no current passes until an elec-

trical pressure adequate to produce a spark is attained. This

AUXILIARY
SPARK GAP (A).

B, Spark Plug.

device is at present little used in separate form, but the principle
underlying it is frequently embodied in ignition apparatus.

Axle, Cambered — An axle which is so formed or set that its
ends, upon which the wheels are carried, are given a slight
slant downward from the horizontal. This causes the wheels
to converge slightly toward their points of contact with the
ground. The camber or set of an axle, if dished wheels are
used, brings the spokes -which are under load in a truly verti-
cal position, thus utilizing the full strength of the wheel.

Axle, Channel Section— An axle the cross section of which is
of a U shape. (See channel.)

Axle, Dropped—
An axle so formed
that the whole or
a part of the por-
tion between its
ends is on a lower

level than the ends themselves, upon which the wheels turn.
The form of such an axle is that of a shallow U.

Axle, Equalizing — A live axle in which is incorporated
special mechanism permitting the two wheels driven thereby to
freely turn at different speeds when curves are traversed — a
substitute for the ordinary type of live axle in which the above
result is secured by the use of a differential or compensating
gear.

Axle, Floating (full floating)— A form
of live rear axle in which the shafts that
drive the wheels are "floated," that is,
they are not restrained in bearings and
are not under bending stress, as they

SECTIONAL VIEW OF FULL FLOATING REAR AXLE.

A, Axle Housing; B, Shaft; C, Hub; D, Differential Housing; E Bevel
Gear Housing; F, Clutch; C, Hub Cap.

20

support none of the weight of the car, but act only under
twisting stress. The axle casing or housing supports all the
weight. This result is attained by supporting each wheel bear-
ing upon the outside surface of its end of the casing and by
supporting the frame of the differential gear rigidly upon the
inside of the casing. The inside ends of the driving shafts are
usually squared into the hubs of the main gears of the differ-
ential, in a slightly flexible manner, and each outside end of the
driving shafts is provided with some form of jaw clutch mem-
ber which engages with a corresponding . clutch member
on its respective wheel hub, a slight degree of flexibility to
changes of alignment being permitted. Superior strength and
the readiness with which it may be taken apart are the chief
advantages of this type of axle.

Axle, Flared Tubular — A live axle, the tubular casing or
housing portion of which increases in diameter from a point
near each wheel to the central portion where the driving and
compensating gears are located. This flared form of casing is
adopted in order to secure increased resistance to bending
stresses.

Axle, I=Beam — An axle the cross section of the metal of
which is generally forged, but occasionally cast into the form
of an I. This form of cross section affords a degree of rigidity,
particularly to transverse stresses in a vertical plane, greatly
superior to that afforded by the use, for instance, of a solid
square or circular section containing the same mass of metal.
This form of cross section is generally employed for front
axles and sometimes for fixed rear axles.

Axle, Live — A form of axle in which are incorporated
the two driving shafts that transmit the motive power to their
respective wheels. In the restricted sense, the typical form of
non-floating live axle, in which each driving shaft is re-
strained in two bearings carried by the inside surface
of the tubular casing, one near its outer end, under the spring,
and the other near its inside end, where it is secured to its
respective main gear of the differential. The driving shafts
thus carry the weight of the differential and drive gears, any
transverse stresses due to the driving effort, and the entire
vehicle load which falls upon the axle. This type of live axle
is becoming obsolete. All gear or worm driven cars, and all
cars driven by a single chain are fitted with axles which are

21

"live" in the general sense of the term, but not necessarily
so in the restricted sense.
Syn. : Divided axle.

Axle, One Piece — A fixed or solid axle, which is forged, cast
or pressed complete as a single piece and not forged in two
pieces which are subsequently welded together. Sometimes
applied to a front axle in which the axle itself, the spring seats
and the steering yokes are formed integrally.

Axle, Pivoted— A form
of axle peculiar to self-pro-
pelled vehicles, which car-
ries the steering wheels
and is generally the front
axle. Each end thereof is
vertically forked and a ver-
tical pivot turns in each of
these forks. To these piv-
ots are attached the hori-
zontal swinging spindles or
axle stubs upon which the
road wheels are journaled.

By this arrangement the front wheels may be set in any desired
vertical plane and steering effected without moving the axle,
as a whole, as in horse-drawn vehicle practice. (See steering.)

Axle, Semi=FIoating — A form of live axle in which the
driving shafts are rigidly restrained in bearings at their outer

SECTIONAL VIEW OF PIVOTED AXLE.

SECTIONAL VIEW OF SEMI-FLOATING REAR AXLE.

A, Axle Tube; B, Axle Shaft; D, Differential; E. Driving Gear Casing;
F, Wheel Hub; G, Hub Cap.

22

ends only, these bearings being supported upon the inside sur-
faces of the ends of the tubular casing and the wheels rigidly
mounted upon the shaft ends. The inside bearings are sup-
ported by the hubs of the differential case, and the inside ends
of the axle shafts are somewhat flexibly squared into the main
gears of the differential, so that they are relieved from carrying
the weight of the differential.

Axle, Solid — An axle which does not revolve, and upon the
ends of which the road wheels turn. Similar in principle to
the axles of horse-drawn vehicles. The term is used in con-
tradistinction to the term live axle, and is generally applied to
the stationary rear axles of automobiles, the wheels of which
are independently driven, usually by chains or gears.

Syn. : Fixed, stationary or dead axle.

Axle, Three=Quarters Floating — A form of live axle, inter-
mediate between the semi-floating and full-floating types, in which
the inside ends of the axle shafts are somewhat flexibly squared
into the main differential gears, as in the semi-floating and full-
floating types. The bearings of the outside ends of the axle
shafts are upon the outside surfaces of the tubular casing and
directly in the wheel hub, so as to relieve the shafts of car
weight, but the wheels are rigidly fixed upon the shaft ends
instead of being flexibly driven by means of a clutch connection
as in the full-floating type. »

Axle, Trussed
— An axle which
is strength-
ened against bend-
ing by means of a
truss, of which the
AXLE, TRUSSED. gear housing usu-

A, Truss Rod. ally forms the

strut of the truss

and a rod adjustably attached to the ends of the tubular casing
and centrally secured to the gear housing forms the tension
member.

Axle, Tubular — An axle formed of steel tubing.

Axle, Universally Jointed— A form of axle in which the
axle shafts consist each of two or three parts connected to

23

each other by universal joints. These joints are required in
axles in which the differential and wheel hub centre lines do
not necessarily coincide.

Axle Casing — The portion of a live axle which encloses the
axle shafts — sometimes extended to include the metal enclosing
the differential and drive gears, which is generally integral
therewith. The casing is usually of tubular form of varying
diameter.

Syn. : Axle housing.

Axle Shaft — The shaft of a live axle which transmits the
driving effort from the differential gear to one of the road
wheels. There are two of these driving shafts in each axle.

Axle Shaft Clutch — The clutch or coupling which transmits
the driving effort from each shaft of a full floating axle
to its corresponding road wheel hub. This clutch may be
of the jaw or dog type or in the form of a pair of coarsely
toothed gears. One member thereof is carried by the outer end
of the shaft and the other by the wheel hub, and in the forma-
tion of these members a certain degree of angular flexibility
is generally provided for.

Babbitt — An alloy used for the linings of shaft bearings, which
possesses excellent anti-friction properties and which is not
likely to mar the shafts which run upon it. It is readily melted
and cast into the form required to fill the space between the
shaft to be supported and the caps and stands of the bearing
or journal. Babbitt or some similar alloy is generally used for
gasoline engine crank and cam shaft bearings, for connecting
rod tip bearings, and elsewhere. Its composition is somewhat
variable, but the following is a commonly used formula: Tin,
84.00 per cent. ; antimony, 9.00 per cent. ; copper, 7.00 per cent.
Alloys known as nickel babbitt and white bronze are extensively
used in place of true babbitt.

Backfiring. — The communication of the flame of explosion
in a gasoline engine cylinder to the gas in the intake piping
and that in the carburetor, resulting in an explosion of the
same, the noise of which is known as "popping" in the car-
buretor. It is usually caused by faulty valve action, by very
late ignition, or by the use of a slow burning mixture. In prac-
tice it is usually a sign that the mixture furnished the engine
is too weak, that is, contains too small a proportion of gasoline
vapor,

24

The term is also sometimes applied to the explosion of the
mixture in the crank case of a two cycle engine.

Backlash — Looseness between a driving and a driven part,
which permits the former to be moved relatively to the latter
without producing the intended motion in the latter. It is usually
developed through wear of the acting surfaces of the driving
and driven parts, or may be due to their incorrect adjustment.
Syn. : Lost motion.

Back Kick — The starting of a gasoline engine backward or
in the reverse direction of rotation. It is caused by an explosion
taking place considerably before the piston affected has com-
pleted its upward of compression stroke. If such explosion
occurs while the motor is being cranked in the normal direction,
the operator is likely to be injured thereby. Too early ignition
is the cause of this phenomenon.

Back Pressure — The gaseous pressure which acts to resist
the piston movement of a gasoline engine while its cylinder is
being cleared of burnt gases, on the exhaust stroke. This re-
sults in negative work and a reduction of engine output.

Baffle Plate — A plate placed in a chamber containing fluid to
restrain the free movement thereof. Examples: An oil baffle
plate is a perforated plate placed across the
lower end of a gasoline engine cylinder to
limit the amount of lubricating oil which is
splashed up from the crank case upon the
cylinder walls. Baffle plates are sometimes
fixed within the fuel tank to prevent the ex-
cessive splashing about of the gasoline, when
the car is in motion. (Swash plates.) Such
plates are also used in exhaust mufflers to cause
the spent gases to follow circuitous paths in
their passage to the open air.

Balance — That quality of a moving part or
system of moving parts of a mechanism which
enables it to move without jar or vibration and
without imposing excessive inertia stresses upon
its bearings. (See counterbalance.)

Balance Wheel — A heavy rimmed wheel carried upon the
crank shaft of a gasoline engine and rotated thereby, for the
purpose of steadying the running of the engine. When once
set in motion it tends to continue to rotate and furnishes stored

OIL BAFFLE
PLATE (A).

25

energy to keep the engine turning during intervals of the cycle
when the power required for propulsion exceeds that developed
in the cylinders. The balance wheel may also deliver stored
energy and assist in driving the car during short periods when
an excessive driving effort is called for, as at starting.

Syn. : Flywheel.

Ball Joint — A form of joint for connecting two members
of a linkage so as to permit of a considerable range of angular
relation between them. The connecting end of one member is in

the form of a ball, and that of the
O ^ 1&T~"D — H

other is in the form of a cup or

partial sphere, which encircles and
holds the former. Such joints are
employed in the steering linkages

and in the throttle and spark control linkages of motor cars
and a similar construction is sometimes used to .connect the
forward end of the drive shaft housing to its support upon the
car frame.

Syn. : Ball and socket joint.

Ball Joint, Spring— A form of ball joint employed in the
steering linkage at the forward end of the rod, which connects
the steering device with one of the steering knuckles. The cup
and ball connection is cushioned by springs contained within
the tubular rod, which permit the joint to give slightly when
sudden shocks are communicated to it from the road wheels.
This prevents the communication of these shocks to the hands
of the operator.

Syn. : Spring buffer.

Base Explosion — The accidental explosion of the gas con-
tained in the crank case or base of a two cycle engine, by
flames extending from the cylinder through the transfer pas-
sage. This generally results from too late ignition or from
the use of a slow burning mixture.

Syn. : Crank case explosion.

Battery, Commutated. — An arrangement of the storage cells
of an electric vehicle in which the cells are divided into several
equal groups. These groups, by means of a special controller,
may be connected to the motor, either in multiple or in series,
r\nd thus any one of several voltages may be impressed upon the
motor at will and several speeds obtained from it without the
necessity of much dead resistance being employed.

26

Battery, Divided — An arrangement of the storage battery
of an electric vehicle in which the cells are divided into two
groups, carried in the forward and rear parts, respectively.

Battery, Dry — A battery made up by connecting together
a number of dry cells (q. v.).

Battery, Interchangeable — An electric vehicle battery so ar-
ranged that it is readily removable as a unit from its car when
exhausted and which is replaceable by a similar battery that is
fully charged.

Battery, Storage — A battery formed by connecting together
a number of storage cells or accumulators (q. v.).

Battery, Underslung— A vehicle storage battery, which
instead of being carried in the car body, is suspended under-
neath the vehicle frame.

Battery Box — The box which contains the ignition or light-
ing battery of a car. It is generally carried upon the running
board or under one of the seats and is usually made of pressed
steel and lined with insulating material. Some boxes intended
to hold dry cells are so arranged that the act of putting the cells
in place therein automatically makes the necessary electrical
connections. These are called wireless battery boxes.

Battery Gauge — An instrument for roughly testing the con-
dition of dry cells or storage cells. The dry cell gauge is merely
a low resistance ammeter, reading up to 30 amperes or so.
The dry cell is short circuited through this, the reading indicat-
ing approximately the internal resistance of the cell, a high
ampere reading indicating a low resistance cell and vice versa.

The storage cell gauge is a low reading voltmeter, calibrated
up to 10 v. or so, which indicates the voltage of the cell and
thus furnishes some indication of its state of charge.

Syn. : Battery tester, pocket ammeter and voltmeter.

Battery Platform — A platform used in electric vehicle sta-
tions to facilitate the handling of interchangeable storage bat-
teries. The platform is of such a height or may be raised to
such a height by an elevator that when the vehicle is properly
drawn up alongside it the battery may readily be slid into or out
of it without heavy manual labor being required.

Battery Tray — A tray in which are assembled the cells which
constitute a storage battery or a section of a storage battery,
for convenience in handling.

Baume Scale — An arbitrary scale used to indicate the density
or specific gravity of liquids. There are two such scales, one
used for liquids heavier, and one for liquids lighter than water,
the latter being mainly employed to define the density of gaso-
line. In this scale, the denser the liquid, the lower the Baume
degree which it tests, and vice versa. Gasoline, as at present
obtainable, tests from 62 to 70 degrees Baume (abbreviation B.).
and the following table gives the specific gravity which corre-
sponds to each degree Baume within this range:

Degrees B.
60..

Specific Gravity.,
738

Degrees B.
69....

Specific Gravity.
706

61.
62.
63-
64.
65-
66.

67.
68.

• 735

• 731
.728
.724
.720
.717
.713
.709

70.
7i.
72.
73-

74-
75-
76.

.702
.699
•695
.692
.689
.685
.682

Direct determinations of density according to the B. scale
are generally made by the hydrometer (q. v.).

Bearing — In general, the support of a moving part within
which it moves in a prescribed manner; more specifically, the
support of a shaft within which it is so held as to permit its
rotation. (See bearing, plain; bearing, ball; bearing, roller, etc.)

Bearing, Annular Ball — A form of self-contained, inadj List-
able ball bearing, which consists of two concentric, hardened
steel rings or annuli, one larger than the
other, the internal periphery of the outer
ring, and the external periphery of the inner
ring being appropriately grooved to form
a race which, when the rings are assembled,
one within the other, is filled with a series

^

of steel balls, sometimes separated by spiral
springs. Such a bearing is specially in-
tended to support radial loads, its capacity
to resist end thrust along the shaft being relatively limited.

Bearing, Ball — A form of anti-friction bearing in which the
rotating shaft and the fixed portion of the bearing are not in
sliding contact, but are separated by a series of hardened steel

28

balls. A hardened steel fitting fixed to the shaft rolls upon the
balls, and the balls in turn roll upon a hardened steel fitting se-
cured to the fixed portion of the hearing. The action is thus
nearly a purely rolling one and sliding friction is practically
abolished. There is but little loss of energy in such a bearing
and it requires relatively little lubrication.

Bearing, Cup and Cone — A form of ball bearing in which
a line of balls rolls in a race formed between a hardened steel
cone-shaped fitting fixed to the shaft and
a cup-shaped fitting fixed in the bearing
support. The shaft carried cone rolls
upon the balls and the balls roll upon
their race in the cup, two, three or four
lines of contact being allowed between
the balls and their race in different de-
signs. Such bearings are usually made
adjustable for wear, by moving the cup
and cone closer together. They are well CoNE AND CuP
adapted to resist end thrust on the shaft BEARING.

in either direction, as well as to support
the radial load.
' Syn. : Bicycle type ball bearing.

Bearing, Hardened Steel — A form of plain bearing in which
the shaft rotates in a glass hard steel bushing ground to a true
surface. The shaft is made of relatively soft steel. It is claimed
that such bearings operate with little friction, are not likely
to rough up their shafts, and require only a small amount of
oil. They are not much used.

Bearing, Main — A term applied to the bearings in which
the crank shaft of a vehicle engine rotates.

Bearing, Plain — The common, primitive form of bearing in
which the rotating shaft is in sliding contact with the bearing
which supports it, a considerable area of contact between the
two being allowed.

Syn. : Parallel bearing.

Bearing, Radial — A bearing adapted to resist a radial load,
i. e., a load in a plane at right angles to the axis of the shaft
which the bearing supports, such as the weight of parts carried
upon a horizontal shaft or the effort transmitted through the
connecting rods to the crankshaft of a motor. In radial ball

29

hearings the diameter of contact of the halls is perpendicular
to the axis of rotation of the shaft. The term is used in contra-
distinction to "thrust bearing."

Bearing, Radial Thrust— A hearing capable of resisting both
radial load and thrust. In two point contact ball bearings of
this type, the diameter of contact of the balls is inclined to the
axis of rotation of the shaft, and thus both the inadjustable,
annular "two-in-one"' bearings, with two rows of balls, and the
adjustable cup and cone bearings (q. v.) may be included in
this class.

Bearing, Conical Roller — A form of anti-friction bearing
in which hardened steel rollers are used to secure rolling
contact between shaft and journal.
Such a bearing consists of a hard-
ened steel cone carried upon the
shaft and a concentric internally
coned cup fixed within the bearing
support. Such a bearing is adjust-
able by moving the cup and cone
together, and is well adapted to re-
sist both radial pressure and end
thrust. Used in axles, steering piv-
ots and wheels, on gear shafts, etc.
Syn. : Taper roller bearing.

Bearing, Cylindrical Roller — A form of roller bearing with
hardened cylindrical bearing surfaces, separated by and rolling
upon hardened cylindrical
rollers. Adapted to resist
radial loads and usually
inadjustable.

Bearing, Thrust — A
bearing adapted to resist
pressure parallel with the
axis of rotation of its shaft.

Bearing, Ball Thrust— A form of ball bearing adapted to
resist the pressure upon a shaft in the direction of its length—
the end thrust. It consists of a hardened

CONICAL ROLLER BEARING.

CYLINDRICAL ROLLER BEARING.

steel collar fixed upon the shaft and an-
other corresponding stationary collar fixed
in the bearing support. Between these
collars is a series of steel balls suitably
held in a cage. Used in drive shafts, axles, clutches, etc.

m

L j

BALL THRUST
BEARING.

30

BEARING CAP.

Bearing Bracket — A projection on a structural part or a
specially formed portion of such a part, adapted to support a
bearing.

Syn. : Bearing stand, bearing support.

Bearing Cap — The portion of a plain journal which is de-
tachable from the fixed stand or bracket thereof and which
serves to secure the bearing bushing
and shaft in position. It is usually
secured to the stand or bracket by cap
screws and may be made adustable by
the provision of shims (q. v.)-

Bearing Shell — A removable, hol-
low cylindrical, metal lining, adapted to
be held within the bracket and cap of
a plain bearing, and to the inside of

which is applied the actual bearing surface of' babbitt or similar
anti-friction metal upon which the shaft rotates.
Syn. : Liner.

Bearing Surface — The area of the projection of a bearing
on a plane perpendicular to the direction of the bearing pressure.
In the case of cylindrical bearings (shaft bearings), it is equal
to the product of the length by the diameter.

Bell Crank — A lever with its two arms angularly disposed
and pivoted at their point of intersection, adapted to transform
a push or pull applied to one arm in a
certain direction into a push or pull de-
livered by the other arm in a different
direction, for instance, at right angles.
Used in control linkages.

Benzol — Coal tar benzine (C8Hc), a
product of the destructive distillation of
coal tar. Sometimes used either alone
or in combination with gasoline or alco-
hol as motor fuel, especially in Europe.
Also sometimes used as a rubber 'solvent
in making cements.

Bevel Gear Drive— A method of driving a shaft from an-
other shaft arranged at an angle thereto (commonly at a
right angle), by means of a pair of mitre or bevel gears.. It is
specially employed for transmitting the driving effort of the
motor to the traction wheels of motor cars in which the motor

BELL CRANK.

31

shaft is located lengthwise of the car and thus at right angles
to the axle. Such a drive consists of a universally jointed longi-
tudinally disposed shaft driven by the motor and carrying a
bevel gear or pinion upon its rear end, which meshes with a
corresponding bevel gear secured to the differential frame of the
live rear axle, so as to drive the axle and its two traction wheels.

Ovearhead cam shafts and some of the auxiliaries are some-
times actuated by bevel gear drives.

Bevel Gear Drive, Double — A form of sliding gear (q. v.)
change speed (q. v.) device of the direct drive type, sometimes
employed to drive the countershaft (q. v.) of a double chain
driven car (see chain drive, double) in which two bevel gears,
secured to the differential gear (q. v.) housing are used, one
of which is in permanent mesh with a bevel pinion upon the
end of the layshaft (q. v.) and the other in permanent mesh
with a bevel pinion upon a short shaft to which the engine-
driven sliding shaft (q. v.) is clutched when the direct drive
is in action. When the direct drive is in use the latter bevel
pinion drives the differential and countershaft, the layshaft and
its bevel gears rotating idly, but on all other speeds the layshaft
bevel pinion drives the differential and countershaft and the
other bevel pinion and its shaft rotate idly, the direct drive
clutch being disengaged.

Binding Post — A part of a piece of electrical apparatus to
which attachment of the external circuit is made. Usually some
form of clamping device adapted securely to hold a wire in
electrical contact. The binding post is the point of connec-
tion between the electrical conductors forming a part of the
apparatus itself and the conductors forming the external circuit.

Bleeder — A cock inserted in the wall of a pipe, the opening of
which indicates whether or not liquid is present or moving therein.
A bleeder is sometimes inserted in an oil delivery pipe in order
to permit a test to be made as to whether lubricani is or is not
being forced therethrough.

Blister — A tire defect which results from the separation
of the tread from the fabric to which it should be secured.
Sand frequently enters the space between tread and fabric,
through a cut in the former, lifting the tread and causing an
external swelling upon the tire, the appearance of which justi-
fies the term.

Syn. : Sand boil, sand wart.

Blower Cooled — A term applied to a motor cylinder which
is cooled by air positively circulated about it by means of a
blower. The air is usually definitely confined in ducts surround-
ing the external surface of the cylinder.

Used in contradistinction to "fan cooled" which usually im-
plies that the air is less positively circulated and less definitely
directed upon the cylinder walls.

Blow Off — A tire accident characterized by the edge of the bead
of the tire freeing itself from its fastening to the rim at some
point and the inner tube protruding through the space there
formed, usually resulting in the bursting of the tube and some-
times in the whole tire leaving the rim.

The safety valve of a steam boiler or the valve through
which the boiler may be emptied of water.

Blowout — A tire accident occasioned by a rupture of the
casing and the extrusion of the inner tube therethrough with a
resultant bursting of the same.

Blowout Patch — A sleeve made of canvas, rubber fabric,
leather or some similar material, designed to stop the hole in
a tire casing and to prevent the
inner tube from blowing ou*
therethrough. Such a patch may
be applied between the tube and
the inner wall of the casing (an
inside blowout patch), or it may
be strapped or laced over the
outside wall of the casing.

Syn. : Emergency tire sleeve.

BLOWOUT PATCH.

BLOW TORCH.

Blow Torch — A portable torch, usu-
ally burning gasoline or alcohol, used to
heat the pilot light of a steam car's
burner, and also used in soldering oper-
ations.

Body — The degree of viscosity, ap-
plied to lubricating oils. A thick vis-
cous oil is said to possess more body than
a thin oil.

33

Body, Close Coupled — A form of four or five passenger
body in which the rear or tonneau seat is located somewhat

further toward the
front than usual, fre-
quently well forward
of the rear axle, and
the front seat is lo-
cated somewhat fur
ther back than usual
CLOSE COUPLED BODY. Both seats are thus

included between the

axle lines and are rather close together, allowing no room for
folding tonneau seats. A trunk platform is sometimes placed
at the rear of the tonneau seat.

Body, Fore Door — A body which, in addition to the ordi-
nary side doors that give entrance to the tonneau, is equipped
with similar side doors
closing the entrance
space between the front
seat and the dash. These
fore doors protect the
front seat passengers

from dust
draughts.

and cold

FORE DOOR BODY.

Syn. : Fore door body; vestibule body.

Body, Gunboat — A form of tonneau touring body charac-
terized by the use of fore doors and very high sides, the upper

edges of which form a
nearly straight horizontal
line, nearly coincident
with or slightly higher
than the top of the hood.
A rearwardly sloping
dash is often used and
the lines' of the rear of
the tonneau may be

GUNBOAT BODY.

curved so as to resemble the stern of a gunboat.
Syn.: Torpedo body; flush-sided body.

34

Boiler, Fire Tube— A form of tubular steam boiler, the end
plates of which are connected by a multiplicity of thin metal

tubes with open ends. The space
around the tubes is filled with
water and the hot gases from the
furnace pass through the tubes on
their way to the external air.
The inside surfaces of the tubes
being in contact with the hot
gases, and their outside surfaces
in contact with the water, a free
transference of heat to the water
is permitted.

FIRE TUBE BOILER.

A, Boiler Shell; B, Upper
Tube Sheet; C, Lower Tube
Sheet; D, Wire Winding.

by it in accordance with

Boiler, Flash — A form of

steam generator in which there

is. practically no storage of water

or steam, steam being generated

the demand of the moment. It

generally consists of a rather massive system of connected pipes
or sections which is maintained at a steam raising temperature.

FLASH BOILER.

Into the passages thereof water is pumped at rates dependent
upon the momentary call for steam and is almost instantly
vaporized and furnished to the engine usually in a superheated
condition.
Syn. : Flash generator.

Boiler Tube — One of the thin walled tubes through which
the furnace gases pass in a tube boiler.

35

WATER TUBE BOILER.

A, Outer Shell; B, Inner Shell;
C, Water Tube Coil.

Boiler, Water Tube — A form of steam boiler in which the
water is confined in coils of pipe or communicating cast sections,

which are surrounded by a casing
through which the furnace gases
circulate. Not much used.

Boiler, Wire Wound— A fire
tube boiler the cylindrical shell
of which is tightly wound with
steel wire in order to give it
greater strength against bursting.
Boiler Sheet— The steel plates
which form the ends of a fire tube
boiler, the upper one being called
the crown sheet and the lower
one the bottom sheet. The ends
of the tubes are expanded into
holes drilled respectively in these
two sheets.

Boiler Shell — The cylindrical portion of a fire tube boiler
into the ends of which the crown and bottom sheets are fast-
ened.

Bonnet — See hood.

Boot — A covering designed to afford protection from road
dirt and water, usually made of waterproof fabric; e. g., the
cover placed about a mag-
neto or that hung under
the car mechanism.

Boot, Grease — A bag-like
receptacle of leather or sim-
ilar material designed to
contain lubricant and to
fasten tightly around work-
ing parts, thus keeping the
same enveloped in lubricant

and free from dust. Such a boot permits of some relative mo-
tion between the parts enclosed.
Bore, Cylinder — See cylinder bore.

Boss — A thickened or otherwise enlarged portion of a mechan-
ical part designed to afford a point of sufficient strength for
the attachment of a related part; e. g., the inside of a piston
is provided with two diametrically opposite bosses, which are

GREASE BOOT.

Bow SEPARATOR.

drilled out to receive the ends of the piston pin. They afford

sufficient thickness for bearings and serve to distribute the

stresses at the pin ends to the relatively thin piston walls.
Bottom (v.) — Gears which run together without clearance, the

points of the teeth of each touching the bottoms of the tooth

spaces of the other, are said to bottom. Such gears are pitched

too closely and operate with excessive noise and friction.
Bow Separator — A device for _

holding the bows of a top (q. v.)

out of contact and preventing

their chafing when the top is

folded, consisting of a series of

rubber spacers or distance pieces

interposed between the bows and strapped in
place or of doweled (q. v.) metal distance pieces
attached to the bows, which come into contact
when the bows are folded and strapped together
and hold them apart.

Bow Supporters — A forked, leather lined
iron, one of which is attached to each side
of the rear of a car body to form a rest
H1^° which the bows of a folded top fit and
are secured by straps.
Bowden Wire — A mechanism used to transmit motion from

a controlling device to the part to be controlled thereby, which

dispenses with

levers, rods and

any kind of link-

work. The di-

rection of mo-

tion at the con-

trol lever may

bear any rela-

tion to that of

the part moved,

and the con-

necting mechan-

ism may pass

around inter-

vening obstacles and take almost any convenient form, being sta-

tionary externally. It consists of two parts, a closely coiled,

Bow SUPPORTER

BOWDEN WIRE MECHANISM.

A, Operating Member; B, Device Controller; C,
Wire; D, Flexible Casing; E E, End Fittings;
G G, Stationary Supports.

37

incompressible spiral spring, known as the outer member, and
a practically inextensible steel wire cable, threaded through
the outer member, which forms the inner member. If the
ends of the outer member are fixed so that the distance be-
tween them is invariable, a pull applied at one end of the
inner member will be transmitted as a pull to its other end,
and if both ends of the inner member are fixed, a push applied
to one end of the outer member will be transmitted to its other
end. It is used to operate spark timers, throttles, carburetor,
air controls, muffler cut-outs, etc.

Brake, Air Cooled — A brake, the shoes, drum or band of
which are so arranged as to facilitate the transference to
the surrounding air of the frictional heat developed in service.
The parts are usually ribbed or otherwise formed so as to pre-
sent a large convecting surface to the air.

Brake, Differential — A brake which acts upon the differ-
ential gear of a car. Such a brake may consist of a band
which contracts upon a drum forming a part of or secured to
the pinion frame of the differential, or it may be a double brake,
consisting of two straps or two pairs of shoes, which act re-
spectively upon two drums that are attached respectively to the
two main gears of the differential.

A form at present not much used.

Brake, Double Acting — A brake, the band or shoe of which
exerts nearly the same holding power upon its drum, irre-
spective of the direction of rotation thereof. Such a brake
is thus nearly as effective in checking backward as in check-
ing forward motion of a car.

Brake, Electric — A form of brake sometimes used upon
electric vehicles, the principle of which consists in temporarily
converting the vehicle motor into a dynamo, and dissipating in
electrical heat the energy of motion possessed by the vehicle.
In order to apply the electric brake, connections are made by
the controller, which short-circuit the motor and the electro-
magnetic reactions of the induced currents set up therein hold
back the armature and, through the transmission gearing, slow
down the vehicle.

Brake, Emergency — A brake primarily intended to be used
in making sudden stops. The term is used in contradistinction
to "service brake." In practice the name is applied to the pair
of brakes which is operated by a lever, usually ratchet retained,

EXTERNAL CONTRACTING BRAKE.

A, Drum; B, Contracting Band; C,
Spider; D, Brake Spring; E, Pull Rod;
F, Lining.

and which is used to hold a car at rest as well as to stop it in

an emergency. In current practice the emergency brakes are

usually internal expanding hub brakes.
Brake, External Contracting — A form of brake the external

surface of whose drum is encircled by a band anchored to some

fixed part of the car. By
means of a toggle or simi-
lar mechanism, the band
can be contracted upon the
drum and thus tend to hold
it from turning.

Brake, Foot — A brake or
pair of simultaneously act-
ing brakes which are applied
by a pedal operated by the
driver's foot. The foot
brake is the brake common-
ly used for slowing down
and stopping, in ordinary
driving.

Syn. : Pedal brake.
Brake, Front Wheel — One of the two simultaneously acting

brakes which act upon the front wheels. Little used in this

country at present,

but being intro-
duced in Europe.

The application of

brakes to the front

wheels as well as

to the rear wheels

nearly doubles the

braking power of

a car, and the use

of front brakes

tends to diminish danger from skidding when a sudden stop is

made. As the front brakes turn with their wheels in steering,

their operating mechanism is necessarily somewhat complicated.
Brake, Hand — The brake or pair of simultaneously acting

brakes which are applied by means of a hand lever, which is

usually provided with a ratchet locking device.
Sj-n. : Lever brake.

FRONT WHEEL BRAKE.

INTERNAL EXPANDING
BRAKE.

Brake, Hub — A brake which acts upon a drum secured to
one of the wheels, the drum being usually an integral part of
the wheel hub and frequently bolted through the spokes. Such
brakes are employed in pairs; in ordinary practice one on each
rear wheel hub, both being simultaneously actuated by means of
a single pedal or lever and a suitable connecting linkage.

Brake, Internal Expanding — A brake which consists of a
drum secured to a wheel hub or upon a transmission shaft
against the inside periphery of which
can be applied a band or a pair of
shoes that are anchored to a fixed por-
tion of the car. The band or shoes
are expanded into friqtional contact
with the inside of the drum by means
of a toggle, cam, wedge or- other equiv-
alent mechanism.

Brake, Metal to Metal— A brake
in which a metal band or metal shoes
act against a metal drum, the metals
being chosen so as to possess a high

A, Drum; B, Shoe; C, f fictional effect and a low degree of
Spider; D, Brake Spring; L, , , • • ^M • r

Pull Rod; F, Cam. mutual abrasive action. Oil is often

used between the frictional surfaces.

Brake, Motor — A form of brake used upon electric vehicles,
which acts upon a drum carried upon the armature shaft of
the motor.

Brake, Prony — A form of absorption dynamometer (see
dynamometer), used in determining the output of motors, con-
sisting of a brake band or a
series of brake shoes clamped,
with adjustable pressure,
upon the face of the motor
flywheel and a counterbal-
anced arm of known effective
length, upon which weights
can be hung. When the PRONY BRAKE.

motor is in operation weights

are added to the arm until the moment of friction exerted by the
brake exactly balances the torque (q. v.) developed by the motor
and the horse power delivered is computed by the formula H. P.
= 0.0001904 LWS; where L is the effective length of the arm in

40

feet, W the weight acting on the arm in pounds, and ^ the speed
of the motor in revolutions per minute.

Syn: Friction dynamometer. See horse power, brake.

Brake, Ratchet Retained — A brake, the operating lever or
pedal of which is provided with means for locking it in any
position in which it is set, so that the brake may be left in a
more or less applied condition (especially when the car is left
standing).

Brake, Service — The brake, or simultaneously operated pair
of brakes, which is adapted to be used in the slowing down
and stopping of a car in ordinary driving. The term is used in
contradistinction to "emergency brake." The service brake is
usually a pedal brake, operated by the driver's right foot.

Brake, Transmission— A brake which acts not upon a wheel
hub drum, but upon a drum secured upon a transmission shaft,
which is in motion so long as the car is moving. The effect of
such a brake is transmitted to the driving wheels and the road
through the intervening transmission mechanism. In practice
the transmission brake of a shaft driven car is applied to a drum
carried by the driving shaft, located inside of or outside of
the gear box. In a double chain driven car, a pair of simultane-
ously operated brakes act upon drums, usually applied to the
two front sprockets.

Brake, Water Cooled — A brake through channels in the shoe
or drum of which water is passed from a tank carried upon the
car, to prevent the parts from overheating under very severe
service.

Brake Anchor — That part of a brake mechanism which acts
to prevent the rotation of the band or shoes when they are
forced into contact with the rotating drum. The anchor is a
rigid support usually fastened at one end to the axle casing (in
the case of a wheel brake), and at the other to the operative
portion of the brake.

Brake Band — A more or less flexible band, anchored at its
ends to fixed supports and adapted to be contracted upon the
external surface or expanded against the internal surface
of a brake drum, so as to tend to prevent by friction
the rotation of the drum. Such a band may- have a
metallic frictional surface, or it may be faced with fibre or
special fabric.

41

Brake Beam — An equalizer bar. (See brake equalizer.)

Brake Cable — A flexible wire cable, sometimes used to
transmit the pull exerted at a brake lever or pedal to the
mechanism at the brake itself that forces the band or shoes
against the brake drum.

Brake Cam — A cam, forming a part of a brake mechanism,
which acts to force the band or the shoes into frictional en-
gagement with the drum.

Brake Drum — A hollow cylindrical metal part, secured axial-
ly upon a transmission shaft or upon the wheel hub of a car,
adapted to be frictionally engaged by a band or by shoes con-
tracting upon its outside cylindrical surface or expanding
against its internal surface.

Brake Equalizer — A device which is applied to brakes that
are simultaneously operated in pairs from a single lever or
pedal (hub brakes, for in-
stance). Its function is to (^ ^)

insure that each brake of n ^ ^V*"6 rr

the pair shall, under all '
conditions, be applied with
equal force, so that one
wheel may not be braked
more violently than the
other. A common form
consists of a freely support-
ed horizontal lever, to the C
centre of which is attached BRAKE EQUALIZER.
the pull rod from the oper-
ating lever or pedal, and to A, Equalizer Bar; B B, Brakes.
the ends of which are at-
tached the pull rods, which act respectively upon the two
brakes.

Brake Horse Power — See horse power, brake.

Brake Housing — The casing which encloses the mechanism
of a brake, thus protecting it from water and road dirt, and
permitting of its effective lubrication. The housing is usually
a thin casting or metal stamping attached to the axle casing
(in the case of hub brakes), and closing the opening of the
brake drum.

Brake Latch — That portion of a brake that is capable of
being locked in position, which engages with a ratchet and
holds the brake lever or pedal set in the
desired position. It consists of a thumb or
'toe piece, connected with which is a spring
actuated linkage acting to hold the detent
in engagement. Syn. : Brake detent

Brake Lever — The operating lever by
which a brake or pair of brakes is applied.

Brake Lining — A thin strip of material
riveted to the working surface of a brake
band or shoe, which forms the actual fric-
tional surface that bears upon the drum,
^ome flexible material, capable of resisting
abrasion and heat and possessing a high co-
efficient of friction with the metal of the
drum, such as vulcanized fibre, belting or a
special non-combustible fabric consisting of
asbestos fibre woven on metal gauze, is
generally used.

Brake Linkage — The mechanism which transmits the motion
of a brake operating lever or pedal to the brake shoes or band.
Syn. : Brake rigging.

Brake Pedal — The operating foot lever or
pedal which actuates a brake or pair of
brakes.

Brake Pull Rod — The rod or rods which
transmit the pull set up at a brake operating
lever or pedal to the mechanism at the brake
itself which applies the band or shoes.

Brake Quadrant — The fixed sector shaped
guide within which moves the operating lever

A, Brake Latch;
B, Brake Lever
Handle; C, • Brake
Quadrant.

BRAKE PEDAL

A, Pull Rod; B, (Or pedal) of a brake and on which the
Chassis rrame. , , . , .

locking ratchet is usually mounted.

Brake Shoe — A block, more or less segmental in form, anchor-
ed to a stationary part of the car mechanism, which is adapted
to be forced agairst a revolving brake drum to retard vehicle
motion. Brake shoes are usually operated in pairs, through a
toggle, cam or wedge action and are generally of metal. They
are used chiefly in internal expansion brakes.

43

Brake Spider — The support for the band or shoe and for
the operating mechanism of a brake, generally consisting of a
hub secured to the axle casing within or adjacent to the brake
drum, provided with several arms arranged to give rigid support
to the various operative parts.

Brake Spring — A spring which acts in opposition to the
force which applies a brake and removes the band or shoes
from contact with the drum when the operating pedal or levei
is released. Generally a spiral spring.

Brake Test — Sec dynamometer test.

Brake Toggle — A linkage somewhat of the toggle joint typo,
used in a brake to multiply the force exerted by the pull rod
so that a very heavy pressure shall
result between the band and the
drum when the brake is applied.

Braking With the Motor—
The employment of the resistance
offered by a vehicle motor, when it BRAKE TOGGLE.

is not rotating under its own power,

but being rotated by the kinetic energy stored in a moving car, to
reduce the vehicle speed. The resistance offered is due to the
friction of the motor and to the irrecoverable work done by
the motor pistons upon the gases in the cylinders. Ordinarily,
braking by the motor is accomplished by interrupting its ignition
and retaining the clutch in engagement, the lower the gear which
is in use the greater the braking effect obtained. Some motors
are fitted with special intake and exhaust cams, the use of which
temporarily converts a four cycle motor into a two stroke cycle
air compressor with variable compression, thus increasing the
braking effect, a valve being provided for shutting off the carbure-
tor and admitting air only to the cylinders, with resulting econ-
omy in fuel.

Braking Surface — The actual surface of contact between a
brake drum and the band or shoes which are applied to it;
c. g., if a brake drum is 12 inches in external diameter and the
width of the band which contracts upon it is 2 inches, the braking
surface will be I27j-x2 = 75 square inches, assuming that the band
completely encircles the drum.

Brass — The fixed bronze or composition lining of a bearing
support which forms the actual surface upon which the supported
shaft rotates or slides. A bearing bushing (q. v.).

44

Braze, v. — To join by brazing, which process consists of
closely abutting the cleaned edges of the parts to be joined,
heating them intensely, usually by means of a blast lamp flame,
freeing the abutted surfaces of oxide by means of a suitable
flux (usually borax), and melting into the junction a special
brass or spelter, usually furnished in a granular form, or in that of
wire. The spelter unites with the surfaces of the parts and forms a
joint of considerable strength. The process was formerly largely
used for uniting parts to the steel tubing used for axles.

Breather — A vent tube introduced into the
enclosed crank case of a gasoline engine
to permit of the equalization of the
air pressure therein, which would otherwise
fluctuate considerably with varying positions
of the pistons, absorbing some energy and per-
haps interfering with lubrication. The breather
rises vertically from the crank case, and its
open upper end is usually provided with baffle
plates to prevent the escape through it of lubri-

BREATHER PIPE.

eating oil from the crank case. It is often used as a filler tube.

Breech Block Joint — A special form of threaded joint, some-
times applied to parts that require to be screwed into or onto
each other quickly. Four segmental
portions of both the male and female
thread are cut away so that the pieces
may be slid into their final engaged
positions, one upon the other, by
matching the cut away portion with
the uncut portion of the other and
then rotating one relatively to the
other through one-eighth turn, which
brings all the threads in engage-
ment and locks the parts securely
together.

Bronze— A reddish alloy, of variable BREECH BLOCK.

composition, used for bearing bushings A, Sectional view in po?i-
/„ i i • , >. , tion about to be locked; 1>,

(,see bushing bronze) and minor struc- Bottom view in locked posi-

tural parts, differing from ordinary tion-

brass in its large copper and tin and low zinc content. The
following may be taken as an average bronze specification:
Copper, 84.0 per cent. ; tin, 12.0 per cent; zinc, 3.0 per cent, and

45

lead, i.o per cent. The term bronze is frequently applied to any
red brass, a typical specification for which is : copper, 85.0 per
cent. ; tin, 5.0 per cent. ; zinc, 5.0 per cent. ; lead, 5.0 per cent.

Brush, Contact — A conducting part used to complete the
electrical circuit between a stationary and a moving element of
an electrical device. Brushes are used to convey the current
between the windings of the rotating armatures of magnetos,
dynamos and electric motors, and the stationary portions of
such machines, and for making connection between the rotating
and non-rotating portions of timers and distributors. Brushes
are usually made of wear-resisting metal or of copper-plated
carbon.

Brush Holder — A device adapted to hold one end of a
brush securely but somewhat flexibly in contact with a mov-
ing element of an electric circuit, and supplied
with a binding post or other means by which
a relatively fixed portion of the external cir-
cuit is connected to it and thus to the brush.
In ignition practice it is usually a fixed brass
tube, in which a cylindrical carbon or metal
gauze brush is closely fitted, but capable of slid-
ing therein, under the influence of a spiral spring,
so that wear between the end of the brush and
the rotating part may automatically be taken
up and a reliable contact be secured.

Brush Spring — A spring employed to press
a brush holder into positive contact with the
moving element with which it is to maintain electrical con-
nection.

Buckling — The bending or deformation of a plate of a storage
cell, generally caused by the discharge of current through it at
an excessive rate or by its over-discharge. Under these conditions
the active material in the interstices of the grid swells ard
shrinks excessively, and this causes the buckling of the grid.

A permanent set or deformation produced by excessive pres-
sure, in frames, boiler tubes, headers or in any other plate, tube
or member.

Build Up (v.) — To attain a magnetic condition under the
influence of an electric current. A small but appreciable period

BRUSH
HOLDER.

46

of time elapses between the commencement of flow of an electric
current through the winding of an electromagnet and the attain-
ment of full magnetism by its core. In the case of spark coils,
for instance, current must be allowed to flow through the primary
winding for an adequate length of time before each ignition is
called for, or otherwise a full discharge will not take place in
the sparking circuit and only a weak spark occur, because of the
failure of the magnetism fully to build up in the time of con-
tact allowed.

Bumper — An elastic member, placed between two members
which may strike one another when in action, in order to cushion
the resulting shock when this occurs.
A metal spring or a properly shaped
piece of rubber, leather or similar
material is generally used, it being
fastened to one of the parts so as to
be interposed between the two.

Syn. : Buffer.

Bumper, Collision — A strong
horizontal bar, carried crosswise of
and at a little distance from the
front or rear end of a car, which is
guided so as to be capable of a
limited movement along the car's
axis of length, and which is kept
pressed away from the car by heavy
springs. In event of collision be-
tween the car and another vehicle
or fixed object, the energy of the
collision is partly absorbed in com-
pressing the springs and the lia-
bility of breakage of car parts is re-
duced.

BUMPER.

BUMPER, COLLISION.

Burn Out (v.) — To destroy the conductivity of or to break
down the insulation of a conductive portion of an electrical de-
vice by an accidental electrical discharge, or by the accidental
application of excessive electrical heat. As applied to coils used
in ignition, a burnout usually results from a puncturing of the
insulation and a consequent short circuit or from the passage

4?

of an excessive current, which either melts off the conductors, or
melts, or chars the insulation, resulting in a breakdown and short
circuit.

To loosen the tube ends from the sheets of a steam boiler
by the application of a fire to it when it is insufficiently supplied
with water.

Burner — The device which produces the gas fire for heating
the boiler of a steam car. It consists of a means for vaporizing
the pressure fed liquid fuel, of mixing the fuel vapor with air
and of distributing the flame produced over the exposed area of
the boiler.

Burner Casing — A metal housing surrounding the burner
of a steam vehicle and the space between it and the boiler,
confining the heat to its proper channels and protecting the
flame against air currents.

Burner Jet — The jet of a steam vehicle burner, through which
the liquid fuel is sprayed, under pressure, in a finely divided
condition, previous to its mingling with air to form a perfectly
combustible mixture.

Burner Plate — A perforated metal plate, placed under the
boiler of a steam car, through which the combustible mixture
rises and burns in a multiplicity of flames.

Burner Valve — A valve usually of the needle type, inserted
in the fuel feed pipe and used to regulate the flow of liquid
fuel to the burner jet of a steam vehicle. Such a valve may
be manually operated or under the control of an automatic fire
regulator (q. v.).

Bushing, Bearing — A lining, fixed in a bearing support and
in which a rod or shaft slides or rotates. It is usually made of
'anti-friction metal and is generally capable of renewal or ad-
justment after wear has taken place, so that looseness between
the rod or shaft and its support may be corrected.-

Syn. : Bush.

Bushing, Babbitt — A bushing made of babbitt metal, which
may either be cast on the shaft in the bearing support, and
scraped to fit the shaft, or which may be cast separately and
applied to the bearing support and shaft, or cast in a bronze
liner which is applied to the bearing support.

Bushing, Bronze — A bearing bushing made of bronze, which
metal, if of proper quality, possesses a high degree of wear

48

resisting and anti-friction qualities, when used to carry steel
shafts.

Bushing, Composite — A bushing, the bearing surface of
which is composed of alternate segments of a soft and of a
harder anti-frictio.n metal, usually babbitt and bronze.

Bushing, Compressed — A bushing the metal of which has
been rendered dense and wear resisting by compression, usually
by hammering of its surface.

Bushing, Die Cast — A babbitt bushing, the metal of which
has been rendered dense, hard and smooth by casting it under
pressure in a die or mold. A very fine finish is thus attained and
the bushings thus produced are interchangeable.

Bushing, Insulating — A lining or thimble of insulating ma-
terial threaded over an electrical conductor and fixed in a sup-
port through which the conductor is to pass, so that leakage
of current from the conductor to its support may be prevented.

Bushing, Split — A bushing which, instead of being a com-
plete hollow cylinder, is longitudinally split into halves. This
construction allows of ready removal of the shaft and of some
adjustment for wear of the bushing by filing away the abutting
edges of the bushing halves, or by the removal of shims (q. v.)
which have been placed between the edges so as to keep them
slightly separated.

Butterfly Nut — A form of thumb-nut in-
tended to be turned without a wrench, hav-
ing two wing-like projections formed in-
tegrally with the threaded centre, convenient
to be grasped by the fingers.
Syn. : Wing nut.

Butterfly Valve — A form of valve applied
to a pipe, consisting of a circular damper
capable of nearly or quite filling the
pipe bore and a spindle secured to a
diameter of the damper, which passes
diametrically through the walls of the
pipe and bears therein. A common
form for throttle valves and carbure-
tor air valves.

By=Pass — An alternative path for a
fluid which is being circulated in a
system, used as a means of regulating

BUTTERFLY NUT.

BUTTERFLY VALVE.

43

and directing the flow, e. g., in a pumping system supplying
water to a boiler, there is inserted in the pump delivery pipe,
between the pump and the boiler, a pipe which leads back to the
suction side of the pump. This pipe can be entirely closed, in
which case all the water pumped flows to the boiler, or it can
be partly or fully opened. If the by-pass is partly closed, a
portion of the water will go to the boiler and the remainder will
pass back to the pump through it. Used on steam cars and in
pressure lubricating, and fuel supply systems, in which a pump
is operated continuously.

By=Pass Valve — A valve inserted in a by-pass to regulate
the degree of obstruction to flow there existing and thus to
regulate the rate of. supply of fluid from a constantly operated
pump to some point in the system.

Calcium Carbide — A compound (CaC2) produced by the
reaction of carbon and quicklime in the electric furnace. It
is the source of acetylene gas (C2H2), when water is applied
to it, according to the reaction CaC2 + H2O = C2H2 + Ca O (quick-
lime). The quicklime is hydrated into whitewash by the ex-
cess of water.

Calcium Chloride — A salt (CaCl2) a neutral aqueous solu-
tion of which is sometimes used as an anti-freeze mixture,
if the solution used contains sufficient of the salt to make its
specific gravity 1.22 it will freeze at 'about — 15 degrees Fahr.
Its boiling point is higher than that of water and, when its
volume is reduced by evaporation, pure water only need be
added.

Cam — A mechanism employed to transform rotary into re-
ciprocating motion. As applied, to automobile valve mechanisms,
the cam consists of an irregular cylinder eccentrically fastened
upon a shaft which rotates it. The cam is so shaped that the
distance from the shaft axis to the cylindrical cam surface
along different radii varies in a predetermined manner. Pressed
upon the cam surface by means of a spring or gravity, is a
movable, guided part (the cam follower), which as the cam
rotates is reciprocated. The full stroke of the follower is equal
to the difference in length of the longest and shortest radii
of the cam and the rate and direction of the reciprocation at any
point in the rotation is proportional to the rate and direction
of change of the cam radii at that particular angular position.

Cam, Exhaust Valve — A cam, fixed to a shaft rotating at
one-half engine speed, which acts to open and close an exhaust
valve of a four cycle engine cylinder.

Cam, Ignition — A cam which acts to operate ignition mechan-
ism, for instance, to actuate the make-and-break device of a
contact spark igniter. Such a cam is rotated at one-half engine
speed in the case of a four cycle motor and at full engine
speed in that of a two cycle motor. Used in timers to operate
the primary circuit controlling contacts and in magnetos to
operate the make and break mechanism included in the primary
circuit of the armature.

Cam, Inlet Valve — A cam which acts to open and close
an inlet valve. In a four cycle motor it is fixed to a shaft
rotating at one-half engine speed.

Cam, Integral — A cam which is formed integrally with its
shaft and not made separately and pinned, keyed or screwed
upon the shaft.

Cam, Spiral — A cam the elements of the .working surface
of which instead of being straight lines are helices. It may
be imagined to be formed by uniformly twisting an ordinary
cam around its axis, through a small angle. All cross sections
of such a cam are identical, but each one is somewhat dis-
placed angularly with respect to its neighbor. The follower is
adjustable so as to be actuated at will by any cross section of
the cam and thus the reciprocating motion produced can be
made to vary in its time relation to the rotary motion.
Used to advance and retard ignition.

Cam, Uniform Acceleration* — A form of cam sometimes
used for operating motor valves, the profile of which is such
that, upon both the outward and inward strokes, the motion
of the follower is first uniformly accelerated and then uniformly
decelerated, so that the follower starts and stops gently. A
reduction in the liability of the follower to jump from the cam
surface at high speed, and a consequent reduction in noise as
well as the attainment of a satisfactory speed and duration of
opening are secured by this design.

Cam Profile — The section of a cam taken in a plane at right
angles to the cam shaft and passing through the point of con-
tact of the follower.

51

CAM AND CAM FOLLOWER.

A, Cam; B, Cam Follower; C,
Push Rod; D, Push Rod Guide,

Cam Follower— The mechanical element which is held in
contact with the working surface of a cam, obtaining a re-
ciprocating movement from the
cam's rotary movement and trans-
mitting the same to other me-
chanical parts. A valve cam fol-
lower is usually a roller, or is
mushroom or V shaped, and
affixed to the end of the push
rod. (q. v.).

Cam Lever — A single armed
lever, pivoted at one end, the
free end of which is interposed
between a cam (q. v.) and the end

of its push rod (q. v.) in a gas motor poppet valve (q. v.)
gear to reduce the side thrust otherwise exerted by the push
rod in the push rod guide (q. v.) occasioned by the cam action.
The cam acts upon one specially formed face of the cam lever
end, the other specially shaped face of the cam lever end acts
nearly axially upon the end of the pushrod, nearly all the side
thrust exerted by . the cam being resisted by the pivot of the
cam lever.

Cam Shaft — The shaft upon which a cam is fixed and by
which it is rotated. The cam may be pinned, keyed or screwed
upon the shaft in the direction opposite to its rotation, or it
may be formed integrally with the shaft. If the cam shaft is
supported in ball bearings it is known as a ball bearing cam
shaft.

Cam Shaft, Enclosed — A cam shaft which is housed to pro-
tect it from dust and to insure its continuous lubrication. In

CAM SHAFT AND CAM SHAFT GEAR.

practice, inlet and exhaust cam shafts are located within the
enclosed engine crank case or in a compartment of the same
upon their respective sides of the motor.

Cam Shaft, Exhaust — The shaft that carries the cams which
operate the exhaust valves. In a four cycle motor this is a
sha.ft rotated at one-half the speed of the crank shaft and posi-
tively driven therefrom. This shaft is supported parallel to the
crank shaft in suitable bearings and located in such relation to
the exhaust valves that they may readily be operated by it.

In motors with cylinders (q. v.) of L type both exhaust and
inlet valve cams are mounted upon the same shaft. '

Cam Shaft, Inlet — The shaft which carries the cams which
operate the inlet valves. In a four cycle motor this is a shaft
rotated at one-half the speed of the crank shaft, and positively
driven therefrom, The shaft is supported parallel to the crank
shaft in suitable bearings and located in such relation to the inlet
valves that they may readily be operated from it.

Cam Shaft, Offset — A cam shaft so positioned with respect
to its cam followers that the axes of the latter (extended) do
not intersect the cam shaft axis, but fall
upon the advancing side of the shaft. Side
pressure of the followers in their guides and
the resultant wear, due to cam action on the
outstroke, are reduced by this construction.

Cam Shaft, Overhead— A cam shaft
adapted to the operation of valves located in
the cylinder heads of a motor. It is usually
supported just above the cylinder heads in
bearings attached thereto, being driven from
the crank shaft by means of a vertical shaft
and two pairs of bevel or helical gears or by
means of a chain and sprocket arrangement.
Cam Shaft Gears — The gears which drive
a cam shaft from the crank shaft of a four
cycle motor. A spur gear fast to the crank
shaft meshes .with a corresponding spur gear,
having twige as many teeth, fast upon the
cam shaft. The two gears may not mesh directly, but through
an interposed idle gear. Gears with helical teeth and of non-
resonant materials are used to reduce noise and the gears are
generally housed in an extension of the crank case for pro-
tection.

Syn. : Half time gears, distribution gears, front gears.

OFFSET
CAM SHAFT.

53

Capacity, Electrostatic — A term used in connection with
a condenser, such as forms a part of a magneto or jump-spark
coil, to denote the quantity of electricity which such a condenser
contains when charged by a unit electromotive force. The unit
of capacity is the microfarad = id IS absolute units of capacity.

Capacity (of Accumulator) — A term used in rating storage
cells, representing the amount of electricity which may be ex-
pected to be obtained upon the discharge of such cell from a
fully charged condition. It is expressed in ampere hours, e. g.,
a 60 ampere hour cell may be expected to deliver a current of
one ampere for sixty hours, or a current of 5 amperes for twelve
hours.

Cap Screw — A screw to be used in fastening a bearing cap
to its bracket or stand. In general, a machine screw with a
head adapted to be turned by a wrench.

Carbon Deposit — A deposit which forms upon the piston
heads and the internal parts of gasoline engine cylinders which
are exposed to the combustion. It is composed of more or
less hard and adherent carbonaceous materials, deposited from
the lubricating oil and from overrich fuel mixture and of dust
drawn in through the carburetor.

Carbonization — The collection of carbon deposits, as above,
resulting in the reduction of the clearance space and a consequent
increase in compression pressure ; in the retardation of the escape
of heat through the cylinder and the heating of the carbon
deposit to a point at which it causes pre-ignition (q. v.) and
knocking (q. v.) with a. consequent reduction of motor output.

Carburation — The process of charging air with such a propor-
tion of the vapor of a combustible liquid that the resulting
vaporous mixture becomes suitable for fuel in an internal com-
bustion engine.

Carburetor — A device for carbureting air, the delivery ori-
fice of which is piped to the inlet ports of the cylinders of an
internal combustion engine and which is the agency by which
vaporous fuel is prepared as required for use by the engine.
It is essentially a means by which a current of air, usually
drawn through the device by the suction of the engine itself,
is brought into intimate contact with a properly proportioned
supply of liquid fuel (usually gasoline) supplied from a storage
tank. The liquid fuel is exposed to the air current in such a

54

manner that the latter becomes impregnated with fuel vapor
to such an extent as to become properly combustible.
Syn. : Vaporizer.

Carburetor, Atomizing — A carburetor in which the liquid
fuel supplied thereto is broken up into a very fine mist or spray
by being ejected, under pressure, through one or more very
fine, specially formed orifices contained in a fuel standpipe, which
is located in the midst of the current of air passing through the
carburetor to the engine. The atomized condition of the liquid
exposes a very large surface of it to the moving air and its
thorough evaporation is facilitated thereby.
Syns: Spraying carburetor; jet carburetor.
Carburetor, Automatic — A carburetor so arranged that its
air supply or both its air and gasoline supplies are automatically
so regulated as to cause the propor-
tion of gasoline and air in the mix-
ture to be constant irrespective of
the rate at which the motor is draw-
ing gas through the carburetor.
Non-automatic spraying carburetors
tend to produce mixtures too rich
in gasoline when the demand for gas
is high, which tendency the auto-
matic carburetor in a measure cor-
rects. An ordinary automatic car-
buretor has a main air inlet below
the spray nozzle and an auxiliary
air inlet above or beyond the spray
nozzle, controlled by a suction actu-
ated valve, which admits air in pro-
portion to the strength of the suction, to mingle with the gaseous
charge formed by the air from the main air inlet and the gaso-
line from the nozzle.

Carburetor, Constant Uevel — A carburetor, the level of the
gasoline in which is automatically maintained at a constant height,
irrespective of the demand therefor, usually by means of a float,
which rises and falls with the gasoline within the carburetor and
closes and opens a valve shutting off or admitting the supply
from the gasoline tank, as occasion demands. Nearly all car-
buretors are of the constant level type, the gasoline level being
automatically maintained nearly as high as the spraying orifices

DIAGRAM OF AUTOMATIC
CARBURETOR.

A, Auxiliary Air Valve; B,
Main Air Inlet; C, Throttle
Valve; D, Gasoline Inlet.

55

in the standpipe, so that gasoline flows therethrough whenever
any rarefaction exists around the spraying orifices.
Syn. : Float feed carburetor.

Carburetor, Exhaust Jacketed — A carburetor, the vaporiz-
ing passage or mixing chamber of which is enveloped by a jacket
through which circulates hot gas derived from the exhaust of the
motor. The hot gases keep the vaporizing passage warm and
assist in furnishing the heat necessary to evaporate the liquid
fuel which is passing through them in the form of spray.

Carburetor, Mechanical — A form of carburetor, usually
of the float feed spraying type, in which it is sought to maintain

uniform mixture quality at all
rates of supply, by mechanically
controlling the air supply or both
the air and gasoline supplies in
accordance with the movement of
the throttle. A mechanical con-
nection is provided between the
throttle and the air admitting
valve so that they open and close
at the same time, or there may
be provided a mechanical connec-
tion between the gasoline jet valve
and the throttle so that the two
open and close somewhat at the

same time. Both of these ex-
A, T e Valve; B, Aux liary pedients may be applied in com_

bination.

The term is used in contra-
distinction to "automatic carburetor" in which uniformity of
mixture is attained by actions caused by the fluctuations of
pressure within the carburetor.

Carburetor, Multiple Jet — A
carburetor of the constant level,
atomizing type, in which more than
one spraying jet is employed (gen-
erally two), One jet is constantly
open and exposed to the suction of
the incoming air and suffices to
furnish the gasoline required properly
to carburate the air entering at small DOUBLE JET CARBURETOR.

MECHANICAL CARBURETOR.

Air Valve; C, Spray Nozzle;
D, Air Inlet.

56

and moderate gas demands. As the demand becomes greater
the second jet, and finally the third jet (if any), is opened by
means of a mechanical connection with the throttle, and addi-
tional gasoline sufficient in amount to carburate the progressively
larger amount of entering air is sprayed through the additional
jets. Carburetors of this type possess high flexibility and usually
offer a low resistance to the incoming air.

Carburetor, Puddle Type — A float feed spraying carburetor,
(see carburetor, constant level and carburetor, atomizing) in
the bottom of the mixing chamber (q. v.), of which is main-
tained, by a suitable adjustment
of the fuel level (q. v.), a shallow
pool of gasoline, so located that
the entering air passes over it
at high velocity. Under condi-
tions of low gas demand (nearly
closed throttle), when the action
of the carburetor spraying nozzle
(q. v.) is weak, on account of
the low vacuum acting upon it ;
sufficient fuel is taken up by the
air from the puddle, by surface
evaporation, to insure a properly

rich mixture. At larger gas demands, the fuel is principally
supplied through the spraying nozzle.

Carburetor, Simple — A carburetor having no special pro-
visions for securing uniformity of mixture quality at different
rates of gas demand. A means for hand regulation of mixture
quality is usually provided.

Syns. : Non-automatic carburetor; non-compensating carbure-
tor.

Carburetor, Surface — A carburetor of the non-spraying type
in which the entering air is caused to take up the requisite
quantity of gasoline by being passed over large exposed evaporat-
ing surfaces kept moistened with gasoline and usually kept warm
by heat derived from the motor. This type is practically obso-
lete, as it is not adapted to the use of the heavy grades of gaso-
line in present use.

Carburetor, Strangling Tube — A form of automatic car-
buretor in which the spraying jet is surrounded by a freely

PUDDLE TYPE CARBURETOR.

57

STRANGLING TUBE
CARBURETOR.

A, Strangling
Tube.

guided tube or cage, which re-
stricts the air passages, and in-
creases the speed of the air
around the jet. The tube or cage
is capable of rising progressively
from its seated position, under
the influence of the upward air
pressure upon it due to increas-
ing suction at large gas demands
and, in so doing, progressively in-
creases the amount of air ad-
mitted as required to maintain
a uniform mixture quality, by in-
creasing the area of the air pas-
sages.

A stationary tube which re-
stricts the air passage about a
spraying jet is sometimes called a
"strangling tube."

Carburetor, Vaporizing Tube — A type of carburetor in which
special means are provided for completely vaporizing the sprayed
fuel by heat applied to a vaporizing pas-
sage of extensive surface which generally
carries a very richly carbureted mixture.
The fuel bowl, spraying jet, and atomizing
chamber are joined to the throttle and aux-
iliary air intake by a long, vertical, thin
walled tube (the vaporizing tube), the en-
tire external surface of which is hot jack-
eted. The additional air required to pro-
duce a correct mixture is added at a point
above the vaporizing tube, near the intake
manifold.

Carburetor, Water=Jacketed— A car-
buretor, the vaporizing or mixing chamber
of which is wholly or partly surrounded
by a jacket through which is circulated
warm water obtained from the water cool-

\E

VAPORIZING TUBE
CARBURETOR.

ing system of the engine. The warm R,AV^orizingr Tube!

water furnishes heat to assist
evaporation of the liquid fuel.

the C> Water Jacket; D,
Auxiliary Air Valve;
E. Throttle.

Carburetor Banking Stop — An adjustable stop which limits
the degree of closing of the throttle valve and thus determines
the minimum rate of gas admission. It is usually a screw, against
the end of which a lug carried by the throttle valve makes con-
tact as the valve closes.

Carburetor By=pass — A passage of very small cross-section,
leading from the float chamber into the intake pipe (q. v.)
just beyond the throttle valve (q. v.), through which, when the
throttle is nearly or quite closed, gasoline is drawn directly into
the intake pipe, and a rich mixture is thus
produced for very slow speed running and
to facilitate the starting of the motor.

Carburetor Draw=off — A cock or re-
movable plug placed at the lowest point of
a carburetor float chamber, the opening
or removal of which permits the chamber
to empty itself of fuel and of any foreign CARBURETOR

matter which may be present. DRAW-OFF.

Syn. : Carburetor drain.

Carburetor Flange — The flange at the outlet of a carburetor
which is bolted to a similar flange formed upon the end of the
intake pipe.

Carburetor Float — A freely moving, buoyant part of a
carburetor, contained within the fuel bowl or float chamber,
the function of which is automatically to
maintain a constant fuel level therein, inde-
pendent of the rate of demand. It is
usually a thin walled, liquid tight cylinder,
annulus or sphere of copper, or a solid
piece of shellacked cork of the same form,
that floats in the fuel which partly fills the
bowl, rising and falling with the level of
the same. It operates, either directly or
through a suitable linkage, a valve (usu-
ally of the needle type) which controls

CARBURETOR FLOAT.

the admission of fuel from the supply tank,

the valve closing as the float rises and opening as it falls, an
approximately constant fuel level thus being maintained in the
bowl.

Carburetor Float Chamber— The chamber or bowl of a car-
buretor from which fuel is supplied through a passage or pas-
sages to the spraying nozzle or nozzles.

Syn : Fuel bowl.

Carburetor Float Depressor — A device arranged to de-
press a carburetor float below its natural level in the fuel and
thus cause the fuel valve to open and the
fuel level to rise above the spraying
nozzle.' This permits the fuel to escape
therethrough into the vaporizing chamber,
which facilitates the formation of the rich
mixture required in starting a motor.

FLOAT DEPRESSOR. Syn' : Carburetor Primer> carburetor
flooding device.

Carburetor Float Valve — The valve which admits fuel to the
float chamber of a carburetor and which is under the automatic
control of the carburetor float.

Carburetor Needle Valve — The valve which controls the rate
of flow of fuel to the spraying nozzle or jet of a carburetor. It is
usually an adjustable, taper seated needle valve in the passage
from the fuel bowl to the spraying nozzle.

Syn. : Carburetor gasoline adjustment.

Carburetor Spraying Nozzle — The aperture or apertures
through which liquid fuel is ejected in a more or less finely di-
vided state from the standpipe of a carburetor into a con-
tracted portion of the current of air within the vaporizing
chamber. The apertures are usually in the end or in the
wall of the standpipe and are so formed as to conduce to the
thorough atomization of the fuel.

Syn.: Carburetor jet.

Carburetor Standpipe — A vertical pipe which rises centrally
within the carburetor vaporizing chamber, usually terminating
at a contracted portion thereof, and which carries the spraying
orifice or orifices in its end or side walls.

Cardan Shaft — A shaft provided at one or at both ends with
a universal (Cardan) joint, so as to enable it to rotate freely
when in varying angular relations to another connected shaft or
to two other connected shafts, attached to its respective ends.

Syn. : Universally jointed shaft.

Caseharden (v.)— To harden iron or steel superficially, in
order to increase its wearing qualities by adding to the car-
bon content of the external layer of the metal. The part to be
casehardened is heated, sprinkled with powdered ferrocyanide of
potassium and then heated again, the carbon resulting from
the decomposition of the ferrocyanide, uniting with the outside
part of the metal, then it is quenched. Or the part to be
treated is packed in horn parings, to which a little common salt
has been added, heated for a time and quenched.

Castellated Nut — A form of lock nut which is secured from
turning after being tightened, by means of a pin passed through
a hole in the bolt and also secured in slots cut into the upper sur-
face of the nut, which slots are provided
entirely around the top of the nut.

Caulk (v.) — To make a tight joint be-
tween abutting metal parts by forcing
metal into the interstices between them
with a form of chisel, called a caulking
tool, and a hammer. The metal may be
CASTELLATED raised from the edges of the parts or
NUT. may be taken from a wire of softer metal.

Used in the production and repair of steam boilers.

•Cell, Dry — A primary or voltaic cell the electrolyte of which
is not a free liquid, but is absorbed in a porous material, placed
between the elements, so that the dange.r
of its spillage is avoided. The common
dry cell consists of a central rod of
corrugated carbon, placed in the axis of a
cylindrical cup of pure zinc. In internal
contact with the zinc cylinder is a layer of
absorbent material, such as blotting paper,
saturated with sal ammoniac solution-. The
annular space between the absorbent layer
and the carbon element is packed with a
mixture of pulverized Carbon, manganese
dioxide and sometimes other materials,
which is moistened with electrolyte. The
top of the cell between the elements is
sealed with insulating compound and the whole cell is slipped
into a paper carton. Binding posts are provided upon the zinc
and carbon elements. Used as a source of ignition current.

DRY CELL.

A, Carbon Rod; B,
Zinc Cup; C, Ab-
sorbent Paper; D,
Depolarizer.

61
Cell, Storage — See accumulator.

Cell, Voltaic or Primary — A cell which is the primary
source of electrical energy developed by the irreversible chemical
actions of the materials contained therein. The electrical energy
developed results from the combination of zinc with various acid
radicals. The term is used in contradistinction to "secondary
cell," which refers to a storage cell or accumulator which is
not a true source of electrical energy, but a device for accumu-
lating electrical energy developed elsewhere.

Centre of Gravity — In general, the point of application of
the resultant of the gravitational forces acting upon a freely sus-
pended body in equilibrium. The vertical distance of the centre
of gravity from a horizontal plane upon which the wheels of a
motor car are resting is the most important factor determining
its stability against overturning. t

Centre Control — The location of the control devices of an
automobile — the brake and gear shifting levers in a gasoline car —
at the centre of width of the front seat space, so that neither
the driver 'or front seat passenger need climb past them in
entering or leaving the car. In cars with left hand control (q. v.)
the levers are convenient to the operator's right hand.

Chain, Block — A form of chain used to transmit power from
one sprocket to another, consisting of a series of hardened steel
blocks joined by pairs of side pieces, which are secured together
through the ends of the blocks by hardened steel rivet pivots, en-
closing a sprocket tooth and preventing the chain from slipping
sidewise from the sprocket.

Chain, Detachable — A form of sprocket chain, the links of

which are so put together that
when the chain is removed
from the sprockets by the re-
moval of the master or fast-
ening link, the links may
readily be detached one from

DETACHABLE CHAIN. another without tools being

required.

ROLLER CHAIN.

62

Chain, Roller — A form of sprocket chain, in which the con-
tact of the links with the sprocket teeth is of a rolling rather

than of a sliding character, in
order to reduce wear upon
the parts. It consists of a
series of hardened steel rollers
which fit between adjacent
sprocket teeth and which turn
upon hardened steel pins that
also secure the rollers to the
side pieces which hold the

chain together, enclose the sprocket teeth and prevent the side-
wise slipping of the chain from the sprockets. As the chain meets
a sprocket tooth the roller which makes the contact is supposed
to rotate upon its pin and to prevent sliding friction between the
chain and the tooth.

Used for the final drive of most chain driven cars.

Chain, Silent — A form of chain adapted for use upon sprock-
ets, which possesses a very high transmission efficiency, op-
erates almost noiselessly, wears very slowly, and compensates for
such wear as takes place. The sprockets are of rather wide
face and resemble spur gears. The
chain is built up of a large number
of hardened sheet steel stampings,
each individual stamping being so
formed as to present two V shaped
teeth toward the sprocket face.

Adjacent links are jointed together flexibly, the stampings of
one link alternating with those of the next on the pivot pin.
In action the tooth driving faces of each link make direct con-
tact with the sprocket teeth, and as the chain moves on, leave
the sprocket without slippage on the points of contact. As the
chain stretches the points of link contact move outwardly on the
sprocket teeth, but the driving action is free from slip, unless
chain stretch becomes excessive. Used in the transmissions of
electric vehicles, for driving cam and auxiliary shafts and oc-
casionally as the final drive of gasoline cars.

Syn. : Link belt.

SILENT CHAIN.

Chain, Tire — See tire chain.

63

CHAIN AND SPROCKET.

Chain and Sprocket Gear — A method of rotating a shaft
from another parallel shaft at any desired speed ratio therewith.

Each shaft carries fixed upon
it a toothed wheel or sprocket,
the two being located in the
same plane, and a .flexible end-
less chain, composed of a
series of pivoted links, each
equal in length to the pitch of
the sprockets, runs upon the
sprocket teeth, thus maintain-
ing the two shafts in definite

but not absolutely inflexible driving relation. The ratio of the
rotative speed of the driven shaft to that of the driving shaft is
inversely as the ratio of the number of teeth in the driven
sprocket to the number of teeth in the driving sprocket.

Chain Case — A housing arranged to enclose a chain and
sprocket gear, adapted to exclude dust, retain lubricant and
deaden noise. When used in
connection with the driving
chains of motor cars it is usu-
ally a tight, sheet metal con-
struction conforming in shape
to the path of the chain, sup-
ported at its front end upon
the shaft of the driving
sprocket and at its rear end
upon the driving axle, means

being provided to permit free movement of the axle under spring
action and to allow of chain adjustments. .

Chain Drive, Double — That form of final drive in which power
transmission is effected by two chains each running from a sprocket
fixed upon one end of a horizontal, transverse, divided shaft
carried by. the vehicle frame to a corresponding sprocket at-
tached to one of the driving wheels.

Chain Drive, Single — That form of final drive in which
power transmission to the traction wheels is effected by means
of a single chain, running from a sprocket carried upon a hori-
zontal, transverse, engine-driven shaft, carried upon the vehicle
frame to a corresponding sprocket secured to the pinion frame
of the differential gear of a live driving axle.

CHAIN CASE.

64

Chain Oiler — An automatic journal oiling device consisting
of an oil reservoir formed in the bearing stand or bracket and
a short endless chain, threaded around the shaft, so arranged that
its lower portion dips in the oil in the reservoir. As the shaft
rotates, the chain is carried over it and distributes oil upon it.

Chain Tool — A special form of clamp adapted
to draw together and hold in position upon the
sprocket the ends of a chain, while they are being
secured together.

Chamfer (v.)— To bevel the engaging edges
of the teeth of sliding gears to a somewhat wedge
form so that they may readily enter the tooth
spaces of their mates.

Change Gears (v.) — In the operation of a
gasoline car, the act of altering the ratio of
the rotative speed of the motor to that of the
driving wheels, by the use of some form of CHAIN TCOL.
change speed gear, in order that a higher or a
lower vehicle speed may be attained, or that a
greater torque or driving effort at the traction wheels may be
realized.

Change Speed Gear — A mechanism, forming one of the trans-
mission elements of a gasoline vehicle, which permits the ratio
of the rotative speed of the driving wheels to that of the motor to
be varied at the will of the operator. It is employed so that a
wider range of driving effort and of speed at the traction wheels
may be obtained than can be secured by control of the motor
itself. The required changes of speed ratio are generally obtained
by the oise of combinations of spur gears (the sliding gear, indi-
vidual clutch system and the planetary gear, q. v.), or by some
type of variable friction drive device (q. v.)

The mechanism for producing backward motion, the reverse
gear, is generally a part of the change speed gear.

Syn. : Transmission (not the best usage).

Channel — A form of structural steel having a U shaped cross
section and used in the construction of vehicle frames and sub-
frames. This section is sometimes used in front axles and in
minor pressed steel parts.

65

/Pouin-

TiryafA

**

Characteristic Curve — A graphic representation of the re-
lation of torque (q. v.), speed and output of an internal com-
bustion motor, prepared by plotting on cross section paper re-
spectively, as abscissas
and ordinates, simulta-
, neous observations, cov-
ering the practicable
'$ speed range of the mo-
tor, of speed in revolu-
'* tions per minute and
§ torque in pounds-feet,
'£ and drawing a curve
\ through the points thus

plotted. An output
curve, the points of
which are obtained by
computation, is usually
drawn upon the same
plot with revolutions per
ptvoiut**, P.- Mn*i, minute as abscissae and

horse power as ordinates

CHARACTERISTIC CURVE. and a fuel consumption

curve is frequently

added, with the same horizontal scale and pounds of fuel per
horse power hour as ordinates. Such curves are usually plotted
from observations taken at full throttle opening with the most
advantageous ignition timing and thus represent maximum per-
formance.

Charge (v.) — To pass an electric current through an ac-
cumulator or storage cell, from an external source, in the di-
rection opposite to that in which the accumulator furnishes use-
ful current, in order to cause chemical changes, the reversal of
which, upon the subsequent discharge of the cell, results in the
useful return of a part of the electrical energy supplied.

Charge (n.) — The electrical energy supplied an accumulator,
to be later returned, in part, as useful work, during the process
of discharge.

Charge (n.) — The combustible fuel mixture which is con-
tained in the cylinder of an internal combustion motor, generally
a suitably proportioned mixture of gasoline vapor and air.

66

Charge, Freshening — A special charge given an accumulator
or storage cell the plates of which have become sulphated, for
the purpose of restoring it to normal condition. Such a chargf
is usually of long duration at such a low rate that the tempera-
ture of the electrolyte does not rise above ioo°F., and is usually
carried somewhat beyond the ordinary point of full charge.

Charge, Rate of — The volume of current, usually expressed
in amperes, which is employed in charging an accumulator.
The greater the capacity of the accumulator the higher the rate
of charge, and a higher rate is generally used at the beginning
than toward the end of a charge. The rate of charge is usually
that which will entirely charge an accumulator in from 4 to 8
hours. Charging rates of ignition accumulators range from 3
to 6 amperes, and those for pleasure vehicle batteries from 10
to 30 amperes.

Charge Ratio — The ratio of the weight of the charge actually
drawn into the cylinder of an internal combustion motor per
cycle, when operated at a known speed and full throttle opening
to the computed weight of the charge required to fill its piston
displacement at atmospheric pressure and normal air temparture.
This ratio is in practice always less than unity and approaches
unity in proportion as the intake resistance (q. v.) and the pre-
expansion (q. v.) are less.

Syn. : Volumetric efficiency.

Charging Plug — A plug, attached by a flexible conductor to

a source of continuous electric
current, adapted to be inserted
in a corresponding socket carried
upon an electric vehicle and thus
CHARGING PLUG. automatically to establish connec-

tion between a vehicle battery
and a charging source.

Charging Resistance — An adjustable resistance inserted into
the charging circuit of a storage battery to regulate the volume
of the charging current (rate of charge). Adding more resist-
ance to the circuit diminishes the charging current and vice
versa.

Charging Stroke — See aspirating stroke.

Chassis, (pronounced shassee) — A motor vehicle, complete as
to its essential mechanical parts, but without a body and certain
other parts which are generally carried in or on the body.

07

Chassis, Stripped — A chassis from which such parts as the
tires, fenders, running boards and all but the essential mechanical
parts have been removed.

The significance of these terms is not rigidly exact.
Chatter, v. — To produce a rapid, irregular vibration with ac-
companying noise. Applied to the action of a pair of meshed
gears, between the teeth of which backlash exists. Whenever one
of the pair changes from the condition of the driver to that of
the driven gear, or vice versa, their teeth strike together and
chattering results. In clutches, the surfaces sometimes spas-
modically engage and disengage a number of times before perma-
nent engagement takes place, with resulting chattering.

Chauffeur (pron. shofer) — The paid operator of a motor
vehicle; one who makes a business of driving motor vehicles
for money. (In France, where the term originated, it is used
in the sense of automobile owner.)

Check Valve — A valve designed automatically to permit the
passage of fluid in one direction and to prevent its passage in
the other. One form of check valve con-
sists of a pipe fitting enclosing an an-
nular seat upon which a valve ball is
lightly forced by a spring or by gravity.
Fluid pressure acting from under the
seat lifts the ball and forces a passage,
but pressure in the opposite direction
merely forces the ball more tightly upon
CHECK VALVE ^s seat- Used in the piping of steam

cars, in some' lubrication and fuel supply
systems on gasoline cars and in self-starters.
Syn. : Non-return valve.

Cheek — That portion of a crank shaft, which extends at an
angle with the axial or bearing portion of the shaft and con-
nects the same with a crank pin.
Syn. : Crank shaft web.

Choke, v. — In a gasoline engine, to miss explosions or to ex-
plode weakly on account of such an excess of fuel in the mix-
ture supplied the cylinders that it becomes imperfectly com-
bustible or actually non-inflammable.

Circuit, Closed — A system of electrical conductors forming
a completely closed path through which an electric current
can flow. Syn. : Complete circuit.

Circuit, Open — A system of electrical conductors which
does not form a completely closed path through which an
electric current can flow.

Syn. : Broken circuit ; incomplete circuit.

Circuit, Primary — In the case of two or more electrical
circuits, arranged in inductive relation, that one is the primary
circuit in which the electrical energy existing in the system
was originally developed, e. g., in a spark coil, the circuit in
which is included the battery, dynamos or magneto is the pri-
mary.

In apparatus designed to raise the electrical tension above
that of the original source, the number of turns of conductor
in the primary circuit is less than that in the secondary and
of correspondingly larger cross section.

Circuit, Secondary — In the case of two or more electrical
circuits, arranged in inductive relation, the circuit or circuits in
which the electrical energy manifested does not orginate, but
is produced by induction, are secondary circuits. In apparatus
designed to raise the electrical tension above that of the prime
source thereof, the number of turns of conductor in the sec-
ondary circuit is greater than that in the primary, and the con-
ductor used is of correspondingly smaller cross section.

Circuit Breaker — An automatic protective device intended
to break or open an electric circuit whenever certain predeter-
mined electrical conditions prevail, which may be deleterious
to the apparatus involved. In charging electric vehicle and
lighting accumulators a circuit breaker is sometimes so con-
nected as to act whenever the supply of charging current fails
or weakens and thus to prevent the battery from discharging
back into the charging source. It may also be arranged to act
whenever the voltage of the battery indicates that it is fully
charged or whenever the charging current becomes excessive.
Also a timer (q. v.) or a magneto make-and-break (q. v.).

Circulating Pump — A pump employed to keep in motion, in
a closed path, a body of liquid, generally water or oil. Such a
pump is usually driven by the vehicle motor, and the circuit
includes the pump, the apparatus through which the circulation
is to be maintained and the necessary connecting piping and
reservoir. (See water pump.)

Circulating System (of lubrication) — See lubrication, cir-
culating system.

Circulating System, Water— The cooling system of a water
cooled motor. See water cooling.

Circulation Gauge — A gauge used to indicate the liquid
pressure acting in a circulating system. The failure of such a
gauge to show a pressure denotes the cessation of action of
the circulating pump or that the liquid in the system is exhausted
or escaping.

Circulation Indicator — See sight feed.
Clash Gear — See sliding gears.

Clearance Space — The space in the
head end of a gas engine cylinder above
the piston head when the piston is in its
extreme upward or inward position, in-
cluding valve pockets and ports. The por-
tion of the cylinder volume not swept by
the piston. In this space the charge is
compressed and fired at or near the end
of the compression stroke. It is common
CLEARANCE SPACE, practice to make this space from 20 per cent,
to 40 per cent, of the volume swept by the
piston.

A, Clearance Space.

B, Piston.

Syn. ; Compression space ; combustion space.

Clearance, Gear — In setting meshed gears, the slight freedom
intentionally provided between the tooth faces, so that they may
not jam.

Loss of energy through friction, and noise are prevented by
the provision of clearance.

Clearance, Ground — The shortest perpendicular distance from
a plane upon which the wheels of a motor car are resting to
any part of the car. This distance is usually the perpendicular
distance from the lowest point of the front axle, of the rear
axle housing or the flywheel to the level ground upon which
the car is standing.

Clearance, Valve — A small amount of lost motion allowed at
some point or points between the cam follower and the valve
stem in the mechanism which operates a poppet valve of a gas
engine, in order to insure that the valve spring may always be
able to seat the valve even though the parts of the mechanism
may be expanded by heat.

Clevis — The forked end of a rod, or the part by which it is
connected in operative relation to some other part.

CLEVIS.

Clevis Pin — A pin which secures to-
gether a clevis and an attached part, the
pin passing through holes drilled in both
arms of the clevis fork and a correspond-
ing hole in the other part.

Climb (v.)— That action of a badly
fitted sprocket chain caused by the failure
of the links properly to fall into place between the sprocket
teeth. The links ride upon the teeth, making the path of the
chain longer than normal, tightening it excessively and some-
times causing its breakage, the breakage of sprocket teeth or the
springing of the sprocket shafts. The stretching of the chain,
through wear, so that its pitch is increased, is the chief cause of
this action.
Syn. : Ride.

Clockwise Rotation — Rotation in the same direction as that
of the hands of a clock.

Syn. : Right handed rotation.

Clutch, Cone— A clutch, the engaging
frictional surfaces of which are the sur-
faces of conical frusta. In the face of one
member, generally the driving member and
usually the motor flywheel itself, a con-
centric, conical recess is formed. The
periphery of the driven member is conical
and so shaped as exactly to fit into the
conical recess in the driving -member, and
is held in alignment therewith, the two
members being forced into engagement
axially by a spring and being drawn apart
by a mechanism usually operated by a
pedal. With conical surfaces, a high pres-
sure between the members can be secured
with a relatively low axial spring pressure.
The engaging surface of the driven mem-
ber is commonly faced with leather or
some fabric to secure a high coefficient
of friction.

Clutch (Friction) — A device adapted to connect in a gradual
manner and to disconnect the motor of an automobile to and from
the transmission mechanism through which the traction wheels

c,

CONE CLUTCH.

A, Flywheel;
Clutch Cone;
Clutch Spring; D,
Clutch Slip Spring;
F., m Spring Thrust
Bearing.

71

are driven, thus permitting the motor to be run freely without
moving the vehicle and providing for the vehicle's gradual
acceleration. It consists of a member or members fast upon
and rotated by the motor shaft and another member or set
of members fast upon and rotating with a shaft connected in
driving relationship to the driving wheels. These two members
or sets of members are in close juxtaposition and in alignment,
and are arranged to be forced one against the other, or to be
drawn apart by means of a suitable control mechanism. When
forced together, the friction developed between them tends to
cause the member rotated by the mo-
tor to rotate the other member at a
speed less than or equal to that of
the motor (depending upon the force
of friction acting) and to set in mo-
tion the driving mechanism and the
traction wheels.

Clutch, Contracting Band — A

clutch, the driving member of which
is a drum secured upon and rotating
with the driving shaft. The driven
member consists of a somewhat
flexible metal band, encircling the
driving drum and carried by a spider
fast upon the driven shaft. The band
is so arranged that it may be con-
tracted upon the drum by means of a toggle, cam or wedge
mechanism actuated by one or more springs and a linkage, and
loosened therefrom by pressure upon a pedal. When contracted,
the band and its attached mechanism rotate with the drum, under
the fractional forces acting. The band is usually lined with some
friction increasing material.

Clutch, Dry Plate — A clutch of the disc or plate type, the
engaging surfaces of which are not lubricated. (See clutch,
multiple disc.)

Clutch, Expanding — A clutch, the driving member of which
is a drum, fast upon the driving shaft. The driven member

CONTRACTING CLUTCH.

A, Contracting Band;
B, Clutch Drum; C,
Spider; D, D, Operating

Arms.

F, F, Operating Arms;

C, C, Rollers for Arms;

H, H, Operating Lever
Tips; J, Spring.

consists of a somewhat flexible metal
band carried upon a spider fast to the
driven shaft and capable of being
expanded against the inside, cylin-
drical surface of the drum by a
spring actuated cam, wedge or tog-
gle mechanism. The band may or
may not be lined with a fabric or
similar material. Instead of a con-
tinuous band, the driven member may

consist of a EXPANDING CLUTCH.
series of shoes -A'~ E*Pandi.ns -Ring-
which are
forced outward-
ly against the inside surface of the drum.
The flywheel itself may be utilized as the
drum.

Clutch, Floating Ring— A form of
plate clutch, consisting of one plate fast
upon the motor shaft (sometimes the fly-
wheel itself), another plate fast upon the
driven shaft, and between them a metal
ring which is fast to neither shaft. When
FLOATING RING tne driven plate is forced towards the driv-
CLUTCH. ^ jng plate, by spring action, the floating ring
B,A' Flywhetl;Rinc;, is caught between them and engagement
Driven Drum. ' takes place. The use of the floating ring

doubles the surface over which
friction is distributed. It is often
provided with cork inserts (q. v.)-
Syn. : Three plate clutch.
Clutch, Hele«Shaw— A form
of multiple disc clutch (q. v.) in
which the discs are thin rings al-
ternately of phosphor bronze and
mild steel. The rings are not flat,
but formed with a V-shaped cross
section. In action, the annular V of
one ring enters into and makes fric- HELE-SHAW CLUTCH.
tional contact with the A-shaped . A> Hele-Shaw Discs; B,

, , . Inner Drum; C, Outer

annular depression of the adjacent Drum; D, Flywheel; E, Cas-
ring. Named from its inventor. ggjtj; Driving Shaft; G>

73

Clutch, Jaw — A clutch, not of the frictional, but of the posi-
tive engagement type, consisting of two members which, when
brought together, lock in driving relationship by projections upon
one entering corresponding depressions in the other. A closely
related form of clutch (the gear type) consists of two members,
one a spur gear of coarse pitch and special tooth outline and the
other an internal gear of. such size and tooth form that the first
member speeds in constantly meshed (individual clutch) gearsets
and also in driving power air pumps from vehicle motor.

Clutch, Magnetic — A clutch, the surfaces of the driving and
driven members of which are held in engagement by magnetic
force induced by a coil carried by one of the members through
which an electric current can be passed at the will of the operator.

Clutch, Metal to Metal — A clutch, the engaging frictional
surfaces of which are of similar or dissimilar metals and not of
organic material. Such clutches generally require lubrication
and must possess rather large contact areas. Most multiple disc
and plate clutches and occasionally cone and expanding clutches
are of the metal to metal type.

Clutch, Multiple Disc — A clutch, the engaging members of
which consists of two alternated, closely juxtaposed sets of rather

numerous thin, annular discs of
metal or of metal fabric lined,
arranged concentric to and in a
plane at right angles to the shaft
axis. The discs of one set are
held from turning upon the driv-
ing shaft, and the discs of the
other set are held from turning
upon the driven shaft, but both sets
are free to move slightly along
the shaft axis. One or more
springs act to force the whole col-
lection of discs together, and as
the discs of the two sets alternate,

each disc of one set is thus
MULTIPLE Disc CLUTCH. pressed between two discs of. the

A, Discs; B, Compressing other set and engagement is there-
Member; C, Flywheel; D, , ... , A , ,
Driving Plug; E, Inner Drum; ^ effected. A releasing device,

0, Shaft. usually pedal operated, is pro-

74

vided to overcome the spring pressure and to allow the discs

of the two sets to separate and disengage. When metal discs are

used, the discs usually operate in an oil bath.

Clutch, Reversed Cone — A form of cone clutch in which the

conical engaging surfaces converge away from the motor instead
of toward it, as in the ordinary con-
struction. Engagement is thus effected
by moving the driven member away
from the motor instead of toward it.

Clutch, Slipping of (v.) — An action
sometimes intentionally caused by the
partial engagement of a clutch, char-
acterized by more or less relative mo-
tion between the two members. The
two members do not grip positively, but
slide more or less one upon the other.
It is necessary when a car is to be
gradually accelerated from rest, when a
car speed lower than that corresponding

REVERSED CONE CLUTCH, to the lowest motor speed is required

A, Flywheel; B, Male an(} when it is desired partially to re-
Cone; C, Bolted on ™~
male Cone.

Fe-

lieve the motor of a load too great for
it to carry. It accidentally occurs when

the clutch spring is too weak or when the co-efficient of friction
between the members is abnormally low.

Clutch Bearing (Radial) — The bearing upon which rotates
the driven member of a clutch when the clutch is not in positive
engagement. The driven member is usually held in alignment
with the motor shaft by being mounted upon an extension of the
same, and the clutch bearing is between the hollow shaft of the
driven member and the engine shaft extension.

Clutch Bearing (Thrust) — A bearing designed to take the axial
pressure of the clutch spring when the clutch members are separ-
ated in disengagement. This is usually a ball bearing of the end
thrust type interposed between the spring and the collar or spool
upon which the disengaging mechanism acts.

Clutch Brake — An automatic device designed to arrest the
rotation of the driven member of a clutch and its attached shaft
and gears, when disengagement has taken place, and thus to
render easier the meshing of another gear in changing speeds.

75

The disengaging movement of the driven member produces con-
tact between some part of it and a stationary brakeshoe, the
friction of which tends to bring the spinning member to rest.

Clutch Case — An enclosure placed about a clutch to exclude
dust and to retain lubricant.
Syn. : Clutch housing.

Clutch Collar — A collar or ring to which is applied the force
which acts against the clutch spring (q. v.) to disengage a
clutch. It is usually located in a circumferential groove formed
in the clutch spring housing, which is secured to the driven
clutch member and the disengaging motion is communicated to it
by the ends of the clutch throwout yoke (q. v.) which engage
with it. A ball thrust bearing is provided between the collar and
the flanges of the grooves to resist the spring pressure and upon
which the collar rotates when the clutch is disengaged.

Clutch Disengaging Spring — A small spring, one or more
of which are often placed between adjacent discs of a multiple
disc clutch in .order to insure their separation when the clutch
is thrown out. Such a spring may be simply a bent-out, resilient
portion of the disc itself. Used especially in oil immersed
clutches in which the viscosity of the lubricant is likely to pre-
vent the proper parting of the discs, even though the releasing
mechanism has been operated and thus to cause an objectionable
dragging of the clutch.

Clutch Interlock — A mechanical connection between a clutch

disengaging mechanism and
the operating device of a brake
or pair of brakes (usually the
lever brake), so arranged that
the application o'f this brake
automatically disengages the
clutch. The object is to pre-
vent brake application until the

,., T driving power has been cut off

CLUTCH INTERLOCK. ,. .

and to prevent the application

A, Brake Lever; B, Link Con- of the motive power, for the
necting to Cam; C, Cam; D, .

Lever Operating Clutch Fork; E, purpose of Starting the car

Clutch Fork. when the brakes are set

Clutch Lining — An application, usually of some non-metallic
material, made to one of the members of the clutch, so as to
form its actual engaging surface. Leather, fabric belting, vul-

76

canized fibre or special asbestos fabric is used, the material
being chosen as being superior to metal in one or more
of the following respects : As producing a higher co-efficient
of friction, giving a more gentle action, wearing better
or obviating the necessity of using oil. The material used is gen-
erally riveted to the face of the engaging member.

Clutch Operating Device — The mechanism which transmits
the force applied by the operator to the pedal (or lever) to over-
come the spring and disengage the clutch. It usually consists of
a linkage, designed to multiply the force applied to the pedal,
and a yoke, which presses against a thrust collar acting against
the end of the clutch spring.

Clutch Operating Shaft — A transverse shaft upon which are
secured the clutch pedal and the clutch throwout yoke, and by
the partial rotation of which the disengaging motion is trans-
mitted from the pedal through the yoke to the clutch collar.

Clutch Pedal — The pedal by pressure upon which the opera-
tor disengages the clutch.

Clutch Shaft — The shaft upon which the driven member of
a clutch is carried and which conveys the driving effort to the
change-speed gear and to the final drive of an automobile. This
shaft is usually a sleeve at its forward end, and is supported
upon an extension of the motor shaft. At its rear end it usually
carries some form of universal and slip joint, which connects
with the shaft entering the change gear case. This latter shaft,
which carries a constantly meshed gear, is sometimes considered
a part of the clutch shaft.

Clutch Spider — A construction usually formed of several
arms radiating from a hub, secured to and rotating with one
of the shafts of a clutch and carrying the engaging portion of
one of the members thereof.

Clutch Slip Spring — One of a series of springs placed under
the lining of a clutch (see clutch lining) and tending slightly to
lift the lining at the points of their application so that, when
the clutch commences to engage, frictional contact will first be
established at these points and later, as engagement progresses
the springs are compressed, the lining flattens and the whole of
it finally comes into action. The engagement of the clutch is
thus progressive and any tendency to grab (q. v.) is obviated.
See diagram of clutch, cone.

Syn. : Spring insert, engagement spring, expansion spring,
spring plunger.

77

Clutch Spring — A spring which acts to force together the
frictional surfaces of two clutch members or sets of members.
A single spring or a number of springs so placed as to dis-
tribute the engaging pressure over all parts of the frictional
surfaces, may be used.

Clutch Throwout Yoke — A fork, fastened centrally upon
the clutch operating shaft, the ends of the arms of which act
upon the clutch collar (q. v.) to disengage the clutch when the
yoke is partially rotated by the shaft.

Syn. : Clutch shipper-yoke, clutch fork.

Coast (v.) — To allow a car to move without the application
of engine power, under the influence of gravity as in running
on a down grade. In coasting, the clutch is disengaged, and
the gears generally thrown out of mesh. To allow a car to
run upon the level under its own momentum may be called
coasting, but more properly "drifting."

Coil, Induction — An electrical apparatus for the transforma-
tion of a low tension into a high tension current by means

of electromagnetic induction, com-
prising a laminated, soft iron core
and two coils of insulated wire
wound upon it. One of these, the
primary, consists of a relatively
small number of turns of rather
INDUCTION COIL coarse insulated wire, through which
DIAGRAM. the low tension current flows, and

A, Primary Winding; B, the other' the secondary, consists of
Secondary Winding; c, Iron a very large number of turns of fine
insulated wire. When the current
flowing in the primary winding is

abruptly broken, a very high electrical pressure is developed
between the ends of the secondary coil, sufficient to cause a
spark to pass through a short gap from one secondary terminal
to the other. A condenser (q. v.) is generally connected to
the primary winding. All jump spark ignition coils are in-
duction coils.

Syn.: Step-up coil, step-up transformer, jump spark coil.

Coil, Plain — An induction coil, for ignition purposes, which
is provided with no automatic means for making and breaking

78

the primary current, the quick acting make and break device
being separate from it. A condenser is generaly attached to
such a coil.

Syn. : Non-vibrator coil.

Coil, Primary — That winding of an induction coil for ig-
nition purposes through which circulates the primary or low
tension current, derived from a battery or low tension magneto
winding and which is in circuit with the timer (q. v.) and
the vibrator or other means for abruptly breaking the current.

Coil, Secondary — That winding of an induction coil, for
ignition purposes, in which a high tension current is generated
by induction, and the terminals of which are connected to a
spark plug in a jump spark ignition system.

Coil, Self Induction — A coil, consisting of a laminated, soft
iron core upon which are wound a small number of turns of
coarse wire, through which a low tension current is passed.
When the circuit including it is abruptly broken, a momentary
high tension current, due to the self-induction of the coil,
passes in the form of a spark or arc across the break. Used
to produce the igniting spark in some low tension contact
spark (q. v.) systems.

Coil, Tubular — A form of plain induction coil, for ignition
purposes, which is enclosed in a tubular water and oil proof
case. Used when the coil is to be placed out of sight under
the hood or flooring of a car, and is likely to be exposed to
oil or water. Used also on motor bicycles.

Coil, Unit — A form of ignition induction coil so designed
as to be interchangeable with other similar coils. It is de-
signed to be put into service by inserting it in a coil box
containing spaces for a number of identical -coils. In-
serting any coil unit into any space in the box automatically
makes its connections with the external circuit which is wired
to contacts fixed in the inside of the box. Such coils are
used because they are instantly changeable, in case they be-
come damaged and because they are readily interchangeable
from one circuit to another by which the location of ignition
defects is facilitated.

Coil, Vibrator — An ignition induction coil with which is in-
corporated an electromagnetic vibrator (q. v.) for abruptly
making and breaking its primary circuit. The vibrator is usu-

79

ally mounted upon one end of the coil, and its armature is
operated by the magnetism of the core of the coil itself.

Syn. : Buzzer coil, trembler coil.

Coil Box — A box designed to contain one or more induc-
tion coils for ignition purposes and provided with the necessary
binding posts for their connection to their respective external
circuits. Usually adapted to be mounted upon an automo-
bile dashboard.

Cold Chisel — A short, stout chisel with a hardened edge of
V-shaped section, adapted to be used with a hammer in cutting
or chipping metals when in a cold condition.

Cold Test — A test applied to lubricating oils, which con-
sists in determining the reduction of temperature which an
oil can withstand without passing from the fluid to the non-fluid
condition. An oil of high cold test is one which becomes non-
fluid only at a very low temperature.

Collar — An enlarged portion of a shaft, either integral with
the rest of the shaft or applied in the form of a ring sometimes
fastened upon the shaft by set screws, designed to limit the end
play of the shaft or to support end thrust.

Collector Ring — A conducting ring carried by a rotating
portion of an electric device with which a stationary brush
makes contact. Designed to convey electricity to and from
the rotating element.

Combustion Lag — The very short period of time which
elapses between the instant at which the ignition spark passes in
the cylinder of an internal combustion motor and the instant at
which the maximum gas pressure is developed. It is dependent
upon the time required to complete the inflammation of the
charge and to raise the gases to their maximum temperature, and
this is modified by the character and location of the spark or
sparks, the quality of the mixture, the dimensions and form of
the combustion chamber, etc.

Combustion Space — See clearance space.

Common Terminal — A terminal or binding post to which
more than one circuit is attached.

Common Wire — A wire which forms a part of more than
one electric circuit, e; g., a ground wire which simultaneously
grounds several distinct circuits.

Commutator — A device for automatically reversing the di-
rection of current flow in an electric circuit. In a direct current
dynamo, a device for automatically reversing
the connections of each armature coil to the
external circuit, when the direction of the
current induced in it reverses, so that the cur-
rent which it supplies to the external circuit
shall always flow in the same direction.
It consists of a cylindrical shell of hard cop-
COMMUTATOR Per> mounted upon an insulating bushing, se-
cured upon one end of the armature shaft.
This shell is axially split into equal insulated segments, usually
the same in number as the armature coils. Adjacent ends of
adjacent armature coils are electrically connected to the same
segment. Upon the commutator bear two or more sets of sta-
tionary, conducting brushes (q. v.).

The term commutator is sometimes applied to the ignition
timer (q. v.).

Compensating Gear — See differential gear.
Compression — The reduction of the space occupied by a gas
or vapor, attended by -rise of pressure and the evolution of heat.
In internal combustion engines, compression of the fuel charge
is effected by the motion of the tightly fitted piston in the
cylinder. During the suction stroke, the cylinder and its com-
pression space are completely filled with fuel charge, at or near
atmospheric pressure, and the valves are then closed, thus con-
fining the charge within the cylinder. As the piston, starting
at its extreme outward position (downward position in the case
of a vertical motor), performs its inward or upward travel,
the space occupied by the charge is progressively reduced until,
when it reaches its extreme inward or upward position, the total
charge is crowded into the clearance space. The main object of
compression is to reduce the exposed surface of the charge at
ignition, and thus to reduce its great heat losses.

High compression and low compression are relative terms, but
vehicle motors which carry a gauge compression of not over
70 pounds per square inch may be called low compression and
those carrying higher pressures, high compression motors.

Compression, Ratio of — The quotient obtained when the
total volume of the cylinder of an internal combustion motor,
from the beginning to the end of the piston stroke, plus the

81

COMPRESSION COCK.

A, Valve Cap; B, Cyl-
inder Wall.

clearance volume, is divided by the clearance volume. In auto-
mobile practice, the compression ratio is usually between three
and four.

Compression Cock — A cock communicating with the clear-
ance space of the cylinder of an internal combustion engine
which, when opened, permits the es-
cape of the charge as the piston makes
its compression stroke. Used to re-
duce the labor of cranking at start-
ing, as an indicator that the cylinder
is firing properly and as a means of es-
cape of superfluous lubricating oil from
the combustion space.

Compression Gauge — A pressure
gauge adapted to be so connected to the
clearance space of an internal combus-
tion engine as to indicate the pressure above the atmosphere
existing in the cylinder during the compression stroke. Princi-
pally used to detect leakages of the charge from the cylinder.

Syn. : Compressometer.

Compression Release — A mechanism for reducing the com-
pression pressure within a gas engine cylinder, and thus of re-
ducing the effort required at cranking.
It consists of a special exhaust valve cam,
so formed and so timed as to hold the ex-
haust valve open during the first part of
the compression stroke, thus allowing a
portion of the charge to escape. The spe-
cial cam is substituted for the regular cam.
at starting, by means of a small lever,
within reach of the operator, and, in multi-
cylinder engines, the cams of all fhe
cylinders are brought into action by the
same movement, which generally consists
of an endwise displacement of the exhaust
cam shaft.

Compression Stroke — In a four stroke cycle internal com-
bustion motor, the inward (upward in a vertical motor) piston
stroke, during which the fuel charge is compressed in the
clearance space of the cylinder, preparatory to being fired. It

COMPRESSION
RELEASE.

A, Relief Cam; B,
Exhaust Cam.

is usually regarded as the second stroke in the four-stroke cycle.
In a two-stroke cycle motor, the compression stroke is that
stroke during which the fuel charge is being compressed back
of the piston and mixture is also being drawn into the crank
case or separate pump, preparatory to being transferred, under
pressure to the working cylinder to form the charge for the
succeeding cycle. The compression and intake strokes are there-
fore identical.

Condenser, Electrical — A device used in connection with
ignition apparatus to suppress the spark or arc produced at the
point where the primary circuit is
broken, and, by increasing the
abruptness of the break, to increase
the intensity of the igniting spark
delivered by the secondary circuit.

It consists of a large number of
DIAGRAM OF ELECTRIC sheets of tinfoi, piled togetherj each

CONDENSER. sheet bgi separated from its neigh-

A. Positive Electrode; B, ,

Negative Electrode. bor by a sheet of mica, or other in-

sulating material. Alternate tinfo'ls

are all connected together, making two series thereof, one of
which is electrically connected to one side of the point at which
the circuit is to 'be broken, and the other set to the other side
of the break. When the primary circuit is interrupted, the elec-
tricity, which would otherwise be expended in an arc at the
point of break, thus delaying the opening of the circuit and
burning the contacts, is absorbed by the condenser. A condenser
is usually installed with each ignition induction coil, and in high
tension magnetos one is usually incorporated with the armature
connected around the make and break device.

Condenser, Steam — A means of conserving the water supply
of a steam car, by condensing the exhaust steam upon the ve-
hicle instead of allowing it to escape into the atmosphere. It
consists of an arrangement of numerous thin walled tubes, ex-
posing a very large surface to the air, usually carried at the
extreme front of the car, and sometimes assisted by an air fan,
into which tubes the steam from the engine is exhausted. The
cool air, impinging upon the tubes, extracts the heat from the
steam, reducing it to water. It is then returned to the supply
tank or boiler after oil separation.

83

Condenser Pump — A pump, usually driven from the engine
of a steam car, which returns water from the condenser to the
supply tank or boiler.

Conductor, Electric — A substance through which a current
of electricity can flow. Theoretically all materials are in a de-
gree conductors, but only those such as metals, carbon and
aqueous solutions through which electricity can flow with com-
parative freedom, are so classed. Copper wires and cables are
the most common forms of conductor.

Connecting Rod — The rod which connects the piston of a
steam or gas engine with the crank, and converts the recipro-
cating motion of the
former into rotation of
the latter. Its own mo-
tion is a combination of
reciprocation and oscil-
lation. In the ordinary
type of gasoline vehicle
motor, its upper or

CONNECTING Ron.

A, Piston Pin Bearing; B, Con-
necting Rod Head; C, Connecting
Rod Cap.

"head" end is secured to

the trunk piston by the

piston pin (wrist pin).

Its lower or "crank" end

contains a bearing which

secures it to the crank pin, upon which it freely turns. The

end of the rod which is attached to the crank pin is generally

made of greater cross section than the other, and is known as

the "big end."

Connecting Rod, Angularity of — The maximum angle made
by the connecting rod with the axis of the cylinder. The greater
the ratio of the piston stroke to the length of the connecting
rod, the greater is the angularity. A high degree of angularity
is objectionable, in that it results in excessive side pressure of
the piston upon the cylinder walls.

Connecting Rod, Hinged Type — A connecting rod, the
crank end of which contains half the crank pin bearing; the
bearing cap, which contains the other half of the bearing, being'
hinged to the rod end at one side and held in place at the other
by bolts.

Connecting Rod, I Section — A connecting rod, the cross
section of which is an I, placed with its web in the plane of its

84

O

o

HEAD OF MARINE TYPE
CONNECTING ROD.

movement. The use of this section secures greater rigidity
lhan can be obtained from the same mass of metal in a solid
section.

Connecting Rod, Marine Type — A form of connecting rod
of great ruggedness. The rod proper is a steel forging, the
crank end of which is flanged out to
the size of two bronze castings, each
of which contains one-half the crank
pin bearing. These bronze castings or
brasses are drawn together and
against the end of the forging by
means of four bolts which pass
through the flanged end of the rod
and both brasses.

Connecting Rod, Tubular — A connecting rod, the section of
which is a circular or oval tube. The use of this section secures
greater rigidity than is obtainable from the same mass of metal
in a solid section.

Connecting Rod Cap — The cap which secures the large end
of a connecting rod to the crank 'pin and which contains half
the bearing bushing. It is bolted to the rod end.

Connecting Rod Tip — The large end of a connecting rod
which has a bearing upon the crank pin.

Contact Breaker — See mechanical make-and-break, magnetic
vibrator, magneto make-and-break.

Contact Point — A small piece of infusible, non-oxidizable
metal, usually platinum or an alloy of platinum and iridium,
adapted to withstand the action of the electric arc. Such points
are used in pairs in the make-and-break devices of ignition ap-
paratus, the primary circuit being completed by their contact and
interrupted by their separation.

Contact Screw — A screw carrying a con-
tact point which, when screwed in or out of a
stationary support, adjusts the distance between
its contact point and another similar contact
point, in a make-and-break device.

Continuous Current — An electric current
which flows always in the same direction.
Such a current is produced by primary and

CONTACT SCREW.

Scre\

Contact

, B, Con-
storage cells, and by dynamos and magnetos tact Point; C,
_ ... , . , . Clamping Screw;

fitted with commutators, and is required for D, Contact Post.

85

the charging of storage batteries. The term is used in contra-
distinction to "alternating current."

Syn. : Direct current.

Control Device — A general term applied to all handles, pedals
and so forth, by means of which the speed and direction of an
automobile are regulated by the operator, including those which
operate the steering mechanism, brakes, clutch and change speed
gear, and those which vary the operation of the motor or
engine.

Controller — A device which regulates the flow of current
from the battery to the motor of an electric vehicle, and thus
controls the motor out-
put and the speed and
tractive effort of the
vehicle. It consists of a
hand operated lever
which, when moved by
the operator into certain
positions or "points,"
makes and breaks suit-
able contacts by the ac-
tion of which a succes-
sion of graded electrical
pressures or voltages are
applied to the motor, or
by means of which the current may be completely cut off.

Controller, Continuous Torque — A type of electric vehicle
controller, the contacts of which are so arranged that, at the
moment when it is being changed from one speed or point to
another, there is no cessation of driving power, and thus no
jerk is imparted to the vehicle. This result is secured by closing
the contacts corresponding to a certain speed just before the
connections corresponding to the preceding speed are opened.

Controller, Field Commutating — See field commutation con-
trol.

Controller, Magnetic — A type of controller in which the
combinations of contacts corresponding with the several speeds
are not effected by the direct action of the operator's hand, but
by electromagnets actuated by an electric switch button or lever
moved by the operator.

ELECTRIC VEHICLE CONTROL.

Controller, Resistance Type — See resistance control.

Controller, Series Parallel — A form of controller in which
the gradations, of voltage applied to the motor, and hence the
speed variations, are obtained by the use of a battery usually
divided into two equal sections, which sections, when coupled
in parallel, supply a low voltage to the motor and, when coupled
in series, supply double this voltage.

Controller Contact — A metal contact piece forming part
of a controller, generally a movable contact.

Controller Cylinder — The cylinder, of insulating material,
which is rotated by the operator in changing speeds and upon
which are mounted the conducting segments with which the
controller ringers make contact.

Syn. : Controller barrel.

Controller Finger — The stationary contacts of a controller,
which are spring-pressed upon the movable contacts, and to
which the controller leads to the motor, battery, rheostat and
other parts of the control system are attached.

Cooler — See radiator.

Cooling Flange — A thin conductive rib or flange, a number
of which are formed integrally with or applied to a part which
it is desired to cool by exposure to the surrounding air, such as
a gas motor cylinder (see air-cooled), an exhaust pipe or brake
drum. Such flanges offer a large surface to the air and convec-
tion rapidly removes heat through them from the part which
bears them.

Syn. : Radiating flanges.

Cooling System — A term applied collectively to parts the
function of which is to abstract excess heat from the cylinder
walls of an internal combustion motor and thus to maintain
them at a proper working temperature. It consists of means for
passing a fluid (air or water) around and in contact with the
external surfaces of the cylinders, which fluid, mainly by con-
vection, absorbs heat therefrom and carries it away to be dis-
sipated in the external air. It includes such parts as air and
water jackets, water piping, circulating pumps, radiators and fans.

See air cooling and water cooling.

87

Core, Magnetic — The mass of soft iron .about which are
wound the wire coils of an induction coil, magneto or dynamo
armature, or other form of electro-magnetic device. The func-
tion of the core is to multiply the magnetic effect set up by the
electric currents circulating in the windings or to serve as a path
for magnetism created by an external magnetizing force.

Cork Insert — A plug of compressed cork adapted to be set
into the surface of one of the members of a frictional device
such as a clutch or brake, or into the
face of a belt driven pulley. A series
of holes are drilled in the frictional
surface of the member and a properly
formed piece of cork is forced into
each, under pressure, so that it pro-
trudes slightly beyond the surface.
When pressure is applied between the
working surfaces, the corks first make
contact with the opposing frictional
member, resulting in a gentle engage-
ment and finally the corks are sufficient-
ly compressed so that the entire work-
ing surfaces contact, securing positive
engagement. The use of cork inserts is claimed to increase the
coefficient of friction, to diminish the rate of wear of the sur-
faces, to reduce the necessity for lubrication and to prevent
harsh action.

Cotter Pin — A split metal pin, used to
prevent a nut from backing off its threads,
to hold small parts together and for
various similar purposes. A hole is drilled
through the bolt or stud at a point just
beyond the nut. The pin is passed through
the hole and its halves are bent apart,
so that it cannot pass back through the
hole.

Syn. : Split pin.

CORK INSERTS USED

IN AUTOMOBILE

BRAKE.

A, COTTER PIN.

Counterbalance (n.) — A weight or weights so distributed
upon and attached to a moving part as to balance it, thus pre-
venting vibration, noise and sudden pressures upon the bearings.

88

A, COUNTERBALANCE.

When a counterbalance is so ap-
. plied to a rotating part that the
centre of gravity of the whole
system lies in the axis of rota-
tion, the part so counterbalanced
is in static balance. When so
applied, that, during rotation, the
inertia forces produce no result-
ant component at right angles to
the axis of rotation, the system
is in dynamic balance; e. g., in

the case of a one cylinder engine, with a single throw crank-
shaft, the mass of the crank is entirely upon one side of the
crankshaft and a mass of metal is so -distributed upon the other
side of the crankshaft as to counterbalance it, and, at the same
time, to partially neutralize the unbalanced effect of the re-
ciprocating parts,
v. To apply a counterbalance.

Counterbore (n.) — A hole bored in a part concentric with
another hole and superposed upon it, but of a larger diameter,
resulting in a shoulder, where the two bores meet. Also the
tool used in this operation, consisting of a guiding spindlev fitting
the smaller hole, which forms the end of a boring-bar, the cutter
of which is of an effective diameter equal to that of the desired
larger bore. v. To perform the above described operation.

Counterclockwise Rotation — Rotation in the direction oppo-
site to that of the hands of a clock. Left handed rotation.

Countershaft — A subsidiary shaft driven from a main shaft.
In a gearset of the sliding gear, direct drive type, the shaft
which is driven from the clutch shaft through permanently
meshed gears is often called the countershaft. Syn. : Lay-shaft.
In a double chain driven car, the transverse shaft which carries
the differential gear and the driving sprockets is so called.

Syn. : Jackshaft.

Countershaft Unit — A term applied to the combustion of
parts employed in double chain driven (see chain drive, double)
motor cars, consisting of the bevel driving gears, the differential
gear (q. v.) and countershaft (q. v.), and, in some cases, includ-
ing the change speed gear,

COUPE.

Coupe — A rather short, permanently closed-in body, usually
seating two inside, with outside seat for the operator.

Coupe, Inside-
driven — A form of
coupe body, mounted
well forward on the
chassis, within which
the steering column
and levers are in-
cluded, so that a car
equipped with it may
be driven without ex-
posure of the opera-
tor to the weather. It usually seats one besides the operator.
Crank (n.) — An offset in a driving or driven shaft, to permit
of a rotary motion being imparted to the shaft from a reciprocat-
ing part, or of a reciprocating motion being imparted to a part
from the rotation of the shaft. A crank consists of two webs or
cheeks projecting from the shaft nearly at right angles thereto,
the extremities of which are joined by a cylindrical shaft-like
portion — the crank pin — parallel to the crankshaft.

Crank (v.) — To turn over a gasoline motor by hand, in
order to draw fuel charges into its cylinders and to cause the
ignition apparatus to act, so that a charge may be fired and
the motor may commence to operate under its own power.

Crank, Safety Starting — A form of starting crank, so ar-
ranged that in case the motor upon which it is used "kicks
back/' the reverse turning force of the motor is not trans-
mitted to the crank and the operator's hand, and possible in-
jury to him is thus prevented.
Crank, Starting — A hand
crank adapted to engage with
the end of the crankshaft of a
gasoline motor, which enables
the operator to turn over the
motor to start it. The crank is
slidably guided in a bracket
attached to the car frame, and
its end is formed with a
ratchet face, which can be en-
gaged with a corresponding

STARTING CRANK.

ratchet face upon the motor crankshaft end. A spring acts to
slide the ratchet faces out of engagement and they are so shaped
that they are automatically disengaged when the motor starts.
A strap, or similar device, is generally provided to prevent the
crank from swinging when it is not in use.

Crank Case— The case or housing, generally of cast iron,
aluminum or pressed steel, which encloses the crankshaft, con-
necting rods and some other parts of a gasoline motor, contains

the crankshaft bearings
and retains lubricant for
the oiling of the moving
parts. The flanged crank
ends of the cylinders are
bolted to the top of the
crank case, in which

CRANK CASE.

suitable spaces for the
play of the connecting
rods are provided, and the case itself is usually provided with
projecting arms, by means of which it and the entire engine are
secured to the vehicle frame.

Syn. : Engine base.

Crank Case, Barrel Type — A crank case cast in one piece,
except that one or both ends an. not included. The crankshaft
is inserted through the open ends, which are closed by end
plates in which are the end bearings of the crankshaft.

Crank Case, Divided — A crank case which is split in halves
in the plane of the crankshaft. The upper half, to which the
cylinders are secured generally carries the bearings of the crank-
shaft and the arms or web by which the engine is fastened
to the vehicle frame. The lower half generally performs only
the function of retaining oil and excluding dust.

Crank Case Arm — A projection formed upon a crank case,
by means of which the motor is bolted to its foundation.

Crank Case Compartment — One of the longitudinal sub-
divisions of the crank case of a multiple-cylinder motor. The
divisions are usually but partial, being formed by transverse parti-
tions arising somewhat from the bottom of the case. Compart-
ments are used to prevent the oil supply, carried in the case, from
collecting in one end thereof and thus stopping the lubrication of
certain cylinders, when the motor is inclined fore and aft.

Syn. : Crank case section.

91

Crank Case Compression — In a two-stroke-cycle motor, the
practice of using the crank case and the piston as a pump to
force the fuel mixture through a transfer passage into the
working cylinder. Mixture is drawn from the carburetor into
the tight crank case during the upstroke of the piston, through
a non-return valve arrangement and, being trapped therein, it
is compressed during the succeeding downstroke to a pressure
sufficient to force it through the transfer passage into the
cylinder and to displace some of the burned gases.

Crank Case Drain Cock — A cock communicating with the
lowest point of a crank case compartment, through which the
lubricant contained therein can be drawn off.

Crank Case Explosion — See base explosion.

Crank End — The end of an engine cylinder nearer the crank-
shaft.

Crank Pin — The cylindrical portion of a crank, parallel to
the crankshaft and at a perpendicular distance from it of one-
half the piston stroke, to which the large end of the connect-
ing rod is secured and upon which it rotates.

Crank Pit — A depression in the bottom of a crank case
shaped to conform somewhat with the path of the crank,
and which generally contains a supply of lubricant which is
distributed by the splashing action of the crank and connecting
rod tip.

Crankshaft — The main shaft of an engine, in which are
formed the crank or cranks. It is supported in several bearings
(usually carried by the crank case), with its axis at right
angles to the axes of the cylinders, and upon it is secured the
balance wheel or flywheel. It communicates the turning effort

CRANKSHAFT.

of the engine to the driving member of the clutch, which is
secured upon it.

Crankshaft, Ball Bearing — A crankshaft supported upon
ball bearings, generally of the annular type, instead of upon
plain bearings.

BUILT-UP CRANKSHAFT.

Crankshaft, Built=up — A crankshaft whch is not a single
piece of metal, forged and machined into form, but which is
made up of several sections, so formed
as securely to lock together when assem-
bled. They are not much used and were
devised mainly to permit the use of ball
bearings which cannot readily be applied
to the centre bearings of integral shafts.
Crankshaft, Double=Throw— A
crankshaft with two cranks arranged
side by side upon it, in the same plane

but opposite, one to the other. Used in two cylinder twin and
opposed motors and sometimes in four cylinder motors of the
V type.

Crankshaft, Five=Bearing — A crankshaft supported upon
five bearings, a type which is commonly used in four cylinder
motors the cylinders of which are separately cast.

Crankshaft, Four=Bearing — A crankshaft supported upon
four bearings, and used in three and six cylinder motors.

Crankshaft, Four=Throw — A crankshaft used in four
cylinder motors, carrying four cranks in the same plane, the
two end cranks being located upon the same side of the shaft,
and the two middle cranks being located upon the other side of
the crank or at an angle of 180 degrees from the end cranks.

Crankshaft, Offset — A crankshaft so positioned that its cen-
tre line is not in the plane including the axes of its cylinders,
but is somewhat displaced along a line at
right angles to the cylinder axes toward
that side of the crank chamber in which
the crank is located during the compres-
sion stroke. The object of offsetting the
shaft is to bring the connecting rod thrust
more nearly into the axis of the cylinder
and thus to reduce the side pressure ex-
erted between the piston and the cylinder
walls during the power stroke. An off-
set equal to 1-6 the piston stroke is quite
common.

Crankshaft, Roller Bearing — A crankshaft supported upon
roller bearings for the purpose of reducing frictional losses.

OFFSET
CRANKSHAFT.

93

Crankshaft, Seven Bearing — A crankshaft supported in
seven bearings, and used in six cylinder motors, the cylinders
of which are separately cast.

Crankshaft, Single Throw — A crankshaft with a single
crank, used in single cylinder motors and also in two cylinder
V motors.

Crankshaft, Six Throw — A crankshaft with six cranks,
used in six cylinder engines. The cranks are located in three
planes at angles of 120 degrees. Numbering the cranks from
one end of the shaft: Cranks I and 6 are in the same plane,
cranks 2 and 5 are in a plane making an angle of 120 degrees
therewith and neighboring cranks 3 and 4 in the remaining
plane, at 120 degrees from those occupied by the other two
pairs.

Crankshaft, Three Bearing — A crankshaft supported in
three bearings and used in four cylinder and two cylinder twin
motors.

Crankshaft, Three Throw — A crankshaft with three cranks
arranged in planes making angles of 120 degrees, one with an-
other, used in three cylinder motors and in six cylinder motors
of the V type.

Crankshaft, Two Bearing — A crankshaft supported at its
ends only, used in motors of one to four cylinders.

Creep (v.) — In the case of a tire, to rotate gradually upon its
rim in a direction opposite to the rotation of the wheel, under
the stress of the tractive effort. The cause is usually insufficient
inflation or insecurity of the fastening devices, and the result is
sometimes to tear the valve stem from the inner tube where it
passes through the felloe. A similar action sometimes takes
place with tire chains and tire bands, which creep relatively to
the tire itself.

Crosshead — That part of a steam engine which forms the
connection between the piston rod and the connecting rod and
on which the latter pivots. It is a
block-shaped member so formed that its
sides are slidably restrained in guides
which permit of its reciprocating in line

with the piston movement. The pis-

CROSSHEAD. , . , , ,- , ,

ton rod is secured in the head end of

the crosshead and a wrist pin passes through the crosshead and
the head end of the connecting rod and secures them together.

94

Crosshead, Ball Bearing — A crosshead in which a series of
balls is arranged between each of its guided sides and the guides
themselves upon which the crosshead slides with very slight
friction and wear.

Crosshead Guide — In a steam engine the two parallel
guides or ways, located in line with the piston movement and
usually fixed to the engine frame, in which the crosshead slides.

Cross Member — A transverse structural member which unites
the two side members of an automobile frame and gives it
form and rigidity. Such a member is placed at each end of the
frame and others are distributed at intermediate points, usually
in such positions as to form supports for the motor, clutch and
gear box.

Syn. : Transverse member.

Crystallization — The alleged deterioration of a metal from
a tough, fibrous condition to a brittle crystalline condition,
brought about by its long continued subjection to vibratory
stresses. See fatigue.

Current Tap — An electrical fitting so arranged as to permit
of the convenient connection of a storage battery in series with
an incandescent lamp or group of lamps
for the purpose of charging the battery
from a direct current circuit, the number
of lamps used definitely limiting the charg-
ing current. It consists of a number of
lamp sockets connected in multiple to the
supply circuit, and a receptacle wired in
series with one side of the lamp group,
into which may be inserted an attachment CURRENT TAP.
plug.

Cut=off, Point of — In the operation of a steam engine, that
point in the piston stroke at which the valve ceases to admit
live steam.

Cut=out, Muffler — See muffler cut-out.
Cut-out Button — See ignition cut-out.

95

Cut out Switch, Individual — A switch, by means of which
the ignition of one cylinder of a multicylinder gasoline engine
may be thrown on or off. By the itse
of a series of such switches it is possible
to determine which cylinder or cylinders
are receiving imperfect ignition. When
the engine is running and one of these
switches can be opened without reduc-
ing the engine speed it is an indication
that that cylinder is not firing. If the
engine is running irregularly, and, upon
opening the switch pertaining to a cer-
CUT-OUT SWITCH. tain cylinder, the irregularity ceases, it
indicates that that particular cylinder is
missing explosions. (See ignition cut-out.)

Cycle of Operations — The successive actions of the working
fluid of a heat engine upon its piston and of its piston upon
the working fluid, commencing when a certain relationship be-
tween the two exists and ending with the next recurrence of the
same relationship, e. g. In a four cycle gas engine, commencing
with the suction of the charge and continuing through its com-
pression, its .ignition and expansion and through its exhaust,
when suction again begins.

Cylinder — That portion of a heat engine in which the trans-
formation of heat energy into mechanical energy takes place, as
the result of the expansion of a gas or vapor. In a reciprocating
steam or internal combustion motor, a nearly cylindrical metal
vessel, closed at one or both ends and provided with an axially
placed truly cylindrical bore, in which a closely fitted piston slides
back and forth, and with suitable port openings controlled by
valves giving ingress and egress to the working fluid. In an
internal combustion motor of the trunk piston type, a nearly cyl-
indrical casting. of specially adapted iron, closed at the head end
and open at the other end, where it is secured to the crank case,
with a truly cylindrical axial bore and with provisions near the
head end for the placing of the inlet and the exhaust valve, and
with the necessary ports cored out in the cylinder wall to permit
communication between the valves and the bore.

Cylinder, Air Cooled — See air cooling.

CYLINDER, BLOCK CAST.

Cylinder, Block Cast — A cylinder which is formed together
with one or more other similar cylinders as a single casting,
the water jackets, valve
pockets and often a por-
tion of the piping of all
the cylinders being in-
cluded in the casting.
Compactness, rigidity
and a smooth external
appearance are secured
by this method. The
term is particularly ap-
plied to cylinders cast
in groups of four and
the practice is at pres-
ent most commonly applied in the manufacture of rather small
four cylinder motors.
Syn. : Cylinders en bloc.

Cylinder, Dome Head — A cylinder, the head of which is of
somewhat hemispherical shape and which, when used with a
piston with a concaved head, affords a compression space of
somewhat spherical form, which possesses certain thermodynamic
advantages. It is most often employed in overhead valve (q. v.)
motors.

Cylinder, Double Acting — A heat engine cylinder with a
head and an expansion chamber at each end thereof and means
for admitting and exhausting the working fluid from both ex-
pansion chambers. The cylinders of most steam vehicle engines
are of the double acting type.

Cylinder, Double Diameter — A form
of cylinder the bore of which is larger at
the crank end than at the head end, and
concentric with it, a shoulder or step being
formed where the two bores meet. In it
reciprocates a double diameter piston, the
two sections of which respectively fit the
two cylinder bores. This type is used in
some two cycle motors, the smaller piston
being the working piston and the larger
bore and piston, in conjunction with the
shoulder between the two bores, forming

CYLINDER, DOUBLE
DIAMETER.

07

an annular space which is used as the cylinder of a pump by
means of which the fuel charge is forced into the working cylin-
der. The double diameter cylinder has also been used to render
a gasoline motor double acting, both the smaller cylinder and the
annular space above referred to being used as working cylinders.

Cylinder, L-Type — A gasoline engine cylinder having cast
upon one side of its head a chamber or pocket or a pair of
closely adjacent pockets designed for the
reception of one or both of its valves.
An axial section through the valve cham-
ber of such a cylinder, when inverted, re-
sembles the letter L, whence the name.
Used in engines which have all valves
upon one side and also in those which
have one set of valves upon one side
and the other set in the cylinder heads.

Cylinder, Pair Cast— A cylinder which
is formed together with another similar
cylinder in a single casting which includes
the water jacket, valve pockets and ports L-TYPE CYLINDER.
of both.

Syn. : Twin cast, dual cast cylinders.

Cylinder, Ribbed — A cylinder the external surface of which
is provided with ribs, fins, flanges or other projections, either
cast integral therewith or applied thereto,
which expose a large surface and assist in
the dissipation of excess heat. Air cooled
cylinders are usually so made.
See air cooling.

Cylinder, Separately Cast — A cylinder
which is cast singly and not in combination
with other similar cylinders.

Cylinder, Single Acting — A cylinder hav-
ing a head and expansion chamber at one
RIDDED CYLINDER, end only. Practically all gasoline vehicle
motors are single acting.

Cylinder, T=type — A gasoline engine cylinder cast with a
chamber or pocket for the reception of the inlet valve upon

98

T-TYPE CYLINDER.

one side of the head and a similar
chamber for the exhaust valve upon
the diametrically opposite side of the
head. An axial cross section of such
a cylinder, through the valve cham-
bers, resembles a letter T, hence the
name.

Cylinder, Water Cooled— See
water cooling.

Cylinder Barrel — The cylindri-
cal portion of a cylinder exclusive
of the head, valve pockets and water
jacket.

Cylinder Bore — The truly cylindrical chamber or cavity
forming the inside of a cylinder, within which the closely fitted
piston reciprocates and which, together with the clearance space,
is the seat of action of the gases concerned in the operation of
the motor. Also the diameter of the bore, usually expressed
in inches or millimeters.

Cylinder Counterbore — A slight enlargement of the bore
of a cylinder, beyond the limit of piston travel, at the head
end where it joins the clearance space.

Cylinder Flange — A flange cast around the crank end of a
trunk-piston engine cylinder, through which pass the studs or
other fastening devices which secure the cylinder to the crank
case.

Cylinder Head — The somewhat circular end portion of a
cylinder, which closes it and which, in conjunction with the
piston head and the walls of the cylinder bore, forms the
closed combustion and expansion space within which the work-
ing fluid acts.

Cylinder Head, Integral — A cylinder head which is cast as
one with the cylinder barrel and other related parts.

Cylinder Head, Removable — A cylinder head which is not
cast as one with the rest of the cylinder, but is cast as a separate
piece, which often includes the valve pockets and parts of the
water jacket, and which is secured to the cylinder barrel usu-
ally by means of studs. A gasket or packing is generally in-
serted between the abutting surfaces of the head and of the
rest of the cylinder in order to secure a tight joint.

99

Cylinder Plug— A removable portion of the cylinder head
of a gasoline motor, the removal of which gives access to the
combustion space.

Cylinder Oil — A grade of oil specially adapted to the lubrica-
tion of the pistons and cylinder walls of steam and gasoline
motors, the properties of which are such that it lubricates ef-
fectively at the high temperatures to which the parts attain in
practice.

Cylinder Oil, Gas Engine — A grade of mineral oil especially
adapted to the lubrication of internal combustion engine cylin-
ders, characterized by a satisfactory fire test (q. v.) and flash
test (q. v.), and a minimum tendency to leave solid residue at
the very high temperatures to which it is exposed.

Cylinder Oil, Steam — A grade of oil, usually a compound
of mineral and animal oils, specially adapted to give the best
lubricating results at the temperature to which live steam raises
the cylinders of a steam engine.

Dashboard — That portion of an automobile body which forms
the front of the forward seat space, and, in the accepted type
of "motor-in-front" construction, the back of the bonnet space
in which the motor is
housed. It acts as a
wind break, and as a
support for various
indicating and control
devices. It is made
either of wood or of
metal. DASHBOARD.

Syn. : Dash.

Dashboard, Hooded — A rearwardly concave form of dash-
board, usually made of pressed steel,
the edges of which are curved back-
wardly so as to form surfaces which
somewhat protect the front seat pas-
sengers by deflecting the moving air
away from them. A common type
upon runabouts, roadsters and speed
cars.

Dashboard Adjustment — An ar-
rangement which enables a carburetor
HOODED DASH. to be adjusted from the driver's seat,

100

consisting of a handle mounted upon the dashboard so connected
by a linkage with the needle valve or air intake control of the
carburetor as to permit of its regulation by the driver while the
car is in motion.

Dashpot — A device for automatically dampening or slowing
down the movements of a part without preventing its free change
of position. It consists of a piston fitting in a cylinder filled
with a fluid, generally air, gasoline, oil, glycerine or mercury.
Small orifices are provided for the gradual escape of the fluid
from the cylinder. The dashpot piston is connected to the
part the sudden motion of which is to be checked and the
slow rate at which the fluid can enter or leave the cylinder
prevents sudden movements. Used to prevent the fluttering of
the air valves of carburetors under sudden fluctuations of en-
gine suction.

Dead Centre — In a reciprocating steam
or internal-combustion engine the two po-
sitions of the crank and the connecting
rod in which they are in the same straight
line. When so placed, pressure acting upon
the piston cannot cause rotation of the
crankshaft. Of these two positions, that
in which the crank is upon the side of CRANK^TN DEAD
the crankshaft toward the piston is the CENTRE

inward dead centre and the other posi- POSITION

tion is the outward dead centre.

Dead Storage — In garage practice, the housing of an automo-
bile (usually at a special low rate), upon an understanding with
the owner that it is not to be used, but is to remain idle.

Decarbonize (v.) — To remove carbon incrustations from the
piston head, valves and combustion space of an internal-com-
bustion motor.

Decarbonizer — A substance or device used to decarbonize a
motor. Chemical or solvent decarbonizers are liquids or pow-
ders intended to be introduced into the combustion space and
which are capable of disintegrating and loosening the deposits
through a solvent action upon their binding materials. Mechani-
cal decarbonizers are those devices which scrape or break off
the deposits from the metal surfaces.

Syn. : Carbon remover.

Decelerate (v.) — To decrease in speed or velocity.

101

Deceleration — The rate of decrease in the speed or velocity of
a moving body. Strictly speaking, the limiting ratio of the loss
in velocity during an infinitely short period of time to the length
of the period of time itself. In practice deceleration is generally
measured in feet per second per second. The antonym of accel-
eration and used in connection with the effect of automobile
brakes.

Syn. : Retardation, which is preferable.

Deflate (v.) — To reduce the pressure within a pneumatic tire
by allowing the air within it to escape.

Deflector Plate — A specially formed, usually curved plate on
the pistons of two stroke cycle engines, the function of which is
to cause the fuel charge, as it enters the
cylinder, to take such a path that it par-
tially forces out the remaining exhaust
gases, but does not escape wastefully
through the exhaust passages.

Deflocculated Graphite — Graphite in
such a very finely divided state that it
will remain almost indefinitely in suspen-
sion in a liquid. It is added to oils and
greases to increase their lubricating quali-
ties and especially to gas engine cylinder
oil for use in vehicle motors.

Demi Limousine — A form of limousine body in which, while
the extreme rear portion is permanently enclosed and the roof is
fixed, the sides are not entirely enclosed.

Demi Tonneau — A form of touring body with a small ton-
neau, usually seating two, which is occasionally made detacha-
ble. The front seat is usually placed well forward as in the
roadster type.

Syn. : Baby tonneau ; miniature tonneau ; toy tonneau.

Denatured Alcohol — Ethyl or grain alcohol, which has been
rendered undrinkable by the addition of wood alcohol, benzine
or other substances, and which is sold at a much lower price
than grain alcohol, on account of not being taxed. When added
tc water it forms an excellent anti-freeze solution for use in
the circulating systems of water cooled cars and in acetylene
generators. Mixtures of denatured alcohol and water contain-

DEFLECTOR PLATE.

A, Deflector.

102

ing the following percentages of alcohol freeze at approxi-
mately the temperatures given below :

20% + 14° F.

30% -5° F.

40% —20° F.

50% -35° F.

Also used to a limited extent as a fuel for internal combustion
motors, either alone or in combination with gasoline and benzol.

Depolarizer — A chemical substance with which the carbon or
copper element of a primary battery cell is surrounded and which
prevents the reduction of the cell's activity, known as polarization,
that results from the accumulation of hydrogen upon the element.
Depolarizers are substances which readily give up oxygen which
combines with the hydrogen while in a nascent state, forming
water. Manganese dioxide is used in dry cells.

Diaphragm — A thin, somewhat flexible, usually circular plate
or sheet of rubber, metal or other resilient material, held rigidly
at its edges and so arranged that one side
is subjected to a fluid pressure which
bulges the central portion of the plate.
Such deformation, the amount of which is
somewhat proportional to the pressure act-
ing, makes the diaphragm a detector of
pressure variations and adapts it for use
in pressure regulating devices. It is used
to regulate the fire in steam vehicles, the
diaphragm being under the influence of the
steam pressure and acting upon the fuel
valve; also in gasoline motor speed gov-
ernors, the diaphragm being under the influence of the circu-
lating water pressure, and controlling the throttle opening. A
diaphragm, acted upon by a succession of intermittent pressures,
is sometimes used as an impulse pump to pump gasoline or air
in fuel feed systems.

Dielectric — An insulator or non-conductor (q. v.).
Differential Brake— See brake, differential.
Differential Carrier — The frame which carries the driven
bevel gear, the differential gear and the bearings thereof in a
floating type rear axle (see axle, full floating), and which is

DIAPHRAGM
DEVICE.

103

bolted to the inside of the axle housing in such a manner that it
may be detached and removed therefrom through a handhole
(q. v.) in the housing when the axle shafts have been withdrawn.

Differential Case — The housing that encloses and forms the
main structural part of a differential gear. It is usually of cast
iron or pressed steel, made in halves and provides two bearings
in which the two master gears of the differential are sup-
ported. In it are fastened the studs upon which the differential
pinions rotate and to it is also secured the driven gear or
sprocket which receives the driving effort. It is often not a
tight housing, but somewhat open to allow lubricant to enter
from the axle housing. The term is often applied to the en-
larged portion of the axle, housing which, in shaft driven cars, en-
closes the driving gears as well as the whole differential.

Differential Gear — A combination of gears included in the
transmission system of an automobile, which permits driving
effort to be equally transmitted to each of the two traction
wheels, even when they are rotating at different speeds, as in
rounding corners. It is mounted upon the driving axle in live
axle cars and upon the divided countershaft in double chain
driven cars, and forms the connection between the two axle
shatts, or between the two sections of the countershaft re-
spectively. It consists 'of two master gears, one of which is
secured to each of the adjacent ends of the divided shaft and
between which, and in simultaneous mesh with both of which
gears is a series of pinions carried upon studs fixed in a rotat-
ing frame or housing. To this frame or housing is fastened
the driven gear or sprocket which receives the driving effort of
the motor. So long as the traction wheels of the car are re-
quired to rotate at the same speed, driving effort is transmitted
from the frame or housing, through the pinions equally to the
two master gears and their shafts, and no rotation of the
pinions takes place. When however, the traction wheels are re-
quired to rotate at differing speeds, the pinions rotate upon
their studs and simultaneously revolve upon the master gears,
permitting relative motion of rotation between the latter, and
allowing each to turn at the speed required by its respective
road wheel to which equal tractive efforts are transmitted.

Syn. : Differential; compensating gear; equalizing gear; jack-
in-the-box.

104

BEVEL DIFFERENTIAL.

Differential, Bevel— A

type of differential gear, the
two master gears and the
pinions of which are all of
the bevel type, two, three or
four of the latter generally
being used.

Differential, Spur — A type of differential gear in which
spur gears and pinions are substituted for beve1?;. To each
of the adjacent ends of the divided axle
or countershaft is secured a spur master
gear and the frame or housing supports,
two, three or four pairs of spur pinions.
The two parallelly arranged spur pinions
of each pair are in mesh with each other
upon the inside half of their tooth faces,
and one pinion of each such pair is in
mesh upon the outside half of its tooth
face with one of the master gears, while
the other pinion of each pair is in mesh
on the outside half of its tooth face with
the other master gear. The action of the
spur combination is, in effect, the same
as that of the bevel arrangement.

Differential Lock — A device which, when in action, prevents
the operation of the differential gear and which is installed upon

some cars for the pur-
pose of facilitating start-
ing even though one
driving wheel may lack
adhesion on account of
slippery road conditions,
in which case it would
slip and fail to drive and
the other wheel would
fail to rotate. The dif-
ferential lock acts to so
fasten together the mas-
ter gears of the differ-

SPUR GEAR,
DIFFERENTIAL.

DIFFERENTIAL LOCK.

A and B, Master Gears.
C and D, Spur Pinions.
When A is shifted to the dotted position
it meshes with C and D at the same time,
thus locking the differential.

ential, that they and

105

their shafts cannot rotate relatively and the traction wheels thus
being rigidly fastened together turn at the same speed. It is
usually put into action by means of a pedal.

Differential Master Gear — One of the main gears of a
differential which is fastened to one of the abutting ends of a di-
vided axle or countershaft and with which and the other
master gear the pinions simultaneously mesh.

Differential Pinion — One of the small gears which acts to
transmit the driving effort from the frame or housing of a dif-
ferential to the master gears and their shafts and to divide the
tractive effort equally between the two driving wheels.
Differential Piston — See piston, double diameter.
Differential Spider — A part consisting of a hub and two,
three or four symmetrically disposed radial arms which carry
studs upon which the pinions of a differential gear rotate. It
is rotatably mounted upon the ends of the two divided shafts
or upon the inside portions of the hubs of the master gears.
The outer ends of its arms are fast in the differential frame
or housing.

Syn. : Pinion frame.

Dimmer — An arrangement for reducing the intensity of elec-
tric headlights, usually consisting of a rheostat (q. v.), more or
less of the resistance of which can be introduced into the head-
light circuit at the will of the operator.
Direct Current — See continuous current.
Direct Drive — The transmission of the driving effort of a
vehicle motor from the crankshaft to the final drive mechanism

without the use of a countershaft
or system of gears under load.
In a shaft driven car, when on
the direct drive, transmission is
effected by a connection of the
crankshaft through the clutch,
clutch shaft, the main shaft of
the gearbox (in line with the
clutch shaft), the drive shaft and
its universal joints and the pro-
peller shaft to the driving pinion
at the rear axle, all these parts
rotating at crankshaft speed. Re-

DIRECT DRIVE BY MEANS
. OF JAW CLUTCH.

A, B, Jaw Clutch.

106

duced frictional losses and noise are advantages of the direct
drive. (See sliding gears, direct drive type.)

Direct Drive, Double — The transmission of the driving effort
from a vehicle motor to the road wheels at two different speed

ratios, without the

use of a countershaft
P*L wr^r

\\ -BnnxrvJ&liL* °T * ^V^™ °* C"3"?6

I f^lfjllljftl speed gears under

load. In a shaft
driven car with the
gearbox and rear axle
constituting a single
unit, a double direct

DOUBLE DIRECT DRIVE. drive is sometimes se-

cured by mounting
upon the differential

housing two bevel gears of different diameters which are in
constant mesh with two bevel pinions of correspondingly differ-
ing diameters which are loose upon the propeller shaft except
when one or the other of them is made fast thereto by means of
a double jaw clutch controlled by the gear shaft lever.

Discharge (n.) — In a storage cell, the flow of stored elec-
tricity therefrom into an external circuit. The opposite of charge.

In ignition practice, the passage of high tension electricity
through a dielectric, usually an air gap in the form of a spark
or arc; e. g., the disruptive discharge between the points of
a spark plug. Discharge (v.). To produce such a flow or pas-
sage of electricity as above described.

Discharge, Rate of— The rate at which electricity flows
from a storage cell through an external circuit, usually measured
in amperes.

Discharge Terminals — The two conducting points between
which a disruptive discharge of high tension electricity takes
place. In a jump spark plug, the two discharge terminals are
usually of platinum or an alloy thereof or of other not readily
fusible or oxidizable metal. Syn. : Sparking points.

Distance Rod — A rod the function of which is to maintain
related parts at a fixed distance apart. The term is specifically

107

DISTANCE ROD.

A, Frame; B, Spring; C, Rear Axle Tube;
D, Rear Axle.

applied to the two
rods that maintain
the fore and aft po-
sition of an axle, es-
pecially that of the
driving axle, by re-
sisting the reaction of
the tractive effort
which tends to shift
the driving axle for-
ward relatively to the

rest of the car. The rods are usually of steel tubing, pressed

steel or steel forged into an I-section.
Syn. : Strut rod.

Distributor — A device for directing high tension ignition
current from a single secondary winding to the respective spark
plugs of a multicylinder engine
in the correct firing order. It
consists of a stationary plate of
insulating material, upon the
surface of which are fastened
symmetrically spaced, circu-
larly disposed contact segments,
in number equal to the cylin-
ders to be served. A shaft,
operated at one half motor speed, passing through the shell car-
ries an insulated contact brush, which, when in rotation, success-
ively contacts or nearly contacts with the segments. One ter-
minal of the secondary winding is electrically connected to the
rotating brush and the other is grounded, and each segment is
electrically connected to a spark plug. A distributor forms a
part of nearly all synchronous jump spark magnetos and of all
single-coil battery systems adapted to multicylinder motors.

Syn. : High tension distributor ; secondary commutator.

Distributor Valve — See valve, distributor.
Distribution Gears — See half time gears.

Double Ignition — Ignition which can be obtained at will from
either one of two complete and distinct ignition systems, which
are in no way dependent one upon the other, and which can

MAGNETO DISTRIBUTOR.

108

generally be' used simultaneously, if desired. A double ignition
outfit generally consists of a synchronous magneto, serving one
set of spark plugs and some form of battery system serving another
set of spark plugs, with a switching arrangement adapted to put
into action, at will, either ignition source or both together.

Double Motor Equipment — In an electric vehicle, the pro-
vision of two electric motors each one of which drives its respect-
ive traction wheel only, being direct connected or geared there-
to. No differential gear or live driving axle is thus required.

Double Spark Ignition — Ignition which is effected by two
sparks produced simultaneously at two separate points in the
combustion space of a gas motor, the object being to secure a
more rapid combustion of the fuel charge. Two plugs, placed
at a distance apart in the combustion space of each cylinder and
served by two synchronized magnetos or a double magneto,
are employed.

Syn. : Multipoint ignition, twin spark ignition.
Dowel Pin — A pin, usually of steel, fixed in a part which is to
be positioned exactly upon a related part. Such pins exactly
fit in corresponding, properly located
holes, in the related part, and, when the
pins are inserted in the holes, the two
parts are always in exactly the same re-
lationship.

Drag (v.)-The faulty action of a
clutch which, even when in the released

position, still communicates a slight turning effort from the driv-
ing to the driven member, and its shaft, occasioned by the failure
of the engaging surfaces or the lubricant upon them completely
to move out of contact.

In a brake, the failure of the band or shoe completely to move'
out of contact with the drum upon which it acts, even though the
controlling mechanism is in the released position. Generally due
to faulty adjustment or design.

Drag Link — In a steering gear, the rod which connects the
steering device, mounted upon the vehicle frame, to one of
the axle stubs and transmits the

no

steering movements of the opera-
tor to the steering wheels. As the
steering device has an up and
down motion relatively to the DRAG LINK.

109

axles the ends of the drag link have a universal movement at
their fastenings, and ball joints are thus generally used Ht these
points.

Drain Cock — A small cock, arranged to communicate with
the steam chest of a steam engine cylinder which, when opened,
permits the water of condensation to escape therefrom, thus
preventing possible damage to the cylinder caused by the piston
forcing water against the cylinder heads.

Also, any cock which is used to drain a liquid from a space in
which it is confined.

Draw=off Plug — A plug inserted in a hole at the lowest point
of an enclosed space containing liquid, the removal of which per-
mits the liquid to escape. Used in the bottoms of crank, gear
and axle cases and carburetor bowls and in water and oil cir-
culating systems, etc.

Drift Pin — A tapered steel pin used to line up two or more
holes in parts which are to be put together, so that the bolt, pin
or other part which is to be inserted in the holes may readily be
passed through them.

Drive Shaft — In general, a shaft which transmits driving ef-
fort from one rotating part to another. In a shaft driven car, the
shaft which transmits
the driving effort from
the transmission parts
that are mounted upon
the vehicle frame to the
transmission parts at the DRIVE SHAFT

driving axle. In a car
with a rear axle mount-
ed gear box, the front end of the drive shaft is connected, through
its universal joint, to the driven member of the clutch and it*
rear end is connected to the primary shaft of the gearset. In
other shaft driven constructions, the front end of the drive shaft
is universally connected to the final shaft of the gearset and its
rear end to the pinion shaft in the rear axle, or it carries the
driving pinion directly upon its rear end.

Drive Shaft, Double Jointed — A drive shaft with a universal
joint at each end and usually including a slip joint.

Drive Shaft, Single Jointed — A drive shaft with a universal
joint at its front end only, the shaft housing acting as a torque
and distance rod, and the driving pinion being carried directly

no

upon the rear end of the shaft, except in that type of construc-
tion in which the gearbox is integral with the rear axle housing.
Drive Shaft Housing — The tubular casing which encloses the
drive shaft on a shaft driven car, supports the shaft bearings,
excludes dust therefrom and retains lubricant. It also some-
times performs the functions of a torque rod and of a distance
rod, preventing the axle casing from rotating unduly and from
moving forward relatively to the rest of the car under the reac-
tion of the tractive effort.

Driven Member — That one of two connected mechanical ele-
ments which receives its motion from the other, e. g., the mem-
ber of a clutch which is not fast to the motor shaft; the gear
which is mounted upon the differential housing in a shaft driven
axle.

Driving Member — That one of two connected mechanical ele-
ments which transmits motion to the other, e. g., the member of
a clutch which is secured to the motor shaft, the pinion upon the
drive shaft of a shaft driven car.

Drop Forging — The process of producing parts from steel
and other malleable metals when heated to a malleable condition,
by forming the metal into the desired shape
by repeated blows from dies carried in a pow-
erful drop hammer. The term is used in con-
tradistinction to "hand forging," and is also
applied to the parts produced by the process.
Syn. : Die forging.

Dry Battery, Dry Cell— See cell, dry.
Dual System — A system of ignition em-
ploying two current sources, namely, a syn-
chronous magneto and a battery. The make-
and-break, the distributor, the transformer
coil, the wiring and the plugs of the magneto,
or a part at least of these elements are trav-
ersed in common by both battery and mag-
neto current, the battery current utilizing the
magneto parts, as the elements of a single coil and distributor
battery system. This system facilitates starting of the motor by
the use of battery current. A switch applies either battery or
magneto current at will. Such a system may provide a timer for
the battery current entirely distinct from the magneto make-and-
break and, in this case, only the magneto distributor and the
spark plugs are common to both systems of ignition.

DROP (FORGING)
HAMMER.

Ill

DUST CAP.

Dust Cap — A cap, screwed over the valve stem of
a tire, seating upon the inside of the felloe. It pre-
vents dust and water from entering the valve stem
hole in the felloe and accumulating between the tire
casing and rim.

A cap arranged over the exposed end of a bearing
or over the exposed parts of a mechanism, to pre-
vent the entrance of dust.
Dust Hood — See top cover.
Dust Pan— The sod pan (q. v.).
Dynamo— A mechanical generator of electricity, the soft iron
field magnets of which are charged by current generated by the
machine itself. It consists of an
electro-magnetic field between the
poles of which is rotated, by ex-
ternal mechanical power, an ar-
mature (q. v.). The cutting of
the magnetic field by the arma-
ture conductors generates in them
an electromotive force (q. v.) and

in the operation of the machine DYNAMO.

mechanical energy is transformed into electrical energy. A commu-
tator (q. v.) and brushes (q. v.) are used to convert the current
produced in the armature conductors into a continuous current
(q. v.) in the external circuit. A relatively small portion of the
output of the machine is utilized in magnetizing its fields. Used
to charge the storage batteries of electric vehicles and also in-
stalled upon motor cars to charge storage batteries for lighting
and ignition service.

Syn. : Dynamo electric machine.
Dynamo, Bipolar — A dynamo, the
magnetic field of which produces a
single north and a single south pole,
arranged diametrically opposite with
respect to the armature.

Dynamo, Compound Wound — A
dynamo, the field magnets of which
are magnetized by a combination of
the methods used in the shunt wound
dynamo (q. v.) and in the series

COMPOUND WOUND
DYNAMO.

wound dynamo (q. v.). It is used in some vehicle lighting systems.

112

Dynamo, Constant Current — A dynamo, so designed that
the current it furnishes to the external circuit increases but
sightly above normal with increased driving speed and reduced
external resistance. Internal reactions caused by any slight in-
crease of current produce a rapid drop in the external voltage
and prevent further current increase. (See inherent regulation.)
Used to charge the storage battery in some lighting and self-
starter systems.

Dynamo, Constant Voltage — A type of dynamo used in
vehicle lighting, which delivers a nearly constant electrical pres-
sure to the external circuit, independent of the speed of the
vehicle motor which drives it. An automatic clutch, under the
control of a device sensitive to speed fluctuations, may be inter-
posed between the engine and the dynamo and the speed of the
latter be maintained nearly constant by clutch slipping, or the
field magnets may be automatically weakened and strengthened
in proportion with increases or decreases of speed and the
voltage produced thus regulated to a nearly constant, value.

Dynamo, Multipolar — A dynamo, the magnetic field of
which comprises more than one pair of poles, produced by more
than one electromagnet and symmetrically disposed around the
armature. Each armature conductor cuts the magnetic field
as many times per armature rotation as there are poles. The
multipolar dynamo, especially the four pole type, is commonly
used in vehicle lighting, as it is adapted for operation at a lower
speed than is the bipolar type.

Dynamo, Series Wound — A dynamo, the field magnets of
which are charged by coils of rather coarse wire and compara-
tively few turns, through which the entire current generated in
the armature passes on its way to the external circuit.

Dynamo, Shunt Wound — A dy-
namo, the field magnets of which are
charged by coils of rather fine wire
and numerous turns wound about
them. The coils are connected in
series and one terminal of the series
is connected to one brush and the
other terminal to the other brush of
the machine. A part of the current
generated in the armature thus tra-
SHUNT WOUND DYNAMO, verses the field coils and the remain-

113

tier supplies the external circuit. At a constant armature speed,
this type of dynamo maintains a nearly constant electrical pres-
sure, even though the current supplied the external circuit varies
quite widely and it is therefore largely used in charging electric
vehicle batteries and in vehicle lighting.

Dynamo Bracket — A support provided upon the base of a
gas vehicle motor, for the convenient mounting of a dynamo
in suitable driving relationship to some moving part of the
engine.

Dynamometer — In general, an instrument or apparatus de-
signed to measure the rate at which mechanical energy is being

delivered by or to a power
producing or power trans-
mitting mechanism. In auto-
mobile practice, an instru-
ment capable of measuring
the rate at which mechani-
cal energy is being delivered
by a vehicle motor which is
used by automobile manu-
facturers to determine
whether such motors are
in proper working condi-
tion. Also occasionally used
to determine the rate at
which mechanical energy is
being delivered to the trac-
tion wheels of an automo-
bile and for similar pur-
poses. A dynamometer
measures the torque or

turning effort received by it in pounds-feet, and by multiplying
its indication by the angular speed in radians per minute, and
dividing the product by 33,000 the horse power is obtained. A
dynamometer which dissipates the energy to be measured is
an absorption dynamometer, and one which measures the turning
effort transmitted to another machine is a transmission dyna-
mometer. The fan dynamometer and the prony brake are ex-
amples of the former type, and the electric cradle dynamometer
and the power scale are examples of the latter type.

FAN DYNAMOMETER.

114

Dynamometer Test — As applied to an automobile motor,
a test made upon it by means of a dynamometer to determine
its output at various speeds, before mounting it upon the vehicle
which it is to drive.
Syn. : Brake test.

Eccentric — A circular metal plate or disc fixed to a power
shaft with its plane at right angles thereto, the centre of which
disc does not coincide with the axis.
The distance from the centre of the ec-
centric to its shaft axis is known as its
eccentricity. It is used in connection
with other parts to convert rotation into
reciprocation of rather short stroke.

Eccentric Bushing — A bearing bush-
ECCENTRIC *n£ the outside cylindrical surface of

A Eccentric Plate- B which is not concentric with its bore
Eccentric Strap; C, in which the shaft bears. By turning
Connecting Rod; D, 111- • « « ' •

Shaft. the bushing in the bearing support, the

position of the shaft axis can be slightly

altered. Used to adjust shafts, especially those which carry
gears that require to be exactly pitched.

Eccentric Rod — The rod which transmits the motion of an
eccentric strap to mechanism which is to be operated thereby.

Eccentric Strap — A metal strap which is fitted about the
periphery of an eccentric and which transmits motion from an
eccentric to an eccentric rod.

Efficiency — The ratio of the rate at which energy is given
out by a machine or apparatus for the conversion of energy, to
the rate at which energy is received by it. It is expressed as a
percentage always less than 100. The energy received less the
resulting losses of energy, divided by the energy received in a
given period of time, gives the efficiency.

Efficiency, Ampere Hour — In a storage cell, the ratio of the
total ampere hours of current delivered by it during discharge
to the total ampere hours of current required to charge it to
the condition from which it is discharged.

Efficiency, Dynamo — The ratio of the mechanical equivalent
of the rate at which useful electrical energy is developed by a
dynamo to the rate at which mechanical energy is expended in
driving it.

115

Efficiency, Electric Motor— The ratio of the rate at which
useful mechanical energy is given out by an electric motor to
the mechanical equivalent of the rate at which electrical energy
is absorbed in driving it.

Efficiency, Ideal — In a steam or internal combustion motor,
its efficiency as computed by the application of thermodynamic
laws, when certain assumptions not realized in practice are made.
It is the maximum limit of efficiency which may be approached
but never be attained, as actual conditions approximate more
closely to the assumed or ideal conditions.

Efficiency, Mechanical — In a steam or internal combustion
motor, the ratio of the rate at which useful mechanical energy
is delivered at the driving end of the crankshaft to the rate at
which mechanical energy is supplied to the piston or equivalent
part by the working fluid.

Efficiency, Storage Battery — See efficiency, watt hour.
Efficiency, Thermal — In a steam or internal combustion mo-
tor, the ratio of the rate at which mechanical energy is de-
livered to the piston or equivalent part by the working fluid to
the mechanical equivalent of the rate at which thermal energy is
supplied the motor by the fuel used.
Syn. : Indicated efficiency.

Efficiency, Transmission — In a power transmitting device or
systems of such devices, the ratio of the rate at which energy
is delivered, to the rate at which it is received; e. g., in a motor
car, energy is received from the motor at the clutch, at the rate
of 30 horse power and delivered at the driving wheel rims at
the rate of 21 horse power. The efficiency of transmission is thus

21
-=0.70%.

Efficiency, Useful — In a steam or internal combustion mo-
tor, the ratio of the rate at which useful mechanical energy is
delivered at the driving end of its crankshaft, to the mechanical
equivalent of the rate at which thermal energy contained in the
fuel used is supplied to it.

Efficiency, Watt Hour — In a storage cell, the ratio of the
total electrical energy available during discharge to the total
electrical energy required to charge it to the point from which
it is discharged.

Efficiency, Weight — In a mechanism capable of delivering
energy, the weight thereof per unit of output, e. g., in a gasoline

116

engine weighing 500 pounds, and capable of delivering 25 horse
power, the weight efficiency is 20 pounds per horse power. Ap-
plied also to storage cells.

Syn. : Activity, which is rather to be preferred.

Eight Cycle (v.) — In a four cycle gas engine cylinder, to
fire alternate charges only, so that a power impulse is produced
but once in eight strokes. This faulty action is usually caused
by the presence in the cylinder during the missed strokes of
a mixture too foul to ignite, which is expelled unburned and
replaced by a less foul charge during alternate cycles, the cyl-
inder having been well scavenged during the inactive cycle.

Elastic Limit — The maximum stress per unit of cross sec-
tion which can be applied to a certain material, such as a metal,
without the production of a noticeable permanent deformation
of the same. Stresses below the elastic limit produce temporary
deformations, which disappear upon the removal of the stress.
The elastic limit is usually expressed in
pounds, per square inch and, unless
otherwise stated, refers to tensile
stress.

Electric Horn — An alarm or sig-
naling device sounded by electricity.
It consists of a diaphragm or reed
vibrated by an electromagnetic vibra-
tor or a diaphragm vibrated mechani-
cally by means of a small electric
motor driving a toothed wheel. A

horn-shaped resonator amplifies and directs the sound waves set
up by the diaphragm. Such horns are usually operated by bat-
tery current controlled by a push
button located upon the steering
wheel.

Electric Motor — A machine for
converting energy in the electrical
form into energy in the mechani-
cal form, the construction of which
is identical with that of a dynamo
(q. v.)- In fact, the same appara-
tus acts as a dynamo when its
armature is rotated by mechanical
ELECTRIC MOTOR. energy, and as a motor when elec-

ELECTRIC HORN.

117

tricity is supplied to its windings from an external source. When
used as a motor, electromagretic reactions continually take place
between the field and the armature conductors, and the armature
shaft is rotated, delivering- mechanical energy. It is used to
propel electric vehicles, the supply of current being derived from
a storage battery carried upon the vehicle.

Electric Motor, Axle Suspended — An electric motor which
is supported by or upon the axle of the vehicle which it drives
or upon some part attached to the axle, which is not spring
supported.

Electric Motor, Back Geared — An electric motor the frame
of which supports a countershaft which is driven from the
armature shaft by gears or silent chain. A speed reduction
is thus made at the motor itself.

Electric Motor, Bipolar — See dynamo, bipolar, which is
identical in construction therewith.

Electric Motor, Compound Wound — See dynamo, com-
pound wound.

Electric Motor, Frame Supported — An electric motor
which is mounted upon the vehicle frame, its weight being thus
supported by the vehicle springs. The accepted practice in ve-
hicle motor mounting.

Electric Motor, Ironclad — A type of motor the field mag-
net frame of which is so formed as to enclose the field coils,
armature and commutator, thus preventing the entrance of
water, oil and dust. Most vehicle motors are of this type.

Syn. : Motor, enclosed type.

Electric Motor, Multipolar — See dynamo, multipolar. All
vehicle motors are of this type, being usually of four or six
pole construction. They operate at lower speeds than the bipolar
type, and less speed reduction is required between the motor
and the driving wheels.

Electric Motor, Series Wound — See dynamo, series wound.
Practically all vehicle motors are of this type on account of
their superior flexibility and large torque development at low
speeds. Their field coils are frequently wound in sections, dif-
ferent combinations of which, effected at the controller, produce
different field strengths and corresponding speed variations.

Electric Motor, Shunt Wound — See dynamo, shunt wound.
A type rarely, if ever, used in electric vehicle practice.

Electrical Pressure — See electromotive force.

118

Electrolyte — In general, a liquid which is decomposed when
an electric current is passed through it. Specifically, a solu-
tion used to charge electric batteries. The electrolyte used in
a lead storage cell consists of distilled water to which sufficient
pure sulphuric acid has been added to make the specific gravity
of the mixture about 1.250 at 60 degrees Fahr. In a storage
cell of the Edison type the electrolyte is an aqueous solution
of potassium hydrate and in a dry cell an aqueous solution of
salammoniac.

Electromagnet — A magnet which owes its magnetic proper-
ties to the inductive action of an electric current, and which
ceases to be magnetic upon the cessation
of the current, being thus distinguished
from a permanent magnet which requires
no current to maintain its properties. It
consists of a core of soft iron around
which is wound a coil of insulated wire

through which an electric current is passed.
ELECTROMAGNET. The cores of induction coils are electro

A, Core; B, Coil. . , , , - ,

magnets, as are also the fields of dyna-
mos.

Electromotive Force — The force, analogous to a pressure,
which maintains a flow of electricity through a closed circuit.
The unit of electromotive force is the volt (q. v.).

Syn.: Electrical pressure; voltage. Abbreviation: e. m. f.

Electromotive Force, Counter — An electromotive force act-
ing oppositely to the applied or impressed electromotive
force or to the normal electromotive force. In an electric
motor, the electromotive force set up by its armature acting in
the capacity of a dynamo armature.

Element — One of the substances used in a battery between
which and a dissimilar substance an electromotive force is set
up by chemical action. The carbon and zinc plates of a dry cell
and the positive and negative plates of a storage cell are the
elements of these two types of battery.

Emergency Brake — See brake emergency.

Emergency Car — A motor car, equipped with tools, supplies,
spare parts and towing tackle and carrying one or more automo-
mobile mechanics, which is maintained at some public garages and
which is sent to the assistance of cars that have become disabled
at a distance from repair facilities,

119

Emergency Tank — See auxiliary fuel tank and auxiliar>
oil tank.

Enamelled Wire — Wire which is insulated by coating it with
a cellulose or other non-conductive enamel, instead of with silk
or cotton. It is used for the windings of some induction coils
because of the compact coils which it produces.

En Bloc — See cylinder, block cast.

End Play — A slight motion along its axis allowed a shaft
rotating in bearings. Its object is to distribute bearing wear, to
guard against excessive wear at thrust collars and to provide
for slight inaccuracies of movement of parts attached to such a
shaft.

End Thrust — Pressure in line with the axis of a shaft as
distinguished from radial pressure, which acts at right angles
to its axis and against its supporting bearing surfaces, e. g., the
pressure acting along the driving pinion shaft of a bevel driven
car due to the reaction of the gear tooth pressure.

Engine — See motor and steam engine.

Engine Base — The structural portions of a vehicle engine
by which it is attached to the car frame. See crank case.

Engine Casing — A casing, usually of sheet metal, sometimes
used to enclose a steam vehicle engine for the purpose of ex-
cluding dirt and of retaining heat 'and lubricant

Envelope — A perforated pocket, made of thin insulating ma-
terial, used to enclose a storage cell plate for the purpose of
preventing detached active material from shortcircuiting between
neighboring plates. Also a top cover (q. v.).

Epicyclic Gear — See planetary gear.

Equalizer — See brake equalizer.

Equalizing Gear — See differential gear.

Exhaust (n.) — The working fluid of a heat motor which is
rejected in an expanded condition from the power cylinder, at
the end of the cycle of operations, after the available heat energy
contained therein has been converted into mechanical energy. In
an internal combustion motor the exhaust consists of a mixture
of steam, carbon dioxide and nitrogen with more or less carbon
monoxide, oxygen and hydrocarbon vapors. The exhaust from a
steam engine is steam at a temperature and pressure relatively
low as compared with its condition at entering the cylinder.

Exhaust (v.) — To reject the gases or vapors from a heat en-
gine after they have given up their available energy.

120

Exhaust, Auxiliary — See auxiliary exhaust.

Exhaust Alarm — An auditory warning or signaling device
which is operated by the movement of the gases exhausted from
a gasoline vehicle motor. The sound
producing device is usually of the
organ pipe type and one or several
such pipes may be sounded separate-
ly or simultaneously upon the open-
ing of a valve or valves which
allows exhaust gas to flow from the
exhaust pipe therethrough. A pedal
arrangement is generally used to
control the valve.

EXHAUST ALARM.

EXHAUST MANIFOLD.

Exhaust Manifold — The common pipe or chamber into which
pass the exhaust gases of all the cylinders of a multiple cylinder
motor, on their way to the exhaust
pipe and muffler. It is usually a
casting of tubular form with short
branch pipes ordinarily equal in
number to the cylinders to be served,
the ends of which branches are
clamped or bolted over the exhaust
port openings of the several cylin-
ders.

Exhaust Manifold, Air Cooled — An exhaust manifold, the
external surface of which is ribbed, corrugated or otherwise so
formed as to present a large convecting surface to the surround-
ing air to assist in the dissipation through it of the heat of the
exhaust gases.

Exhaust Manifold, Ejector Type — A manifold for multi-
cylinder gas engines, so constructed that the rush of exhaust
gas through it from any one of the cylinders at the end of its
power stroke is made to produce, through ejector action, a
rarefaction in one of the other cylinders which is on its ex-
haust stroke, thereby causing the waste gases to be more fully
ejected or scavenged from the latter cylinder.

Exhaust Manifold, Integral — An exhaust manifold which
is formed as an integral part of a cylinder casting. Largely
used in motors the cylinders of which are cast en bloc (q. v.).

Exhaust Manifold, Water Cooled— An exhaust manifold
provided with "a jacket through which the cooling water of the

121

motor is circulated, with the object of rapidly contracting the
heated gases and producing a more quiet exhaust.

Exhaust Manifold Clamp — A clamp which fastens the ex-
haust manifold to the cylinders of a gas motor and secures a
tight joint between the manifold branches and the exhaust port
openings.

Exhaust Pipe — The pipe through which the exhaust gases
or vapors escape from the exhaust port of a single cylinder en-
gine or from the exhaust manifold of a multicylinder en-
gine to the exhaust muffler or silencer.

Exhaust Port — The passage leading from the combustion
space of an engine cylinder through the cylinder wall, to which
the exhaust manifold or exhaust pipe is connected and through
which, upon the opening of the passage, the exhaust gases es-
cape.

Exhaust Port, Auxiliary — See auxiliary exhaust.

Exhaust Port, Siamesed — A form of exhaust port some-
times used in multicylinder gas engines which have twin cast
cylinders. The exhaust passages leading from two adjacent
cylinders are brought together into a single passage, so that a
single branch of the exhaust manifold receives the exhaust from
two cylinders.

Exhaust Stroke — In a four cycle gas engine that inward
stroke of the piston (upward stroke in a vertical engine) during
which the exhaust valve is open and the piston forces the gases
out of the cylinder through the exhaust valve. This stroke is
generally considered the fourth and final stroke of the four
stroke cycle.

Syn. : Scavenging stroke.

Exhaust Valve — The valve which controls the passage of
gases from the cylinder through the exhaust port. Exhaust
valves are generally of the poppet type (see headings under
"valve") operated by cams (q. v.). In common practice the ex-
haust valve is set to open at about 40 degrees of crank angle
ahead of bottom dead centre and to close at about 5 degrees
past top dead centre.

Expand (v.) — To increase slightly, by internal pressure, the
diameter of a steam boiler tube at the points where it enters
the end sheets of the boiler, in order to secure tight joints be-
tween the tube and the plates. The tubes are so treated in the
construction and repair of a boiler.

122

Expander — A tapered pin or swage of such diameter that,
when forced into the end of a tube it will expand the latter.

Expansion, Ratio of— In an internal combustion motor, the
ratio of the volume occupied by the charge at the instant of ex-
haust (q. v.) to the volume occupied by it at the end of the com-
pression stroke (q. v.). It is of practically the same numerical
value as the ratio of compression (see compression, ratio of).

Expansion Joint — A form of slip joint included in a rigidly
supported part which is subjected to wide variations of tempera-
ture, in order to provide for its . changes
of length in such a manner as to avoid
straining it or its supports. The two sec-
tions of the part can move relatively at
EXPANSION JOINT. the joint, thus making allowance for
changes in length.

Sometimes applied to long exhaust manifolds and exhaust pipes.

Explosion Pressure — See pressure of explosion.

Extra Current — The high tension current set up by the electro-
motive force of self induction in the winding of an electro-
magnet, when the magnetizing current is abruptly broken. The
extra current is discharged across the break in the circuit in the
form of an arc. The igniting spark utilized in contact spark igni-
tion systems which employ make-and-break spark plugs is pro-
duced by the extra current.

Eye Rod — A rod, the end of which is flattened and pierced
with a hole or eye, through which a pivot bolt or pin is passed
to secure it to some operative part, for instance, within a clevis
(q. v.) or yoke end. Used in control linkages.

Fan — As applied to gasoline vehicle engines, a rotary fan of
several sheet metal blades, generally carried by a horizontal
shaft driven from the en-
gine, and so arranged as to
create a blast of cool air to
assist in conveying away
excess heat from the cyl-
inders. On air-cooled en-
gines the fan is so placed
in front of the engine as to
deliver its blast upon the
cylinders and cylinder
heads, the heated air escap- FAX.

123

ing to the rear of the car. (See air cooling.) On water cooled
cars, the fan is placed just back of the radiator, and creates a
draft through it. (See water cooling.)

Fan, Belt Driven — A cooling fan, which is driven by means
of a belt which passes around a pulley upon the fan shaft and
around another pulley upon the crankshaft, camshaft or auxil-
iary shaft of the motor.

Fan, Condenser — The engine driven fan used upon a steam
car to force cool air through the condenser (q. v.) and thus
increase its effectiveness.

Fan, Gear Driven — A cooling fan which is driven by a train
of gears. A friction coupling is usually provided at some point
in the drive to prevent too sudden starting of the fan when the
motor goes into operation.

Fan Belt — The belt which drives a cooling fan. This may
be a flat leather or fabric belt running on flanged pulleys, a
V section leather belt or a leather covered metal link belt
running in V grooved pulleys.

Fan Belt Idler — An idler pulley over which a fan belt runs
and which is adjustable in position so as to permit slack in the
belt to be taken up.

Fan Guard — A circular metal guard arranged about the out-
side edges of a cooling fan, either fixed to an independent sup-
port or forming a part of the fan itself. It prevents objects
from being struck by the fan blades and, in some instances, acts
to concentrate the suction of the fan.

Fan Pulley — A pulley, fast upon a cooling fan shaft, by
which it is driven by belt from an engine shaft. Usually a
flanged or a grooved pulley.

Fan Support — The bracket or column which supports a fan
shaft. This may be a bracket fastened to the forward cylinder
of the engine, a column arising from the engine base or a struc-
ture supported by the radiator frame.

Syn. : Fan bracket.

Fatigue — The weakening of a metal brought about by its long
continued subjection to frequently recurring intermittent or re-
versed stresses, such as act in the working parts of motor cars.
Metals which possess special resistance to fatigue are known as
anti-fatigue metals. The failure of metals through fatigue is
sometimes held to be due to crystallization (q. v.).

Feather — See key.

124

Feed Pump — The pump which delivers water from the water
tank to the boiler of a steam vehicle. Usually a piston pump,
continuously driven from the crosshead of the engine or from a
rocking shaft driven from the engine. Its rate of delivery to the
boiler is regulated by a hand adjusted by-pass (q. v.).

Feed Water Heater — A means for warming the feed water
as it is pumped from the supply tank to the boiler of a steam
vehicle. The water is passed through a coil of pipe which is
surrounded either by exhaust steam or by hot chimney gases.
The preheating of the feed water tends to reduce the fuel con-
sumption.

Felt Washer — A ring shaped piece of thick springy felt, used
to prevent the escape of oil from a lubricated part and the
entrance of dust thereinto. Such washers are used at the
points where a shaft emerges from a bearing or housing, the
washer being tightly held against the inside surface of the
part and around the shaft itself, thus sealing the slight opening
which there otherwise would be.

Fender — A guard placed around and over the wheels of an
automobile to prevent the spattering of mud upon the body and

its occupants. The rear
ends of the front guards
are often united to the
front ends of the rear
guards by the two hori-
zontal running boards (q.
v.). The guards are
usually of sheet metal, and
are supported from the ve-

FENDER. llicle frame b^ irons. They

usually conform, upon their

inside edges, to the shape of the body, and thus form,
with the running board and its extensions, a continuous protec-
tion against flying mud.

Syn. : Mud guard.

Field, Magnetic— The space between and around the poles
of a magnet, within which magnetic influence is exerted. For
purposes of illustration the magnetic force is represented by im-
aginary lines (lines of magnetic force) extending from the north
to the south pole of the magnet in the field. The directions of

125

these lines represent the direction of the magnetic influence
and their number per unit of cross section is proportional to the
strength of that influence at the cross section in question. When
a conductor is moved through such a field in a direction such
as to make an angle with the lines thereof, it is said to cut
the lines of force and an electromotive force is developed in it
of a value proportional to the rate at which the lines are cut.
This is the principle involved in the operation of a dynamo
or magneto.

Syn. : Field of magnetic force.

Field Coil — A coil of insulated wire, through which is passed
a current of electricity to magnetize the soft iron core which it
encloses and thus to induce the magnetic field of a dynamo or
electric motor. All the field coils, considered as a unit, consti-
tute the field windings.

Field Commutation Control — A system of speed control
employed in connection with series wound electric vehicle mo-
tors. The field magnet windings are divided into sections all or a
part of which can be connected either in series or parallel by
means of the controller (q. v.) to produce several graded field
strengths. As motor speed increases with decrease of field
strength and vice versa, several vehicle speeds can thus be se-
cured. This method of control is often used in connection with
series and parallel arrangements of the battery to secure many
gradations of speed.

Field Magnet — A magnet which produces the magnetic field
that is cut by the armature conductors of a dynamo, magneto or
electric motor, in the process of its operation. The field magnets
of dynamos and electric motors are electromagnets, and those
of magnetos are permanent magnets (q. v.) of very hard steel.

Fierce Clutch — A clutch which is incapable of gentle engage-
ment, and which cannot be so operated that various rates of
slippage between the driving and driven members may be main-
tained. When its members are brought into contact, even though
very gently, the driven member almost instantly assumes the
same speed as the driving member, and the driven parts are
started into motion with a sudden jerk.

Syn. : Grabbing clutch.

Filler Board — A finished board so shaped as to fill the space
between the upper edge of the dashboard (q. v.) and the lower

126

edge of the windshield (q. v.) of a car and fastened to these two
parts so as to help to support the latter.

Fillet — In machine parts, where two surfaces intersect, a
portion of the material left around the line of intersection,
whereby a sharp corner is avoided. The object of a fillet is
to obviate an abrupt change of cross section of the part and
thus to avoid a dangerous concentration of stress at a particu-
lar point.

Filter— A device designed to remove foreign matter from a
liquid which is caused to flow through it. It usually consists of

one or more sheets of fine metal
gauze, or of chamois leather so
held that the liquid is constrained
to pass through it. Such a metal
gauze filter is generally included
in the fuel pipe leading from the
tank to the carburetor, or in the
delivery to the carburetor float
chamber, also in the oil delivery
passage of a self-contained lubri-
FILTER eating system, and in the water

circulating system. A chamois

filter is generally secured in the funnel through which gasoline
is poured into the fuel tank, and a gauze filter is often placed
within the filling holes of oil reservoirs.

Final Drive — The mechanism which transmits the driving ef-
fort of a vehicle motor from the transmission parts mounted
upon the frame to the axle supported transmission parts. A
chain or a pair of chains forms the final drive of a chain driven
car and a shaft carrying bevel or worm gears forms the final
drive of a shaft driven car.

Fire Test — A test sometimes applied to a lubricating oil to
determine to what temperature it must be raised to cause it to
burn.

Firing Order — In a multiple cylinder internal combustion
motor, the sequence in which the cylinders perform their work-
ing strokes. Numbering the cylinders, in order, from the front
to the rear, the firing order in four cylinder, four cycle engines
is i, 3, 4, 2. or i, 2., 4, 3 and in six cylinder engines the orders

127

I. 2, 3, 6, 5, 4; i, 5, 4, 6, 2, 3, and i, 2, 4, 6, S? 3 are customary.
Syn. : Firing sequence.

Firing Point — See ignition, point of.

First Speed — The lowest forward gear ratio obtainable from
a change-speed gear. This gear is used when a car is started
from rest and under conditions of extreme road resistance and
grade.

Syn. : Low speed, slow speed.

Fixed Air Inlet — See air inlet, initial.

Flame Propagation — The spreading of the combustion of the
fuel charge in a gas motor cylinder from the point at which the
spark takes place to other portions of the charge.

Flange — In general, a projection formed around the surface
of a part, usually at or near its edge, and ordinarily designed
to receive the fastening devices which secure it to another part.

A disclike enlargement formed upon the end of a shaft by
means of which it is bolted to another part, sucn as a wheel or
another aligned shaft. A flange coupling.

Flash Generator — See boiler, flash.

Flash Test — A test applied to a lubricating oil to determine
the temperature at which it begins to give off inflammable vapors
capable of being ignited. The temperature at which this occurs
is the flash point. The flash test is used to determine the relative
abilities of various oils to withstand the temperatures to which
they are exposed in the cylinders of internal combustion motors.
The flash points of gas engine cylinder oils are usually between
400° and 500° Fahr.

Flexibility — In an internal combustion motor, that quality
which enables it to do useful work through a very wide speed
range. The measure of flexibility is the ratio of its highest
useful speed to its lowest useful speed. The lowest useful
speed of a particular motor is the lowest speed at which it will
run, under load, without missing explosions and without labor
(q. v.), and its highest useful speed is that speed at which any
increment thereof fails to increase the output; e. g., a motor
possessing a useful speed range of from 100 to 1,200 r. p. m. has a
flexibility of 12, and one possessing a useful speed range of
from 200 to 1,600 r. p. m. has a flexibility of 8.

r

128

Flexible Coupling — A coupling used to connect two shafts,
intended to be in alignment one with the other, which permits
of slight angular motion between their connected ends, and thus

prevents binding of the shafts in
their bearings, which might be
occasioned by slight inaccuracies
in the shaft alignment. Such
couplings are used to connect
magnetos and other auxiliaries to
their driving shafts, and to con-

FLEXIBLE COUPLING.

FLEXIBLE METAL TUBING.

nect together transmission shafts which may at times be thrown
out of perfect alignment through distortion of the vehicle frame.
The Oldham coupling (q. v.) is of this type, and also various
forms of flange coupling, with a resilient material placed between
the two connected flanges.

Flexible Metal Tubing — A kind of tubing formed of con-
centric, closely wound spirals of flat
metal wire, which, while substan-
tially tight to fluids, is capable of
being bent at will. It is used for
connecting horn bulbs to horns, to
convey heated air to carburetors, to
convey oil and grease to inaccessible
points and under other conditions
where neither rubber tubing or stiff
metal tubing is desirable.

Flexible Shaft — A kind of shaft composed of a succession of
connected links enclosed in a tubular casing formed of a close
spiral of metal wire. The ends of the link chain are attached re-
spectively to the driving and driven mechanisms. Such a shaft may
be bent almost at will, without interfering with its action. Used to
drive speedometers from the road wheels and to operate various
tools in garages.

Float, Float Chamber, Float Valve, Float Depressor-
See under carburetor float, etc.

Floated Storage Battery — A storage battery which is con-
nected in multiple both to a charging dynamo and a load, such
as a group of lamps. It is constantly kept charged by the
dynamo, and the load is carried by the dynamo, so long as it is
in operation, no current being called for from the battery under
these circumstances. When the dynamo is not in operation, or

129

not delivering a sufficiently high voltage, it is disconnected from
the circuit, and the battery carries the load. The floated battery
arrangement is generally used in vehicle lighting systems, which
employ a dynamo.

Floating Shaft — A power transmitting shaft, which is not
rigidly restrained except as to rotation. It is thus not subjected
to bending but to twisting stresses only. Such a shaft is usually
supported at its ends only and at these points in such a manner
that it may readily accommodate itself to the movements of the
driving and driven parts without any transverse stresses being
set up in it. E. g., the shafts of a full floating axle.
(See axle, floating.)

Flood (v.) — To cause gasoline to be emitted from the spraying
nozzle of a carburetor into the vaporizing passage in order that
a rich mixture may be obtained when the motor to which the
carburetor is attached, is cranked. The flooding is usually ac-
complished by depressing the carburetor float, thus raising the
fuel level above the spraying orifice, and causing gasoline to
escape therefrom. Syn. : To prime, to flush.

Flooding System — See lubrication, circulating system.
Fluted Shaft — See sliding shaft and key, integral.
Flywheel — See balance wheel.

Flywheel, Fan Spoked — A kind of flywheel, with broad, flat
spokes, the surfaces of which are inclined to the plane of the
wheel. These spokes act as fan blades, and
when the wheel is in motion draw a cur-
rent of air through the radiator into the
bonnet space, thus taking the place of a
separate cooling fan.

Flywheel, Front Mounted — A fly-
wheel carried upon the forward end of
the crank shaft in front of the motor, and
not forming or carrying upon it a member
of the clutch, but frequently provided with
fan spokes on account of its close prox-
imity to the radiator.

Flywheel, Rear Mounted— A flywheel
mounted upon the rear end of the motor
crankshaft and usually forming or carry-
ing one member of the clutch. The ac-
cepted flywheel location.

FAN SPOKED
FLYWHEEL.

130

Flywheel, Web Type— A type of flywheel the rim of which
is joined to its hub by a continuous thin web of metal, instead
of by a series of spokes. This type is generally used when the
flywheel is made use of as the driving member of the clutch.

Flywheel, Wire Wound— A type of flywheel the rim of
which is wound with steel wire to reduce the danger of its
bursting at high speeds under the influence of centrifugal force.
A steel band is sometimes shrunk over the rim of a cast flywheel
to serve the same purpose.

Flywheel Bearing — The crank shaft bearing next to the
flywheel, which chiefly supports the weight of the wheel.

Flywheel Casing — A housing, usually of sheet metal, ar-
ranged around a flywheel to prevent objects being caught by the
wheel and to prevent .the wheel from throwing oil. In unit
power plants in which the flywheel is located between the engine
and the gear box, the flywheel casing forms a part of the cast
structural portion of the unit.

Flywheel Flange — A flange formed upon the end of the
motor crank shaft, to which the flywheel is bolted.

Flywheel Markings — Lines drawn upon the face of a fly-
wheel, the coincidence of which, with a fixed index, indicate the
correct points of inlet and exhaust valve opening and closing,
and sometimes the dead centres of a motor. Syn. : Timing marks.

Foam (v.) — In a steam boiler, to bubble violently on account
of the presence in the water of foreign matter, which renders it
slightly viscous, so that large steam bubbles form, the water
level rises, and much entrained water or priming is carried
over into the steam pipe and engine.

Footboard — One of the boards which form the floor of an
automobile, especially the floor of the front seat space, the re-
moval of which, in most cars, gives access to the clutch, gear
box, etc. Such boards are usually of wood, covered with lino-
leum or rubber matting, or of aluminum.

Foot Brake — See brake, foot.

Foot Throttle— See accelerator.

Footrest — A metal bar secured to the tonneau floor, trans-
versely of the car length, at such
a distance from the rear seat as
to form a brace for the feet of
the passengers. A similar rest is
sometimes provided reaching but FOOTREST.

131

part way across the front floor space, for- the benefit of the pas
senger who is not driving.

Force Feed Lubricator — See lubricator, force feed, and lubri-
cation, force feed.

Forced Draft — The practice of directing the exhaust from a
steam vehicle engine into the uptake, which carries the products
of combustion from the burner, in order to increase the draught
upon the fire.

Forced Induction — The practice of charging the cylinder of
an internal combustion motor with fuel mixture at a pressure
above that of the atmosphere, in order to secure increased
output thereby. The charges are forced in by a pump in-
stead of being drawn in by suction. Not in practical use to
any extent.

Fore=door Body — See body, fore-door (also written four-
door body).

Four=stroke Cycle — The cycle of operations performed by
the so-called four-cycle type of internal combustion motor, in
which one piston stroke in each four is a power stroke. The four
strokes are as follows: I — suction, intake or aspirating stroke;
2— compression stroke; 3— power or working stroke; 4 — ex-
haust or scavenging stroke. '(See aspirating stroke, compression
stroke, power stroke, exhaust stroke and cycle of operations.

Syn. : Otto cycle.

Four Cycle (v.) — In a two-cycle engine cylinder, to fail to
fire each alternate charge. It is usually caused by the presence
in the combustion space, during each missed explosion, of a mix-
ture too foul to be ignitable and most commonly occurs when
very small charges are being admitted by the throttle.

Four=wheel Drive — A form of automobile drive in which
all four wheels exert tractive effort instead of but two, as in
ordinary practice. The entire weight of the vehicle is effective in
causing adhesion of the wheels to the road which is utilized to
resist the driving effort.

Fourth Speed — In a change speed gear which provides four
forward gear ratios, that gear ratio on which the rate of rota-
tion of the traction wheels bears the largest relation to the
rate of rotation of the motor. In some instances, the fourth
speed is the direct drive (q. v.) and consequently the custom-
arily used gear, but in some cases the fourth speed is indirect

132

and the rotative speed of the final shaft of the gearset is higher
than that of the motor, in which case the fourth speed is said
to be "geared up."

Frame — The principal structural portion of a motor car,
which is supported upon the axles by the vehicle springs and
carries the body and the engine, its auxiliaries and the trans-

FRAME.

mission parts which are not axle supported. It usually con-
sists of two horizontal, parallel, longitudinal beams or members
of steel or wood, these side members being joined by a number
of cross members (q. v.),. riveted or otherwise secured to them.
Frame, Armored Wood — A frame the side members of
which consist of beams of wood reinforced and protected by
means of structural steel applied thereto.

Frame, Dropped — A frame each side member of which
is curved upwardly into the form of a shallow U at that
portion of its length which
comes over the rear axle.
This enables the frame to be
hung low and a car with a PART op DROppED p

low centre of gravity to be SHOWING DROP.

secured, at the same time pre-
venting the frame members from striking the axle when the
springs are fully deflected under load.

Frame, Inswept — A frame the side members of which are
closer together at their forward than at their rear portions.

The narrowing of the frame
forward enables the steering
wheels to be turned through a

PART OF INSWEPT FRAME, Sreater an§le without strikinS
SHOWING INSWEEP ^e frame> and thus enables the

car to be turned in a relatively
small circle. Used particularly in town cars.
Syn. : Bottle neck frame.

133

Frame, Laminated Wood — A frame, the side members of
which are built up of a series of relatively thin vertical sections
of wood which are secured together and their grains so arranged
as to secure the utmost strength.

Frame, Offset — A frame the side members of which are
bent, either horizontally to narrow the frame, or vertically to
clear the rear axle. The offset or curve is likely to be the
weakest point of the frame, and the cross sections of the side
members at the offset portions are usually enlarged with this
in view.

Frame, Pressed Steel — A frame constructed of steel mem-
bers which are formed by dies into the desired cross sections
and shapes, the various members being riveted together. The
usual form of the side members is that of a channel with its
web vertical, the spread and the width of flange at different
points being somewhat proportioned to the load to be carried
there. The spring hangers and some other fittings are frequent-
ly formed integral with the side members. Pressed steel chan-
nels or angles form the cross members.

Frame, Trussed — A frame each side member of which is
stiffened against vertical stresses by means of a truss consisting

of a tension
rod, the ends
of which are
fastened r e -
PART OF TRUSSED FRAME. spectively a t

points toward

the ends of the side member and a strut located about mid-
way of the side member. Occasionally a short truss is used,
designed especially to stiffen some particular section of a side
member.

Frame, Underslung — A frame which is suspended under the
axles instead of being supported over them, the deflection of
the springs, under load,
carrying the frame down-
ward and away from the
axles. This construction is
employed when a very low
centre of gravity is desired,

large diameter wheels gen- PART OF UNDERSLUNG FRAME.
erally being required when

134

it is adopted, in order that the ground clearance may not be
too much reduced.

Frame, Wood — A frame made largely or wholly of wood,
usually ash. Used only by very few makers.

Frame, Wood Filled— A pressed steel frame the channels
of which are filled with wood.

Frame Cross Member — See cross member.

Frame Side Member — One of the two main members of
a frame extending fore and aft, forming the sides of the struc-
ture.

Syn. : Side bar, sill.

Freezometer — A hydrometer so calibrated that, when it is
floated in an alcohol-water antifreeze solution, it indicates di-
rectly the temperature at which the solution will freeze.

French Chalk— See talc.

Friction, Coefficient of — The ratio of the force of friction
acting between two bodies in contact to the pressure acting to
force their surfaces together. Its value is dependent upon the
materials of the two bodies and the condition of their surfaces.

Friction Cloth — A heavy cotton fabric the fibres of which are
impregnated with rubber. Used in building up the tire carcase
(q. v.) of pneumatic tire casings, the layers of rubberized fabric
being united by vulcanization (q. v.).

Syn. : Friction fabric, friction duck.

Friction Clutch — See clutch, friction.

Friction Disc — A disc usually with a face of special friction
material, rotated upon a shaft ; so arranged as to drive a wheel,
its shaft and attached mechanism by the force of friction, when
the periphery of the wheel is pressed against the face of the
disc at a point other than its centre.

Used in automobile friction drives.

Friction Drive — In general, a form of drive in which the
force of friction acting between rotating surfaces is employed
to react against and thus to transmit the driving effort. It is
to be distinguished from a positive drive in which the driving
effort acts as a direct pressure between the moving parts con-
cerned. As employed to transmit the power of a vehicle motor
to its final drive mechanism, it usually consists of .one or a pair
of friction discs rotated by the motor, into contact with which
a wheel or wheels, fast to the final drive device, can be forced

135

by means of a pedal or lever. It performs the function of
a friction clutch, power being transmitted when the driving and
driven members are in contact and not being transmitted when
they are out of contact. It also performs the function of the
change speed gear, the angular speed ratio of the driving and
driven members being dependent upon the linear speed of the
portion of the driving member with which the driven wheel
is contacted. It also serves as a reverse gear.

The friction drive is employed to operate lighting dynamos
and non-synchronous magnetos, the periphery of a friction wheel
fast upon the armature shaft being pressed into frictional con-
tact with the inside or outside face of the engine flywheel rim.

Friction Drive, Double Disc — A form of friction drive for
automobiles in which two discs and two wheels are employed.
The rearward extension of the motor
| crankshaft carries two friction discs A and

B, facing each other. On a horizontal,
transverse, divided shaft, located midway
between the discs are slidably keyed two
friction wheels C and D. This shaft has
a very slight rocking motion in the hori-

"yy" zontal plane so that, simultaneously, wheel

•n C may be contacted with disc A and wheel

DOUBLE Disc

^ T, D with disc B, or that, simultaneously,

TRICTION DRIVE.

A, B, Friction Discs. wheel C may be contacted with disc B and

C,' D,' Friction Wheels. wheel D with Disc A. Under the former

circumstances the rotation of wheels C and

D, and their shaft is in one direction, and, under the latter cir-
cumstances its rotation is in the other direction. This provides
for a forward and a reverse drive.

Friction Drive, Grooved Pulley — A form of final drive,
used upon some cars of the buggy type. The motor crankshaft
carries at each end a pulley, the face of which is formed with
a number of c1osely placed V grooves. Fastened upon each
of the driving wheels is a large similarly V-grooved, ringlike
pulley. When the engine driven pulleys are forced into en-
gagement with the wheel pulleys the V-shaped portions of one
enter the V-shaped spaces of the other, and there is a frictional
driving contact established between the sloping surfaces of th.!
pulley faces.

136

Friction Drive, Single Disc — A form of friction drive which
comprises a disc rotated by a rearward extension of the crank-
shaft; another shaft supported in
bearings transversely of the frame
and to the rear of the motor, and
a friction wheel slidably keyed
upon this shaft, with its plane at
right angles to that of the disc,
so arranged that its edge and the
face of the disc may be forced
into and out of frictional engage-
ment at will. When the wheel is
opposite one outside edge of the

SINGLE Disc FRICTION DRIVE.

A, Friction Disc.

B, Friction Wheel.

disc and in engagement therewith, the wheel and its shaft are
rotated at their highest rate in a certain direction. When, how-
ever, the wheel is slid upon its shaft toward the centre of the
disc the ratio of the angular velocities of the wheel and disc
becomes progressively less. When the wheel contacts with the
centre of the disc, no motion is imparted to it. As the wheel is
slid beyound the centre and contacted, its direction of motion
is reversed.

Friction Tape — A kind of fabric tape saturated with a rub-
ber or other sticky compound possessing insulating properties.
When tightly wound about an object it stays in place by ad-
hesion and cohesion, and it is thus used to temporarily bind loose
parts together, to insulate joints in electrical conductors, in mak-
ing minor tire repairs, and to form a soft buffer between parts
which are likely to strike together and rattle.

Syn. : Tire tape, insulating tape.

Friction Wheel — A wheel adapted to make frictional con-
tact with another wheel or a disc, and to be driven by it. It
is usually of metal, with a face or contact portion of some slight-
ly yielding material, such as leather, compressed paper or similar
organic material. Used in the drives of frictionally driven cars,
and upon the shafts of dynamos and magnetos.

Frictionally Driven — Driven by the force of friction, in con-
tradistinction to positively driven, as a frictionally driven car
or dynamo.

Front Gears — See half time gears.

Fuel — A combustible substance the burning of which in the
oxygen of the air results in the conversion of chemical energy

137

into heat. The heat evolved can, in part, be converted into me-
chanical energy, by permitting it to expand a working fluid, such
as air, in a closed vessel containing a movable piston. Fuels usu-
ally consist mainly of hydrogen and carbon, the combustion of
which produces steam and carbon dioxide. The common auto-
mobile fuels are liquids, including gasoline, kerosene, benzol and
alcohol, and mixtures of these substances. See gasoline.

Fuel Economy — In automobile practice, the measure of use-
ful work accomplished in the operation of an automobile, in re-
spect to the quantity of fuel consumed in so doing. It is gen-
erally measured in terms of the weight or volume of fuel con-
sumed in moving a unit weight of car and load a unit of dis-
tance, e. g., pounds of fuel consumed per ton mile. Sometimes
the reciprocal of this is used, and the result is given in ton
miles per pound or gallon of fuel. The gross weight of the
vehicle is generally used, but the net weight of passengers or
goods may be employed, in which case, the result is given in
pounds or gallons of fuel per net ton mile or in net ton miles
per pound or gallon of fuel consumed.

Syn. : Fuel efficiency of a vehicle.

Fuel Feed, Gravity — The common method of feeding fuel
from the fuel tank to the carburetor, in which the natural or
gravity head of the liquid is depended upon to cause the re-
quired flow, the bottom of the supply tank being placed suffi-
ciently above the carburetor, so that even when the vehicle is
pointed up a steep grade the head is still adequate.

Fuel Feed, Pressure — A method of feeding fuel from the
supply tank to the carburetor of a gasoline car, in which the
flow is due to gaseous pressure acting upon the fuel in a
tightly closed tank. The pressure may be produced by pumping
air into the tank space, above the fuel, or may be derived from
the exhaust gases, led from the exhaust manifold through a
pipe and an automatic pressure reducing valve. Pressure feed
is resorted to when the fuel tank is located at a level below or
insufficiently higher than the carburetor, so that a gravity flow
of fuel cannot be secured under all conditions of inclination of
the car and under all degrees of fullness of the tank.

Syn. : Forced fuel feed.

Fuel Feed, Pressure — In a steam vehicle the arrangement
which maintains the fuel supply or a portion of it at a pressure
sufficient to cause its atomization to take place, when it passes
through the atomizer of the burner,

138

Fuel Injection — The practice of furnishing directly, by moans
of a small pump, to the cylinder of an internal combustion
motor the quantity of fuel required for each working stroke,
thus dispensing with a carburetor.

Fuel Level — The height at which fuel is maintained in the
float chamber of a constant level carburetor, by the action of its
float and valve. This level is a matter of importance, for, if it
is too high, fuel will constantly escape through the spraying
apertures and be lost, especially if the motor is not running,
while, if it too low, a considerable rarefaction is required at the
spraying nozzle in order to cause fuel to be emitted, and a suffi-
ciently rich mixture may thus not be secured, especially at
starting.

Fuel Level Adjustment — An adjustment provided in some
carburetors, which permits of the regulation of the fuel level.
It is usually a screw, acting upon the float valve operating link
age, which changes the vertical position of the float at which it
closes the fuel admitting valve.

Fuel Pipe — In a gasoline car the pipe which conveys fuel
from the supply tank to the carburetor. In a steam car the pip-
ing connecting the main tank, pressure tank, fuel pump and
burner.

Fuel Tank, Auxiliary or Emergency — See auxiliary fuel
tank.

Fuel Tank, Main— The vessel which contains the main fuel
supply carried upon a motor car, and from which it flows, as
require'd, to the carburetor or burners. It is usually a prismatic
or cylindrical closed tank of sheet copper, galvanized iron or
drawn steel, securely ironed to the vehicle frame and usually lo-
cated under the front seat, to the rear of the front seat back, on
or in the dash or under the rear overhang of the body. A rather
large filling hole, closed by a screw cap, is usually provided in
its upper surface and its outlet is usually in its bottom. Baffle
plates are commonly fixed inside the tank to prevent excessive
surging of the fuel under rough road conditions.

Fuel Valve — The valve which controls the flow of fuel
through the fuel pipe from the supply tank. Usually a screw
valve of the conical needle type. A lock is sometimes applied,
which makes it impossible to open the valve except by the
use of the key.

Syn. : Gasoline valve, gasoline shut-off.

139

FUEL RESERVE VALVE.

Fuel Valve, Reserving — An arrangement of valves and pip-
ing designed automatically to warn the operator of the approach-
ing exhaustion of his fuel supply.
-q The flow pipe controlled by the main
valve, which is always open when the
car is running, projects upward quite
a distance through the bottom of
the tank, and, when the fuel in the
tank falls below its mouth, no more
will flow through it and the motor
shows signs of stopping. Another
short flow pipe, branching off from
the main flow pipe outside the tank

and controlled by this reserve valve, terminates flush with the
inside of the tank and when its valve is opened the fuel re-
maining in the tank can flow to the carburetor, thus allowing
the car to be driven to a fuel supply station. The accompany-
ing cut shows a combined main and reserve supply valve.

Fuse — In an automobile electric lighting system, a short length
of lead alloy wire included in each circuit which melts and opens
the circuit when the flow of current becomes excessive.

Fusible Plug — An automatic device designed to protect a
steam vehicle boiler from being burned out when its water
level is accidentally allowed to become abnormally low. A
short pipe is inserted into the boiler, near the level of the
bottom thereof, which is normally closed by a plug of metal
that fuses at a comparatively low temperature. When the water
recedes from this pipe, the temperature of the plug is no longer
limited by the presence of water about it and it melts, allow-
ing steam to enter the burner casing and to put out the fire as
well as to visually and audibly warn the operator.

Gage — Of a vehicle. The straight line distance between the
centres of the points of contact with the road, of the two
front or of the two rear wheels. The standard gage for pleas-
ure automobiles in this country is 56 or 56^ inches, although 60
inches is common in certain sections. The gage of heavy com-
mercial vehicles is often greater than that of pleasure cars.
Syn. : Tread, track.

Gage — A device for indicating the quantity of or pressure of
fluid.
Gage, Gasoline — A gage used to indicate the quantity of

140

gasoline remaining in a fuel tank. It usually consists of a float
riding upon the surface of the fuel, the vertical movement of
which is indicated upon a dial, upon the outside of the tank, the
reading of which denotes the gallons of fuel still in the tank.

Gage, Gasoline Pressure — A pressure gage, connected by a
pipe with the interior of the fuel tank of a pressure feed fuel sys-
tem, which indicates the gaseous pressure acting upon the fuel.
It is usually placed upon the dash.
Syn: Air pressure gage.

Gage, Oil — A gage used to indicate the level of lubricating
oil in the oil compartment of a gasoline vehicle engine base. It
may consist of a float riding upon the surface of the oil and car-
rying a vertical stem protruding upward through the case where
its position can be observed. Or it may consist of a glass window
or bullseye, set into the wall of the oil compartment, through
which the level can be directly observed.

Gage, Oil Pressure — A pressure gage connected to the flow
piping of a circulating system of engine lubrication, used to in-
dicate that the pump which circulates the oil is in operation. It
is generally placed upon the dash. See circulation gage.

Gage, Steam — A pressure gage, usually calibrated in pounds
per square inch, used to measure the steam pressure acting within
a vehicle boiler. It is piped into the steam space of the boiler
and protected from the direct action of the steam by a column
of water contained in the connecting pipe. In steam vehicles the
gage is carried upon the dash.

Gage, Pressure — A device used to
indicate and measure fluid pressures,
consisting of a part subjected to the
pressure, which is deformed or dis-
placed thereby proportionally to pres-
sure changes, and an indicator, moved
by this part over a graduated scale,
by means of a suitable connecting
mechanism. Its most common form
is the Bourdon gage, in which an arc
shaped tube A, subjected to the pres-
sure to be measured, is progressively
bent by increases or decreases there-
of, the hand B moved by such bending
PRESSURE GAGE. indicating upon a circular dial C the

141

instantaneous pressure acting in pounds per square inch. The
tube A is connected to the hand B through the intermediary of
an arm D, a link E, a lever and sector F and a pinion G.
Syn. : Manometer.

Gage, Tire — A pressure gage used to
measure the air pressure acting within a
pneumatic tire. Usually a spring gage, or
a small Bourdon gage which is screwed
or pressed into the air connection of the
tire in such a manner as to unseat the tire
valve and allow the air pressure to reach the
gage.

TIRE GAGE.

Gage, Water — A device used to indicate the water level
in a steam boiler, consisting of a glass tube, the upper and lower
ends of which, respectively, are connected
through the boiler shell at points well above
and well below the normal water level.
The water in the tube assumes the same
level as that within the boiler and can be
directly observed. A shut-off or an auto-
matic check valve is provided between each
end of the gage glass and the boiler, so
that the escape of steam may be stopped in
case the glass tube breaks.

Gage, Water Circulation — A pressure
gage, under the influence of the pump pres-
sure acting in a forced system of water
cooling, an indication of pressure by which
demonstrates that the pump is in operation

and that there is water in the system. It is usually located upon
the dash, but is not often installed upon cars.

Gage Cock — One of a series of several pet-cocks, arranged
vertically one above the other, connected through a boiler shell
or into a separate water column connected with a boiler. These
cocks are respectively located above, below and in the vicinity
of the normal waterline. Opening the upper cock should allow
steam to escape and opening the lower should allow water to
escape, thus approximately indicating the position of the water-
line.

Syn. : Try cock.

WATER GAGE.

A, Gage Glass; B,
Drain Cock; C C,
Stop Cocks.

142

Gage Glass — A glass tube or a transparent window set into
a metal tube or into a reservoir containing a liquid, so that the
level of such liquid may be observed therein.

Garage — A building devoted to the storage and care of mo-
tor vehicles, particularly a building in which the business of
storing, caring for and supplying automobiles is conducted in
a public manner.

Pronounced with the final g soft, the final a open and the
accent upon the last syllable.

Gas (v.) — In a storage cell, to bubble violently and give off
gas. An action which takes place mainly at or near the end of
the charging operation, when the chemical changes in the plates
are nearly completed, or when the rate of charge or discharge
is excessive.

Gas Lamp — A lamp which burns acetylene gas, used upon
automobiles for lighting the road. Usually a lamp of the pro-
jector type, which throws a beam of nearly parallel rays, directly
ahead of the car. Two such lamps are commonly used, one
carried upon each side of the front of the car.

Syn. : Gas headlight.

Gas Lamp Controller — A device for altering the intensity
of the light produced by gas headlights without leaving the
driver's seat, either by turning up or down the flame by means
of a valve, by throwing the burner into or out of the focus of the
reflector or by partially shielding the light.

Gas Lamp Igniter — A device for lighting gas lamps from
the driver's seat. The electrical arrangement for this pur-
pose comprises an insulated spark gap,
fastened to the burner of each lamp, a
source of high tension current consisting
of a battery and jump spark coil, a switch
and a valve controlling the flow of gas to
the burners mounted upon the dash. When
the lamps are to be lighted, the valve is
opened and the switch is closed, sending
GAS LAMP a high tension spark across the spark

IGNITER. gaps and lighting the burners.

143

Gas Tank — A tank carried upon an automobile for the storage
of acetylene gas under pressure for consumption in lamps and

self-starters. It is a cylindrical
steel tank, provided with a needle
valve to control the flow of gas
therefrom and filled with an ab-
sorbent material saturated with
acetone, holding acetylene gas in
solution, under pressure. Acety-
GAS TANK. lene gas is forced into the tank at

high pressure, and may be drawn

therefrom at will. The tank is usually carried upon the running
board or under the rear of the vehicle frame.

Gasket — A sheet of somewhat compressible material bolted
between two abutted machined surfaces, with which its shape
conforms, in order to render the
joint between them fluid tight. The
yielding of the gasket, under . the
pressure acting between the surfaces,
causes it to fill any inequalities in
the surfaces and seals the joint. GASKET

Gaskets are of paper, rubber, wire

woven asbestos fabric, leather, sheet copper and asbestos cloth
held between two sheets of thin copper. Used in the seats
of gas engine valve cages and exhaust and manifold connections,
between pipe flanges and the flanged sections of gear, crank and
axle cases which require to be oil tight. Syn. : Packing.

Gasoline — The hydrocarbon fuel most commonly used in in-
ternal combustion vehicle motors and in the burners of steam
cars. It is a light distillate of the so-called "naphtha fraction"
of crude petroleum, and is of variable composition, but consists
mainly of the paraffmes pentane C5Hi2, hexane CoHu, and
heptane C7Hi6. It is a colorless, relatively light fluid, which
rapidly gives off a highly combustible vapor at all ordinary
air temperatures, thus being peculiarly fitted to the production,
with air, of explosive vaporous mixtures. One part by weight
of gasoline to 18 or 20 parts of air is the best practical fuel
mixture. As at present marketed, its specific gravity ranges
from about .747 to .713 or from 58° to 68° on the Baume scale
(q. v.). Its heat value is about 19.900 British thermal units
per pound. Syn. : Petrol, motor spirit, essence.

144

Gasoline Feed, Gasoline Tank, Etc. — See headings under
"fuel."

Gasoline-Electric System — A system of motor car propul-
sion in which the prime mover is an internal combustion engine
which drives a dynamo, but in which the secondary or immediate
source of the mechanical energy that produces the tractive effort
is one or more electric motors geared to the driving wheels,
supplied with electrical energy, through a suitable controller,
from the engine driven dynamo carried upon the vehicle. The
system is chiefly used in heavy commercial car practice, the
elimination of the mechanical change speed gear constituting its
chief advantage. Syn. : Combination system.
Gasoline Gage — See gage, gasoline.
Gasoline Pressure Gage — See gage, gasoline pressure.

Gasoline Measuring Pump — A hand
operated suction pump each stroke of which
raises a definite quantity of gasoline, as
one gallon, from a storage tank and de-
livers it into a receptacle or the tank of a
car. By varying the length of the pump
stroke, any desired fraction of a gallon
can be delivered per stroke. The pump
operates a counter which automatically
registers the quantity of gasoline delivered
and all handling of gasoline for the pur-
pose of measuring is thereby avoided.
Gasoline Motor — See motor.
Gasoline Separator — See filter.
Gasoline Shut=off — See fuel valve.

GASOLINE MEASUR-
ING PUMP.

Gasoline Storage System— A system
of safely storing and drawing gasoline for
use, consisting of a tank of heavy sheet
metal, usually buried in the earth or placed
in an underground vault outside of the
building in connection with which it is
installed. It is provided with a filling
tube and vent placed above the ground
line, and a pipe which extends from it to
the point of delivery, usually within a
garage. A manually operated suction pump
may be used to raise the gasoline as re-

GASOLINE STORAGE
SYSTEM.

145

quired, or a fiuid pressure may be applied to the liquid in the
tank and the gasoline forced to the delivery point thereby.

Gasoline Tester — A hydrometer (q. v.) so calibrated that,
when floated in a sample of gasoline, its specific gravity in
accordance with the Baume scale is indicated.

Gate — See gear-shifting gate.

Gather — A slight forward convergence given to the planes of
the front wheels of a motor car to neutralize the tendency pro-
duced by driving stresses to stretch certain parts and thus to
cause a forward divergence of the wheels.

Syn. : Toe in.

Gear — A contraction of the term running gear (q. v.).

Gear — A toothed or cogged wheel, secured upon a shaft and
adapted to rotate or be rotated by another similar toothed wheel
upon an adjacent shaft. Gears are the most commonly used
mechanism for the positive transmission of rotation from one
shaft to another. The gears of a pair are of such sizes and forms,
and their shafts are so placed that when in action the teeth of
one gear successively enter the tooth spaces of the other, one
or more teeth of the driver being always in contact with cor-
responding teeth of the other gear (the follower). The pressure
of the successively contacted teeth of the driver upon those of the
follower causes rotation of the latter. The tooth outlines are,
whenever possible, such that the teeth of the two gears roll
one upon the other rather than .sliding together, thus minimizing
friction, this result being brought about by making the acting
faces of the teeth (the tooth profiles) arcs of hypocycloids and
epicycloids or arcs of involutes, the latter form being the more
used in automobile practice. The ideal motion of a pair of most
types of gears is as if their pitch surfaces (q. v.) were rotating
together in non-slipping contact.

Gear, Bevel — A type of gear used to transmit rotation from
one shaft to another shaft in the same plane, but making an
angle therewith. The pitch surfaces of
the two gears concerned are the sur-
faces of conical frusta, the common
apex of which is at the point of in-
tersection of their shaft axes. Each
element of each tooth is an element of
a cone, coaxial with the pitch cone.
BEVEL GEAR. The tooth profiles are such that their

146

contact is substantially a rolling one, the involute form generally
being used and the action is that of two cones rolling together
without slip.

Bevel gears (mitre gears) are generally used in the final
drives of all classes of shaft driven motor cars, on the counter-
shaft of double chain drives, in differential gears, etc.
Gear, Change Speed — See change speed gear.
Gear, Composite — A gear, generally of the spur type, cut
from a blank built up of a succession of laminations of metal,
usually bronze, and of some organic material, such as raw-
hide or vulcanized fibre, clamped upon a metal hub. The or-
ganic material reduces the "ringing"' quality of the gear, while the
metal laminations give it strength. Occasionally used in cam-
shaft and auxiliary shaft drives to secure silent operation.

Gear, Crown — A form of gear used to convey motion from
a shaft to another shaft at right angles thereto, with a
considerable change in angular velocity. The large gear
(the crown gear) is a disc with an annular row of teeth
upon its face instead of upon its edge, and the small gear upon
the other shaft is substantially a spur, the teeth of which mesh
with those of the disc gear, which require to be of rather nar-
row face. This form of gearing has been slightly used in a
form of combined multiple direct drive and change speed gear
in which the crown gear fixed to the differential of a live axle
carries several concentric rows of different numbers of teeth
into mesh with any one of which the other gear or pinion, fast
to the drive shaft, may be slid at will, thus producing several
direct drives at different speed ratios.

Gear, Fibre — A gear, usually of the spur type, cut from a
blank of vulcanized fibre and used to drive light running auxil-
iaries under conditions calling for silence of operation rather
than strength, as in driving a speedometer shaft.

Gear, Helical — A gear, cut upon a cylinder to mesh with
another cylindrical gear, the teeth of which are not parallel to
the axes of the cylinders but at an
angle thereto. Such gears are most
commonly applied to shafts which
are not parallel nor in the same plane.

^^^ _^ All the elements of the teeth are

arcs of helices or spirals drawn
HELICAL GEARS. around the pitch (q. v.), top (q. v.)

147

and root circles (q. v.) of the cylinders and the tooth profiles
are usually involute arcs. Such gears are entirely free from
chatter, and are extensively used, in place of bevel gears, to
operate auxiliary shafts which are not parallel with the motor
shafts, such as vertical shafts carrying timers and horizontal
transverse shafts operating magnetos and water pumps.
Syn. : Spiral gear; skew gear.

Gear, Herringbone — A gear consisting of two helical gears
bolted together to form a single gear, the spiral teeth of the
two sections pointing oppositely so that
they form V's upon the gear face and give
the gear the appearance indicated by the
name. Such a gear, when meshed with a
similar gear upon a parallel shaft, pro-
duces a very quiet running combination on
account of the continuous contact of the
teeth characteristic of all spiral gears and is
free from end thrust, the axial pressure
component of one half of the gear being
neutralized by the oppositely directed end
thrust of the other. Herringbone gears
are used in camshaft trains, in. the final

drives of some electric vehicles,, and sometimes for the con-
tinuously meshed gears of change speed devices of the sliding
type.

Gear, Internal — A form of gear, usually of the spur type,
with teeth cut upon the internal periphery of its rim instead
of upon the external periphery
thereof, which teeth mesh with
an externally toothed gear of
smaller diameter carried upon
a shaft., or stud within the
larger gear. Two such gears
turn in the same direction,
while externally meshed spur
gears turn in opposite directions.
Used in some planetary change
speed gears.

Gear, Planetary — See plane-
tary gear.
Gear, Progressive — See sliding gear, progressive.

HERRINGBONE
GEAR.

INTERNAL GEAR.

148

dear, Rawhide — A gear, usually of the spur type, cut from a
blank made up of laminations of rawhide highly compressed be-
tween plates, usually of bronze, secur.ed to a metal hub. Used
where silent operation is required.

Gear, Selective — See sliding gear, selective.
Gear, Semi=selective — See sliding gear, semi-selective.
. Gear, Sliding — See sliding gear.
Gear, Spiral — See gear, helical.

Gear, Spur — The usual type of gear for communicating rota-
tion from one shaft to another parallel shaft. The pitch
surfaces of such gears are parallel
cylinders, and the action of such a
gear pair is that of two cylinders
rolling together in non-slipping .con-
tact. The teeth of such gears are
usually of. involute profile. Used in
all change speed gears, in the final
drives of some steam and electric
cars, in timing-gear trains and for
driving auxiliary shafts which are
parallel to the motor shafts.
Gear, Stub Tooth — A form of spur gear extensively used
in automobile practice the involute teeth of which are shorter
and stronger than those commonly used in other mechanisms in
which strength and lightness are of less importance. The
obliquity of the tooth curves is increased in this system to
20 degrees, giving a steeper tooth and one the action of which
approximates closely to the ideal rolling action.

Gear, Worm — A form of helical gearing commonly used to
transmit the rotation of a relatively fast running shaft to a
relatively slow running shaft, usu-
ally located at right angles thereto
and not in the same plane therewith.
The fast motion shaft normally
the driver, carries an endless screw
or worm which is meshed with a
relatively large helical gear carried
upon the slow motion shaft. In the
single thread worm gear, the pitch of

the worm is the same as that of the WORM AND WORM

gear, and one turn of the worm WHEEL.

SPUR GEAR.

149

shaft advances the worm gear one tooth. In the multiple threaded
worm gear, that most used in automobiles, the pitch of the
worm is several times that of the gear, and one turn of the worm
shaft advances the worm wheel a corresponding number of teeth,
all the threads of the worm included in the multiple driving
simultaneously.

Used as the final drive mechanism of some shaft driven cars,
especially of commercial cars which require a large gear reduc-
tion, the worm being carried by the driveshaft, and the worm
gear being fast to the differential case of the live axle. Also
used in steering devices, the worm being rotated by the steering
wheel and the worm wheel shaft moving the steering linkage.

Gears, Distribution,
Gears, Secondary,
Gears, Timing,

— See cam gears

Gears, Driving — The gears included in- the final drive, by
which the shafts of the driving axle are rotated. In a longi-
tudinal shaft drive, they con-
sist of a relatively small bevel
gear or pinion fixed upon the
rear end of the propeller shaft
or the pinion shaft meshing
with a relatively large bevel
gear fixed to the differential
gear frame at the axle, or ^a
multiple threaded worm car-
ried by the rear end of the
drive shaft, meshing with a
worm wheel fixed upon the
DRIVING GEARS. differential frame.

Gear Blank — The piece of metal or other material, of the
general shape of the finished gear, upon which the teeth arc to
be cut.

Gear Box — A tight housing, usually of cast iron, aluminum or
pressed steel, used to enclose gears to confine their lubricant
and exclude dust. The term is especially applied to the case
which houses the change speed gears,

5yn. ; Gear case.

150

Gear Box Position — The location of the gear box (change
speed gear) with reference to other mechanical elements of a
car. In a unit power plant (q. v.) the gear box and motor base
are combined; in a transmission axle (q. v.) the gear box and
rear axle casing form a single unit, and otherwise the gear box
is a separate unit, placed between the motor and the rear axle.

Gear Face — That surface of a gear upon which its teeth are
cut. The width of face is the perpendicular width of this
surface.

Gear Lever Lock — A detent, carried by a gearshifting lever,
arranged to catch in any one of a series of notches in the quad-
rant of a progressive change speed gear over which the lever
moves. The detent holds the lever in any one of the various
gear positions and in neutral, at the will of- the operator. The
detent is forced into engagement by means of a spring and is
disengaged by means of suitable controlling mechanism placed
convenient to the lever grip.

Gear Lever Interlock — A safety locking device which pre-
vents the movement of the gear shifting lever, unless the clutch
is disengaged, and thus obviates damage to the gears by their
being forced together when under power. It is sometimes so
arranged as to prevent the clutch from -being engaged un-
less a pair of gears is in correct engagement or the gear
shifting lever is in neutral.

Gear Lock — A device applied to the
sliding gears of change speed devices,
which, when one of the gears is in complete
mesh with its mate, holds it in that po-
sition against accidental displacement, until
it is intentionally moved out of mesh.
The lock usually consists of a spring-
pressed plunger which is moved with the
GEAR LOCK. gear, and which, when the gear is in cor-

rect meshed position, enters a stationary

A, Shifting Rod.

B, Gear Case Cover, depression, thus holding the gear from mov-

ing out of mesh prematurely.

151

Gear Pump — A type of positive rotary pump, used for cir-
culating oil or water. See pump, gear.

Gear Ratio — The ratio of the angular
velocities of two shafts driven one from
the other by means of a pair of gears.
Their angular velocities are inversely
proportional to the pitch diameters of their
respective gears and hence inversely as the
number of teeth in their respective gears,
e. g. : if the bevel driving pinion of a shaft
driven car is of eleven teeth, and the large
gear of thirty-three teeth, the ratio of the
GEAR PUMP. engine speed to the axle shaft speed, on the
direct drive is as 33:11=3:1, and the car is

said to be geared three to one. In the case of three shafts, geared
together, a§ in a direct drive gearset, the gear of the first shaft
having A teeth, which is meshed with a gear of B teeth on the
second (lay) shaft, which also carries a gear of C teeth in mesh
with a gear of D teeth on the third (driving) shaft, the ratio

of the speed of the first shaft to that of the third shaft is— x — *

B D

The total gear reduction from the engine to the rear axle on any
gear, is the product of the reduction in the gearset and the
reduction at the final drive. The gear ratio of shafts driven
by sprockets is obtained by the same method used with gears.

Gear Shifting — In the operation of a gasoline car the act
of changing the transmission of power from one set of gears
to another, in order to secure a higher or a lower ratio of driv-
ing wheel speed to engine speed and thus a lower or higher
tractive effort.

Syn. : Gear changing, changing gears.

Gear Shifting Fork — A fork-shaped member within a change
gear case, which acts upon the gears which slide, moving them
into their various positions, under the influence of a shaft and
other mechanism which conveys the operator's effoit from the
gear shifting lever.

Gear Shifting Gate — A guide for the gear shifting lever,
which controls a gearset of the sliding gear, selective type (q. v.).
It consists of a somewhat rectangular, fixed quadrant, containing
a somewhat H-shaped slot, within which the lever, pivoted at its

152

GEAR SHIFTING
MECHANISM.

A, Quadrant.

B, Gear Lever.

lower end, can be moved about. When
the lever is in the centre of the slot,
the gears are so moved that they are
all out of mesh, or in neutral, but
when the lever is placed at either end
of either arm of the H, the gears are
so moved that one of the forward
speeds or the reverse gear is en-
gaged.

Gear Shifting Lever— The hand
lever by means of which the several
gears of a change speed gear are
engaged and disengaged. It is a
lever pivoted at its lower end, mov-
ing in a vertical fore-and-aft plane,
usually placed at the side of, but some-
times in the centre of width of a car.

Syn. : Gear lever.
Gear Shifting Quadrant — A fixed quadrant over which moves
the gear shifting lever of a sliding gear, progressive type (q. v.)
change speed gear. The circumference of
the quadrant bears a number of notches,
in any one of which may be engaged a / Jj

locking device, moved with the lever.

Gear Shifting Shaft— A shaft which
is rotated by the motion of the gear shift-
ing lever and transmits the motions by
which the gears are shifted. In a selective GEAR SHIFTING
gearset there are usually two such shafts, QUADRANT.
acting upon separate pairs of sliding gears,
one shaft being engaged and rotated by

the lever when it is moved in one side of the gate and the
other being so engaged and rotated when the lever is moved
in the other side of the gate.

Geared Up Speed — A drive shaft speed in a sliding change
speed gear which is higher than that of the motor shaft, obtained
by meshing a relatively large gear upon the lay shaft, with a
relatively small gear upon the final shaft of the gearset. Used
as the fourth or highest speed of a gearset in which the third
speed is the direct drive.

153

Gearset — A term applied to any combination of gears Used
to secure several speed ratios between the motor and the final
drive.

Syn. : Change speed gear; see sliding gear, planetary gear, in-
dividual clutch system.

Generator, Acetylene — A device for the production of acety-
lene gas as required for use in gas lamps, consisting of a
closed vessel containing a compartment
which is filled with calcium carbide (q. v.)
and one containing water. The latter is
provided with means by which water may
be allowed to drip upon the carbide, the
resulting decomposition liberating the gas.
A valve is provided to control the flow
of water and the upper portion of the
generator is connected to the lamps by
DIAGRAMMATIC VIEW means of copper tubing. It is usually car-
OF ACETYLENE r^e<^ upon the running board of a car.

GENERATOR.

Gland — The part of a stuffing box (q. v.)

which forces the packing material against the shaft or rod
which is to be made liquid tight in its bearing or guide, con-
sisting of a nut screwing into the external end of the stuffing
box and thus compressing the packing therein.

Glass Front — A normally vertical, transversely placed shield
fastened to the dashboard of a car, consisting of a metal frame
holding a plate glass, through
which the operator can see the
road, while, at the same time,
he is protected from the cur-
rent of air into which the car
is running. Such shields are
usually made in sections, so as
to fold in various ways and
assume various angles, thus
offering more or less protec-
tion from wind, rain and dust
to the passengers.

Syn. : Wind shield. GLASS FRONT.

154

Glycerine — A thick, oily, nearly colorless, sweetish liquid, pro-
duced by the decomposition of animal fats, which is used in
dashpots and sight feeds and, when mixed with water, as an
antifreeze solution (q. v.).

Governor — In general, an automatic device consisting 01 «
mechanism sensitive to changes in' rotative speed and a linkage
moved by this mechanism which acts to maintain such speed at
or near a predetermined value or to maintain constant some action
dependent upon speed. As applied to an internal combustion
motor, a device, such as above described, the function of which
is to maintain engine speed at or near a predetermined value
irrespective of the work which the engine is doing, within the
limits of its capacity.

Governor, Centrifugal— A form of automatic governor, con-
sisting of a weight, or pair of weights, attached to and rotated
by a shaft the speed of which is to be
controlled, the weights tending to assume
positions further from the shaft axis as
the shaft speed increases, this tendency
being resisted by spring action. The
weights thus assume a certain distance
from the shaft axis at any given speed,
remaining further away from it at higher
speeds and vice versa. Their movement
operates a linkage which can be made to
reduce the force driving the shaft, and
hence its speed or vice versa.
Syn. : Flyball governer.

CENTRIFUGAL
GOVERNOR.

A, A, Weights; B.
Cam Shaft; C, Gear
on Shafl ; D, Linkage
to Throttle Valve.

Governor, Dynamo — An automatic vol-
tage governing device applied to dynamos
or magnetos, which tends to maintain con-
stant the voltage delivered irrespective of

the driving speed of the electrical generator. See dynamo, con-
stant voltage.

155

Governor, Hydraulic — A form of governor applied to in-
ternal combustion motors, which are cooled by forced water
circulation, in which the mechanism, that is
sensitive to speed fluctuations, consists of
a diaphragm or spring returned piston, the
deformation or change of position of which
is dependent upon the pump pressure acting
in the water system, and hence upon motor
speed. The motion of the piston or dia-
phragm can be made to regulate motor
speed.

HYDRAULIC
GOVERNOR.

A, Diaphragm; B,
Water Inlet; C, Rod
Actuating Lever D,
which operates But-
terfly Valve E in In-
take Pipe F.

Governor, Maximum Speed — A form
of automatic protective device applied to
commercial vehicles to prevent -their being
driven faster than a certain speed. The
governor mechanism is commonly sealed
to prevent its being tampered with.

Governor, Throttling — A governor of either the centrifugal
or hydraulic type connected through a suitable linkage, so as to
progressively close the throttle valve as the speed increases above
the predetermined value, and vice versa.

Grab (v.) — With reference to a clutch, to engage suddenly
and violently (see fierce clutch).
Syn. : To grip.

Grade, Resistance Due to — The resistance due to gravity
against which a car is propelled up a grade and which is approxi-
mately measured in pounds by the percentage of the grade (see
grade, per cent, of) multiplied by the weight of the vehicle in
pounds ; e. g., the resistance occasioned by a 6 per cent, grade in
the case of a 3,000 pound car is approximately 180 pounds. The
horse power expended at the driving wheels in overcoming grade
resistance alone is H P=o.OQ266GV, where G is the grade re-
sistance in pounds and V the speed of the vehicle in miles per
hour. The engine horse power required is found by dividing the
horse power given above by the efficiency of transmission of the
car expressed in per cent.

Grade, Per Cent, of — The tangent of the angle which an in-
clined roadway makes with the horizontal or the ratio of the

vertical rise of a road to the length of road in which such vertical
rise takes place, reduced to a decimal fraction, e. g. : if a road
rises 50 feet in a distance of 500 feet, its average grade is
= 0.10 or 10 per cent.

(iradometer — An instrument designed to be carried upon an
automobile to measure the grade which it is ascending or de-
scending. One form consists of a spirit Jevel, made in the form
of a circular arc, which is fastened upon the car, convex upward,
in a vertical fore-and-aft plane, with its ends in a line horizontal
with respect to the car. The movement of the bubble of the
level over a scale calibrated in percentages of grade, gives a
continuous indication of the steepness of the road.

Graphite — An allotropic form of carbon, which is of an unctu-
ous nature. When in a state of fine subdivision it is an excellent
lubricant and is mingled with greases and oils used in automo-
bile lubrication. Also used as a substitute for talc powder in
lubricating the exteriors of tire inner tubes in the shoes. See
deflocculated graphite.

Syn.': Black lead, plumbago.

Graphite Grease — A grease or non-fluid oil with which a va-
riable proportion of graphite has been intimately mingled. Used
in bearings and gear cases.

Gravity Circulation — See thermo-siphon and water cooling.
Gravity Feed — 'See fuel feed, gravity and lubrication, gravity.

Gray Iron — A variety of cast iron containing part of its car-
bon in mechanical mixture and a part in the graphitic condition;
the softer grades, such as used in making intricate cylinder
castings for automobiles, containing most of its carbon mechani-
cally mixed with the iron. It is soft and fusible and wears very
smoothly.

Grease — A semi-solid or non-fluid lubricant, manufactured
from a petroleum base, used to lubricate automobile bearings,
from which fluid oil would drip away, and where the pressures
may be high, such as ball and roller bearings, spring pins, steer-
ing joints and so forth. Also used, when thinned with oil, in
gear cases.

Syn. : Non-fluid oil.

Grease Bag or Boot— See boot.

COMPRESSION
GREASE CUP.

Grease Cup, Compression — A device
for manually feeding grease to a bearing,
consisting of a short tube screwed into a
hole in the bearing cup and means for
forcing grease through it from a cup filled
therewith, in which the grease is com-
pressed by screwing down the cup upon
the threaded external portion of the de-
livery tube or by screwing a plunger into
the cup. Such cups are fitted to automo-
bile bearings which have no automatic
lubricant feed, such as spring eyes, joints
in the steering linkage, etc.
Grease Gun — An instrument used to fill bearings, grease boots

and housings with grease, consisting of a metal tube, provided

at one end with a delivery nozzle

and closed at the other with a

screwed-on cap. A tightly fitting

plunger, the stern of which passes

through the cap, is arranged to

be moved through the tube upon

a screw thread, thus forcing out,

through the nozzle, the grease with which the tube is filled.

Greaseway — See oilway.

Grid — The metal frame which supports and conducts elec-
tricity to and from the active material of an element of a
storage cell. The term is especially applied to the lead frames,
formed in gridiron shape, used in cells of the lead type.

Grip (v.) — In. the case of a clutch, to engage too suddenly
and violently. (See fierce clutch.)

Grind (v.) — To smooth metal parts to a true surface by means
of an abrasive, such as emery or carborundum. In grinding pis-
tons, cylinder bores, the bearing parts of shafts and similar cylin-
drical objects, the parts are rotated upon their axes while a rap-
idly rotating abrasive wheel slowly travels on a parallel axis
along the part to be finished, a stream of water usually being
applied to the point where cutting is taking place. In grinding
a poppet valve to a perfect fit with its seat an abrasive paste is
placed between the surfaces and the parts are given a partial
rotary motion while a light pressure is applied between them.

GREASE GUN.

158

o o o o o

Ground (v.) — To connect an electric circuit to the common
return of all circuits which is, in general, the earth. In an auto-
mobile, all the important metallic parts, such as the frame, the
motor and the transmission parts, are electrically connected to-
gether, and these form the common return, or ground, of all
ignition circuits, the use of special return wires thus being
avoided. A wire connected to any metallic part of the car
machanism is said to be grounded.

Ground Joint — A joint between two abutted parts which is
made fluid tight by grinding their surfaces together with an
abrasive until they conform accurately one to the other. Such
a joint, when its surfaces are drawn together, is tight without
the use of a gasket. Sometimes used at manifold connections
and to secure the seating of valve cages.

Gudgeon Pin — The piston pin (q. v.).

Gunboat Body — See body, gunboat.

Gusset Plate — An angular reinforc-
ing plate riveted to two frame members
at their junction.

H Section — A form of cross section
used in members subjected to compres-
sion and bending stresses, such as con-
necting rods, front axles, distance rods
and structural members. The cross sec-
tion consists of two flanges joined by a
perpendicular web, thus resembling a
letter H.

Halftime Gears — The gears which operate the cam shaft of
a four cycle internal combustion motor at one-half the speed of
the crank shaft. See cam shaft gears.

Halftime Shaft — The cam shaft of a four cycle internal com-
bustion motor which runs at one-half the crank shaft speed. See
cam shaft, inlet and cam shaft, exhaust.

Hand Pump, Gasoline Pressure — A hand operated air
pump, used to raise the pressure upon the gasoline supply of a
force feed fuel system previous to starting the engine (before
the engine driven pump begins to act). Also used on cars fitted
with gravity fuel feed systems to increase the fuel flow pressure
on steep hills. It is usually located upon the dash or close to
the heelboard of gasoline cars.

SECTION OF FRAME

SHOWING GUSSET

PLATE.

150

Hand Pump, Oil — A manually operated pump, drawing from
a supply tank used to replenish the supply of lubricating
oil in the base of an engine fitted with the circulating
system of lubrication, or to maintain the oil level in
the crank case of an engine lubricated by the simple splash
system. It is usually located upon the dash or under the hood.

Hand Pump, Water — A hand operated pump drawing from
the water tank, used upon steam cars to force water into the
boiler when the engine driven water pump is not in operation
or when its action is inadequate.

Handhole — An aperture in a housing through which the
hand may be introduced, the parts inspected and • adjustments
be made upon the mechanism within the case. The hole is
covered by a tightly fitting metal plate, fastened in place by
nuts or studs or by a clamp.

Handhole Cover — The cover which normally closes a hand-
hole.

Harden (v.) — To render steel hard by a tempering process,
consisting of heating the metal to a red heat and plunging it into
a liquid, such as water, oil or a saline solution. The metal is
frequently heated again to reduce its hardness (tempering). Hard-
ening increases resistance to surface wear and increases the
clastic qualities of the metal generally, at the same time tending
to render it more brittle.

Head End — The end of a motor cylinder which comprises
the cylinder head.

Header — A pipe from which several pipes branch. The term
is applied to the common water circulating pipe into which the
flow pipes to or from individual water jackets connect and which
leads to or from the radiator. Similar to a manifold.

Heat Treatment — A general term applied to the processes
applied to metals to change their physical properties in which
heating and cooling are involved. It includes hardening, temper-
ing and annealing. The shafts, gears and structural parts of
automobiles are heat-treated.

Heat Value — The amount of heat given out by the complete
combustion in oxygen of a unit weight of a fuel. Heat values are
usually expressed in British thermal units (B. T. U.) per pound,
or calories per kilogram of the fuel in question. The heat value
of gasoline of average quality is commonly taken as 19,000 B. T.
U. per pound, and that of commercial denatured alcohol at 13,300

160

B. T. U. per pound. Heat values are used in calculating the
thermal efficiencies of motors.
Syn. : Thermal value, heat of combustion.
Heater, Vehicle — A device for warming the interiors of closed
cars, consisting of a coil of pipe set into or under the floor of
the car, through which is passed the
hot water of the engine cooling sys-
tem, or a drum into which is ad-

^J? mitted a portion of the exhaust gases,

the heat supplied being directly radi-

VEHICLE HEATER ated or used to heat air whicn is

allowed to enter the car over the

heater surfaces.
Syn. : Foot warmer.

Heelboard — The vertical board or panel which fills the space
between the car floor and the seat board. The board is sometimes
hinged at its lower edge, so as to permit the space under a seat
to be utilized for storage.

Heelplate — A metal plate, set into the floor board to the rear
of a clutch or accelerator pedal, upon which the operator rests
his heel while driving, the wearing out of the mat or other floor
covering at these points thereby being obviated.

Helical Cam — See cam, spiral.

Helical Gear — See gear, helical.

Herringbone Gear — See gear, herringbone.

High Gear — That gear provided in a change speed gear
which, when in use, makes the ratio of road wheel speed to motor
speed the highest.

High Speed Adjustment — A carburetor adjustment used to
regulate the mixture quality when the throttle is widely opened
and the rate of gas demand is high. It usually consists in varying
the strength of the auxiliary air valve spring, but may consist
in regulating the opening of the gasoline needle valve or con-
trolling the action of a second or third jet of a multiple jet
carburetor.

High Speed Clutch — A clutch usually of the jaw type (see
clutch, jaw) employed in gearsets of the sliding type to lock to-
gether the clutch driven shaft and the final driving shaft and thus
to secure a direct drive (q. v.) Also, in the individual clutch
system (q. v.) of speed changing, the clutch which puts into
driving action the high speed gears.

161

High Tension Cable — A kind of very highly insulated flexible
conductor adapted to carry high tension ignition currents without

danger of an escape
therefrom. It consists
of a small stranded cop-
per conductor surround
ed by compressed paper,

HIGH TENSION CABLE. over which is wound a

water and oil proof fab-
ric covering or of a

stranded conductor overlaid with rubber insulation around which
is braided one or more layers of water and oil proof fabric.

Syn. : Secondary cable.

High Tension Current — An electric current produced by an
electromotive force so high as to enable it to pass disruptively
through an air gap or through weak insulation. In ignition prac-
tice high tension currents are of the order of tens of thousands
of volts and are produced in the secondaries of jump spark coils
and by high tension magnetos.

High Tension Ignition — See ignition, jump spark.

High Tension Magneto — See magneto, high tension.

High Tension Wire — A conductor through which passes a
high tension current, e. g., the wires leading from coil secon-
daries or high tension magnetos to jump spark plugs.

The term is used in contradistinction to ''low tension wire/'
which refers to a wire traversed by a battery current or by the
armature current of a low-high tension magneto.

High Wheeled Car — A type of automobile which is mounted
upon wheels of- large diameter, similar to those used upon
horsedrawn vehicles, and which are generally fitted with
solid or cushion tires, the
object being to secure the
easy running and riding
qualities characteristic of
• large diametered wheels
without the disadvantages
inherent in the use of in-
flated tires and also to ob-
tain a large road clearance.

Syn. : Motor buggy, bug-
gy type automobile. HIGH WHEELED CAR,

162

HOMOGENIZING
DEVICE.

Homogenizing Device — A device for
breaking up the particles of liquid fuel en-
trained in the charge carried from the car-
buretor to the motor cylinders, thus assist-
ing in their evaporation and rendering the
mixture more homogeneous or perfectly va-
porous. It usually consists of a small fan,
introduced into the mixture pipe, which is
rapidly rotated by the gas current, the
blades of which, or special parts carried
thereby, churn the mixture and subdivide the fuel globules.

Hood — The removable covering which incloses the motor and
its auxiliaries in cars which carry the motor at the forward end
of the chassis. It is usually constructed of sheet metal, and
may be tight or furnished with slits or louvres in its sides.
Syn. : Bonnet.

Hood, False — A hood which does not enclose the motor or
other mechanism, but gives the car the appearance of the engine-
in-front gasoline vehicle and furnishes space for gasoline and
water tanks or storage batteries or for carrying tools and supplies.
Hood, Sloping — The type of hood used upon cars the radia-
tor of which is placed against the front of the dash. The side
elevation of the hood is a curved line sloping from the radiator
top downward to the frame level,
and the front elevation is usually
more or less curved. It is usu-
ally made in one piece and hinged
at its upper rear edge, so that it
may be lifted from the front
and thus expose the motor.

Syn.: French type hood. SLOPING HOOD.

Hood, Straightline— The type of
hood commonly used upon cars in
which the vertical radiator is mount-
ed upon the extreme front of the
chassis. It completely fills the top
and sides of the space between the
rear surface of the radiator and the
front of the dash and is usually con-
structed in two sections, hinged to-
STRAIGHTLINE HOOD. gether in the longitudinal axis of the

163

car upon a metal rod, the front and rear ends of which are sup-
ported respectively in fittings attached to the radiator and the dash.
Hood Cover — A highly non-conducting covering of padded
leather or pantasote, so fitted as to cover the entire hood and
the radiator front, which is used to facilitate starting and running
the motor in cold weather by preventing it from becoming too
cold.

Hood Lacing — A lacing of rawhide or similar material, in-
terposed between the edges of a hood and the frame, the fitting

upon the dash upon which the
hood rests and the rear edge of
the radiator frame to prevent the
hood's rattling.

Hood Latch — A locking device
for fastening the edges of a hood
to the car frame, two of which
are commonly used on each side
of hoods of the straightline .type.

It consists of a spring catch, fastened in the frame, which, when
engaged with the edge of the hood tends to draw it closely
into place.

Syn. : Hood fastener.

Hood Strap — A Jeather strap, the ends of which are secured
to fittings secured to the side frame members and which is
Passed transversely over a hood and tightly buckled to secure
the hood in place and to prevent its rattling.

Hooke's Joint — See universal joint.

Horn, Bulb Type — A reed horn, which <s sounded by air
forced through it from a rubber bulb compressed by the hand or
foot of the operator, the bulb being connected to the horn by
flexible metallic tubing (q. v.) and the horn being placed under
the hood or on the side of the car. Generally used as an alarm
or signalling device. See siren, electric horn and exhaust alarm.

Horse Power— The customary unit in which is expressed the
rate at which mechanical energy is delivered by or to a machine
and equal to 33,000 foot pounds per minute. In general, the
product of the average force measured in pounds acting for one
minute and the distance in feet through which such force acts
in one minute divided by 33,000 gives the average horse power

164

acting. The horse power is used in defining the output of vehicle
motors. Abbreviation, H. P.

Horse -Power, A. L. A. M. — The horse power which is ob-
tained by applying to a gasoline vehicle motor of the four-cycle
type, the rating formula adopted by the Association of Licensed
Automobile Manufacturers. It gives an indication as to the
horse power which such a motor may reasonably be expected
to develop when running at a piston speed (q. v.) of 1,000
feet per minute. The formula is as follows :

H. P. = — t where d is the cylinder bore in inches and n

2.5
is the number of cylinders.

Horse Power, Brake — The output of a motor, expressed in
horse power, obtained by testing it by means of a dynamometer
(q. v.) or brake, the rotative speed at. which the horse power
stated was obtained usually being quoted. The brake horse
power is the useful or commercial horse power and is equal to
the indicated horse power multiplied by the mechanical effi-
ciency.

Horse Power, Electrical — The equivalent of a horse power
expressed in electrical units, namely, the expenditure of elec-
trical energy at the rate of 746 watts (q. v.). In an electric
motor the output, in horse power, is equal to the product of the
watts supplied to it and the motor's commercial efficiency di-
vided by 746.

Horse Power, Indicated — The horse power delivered by the
working fluid to the piston or pistons of a gas or steam engine,
as computed by the use of an indicator (q. v.), which measures
the mean effective pressure upon the pistons" In a gasoline en-
gine, of the four-cycle type, it is computed by the following
formula, in which d is the cylinder bore in inches, P the mean
effective pressure acting during a working stroke measured in
pounds per square inch, / the length of the stroke in inches, N
the number of revolutions of the crank shaft per minute and
n the unmber of cylinders.

H. P. = .000000991 d2 PI Nn.

In the case of a two-cycle gas engine or single acting steam
engine the formula becomes

H. P, = .000001982 d2 PINn
and in the case of a double acting steam engine it becomes

H. P. = . 00003964 d* PINn.

The indicated horse power is equal to the useful or brake
horse power of a motor pms the horse power dissipated in
friction, and is equal to the useful horse power divided by the
mechanical efficiency (q. v.).

Abbreviation, I. H. P.

Horse Power, Rated — The horse power accorded to a motor
by its manufacturer. A motor may be rated at its brake horse
power or by the A. L. A. M. or some other rating formula, or
the rating may be entirely arbitrary in accordance with the
judgment of the manufacturer. (See rating formula.)

Syn. : Nominal horse power.

Horse Power, Useful— The actual or net output of a motor
expressed in horse power, which is delivered at the driving end
of its shaft.

Syn. : Brake horse power.

Horseshoe Magnet — See magnet, horseshoe.

Hot Air Accumulator — A device for collecting warm air for
the initial air inlet (q. v.) of a carburetor, usually consisting of
a metal sheath affixed to the end of the initial air inlet pipe and
applied closely around the exhaust pipe, a portion of a water
jacket or some other hot part so that air entering it is warmed
by the hot surfaces over which it passes when entering the
accumulator.

Syn. : Hot air collector, hot air horn.

Hot Air Intake — The pipe which conveys heated air to a
carburetor, usually delivering it at the initial air inlet but some-
times to the auxiliary air inlet as well. The pipe is often pro- *
vided with a shutter so arranged as to admit to it variable
proportions of heated and. unheated air, as desired by the oper-
ator.

Hot Riveted — Parts which are secured together by means of
rivets which are applied and upset when in a red' hot condition.
The term is especially applied to vehicle frames, the members
of which are generally so riveted.

Hot Water Jacket — See carburetor, water jacketed.

Housing — A construction, usually of cast iron or aluminum
or of pressed steel, used to enclose parts, especially working
parts, and thus to retain lubricant and exclude foreign matter.
See crank case, axle housing, gear case, differential case, etc.

166

Hub Cap — A cap, usually of aluminum or brass, which is
secured over the outside end of an automobile wheel hub, to
prevent the entrance of road dirt and escape of lubricant to or
from the wheel bearings and, when removed, to give access to
the fastening device which secures the wheel to the axle.

Hub Flange— The flange formed integrally with the hub of
an artillery wheel (see wheel, artillery) between which and a
removable flange the spokes are bolted and to which the brake
drum is bolted or with which it is formed integrally.

Hydraulic Test — A test to which cylinder castings are sub-
jected in the process of manufacture to disclose any leaks therein.
The cylinder openings are tightly closed, water pressure is ap-
plied within the casting and any escape of water through its
walls indicates that it is defective.

Hydraulic Transmission — An arrangement for transmitting
the driving effort of a vehicle motor to the road wheels by
means of the movement of a liquid, usually oil, under pressure,
the function of a change speed gear being also performed there-
by. In one system, a gasoline motor directly drives a three-
cylinder piston pump, the length of. the stroke of which and hence
the rate at which oil is pumped, can be regulated by the oper-
ator. The hydraulic motor, which is geared to the traction
wheels, is also a three-cylinder construction similar to the pump
and connected thereto by piping, forming a circulating system,
but it acts to convert reciprocating motion into rotary motion.
When the stroke of the engine driven pump is adjusted very
short, oil is forced to the motor at a relatively slow rate and
its speed is relatively low, while the speed of the engine may be
relatively high, and thus the effect of a very low gear is pro-
duced. When, on the contrary, the pump is set for full stroke,
oil is circulated at a rapid rate, and the motor rotates relatively
rapidly with respect to the engine, the effect of a high gear
being then produced. Intermediate stroke lengths at the pump
produce the effect of intermediate gear ratios. The elimination
of a mechanical change speed gear and the great number and
range of gear ratios obtained are the principal advantages of
this system. Used on some commercial vehicles.

Hydrocarbon — A chemical compound of hydrogen and carbon.
Gasoline, kerosene and benzol are hydrocarbons or mixtures of
various hvdrocarbons.

167

Hydrometer — An instrument used to de-
termine the specific gravities of liquids. It
consists of a closed glass bulb with a long
stem, the bulb being so weighted that the
instrument floats in the liquid for which it
it adapted, with the stem projecting vertically
out of the liquid. The denser the liquid in
which it is floated the less deeply the in-
strument sinks. The stem is graduated, and
the figure on the stem which coincides with
the surface of the liquid represents the density
of the liquid in which it is floated. Suitably
calibrated instruments of this type are used
for testing gasoline, alcohol and other
anti-freeze solutions and storage battery elec-
trolyte. A thermometer is usually attached
to such instrument to indicate the temperature
of the liquid and permit of the correction of
the reading to the standard temperature.

Hydrometer Syringe A
combined hydrometer and
syringe used in testing and
adjusting the strength of the
electrolyte in storage cells.
The hydrometer floats in the
liquid in the barrel of the syringe, and, when the
latter is filled with electrolyte drawn up from
a cell, the hydrometer indicates its density.

I Section — A cross section similar to an H
section (q. v.) except that the web is longer
relatively to the length of the flanges, giving it HYDROMETER
more the shape of an I than of an H. SYRINGE.

Syn. : I beam.

Idle (v.) — To rotate without doing useful work. A gasoline
or steam engine is said to idle when it is in operation but discon-
nected from the driving wheels either by clutch disengagement
or by the placing of the change speed gear in the neutral posi-
tion and thus developing only power enough to overcome its own
losses. Syn. : To run free.

Idler — One of a train of gears which is not carried upon
a driving or driven shaft, but usually upon a short shaft

HYDROMETER

WITH

TEMPERATURE
CORRECTIONS.

168

or stud supporting it alone. It is used as an intermediate
connecting gear between two shafts which are too far apart
to be directly connected by gears of reasonable diameters,
or which are required to rotate in the same direction. Used
between the crankshaft and camshaft gears and between the
two gears of the reverse pair in gearsets. See reverse idler.
Syn. : Idle gear.

Igniter — The mechanism at which the ignition spark is pro-
duced in contact spark systems. The spark plug of the contact
spark system. See ignition, contact spark.

Ignition — The inflammation or firing of the fuel charge in the
combustion space of an internal combustion motor in order
that it may burn, expand the working fluid and qause it to
exert a useful pressure upon the power piston during its work-
ing stroke. An electric spark, produced in the midst of the fuel
charge, by means of a spark plug (q. v.) at or near the instant
when the fuel is ready to be efficiently burned and when the
piston is about to begin an outward stroke, is the means, of igni-
tion commonly employed.

Ignition, Battery — Ignition in which the spark is produced
by means of electricity furnished from a primary or storage
cattery. The term is used in contradistinction to "magneto
ignition/'

Ignition, Contact Spark — A system of electrical ignition
;n which the spark is produced by the extra current (q. v.)
set up when an electric current is interrupted within the engine's
combustion space. Each cylinder is provided with an igniter
which consists of a fixed insulated electrode inside the com-
bustion space and a movable electrode which can be moved into
and out of contact with the fixed contact point by actuating
mechanism operated from outside. The action of each igniter
is as fol'ows: Shortly before a spark is required in a cylinder,
its mechanism brings the two internal contacts together and a
currert passes therethrough. At about the instant when the
spark is required, the operating mechanism causes the contact
points to separate and the current momentarily bridges the gap
between them in the form of an arc and ignites the mixture.
The contact spark system is little used at present.

Syn. : Touch spark, make and break, low tension ignition.

169

Ignition, Delayed — Ignition which takes place so late in the
cycle of a cylinder that the working pressure is developed after
the piston has begun its power stroke, thus causing an abnor-
mally large part of its action to be lost by the escape of the
working fluid at high pressure through the exhaust.

Syn. : Retarded ignition, late ignition.

Ignition, Distributor — See distributor and ignition, single
coil.

Ignition, Double — See double ignition.

Ignition, Double Spark— See double spark ignition.

Ignition, Dual — See dual ignition.

Ignition, Electrical — Ignition produced by the electric spark,
in contradistinction to hot tube ignition, a system formerly
used, in which a tube inserted through the cylinder wall is
heated by an external flame and fires the charge at or near its
maximum compression point.

Ignition, Fixed — Ignition by means of a spark, the period
of the occurrence of which in each cylinder cannot be altered
by the operator, no spark controlling mechanism being pro-
vided. Such ignition is usually effected by a high tension mag-
neto, on account of its very slight lag (see ignition lag). The
action of the magneto make and break device always occurs
when all the pistons are in the same relative positions, usually
at or just before the inward dead centre. It is mainly used
upon commercial vehicles which are likely to be driven by
rather inexpert operators and simplifies the control while pre-
venting abuse of the motors.

Syn. : Set spark.

Ignition, High Tension — Ignition which is produced by the
discharge of a high tension electric current across the spark gap
between stationary discharge terminals located within the com-
bustion space. The term is used in contradistinction to igni-
tion, low tension (q. v.). The generally used ignition system.

Syn. : Jump spark ignition.

Ignition, Jump Spark — See ignition, high tension.

Ignition, Low Tension— Synonymous with ignition, contact
spark (q. v.).

170

MAGNETIC
IGNITION PLUG.

A, fixed V shaped
electrode; B, movable
electrode which fits
into A; C, magnetic
coil; D, armature,
whose attraction
breaks the contact be-
tween A and B; E,
spring which keeps A
and B in contact
when current ceases.

Ignition, Magnetic Plug — Contact
spark ignition which is produced by an ig-
niter, the make and break action of which
is caused by magnetic attraction instead of
mechanically. The igniter consists of a spe-
cial plug which can be inserted into an
ordinary jump-spark plug hole and which
comprises a fixed and a movable platinum
pointed electrode, the latter being capable
of being drawn out of contact with the
former by the action of an electromag-
netic coil contained within the plug and
traversed by the ignition current. The
source of current is a synchronous, low
tension magneto, the armature of which is
normally short circuited by its make-and-
break device, but, at each ignition period,
the short circuit is removed and a heavy
current is sent to one of the plugs, causing
its contacts to be separated by the mag-
netic attraction of its coil and a spark to be produced at the con-
tacts. In multiple cylinder motors the plugs are energized in
rotation by the action of a distributor (q. v.) geared to the mag-
neto, which sends the current through the wire leading to the
appropriate plug.

Ignition, Magneto — Ignition produced by current furnished
by a magneto, driven by the engine which it ignites. The term
is used in contradistinction to battery ignition. See titles under
magneto.

Ignition, Make and Break — Synonymous with ignition, con-
tact spark (q. v.).

Ignition, Master Vibrator — A system of high tension igni-
tion of the multiple coil type in which the individual coils are
plain coils. In a common wire (q. v.) of the primary system
is inserted a magnetic vibrator (q. v.), known as the master
vibrator, which produces a succession of quick makes and breaks
in the primary circuit of each coil, in sequence, as its circuit
is closed by the timer. The object of this arrangement is to
secure synchronized ignition in all the cylinders, which may
not be obtainable by the use of a number of vibrators which
cannot be identical in their action.

171

Ignition, Multiple Coil — A system of high tension ignition
in which the spark in each cylinder is produced by a separate
spark coil, which may be a vibrator coil or a plain coil. One
secondary terminal of each coil is grounded and the other sec-
ondary of each is wired to the jump-spark plug of its respective
cylinder. One primary terminal of each coil is connected to
the same terminal of the battery or low tension non-synchron-
ous magneto and the other terminal of each is connected to its
respective insulated binding post of the timer (q. v.). The other
terminal of the battery is grounded. If the timer is of the type
which causes a quick break in each of the coil primaries, in
sequence, plain coils are used, and if the tinier merely closes
and opens the primary circuits without quick action, vibrator
coils are used, the vibrator producing the sudden break required.

Ignition, Point of — The point in the cycle of a gas engine
cylinder at which the spark actually takes place. In order that
the pressure of combustion may be fully developed exactly at
the beginning of the piston's working stroke, the spark must
occur at a greater angle of crank shaft rotation before the
inward dead centre in proportion as the motor speed increases,
on account of the ignition lag. See advance, angle of.

Ignition, Premature — The ignition of the fuel charge so
early in the cycle of a cylinder that the explosion pressure is
developed considerably before the piston is ready to commence
its working stroke, with the result that the pressure acts con-
trary to the direction of rotation of the engine during a portion
of an inward stroke, the output is reduced, the working parts
are unnecessarily stressed and a knocking sound is produced.

Ignition, Self — Ignition of the fuel charge caused by the
overheating of some portion of the motor within the combustion
space to such an extent that the charge is fired by contact with
it. Such local overheating may be caused by the failure of the
engine cooling system, by lack of cylinder lubrication and b>
the accumulation of poorly conductive material, such as carbon
deposits upon the surfaces of the combustion space.

Ignition, Single Coil — Ignition in which the discharge from
a single jump-spark coil is employed to successively ignite the
charges in a multiple cylinder motor. Systems employing a
distributor (q. v) are single coil systems. See ignition, dis-
tributor and magneto, high tension.

172

Ignition, Single Spark — Ignition which is produced by a
single spark per cycle of each cylinder, in contradistinction to
ignition produced by a multiplicity of rapidly recurring sparks
delivered in each cylinder per cycle from a vibrator coil. In
single spark battery systems, the timer or equivalent device
makes a single contact and a single rapid break of the circuit
for each cycle of each cylinder, the length of the contact in
some systems being independent of motor speed and only long
enough to charge the coil. A saving in battery consumption is
effected by such systems as compared with vibrator coil systems.

Ignition, Synchronized — Ignition of multicylinder engines
in which the spark occurs in each cylinder at exactly the same
point in its cycle so that the ignition timing of all cylinders is
identical. Such ignition is secured only when the spark in all
the cylinders is caused by the action of the same make and break
device as is the case in the single coil and distributor system
and the master vibrator system, and when high and low-high
tension magnetos are used. In the multiple vibrator coil system
the ignition is not perfectly synchronized because of differences
of action of the several vibrators and the actions of the several
cylinders are caused to vary somewhat thereby, to the detriment
of the running of the motor.

Ignition, Touch Spark — Synonymous with ignition, contact
spark (q. v.).

Ignition Battery — A battery used to supply current to an
ignition system in contradistinction to a battery used for lighting
purposes. Either three cells of accumulator furnishing six volts,
or a battery of dry cells grouped five or six in series and some-
times several series in multiple, is used. Either one or two
ignition batteries may be installed upon a car, one being held
as a reserve while the other is in use.

Ignition Cable — A special insulated cable adapted for use in
high tension ignition systems. See high tension- cable.

Ignition Cut=out — An electric switch, usually in the form
of a button, generally mounted upon the steering wheel, but
sometimes upon the dash or elsewhere, designed to temporarily
interrupt the ignition of a vehicle motor. It is used in mo-
mentarily slowing down a car and in shutting down motors
which are provided with magneto ignition only,

173

Ignition Lag — The very short period of time which elapses
between the instant of action of the mechanism which causes the
spark to be produced, to the instant at which the spark actually
takes place, e. g., the time elapsing between the closing of the
circuit by the timer (q. v.), of a vibrator coil system to the
instant at which the spark passes at the plug. The time is'
taken up partly by the electromagnetic actions and partly by
the mechanical action of the vibrator. This lag plus the com-
bustion lag represents the total delay between the spark pro-
ducing action and the attainment of the full working pressure
upon the piston and renders variable spark timing desirable
in the operation of most motors, especially when battery sys-
tems of ignition are used.
Ignition Lever — See spark timing lever.
Ignition Switch — An electric switch used to turn on or off
the ignition current from a motor, at the will of the operator. It
is usually placed in an insulating housing,
^^^ upon the dash, upon the face of a dash-

IP )B w board coil box or upon the heelboard, the

In HL Ift wires leading to it being concealed. In cars

|J i£ Bi fitted with battery ignition only, it is usu-

* B H\ ally a switch capable of three positions,

MJ namely : One battery in connection, the

other battery in connection and "off." In
flp cars using the dual system, the three switch

positions are battery connected, magneto
IGNITION SWITCH. connected and off. In cars using a mag.

neto only, the two switch positions are

magneto on and magneto off. In cars equipped with double
ignition the switch positions are usually magneto on, both
magneto and battery on, battery on and both systems off.
The switch is usually of the lever type and manually operated,
but may be a kick switch, operated by the driver's foot. When
the switch is mounted upon the steering wheel it is known as
a steering wheel switch.

Indicator, Optical — See manograph.

Individual Clutch System — A form of change speed gear
which consists of a shaft, rotated by the motor, carrying gears
equal in number to the driving ratios required, and of diameters
such as to secure the same and a parallel shaft connected to
the final drive mechanism upon which is mounted a correspond-

174

ing set of gears, of appropriate diameters, each one of which is
in constant mesh with one of the gears upon the engine driven
shaft. The gears on one of these shafts are securely keyed there-
to, while each of the gears upon the other shaft is free to rotate
thereon unless made fast to it by one of a series of clutches,
one being provided for each pair of gears.

In the individual clutch system no gears are clashed together
when speeds are being changed.
Syn. : Separate clutch system.
Induction stroke — See aspirating stroke.
Incrustation — A term applied to the deposits of a calcareous,
earthy or partly organic nature, which form upon the inside sur-
faces of steam boilers, especially when impure feed water has
been used for some time. Their presence retards the conduction
of heat from the fire to the water and reduces the output of the
boiler as well as involving danger of burning the metal thereof.
Boiler compounds, usually composed of sodium hydrate, are
used to loosen such incrustations.

Induction, Electromagnetic — The action which results in
the development of an electromotive force in an electric circuit
when the number of lines of magnetic force (see field, magnetic)
included within it is varied. .Such variation may be caused by
the variation of the current flowing in an adjacent, parallel, but
separate circuit, as is the case in a jump spark coil (see coil, in-
duction), upon the breaking of the primary current or the vari-
ation may be effected by moving the circuit so as to cut a mag-
netic field as in the case of the armature conductors of a mag-
neto or dynamo armature.

Induction, Self — The action which results in the development
of an electromotive force in an electric circuit when the number
of magnetic lines set up by the current circulating in it is varied,
especially by the sudden interruption of the current. See extra
current and coil, self induction.

Inertia — That property of matter by virtue of which it re-
sists changes in its state of rest or motion. Inertia force : The
force required to overcome the inertia of a machine part en-
dowed with periodic motion, like the piston of a motor.

Inflate (v.) — To raise the pressure within a pneumatic tire
by forcing air thereinto by means of a pump or from a supply
of compressed air. Antonym: Deflate.

175
Inflation — The act of inflating.

Inflation, Pressure of — The pressure which is found most
desirable to be maintained in a pneumatic tire. This pressure
increases with the cross section of the tire and with its diameter
and ranges from about 65 to 90 pounds per square inch in rear
tires, of -from 3^ to 5 inches in cross section. The pressure
in rear tires is usually from 20 per cent, to 30 per cent, higher
than in front tires.

Inherent Regulation — A term applied to the tendency mani-
fested in certain specially constructed dynamos, to maintain a
nearly constant voltage independent of armature speed. The
term is specially applied to such dynamos, when used for light-
ing vehicles and which have no external mechanism to regu-
late their voltage.

Initial Air Inlet — The pipe through which air enters a car-
buretor through the bottom of the vaporizing passage and hence
around the regular spraying nozzle. Air is constantly passing
through this pipe, so long as the motor with which it is used
is in operation and it conveys all the air required for the mix-
ture up to the point at which the auxiliary air valve begins to
open.

Syn. : Primary air inlet, fixed air intake.

Initial Air Shut=off— See air damper.

Initial Pressure — The gas pressure acting in an engine cyl-
inder after the entrance thereto of the working fluid. In a steam
engine cylinder it is equal to the boiler pressure, less frictional
and other losses and in a gas engine cylinder it is the pressure
of the charge within it at the beginning of the compression
stroke and is usually somewhat less than atmospheric.

Inlet Port — The port or passage through the cylinder wall
which connects the intake pipe from the carburetor with the
combustion space of an internal combustion motor and through
which the fuel charge is admitted thereinto. In a four cycle
motor, the inlet valve controls this passage and in most two
cycle motors the entrance of the charge is controlled by the
upper end of the piston covering and uncovering the inside end
of the port.

Syn. : Admission port, intake port, induction port.

176

1L

/ion A-3

Q

SIAMESED INLET PORT.

Inlet Port, Siamesed — An inlet port which branches from
a single opening in the external wall of the cylinder structure to
passages leading to the inlet valves
of two cylinders, one branch of the
manifold only thus being required
to supply two cylinders.

Inlet Valve— The valve which
'controls the passage of the charge
through the inlet port from the in-
take pipe and carburetor in a four
cycle engine. The valve is usually
of the mechanically operated poppet
type (see headings under valve) and
is usually timed to be opened by its
cam at about 10 degrees of crank

angle beyond the top dead centre after the exhaust stroke
and to close at about 20 degrees of crank angle beyond the lower
dead centre of the suction stroke. These figures are averages of
recent practice.

Syn. : Admission valve, intake valve, induction valve.

Inner Tube — An endless circular tube made of lightly cured,

high grade rubber, and provided with a spring-closed air valve.

seated in a stem, through which it can be

0 inflated. It is the air containing part of a

pneumatic tire and performs that function
only. It is fitted within the casing or shoe,
and between it and the wheel rim/ The
shoe resists the pressure of inflation with-
in the inner tube which acts to put the
whole shoe in tension and render the tire
INNER TUBE. hard and resilient.

Syn. : Air tube.

Inner Tube, Self Healing — An inner tube which, when
punctured, tends automatically to close the puncture and pre-
vent the escape of air. It usually consists of a double-walled
tube of rubber between the layers of which is a layer of viscous
material which hardens upon contact with air. When a puncture
occurs, some of this material extrudes therethrough, under the
influence of the escaping air, and hardens in the puncture, thus
sealing it.

Svn. : Non-deflation inner tube.

177

Input — The rate at which energy is delivered to a mechanism
to be transmitted in the same form to another mechanism or
to be converted into some other form, e. g., the rate at which
electrical energy is supplied to an electric motor or storage bat-
tery, that at which mechanical energy is supplied to a dynamo or
that at which mechanical energy is supplied to a transmission
device. See horse power and watt. The opposite of output
(q- v.).

Inside Control — The location of the control devices of a
car within the body space of a closed car, so that the operator
is protected from the weather.

Syn. : Inside drive. (See coupe, inside driven.)
Inspection Opening — A hole in a housing through which the
mechanism therein may be inspected. See handhole.

Inspection Plate — A metal plate intended to close an inspec-
tion opening. See handhole cover.
Insulator — See non-conductor.

Intake Manifold — A pipe connected at one point, usually the
centre of its length, with the intake pipe and comprising several

branches, each of which makes
a tight joint with the external
end of the inlet port of one
cylinder of a multicylinder gas
engine. It distributes the
charge received through the in-

INTAKE MANIFOLD. . take P'Pe to the several cylin'

ders and is so designed that
the distribution to all cylinders

is equalized as nearly as possible. The manifold is usually a
casting of aluminum or iron, the ends of the branches of
which seat in ground joints or upon gaskets in the port open-
ings.

Syn. : Inlet manifold, suction manifold.

Intake Manifold, Integral — An intake manifold which is
cast as one with a cylinder casting and usually enclosed within
the water-jacket. Used in en bloc (q. v.) motors. It possesses
the advantage of warming the incoming charge.

Intake Pipe — The pipe, usually vertical, which conveys the
fuel charge from the carburetor to the inlet manifold of a mul-
ticylinder motor or to the inlet port of a single cylinder motor.

178

Intake Pipe, Jacketed — An intake pipe which is surrounded
by a jacket through which circulates warm water from the en-
gine cooling system or hot exhaust gases, the object being to
warm the walls of the pipe and thus to assist in the vaporiza-
tion of the fuel passing through it.

Intake Resistance — The resistance offered to the movement
of the fuel charge as it is drawn into the cylinder of a gas
motor, occasioned by the friction of the intake piping and the
contractions of the passage at the carburetor and inlet valve.
It prevents a charge of full weight from entering the cylinder.
(See charge ratio and volumetric efficiency.)

Intake Stroke — See aspirating stroke.

Integral Construction — Mechanical construction in which
as many as possible of the related parts which might be made
separate are combined into a single unit. Such construction
usually results in greater strength and rigidity, less labor in
assembling, and reduced cost of manufacture.

E. g., the front spring supports of a car may be made separate
and riveted in position upon the vehicle frame, but in integral
construction they are made in one with the side frame members.

Interchangeable Parts — Parts of the same kind and in-
tended for identical use, which are made, so nearly alike in all
their dimensions that one such part may be substituted for any
other such part without any special fitting being required. The
system of interchangeable parts enables any worn or broken
part to be replaced without any machine work being required
upon the new part.

Interconnect (v.) — To connect together two mechanisms so
that a single operating device actuates them both and thus accom-
plishes two related functions ; e. g., in a carburetor, the throttle
lever may not only operate the throttle but, at the same time,
by means of an interconnecting linkage, may operate a me-
chanical air inlet valve, the opening and closing of which is
required to be performed in proportion as the throttle is opened
and closed.

Interconnection — A mechanism which interconnects, e. g., the
linkage which extends from the battery timer to the magneto
make and break in a double ignition syst-em and causes both
systems to be advanced and retarded together.

179

Interlock — An automatic connection between two mechanisms
which prevents the action of one of them unless the other is in
a condition appropriate to the action
of the former; .e. g., an interlock
may be provided to prevent the en-
gagement of the clutch while one or
both of the brakes are set, thus ob-
viating the stresses which would be
occasioned by the application of the
driving power, while the wheels were
locked. A similar mechanism may
be applied to prevent the engagement
of the clutch unless a pair of gears
of a sliding gearset is in complete
mesh, thus preventing the power be-
ing applied to gears which are in
mesh over a part of their faces only.
The starting crank is sometimes in-
terlocked with the ignition timing
mechanism so that it cannot be

INTERLOCK.

A, Clutch Pedal; B, Gear
Shifting Lever; C, Interlock
Sector; D, Clutch Fork.

turned unless the spark is safely retarded.

Intermediate Gear — The second speed or gear provided by
a three speed change speed gear, which produces a ratio of
drive wheel turns to engine turns that is higher than that pro-
duced by the low gear or first speed and lower than that pro-
vided by the high gear or third speed.

Syn. : Middle speed, middle gear.

Internal Combustion Motor — A heat motor, the operation
of which depends upon the combustion of fuel in its working
cylinder, the term being used in contradistinction to engines,
such as the steam engine, the operation of which depends upon
the combustion of fuel outside the cylinder, in the furnace of
a boiler, from which the working fluid is conveyed in a heated
condition, under pressure to the working cylinder. Internal
combustion motors possess no store of heat energy to be drawn
upon as does the steam engine, all the heat concerned being de-
veloped at the instant it is converted into mechanical work. The
gasoline, alcohol and oil motors of vehicles are internal com-
bustion motors.

Syn. : Explosion motor.

180

INTERNAL-EXTERNAL
GEAR CLUTCH.

InternaUExternal Gear Clutch — A form "of jaw clutch, one
member of which consists of an externally toothed gear, re-
sembling a spur gear and the other
member consists of an internal gear
of such size and tooth form that the
external gear can be slid within it
and the teeth be meshed, thus lock-
ing, in driving relationship, two ro-
tating parts to which the two gear-
like members are respectively at-
tached, such as the two gear shafts
concerned in a direct drive (q. v.).
See clutch, jaw.

Interrupter, Electrical — A mechanism which automatically
makes and breaks an electric current. See magnetic vibrator,
magneto make-and-break and timer.

In and Out Storage — Storage of an automobile at a garage
under an agreement that it may be used as desired by the owner
but not including washing, polishing or the performance of any
other work upon it or the rendering of any service in con-
nection with it by the garage.

Iron (v.) — To equip a car body with the necessary fittings
for the attachment of a top or other accessories carried upon
the body.

Irreversible — Not reversible. The term is applied to two
parts arranged in driving relationship in such a manner that
force applied to one can cause motion in the other, but force
applied to the latter cannot cause motion in the former, e. g., a
small pitched worm and its worm wheel ; a cam and a cam
follower ; a steering gear, the turning of the hand wheel of
which readily moves the road wheels, but in which force ap-
plied to the road wheels cannot readily move the
hand wheel.

See steering device, irreversible.
Jack — A device for raising a heavy load, such as
a portion of the weight of an automobile, by hand
power. It consists of a vertically movable guided
member held in a frame, the bottom of which rests
upon the ground or floor, the upper end of the mov-
able member resting under the axle or other part of
the car to be lifted. The power to raise the vertical JACK.

181

member is applied by a ratchet and pawl, worm gear and rack,
screw and nut or other power multiplying mechanism which is
generally operated by a hand lever possessing great mechanical

advantage.

Jacket — A closed casing enveloping a cylinder or other fluid
containing vessel, to confine the flow of a liquid or gas around its
outer walls, which casing conducts a current of liquid or gas from
which heat is imparted to the fluid in the vessel jacketed or by
which heat is abstracted therefrom.

See water jacket, water cooling; carburetor, water-jacketed.

Jackshaft — The transverse sprocket shaft of a double chain
driven car, from which the road wheels are driven. See counter-
shaft.

trn°

JACKSHAFT.

Jack Up (v.) — To raise by means of a jack, as a wheel of an
automobile from the floor.

Jewelers' Sawdust — A variety of very fine sawdust, made
from boxwood, sometimes used, when mixed with lubricant, to
deaden the noise of badly worn gears of change speed de-
vices.

Jig — A guide used to correctly position holes which are to
be drilled in a part in the course of its manufacture, consisting
of a plate in which are drilled guide holes corresponding in
position to the holes desired in the finished parts, which holes
are protected against wear by being fitted with hardened bush-
ings. In use, the jig is clamped in exact position upon the
piece to be drilled and the drill, while doing its work is guided

182

by the bushed holes. Used in the production of interchangeable
drilled parts which are made upon a large scale.
Journal — A bearing (q. v.).

Jump Seat — One of the seats, two of which are located in the
tonneau space of seven passenger touring cars, between the regu-
lar tonneau seat and the front seat. They are usually capable of
rotation upon their supports, of being folded out of the way
when not in use and of being removed entirely if desired.
Jump Spark Ignition — See ignition, jump spark.
Junction Box — In an automobile electric lighting system, a
box or cabinet into which are brought the ends of all the cir-
cuits and where all the connections among them are made and
their fuses located.

Junk Ring — In a sliding sleeve valve gas motor (see valve,
sliding sleeve), a .very wide packing ring (see piston ring) set
into the surface of the portion of the cylinder head which ex-
tends into the cylinder space and acting between it and the inside
surface of the inner sleeve to prevent the escape of gases between
these parts.

Key — A means for securing a member, which is mounted
upon a rotating shaft, against rotation thereon. It may secure a
member, such as a flywheel, in a definite po-
sition upon its shaft, or it may be so fitted as
to secure a member, such as a sliding gear
wheel, so as to permit it to slide along the
shaft, but never to rotate relatively to it.
In its conventional form it consists of a
straight piece of metal, usually of rectangular
cross section, which is seated in a slot formed in the surface
of the shaft, and in a similar coincident slot formed in the hub
of the mounted member.
Syn. : Feather.

Key, Integral — A key, formed as one with its shaft as a pro-
jection, usually of rectangular section, arising from its surface
and extending longitudinally along it.
Syn. : Integrally feathered shaft.

Key, Woodruff — A key, the profile of which is a circular
segment instead of rectangular, the arc shaped edge being seated
in a correspondingly shaped segmental keyway, milled in a longi-
tudinal radial plane in the shaft and the straight edge being
seated in an ordinary rectangular keyway in the inside surface

183

of the 'hub of the member which is to be keyed to the shaft. The
liberal cross section of the key in the shaft secures great holding
power and eliminates the likelihood of the key's turning over
under severe stress.

Keying, Multiple — The practice of fastening a member upon
a shaft by means of more than one key. Two to six keys,
equally spaced about the shaft, may be used. Used to support
sliding gears upon their shafts.

Keyway — The slot in the surface of a shaft or in the bearing
surface of a shaft-mounted member in which -the key is fitted.

Kick Switch — An ignition switch, usually dashboard mounted,
which is intended to be operated by the foot of the operator.

Kilowatt — A unit employed in ex-
pressing the rate at which electrical
energy is delivered and equal to 1,000
watts (q. v.).

Knock (v.) — To make a succession
of blow-like shocks attended by clank-
ing or hammering sounds. A gasoline
motor will knock when its charges are
ignited too early, either by the spark
or by self ignition, thus" causing the
working pressure to act, at times, upon
KICK SWITCH. its working parts contrary to the direc-
tion of their rotation, and resulting in

the abnormal stressing of the parts and the violent taking up of
any lost motion which may exist in the bearings or between the
pistons and their cylinders.

Labor (v.) — In the operation of a gasoline motor, to rotate
jerkily at low speed with noticeable variations in angular velocity
between the instants preceding and the instants following power
impulses. It occurs when a motor is overloaded, under which
condition the energy stored in the balance wheel is insufficient to
maintain a substantially constant angular velocity. Laboring
occurs when a change to a lower gear is too long delayed under
road conditions of increased severity, and it involves unneces-
sarily severe stresses upon the motor bearings and other parts.

184

Lag, Combustion — See combustion lag.
Lag, Ignition — See ignition lag.

Lagging — A non-conductive, non-combustible covering wrapped
about steam boilers to reduce the loss of heat therefrom arising
from radiation and convection, and sometimes also applied to
exhaust pipes and mufflers to prevent their heat from setting
Tire to adjacent combustible parts.

Lamp, Combination — A lamp containing two light sources,
either of which can be used at will. Side and tail lamps are
frequently fitted with both a kerosene
burner and an electric bulb, and head-
lights are sometimes fitted with both an
acetylene burner and an incandescent bulb,
the arrangement being such that either
light source can be placed in the focus
of the projector at will.

Lamp, Electric — A lamp containing as
a source of light an incandescent electric
bulb, usually of the tungsten type (see
tungsten lamp), either placed in the focus
of a parabolic reflector, in the case of head
or search lights ; in a lamp of ordinary car-
riage type, in the case of side lights, or
in a lamp of special construction when

used as a tail lamp (q. v.). An electrical connector of the plug
type is generally used to connect the incandescent bulb to the
car wiring, thus permitting the removal of the lamp for polish-
ing.

Lamp, Gas — See gas lamp.

Lamp, Inspection — An incandescent
electric bulb, provided with a guard and
carried upon a handle. It is supplied with
current through a long flexible conductor
and is thus portable and useful for lighting
obscure parts of an automobile.

Lamp, Oil — A lamp burning kerosene
oil, INSPECTION LAMP.

COMBINATION LAMP.

185

LAMP BRACKET.

Lamp Bracket — A bracket carried by an automobile to
support a lamp. A headlight bracket is usually a Y-shaped
forging, fastened at its central point into a
socket usually formed in the front spring
horn. The two vertical arms of the Y are
placed transversely of the car, and fit into
sockets in the lamp, and are clamped therein
by set screws. A side or tail lamp bracket
is usually a forging bolted to the body or
the dash with a single vertically projecting
arm to which a socket upon the lamp is
clamped.

Lamp Cover — A protecting boot, usually made of enamel
cloth or other water-proof material, made to fit about a lamp,
and to protect it from the weather when it is not in use.
Lamp Lighter — See gas lamp igniter.

Lamp Tie Rod — A rod which joins the two lamp brackets
(q. v.) that support the headlights and tends to prevent their
vibration under road shocks.

Land— One of the annular ridges on the surface of a piston
which are left between the piston ring grooves (q. v.).

Landaulet — A form of. closed body, similar to the limousine,
except that a part of the
enclosed portion of the
body, generally that to the
rear of the entrance doors,
is collapsible— folding up
or sliding out of the way,
so that this section of the
car may be used closed or
open at will. LANDAULET.

Lap — In a steam engine slide valve, the portion added to the
length of the valve to increase the portion of the stroke during
which the ports are covered, beyond the length positively required
to insure the closing of all ports when the valve is in mid-
position.

In a gasoline engine, the delay in opening or closing of a
valve after the dead centre nearest which the valve action is
supposed to take place. It is usually expressed in degrees of
crank movement from the dead centre to the point at which the
valve action occurs. See inlet valve and exhaust valve.

186

Lap (v.) — To finish to mutual conformity surfaces which are
to run in contact, by operating the parts by external power as
they are to operate in practice, while a mild abrasive, floated in
a liquid, is allowed to act between them. The process is used in
perfecting the tooth forms of gears which are to run together
and sometimes in finishing pistons and their cylinder surfaces.

Layshaft — In general, a secondary shaft which is operated
from a primary or principal shaft, specifically, the secondary or
countershaft of a sliding gear change speed device through the
speed reducing action of which the lower and reverse gears are
obtained and which, by being geared to the clutch driven shaft,
is constantly in rotation under load when these speeds are in
use and in idle rotation when the direct drive is in use. See
sliding gear.

Syn. : Countershaft.

Lead (pron. leed) — An electrically conducting wire or cable.
A lead wire.

Lead (pron. leed) — In a steam engine, the amount by which
the steam port is open when the piston is at the beginning of its
stroke.

In a gas engine, the advance in the opening or closing of a
valve prior to the dead centre nearest to which the action takes
place. It is usually measured in degrees of crank movement be-
tween the action of the valve and the attainment of dead cen-
tre. See exhaust valve and inlet valve.

Lead Battery — See accummulator.

Lead Burning — A process used in making electrical connec-
tions between the lead terminals of storage cells. The two ter-
minals are clamped together, a temporary mold is placed around
the junction and the non-oxydizing flame of an oxyhydrogen or
oxyacetylene blowpipe is directed upon the junction. The metal
of the two terminals fuses and runs together, making a perfect
electrical joint, after which the mold is removed.

Leakage, Electrical — The slow escape of electricity through
the defective insulation of conductors, which results in the ex-
haustion of batteries and in the reduction of the sparking effect
when it takes place in an ignition circuit: It is usually caused
by the moistening of the insulation or by its deterioration from
some other cause, which permits a "leak" or a so-called "partial
shortcircuit."

18?

Lean Mixture — A fuel mixture which contains a smaller pro-
portion of fuel vapor and a larger proportion of air than are
present in a mixture of normal quality.

Syn. : Weak mixture, rare mixture.

Lef t=hand Drive — A type of
automobile control in which the
operator occupies the left front
seat instead of the right front
seat of the car. The steering
column and pedals are thus
located further toward the
left of the width of the car
than in the right hand control,
and the gear and brake levers
are placed either at the ex-
treme left side of the car, and
operated by the operator's left
hand or in the centre of width
LEFT-HAND DRIVE. of the car and operated by the

right hand.

Left Hand Thread — A thread cut with a direction of slant
opposite to that of an ordinary or right hand thread, so that a
part so threaded, when turned lefthandedly or counterclockwise
screws into instead of out of a part correspondingly threaded.
Left hand threads are used in securing together rotating parts
which tend to turn loose when right hand threads are used; e. g.,
to secure the left wheels of cars to their axle ends.

Lift — In a poppet valve (see valve, poppet), the distance
through which the valve is moved from its seated or closed
position to its full open position, by the action of the valve gear.
In a valve of given diameter, the lift thereof determines the
area of opening and hence the rate at which gases can pass
through it.

Lighting System, Electric — A system for the lighting of
automobile lamps, consisting. (A) of a source of electric current
which may be (i) a storage battery carried upon the vehicle, and
charged from an electric source, external to the car, or (2) a
storage battery which is maintained in a charged condition by
current supplied through automatic control devices, from a self-

regulated, direct current magneto or dynamo, driven from the ve-
hicle motor, or (3) an automatically regulated dynamo or magneto
driven by the vehicle motor; (B) of the necessary wiring leading
from the source of current to the lamps, the necessary switchea to
throw the circuits on and off, fuses for the protection of the
circuits and measuring instruments, and (C) incandescent elec-
tric bulbs, usually of the tungsten type (see tungsten lamp), of
candle power appropriate to the service required, usually ranging
from 2 to 20 C. P., located within lamps (see lamp, electric).
See also dynamo, constant voltage ; and dynamo, constant current.

Lighting System, Gas — A system for lighting the lamps of
automobiles, especially the headlights, consisting of a source of
acetylene gas, either an acetylene generator (see generator, acety-
len),or a gas tank (q. v.), carried upon the vehicle, connected
through a valve or valves and metal tubing to acetylene burners
located in lamps (usually of the projector type), one being car-
ried upon each side of the front of a car or in a swivel pro-
jector (the searchlight) carried upon the dash.

Limit Gauge — A gauge used in the inspection of interchange-
able parts (q. v.) of automobiles, the dimensions of which are
required to conform very closely to a
standard (usually to within a few thou-
sandths of an inch). Two gauges of
hardened steel are usually provided for
each external dimension to be tested,
one of which is of such size that the
part will not pass within it and the
other a few thousandths of an inch
larger, within which the part to be
tested must just pass. If the part will
pass within the first gauge and will not
pass within the second gauge, it is ac-
cepted as within the limit of accuracy,
but if it will not pass through the first
or will pass through the second gauge
it is rejected as "off-size." The limit

gauges for internal dimensions are similarly arranged. The
minimum and maximum gauge for any one part are generally
made in a single piece.

LIMIT GAUGE.

189

Limousine — A body, the portion of which to the rear of the
il river's seat is permanently enclosed in a coachlike form. This

closed part is glazed
in front and rear, and
at the sides, and en-
trance thereto is by
means of a door on
each side. The roof
of the closed portion
is extended forward
well over the driver's
LIMOUSINE. seat and is usually

joined by a glass wind

shield arising from the dashboard. The driver's seat usually
seats two, and the main enclosed seat three, while accommoda-
tions for two additional passengers are generally provided on
chair seats placed forward of the main seat.

Liner — A shim (q. v.).

Line of Force — See field, magnetic.

Link — A part of the link motion (q. v.) of a steam engine.

Link Belt — A silent chain, see chain, silent.

Link Motion — A mechanism for operating the slide valve of
a steam engine consisting of an arc-shaped link to each end of
which is attached the outer end of an
eccentric rod (q. v.), operated by an ec-
centric (q. v.), carried upon the engine
crankshaft. The eccentrics are secured to
the crankshaft at 180 degrees apart so that
the two eccentric rods move in opposite
phases, causing the link to oscillate about
a point in its centre of length. A block,
capable of sliding in an arc-shaped slot in
the centre line of the link is fastened to
the outer end of the valve rod which re-
ciprocates the slide valve. The link can
be moved in its own plane by means of
a hanger, linkage and the reverse lever so
that the block may be made to occupy any
position in the link slot. When the block

LINK MOTION.

A, Engine Shaft;

B, B, Eccentrics; C,

C, Eccentric Rods;

D, Slotted Link; E,
Link Block; F, Fork,
pivoted on E. ; G.
Valve Rod; H, Bell
Crank operating the
Linkage.

190

is placed in the centre of the slot, which is the centre of oscilla-
tion of the link, the valve is not moved by the engine and
steam is not admitted, but when the block is at either extreme
end of the slot, where the oscillation is a maximum, the slide
valve is given its maximum motion and steam is admitted
through the full piston stroke. When in one extreme position,
admission is such as to turn the engine in one direction, and
vice versa, and thus the mechanism acts as a reversing gear.
When the block is in an intermediate position in the link, the
movement of the valve is less, and steam is cut off (q. v.) at
a fraction of the stroke.

Syn. : Stephenson's link motion. Locomotive type valve gear.

Linseed Oil Soap — A soap made from linseed oil, used in
washing the painted and varnished surfaces of automobiles.
It is capable of removing dirt and oil from such surfaces with a
minimum of damage to their finish.

Live Axle — See axle, live.

Live Storage — The housing of a car at a garage under an
agreement that the full service customarily given a car at a
garage will be rendered in connection with it.

Live Terminal — A terminal of a piece of electrical apparatus
which is not grounded (see ground), and thus is at an electrical
pressure above that of the ground. A live wire is a conductor
leading to or from such a terminal. The live "side" of a piece
of electrical apparatus is the ungrounded terminal thereof.

Local Action — Electro-chemical action among different parts
of the same element of a battery cell, resulting from accidental
differences of chemical constitution existing among them. It
is generally caused by impurities in the material of the zinc
element of a primary cell or by unintentional variations of the
chemical state of a storage cell element. The currents set up
by local action are uselessly dissipated in heat within the element
and represent a loss in energy.

Lock (v.) — To set a brake so tightly that the wheel upon
which it acts is prevented from turning and slides upon the road
until the vehicle comes to rest. It occurs when the moment of
the friction acting between the brake band or shoe and its drum
exceeds the moment of the friction between the tire and the
road.

191

ANGLE OF LOCK.

A, Inner Angle.

B, Outer Angle.

Lock, Angle of — The maximum angle of deflection from the
straight ahead position which can be imparted to a steering

(road) wheel by means of the steer-
ing mechanism. The angle of lock
of the wheel which is on the inside
of the curve which the car is to turn
is greater than that of the outside
wheel, the prescribed condition being
that horizontal lines drawn perpen-
dicular to the planes of each wheel
shall intersect the extended centre
line of the rear axle at a common
point. For cars of equal wheel-base
(q. v.), the greater the angle of lock
the smaller the circle in which turn-
ing can be effected. See turning radius.

Locknut — A nut screwed upon a bolt or other threaded part
and tightened against the outside surface of the regular holding
nut to prevent the latter from working loose.
A locknut may be a special form of holding
nut, e. g., a nut with a split thread, the prin-
ciple of most such nuts being that of creating
sufficient friction between the nut and the
threaded portion to resist any accidental ten-
dency toward turning off.

Lock Switch — An ignition switch which
can be secured in the "off" position by means
of a lock and can be moved into the "on" position only after
being released by means of a key. Its use prevents the operation
of a car by other than authorized persons.

Lockout — The condition existing in a sliding gear (q. v.)
change speed device when the layshaft (q. v.) is not transmitting
power or when it is thrown entirely out of gear, because of the
direct drive (q. v.) being in use. In three speed gears, lockout
is on the third speed and in some four speed gears it is on the
third and in some on the fourth speed.

Lock Valve — A valve which can be locked in its closed
position by means of a key. Sometimes used as a gasoline
valve to prevent the use of a car by other than authorized
persons.

A, Lock Nut.

192

Lock Washer — A kind of washer designed to be placed
around the threaded part upon which a nut is screwed, between
the nut and the surface against which it is
to be tightened, to create friction between
the nut and the surface and thus prevent the
accidental turning off of the former. Such
a washer is a split steel ring, the ends of
LOCK WASHER. which are slightly bent in opposite directions
and somewhat sharpened, forming a spring
washer, one end of which, when the nut is tightened, bears with
considerable friction against the under surface of the nut and
the other end bears upon the surface against which the nut is
tightened.

Long Stroke Motor — A motor the piston stroke of which is
large relatively to its bore. The term is a relative one only, but,
as a purely conventional classification, it has been proposed to
call any motor the stroke of which is more than 1.35 the bore
a long stroke motor, thus for instance, a motor of 4 inch
bore and a stroke of 5.5 inches is a long stroke motor, while
one of the same bore and 4.25 inch stroke is a medium stroke
motor, while a motor of the same bore and a stroke less than
its bore is a short stroke motor.

Among the advantages claimed to appertain to the long stroke
motor are greater output for a given bore, higher fuel efficiency,
superior flexibility and longer life.

Lost Motion — Backlash (q. v.).

Louvre — One of a series of vertical slitlike openings in each
side of a hood through which hot air from the radiator escapes.

Low Gear — First speed (q. v.).

Syn. : Low speed.

Low Speed Adjustment — That adjustment of a carburetor
which is used to regulate the quality of the mixture delivered by
it to the motor when the latter is running at low speed with
the throttle only slightly opened. It may consist of a means oi
varying the tension of the spring which opposes the opening of
the air valve under such conditions ; of means for determining
the degree of opening of the gasoline needle valve under low
speed conditions or an equivalent device.

Low Speed Band — In 'a planetary (q. v.) change speed gear,
the friction band which surrounds and acts as a brake or clutch
upon a drum (the low speed drum), forming a part of the gear.

193

and which, when tightened, causes a planetary or epicylic motion
of the pinions of the device which results in a low geared motion
being imparted to the final drive mechanism of a car.

Low Speed Clutch— That clutch in an individual clutch (q. v.)
change speed gear which, when in engagement, produces the
lowest of the forward gears.

Low Speed Drum — In a planetary (q. v.) change speed
gear the drum which, when held from turning by the low speed
band (q. v.), allows the low speed to be secured.

Low Speed Motor— A purely relative term applied to a
gasoline motor, the rotative speed of which is relatively low as
compared with the generality of motors of the same horse
power and used in a similar service, and the torque of which is
relatively high as compared with the average of such motors.

.In general, a motor which develops its rated horse power at
a rotative speed lower than the average of motors of the same
horse power.

Low Tension Current — A current produced by a relatively
low electromotive force (q. v.), such as produced by batteries and
by the primary windings of the magnetos and dynamos used
upon automobiles. Such currents are not capable of discharg-
ing disruptively through air gaps of appreciable length. The
term is used in contradistinction to the term high tension cur-
rent (q. v.).

Low Tension Ignition — See ignition, low tension.

Low Tension Magneto — See magneto, low tension.

Low Tension Winding — That winding of an induction coil
or of the armature of a high tension magneto, through which
the low tension current- circulates. See coil, primary.

Low Test — A term applied to gasoline which tests low on
the Baume scale, and thus is of considerable density and of rela-
tively low volatility.

Lubricant — A slippery or unctuous liquid, viscous or pow-
dered substance adapted to form a film between surfaces mov-
ing in contact, under pressure, and thus to reduce the friction
acting between them. Mineral oils, non-fluid oils or greases of a
mineral nature, graphite and graphite mixtures are the principal
lubricants used in automobile practice.

Lubrication — The art of applying and maintaining between
surfaces which move together under pressure — such as pistons
in their cylinders and shafts in their bearings — a continuous

194

film of lubricant, for the purpose of reducing the friction acting
between them and that of minimizing the wear, heating and
loss of driving energy occasioned thereby.

Syn. : Oiling.

Lubrication, Automatic— Lubrication which is performed
mechanically, without attention from the operator except to
replenish the oil supply in a reservoir. The supply of oil to the
working surfaces commences and ceases with the starting and

PUMP TYPE, CIRCULATION LUBRICATION. A, Tank; B, Pump.

stopping of the motor or other mechanism oiled. It is the
opposite of hand lubrication.

Syn. : Mechanical lubrication.

Lubrication, Circulating System, Flywheel Type — A sys-
tem of lubrication adapted to gas engines, the flywheels of which
are enclosed in the crankcase or an extension thereof. The
flywheel dips into the oil contained in the bottom of the casing
and raises oil upon its surface which is caught and conducted
by troughs or channels to the bearings and other working parts

195

and finally returned to the crankcase to be again lifted by the
flywheel.
Lubrication, Circulating System (Pump Type) — A sys-

icm of lubrication applied to gas engines of the enclosed crank-
,-ase type in which a considerable body of oil is rapidly circulated
tli rough the main bearings, under pressure created by an engine
driven pump of the gear or plunger type, so that all parts of
these bearings are constantly flooded with an excess of fresh oil,
which, escaping therefrom into the crankcase, returns through
standpipes into the oil reservoir (usually beneath and integral
with the crankcase) from which the pump draws its supply.

Syn. : Flooding system, self-contained system.

Lubrication, Circulating System, Trough Type — A sys-
tem of oil circulation applied to constant level, splash lubricated
motors in which the crankcase is divided into several sections.
Upon the wall of each section is a sloping trough which catches
a portion of the splash and conducts it into the next section.
At the end of the motor toward which all the troughs slope is
a receiving pocket from which the oil drains back by gravity
through a duct to the other end of the crankcase. The result
is a circulation through the several sections and the maintenance
of nearly the same level in the bottoms of them all.

Lubrication, Constant Level — A method of lubrication ap-
plied to vertical gas engines of the enclosed crankcase type, in
which the supply of oil for lubricating the various parts is
contained in the bottom of the crankcase and is maintained at a
constant depth therein so that the moving parts shall always
dip into it to the same extent, and thus always splash it about
at nearly the same rate, speed being taken into account. Among
the methods for automatically maintaining the level constant are
the following: (i) A series of standpipes or overflow dams
may be fixed in the bottom of the case, which drain to a
reservoir, usually located under the crankcase. Oil is supplied to
the case in considerable excess by a pump, and when the level
is higher thar the mouths of the standpipes it is returned to the
reservoir. (2) A pipe may convey oil from an elevated, air
tight reservoir to the crankcase, there terminating in a stand-
pipe, the mouth of which is at the desired level. When the
level falls below the mouth of the pipe air enters it and pass-
ing up to the reservoir displaces oil which is fed to the case
until the level has been raised sufficiently to seal the mouth of

196

the pipe, when no further air can enter it and no more oil
be fed. (Vacuum feed method.) (3) Oil may be fed to the
crankcase by a lubricator (q. v.), at the same rate at which it
escapes therefrom in the operation of the motor, thus maintain-
ing the level. See lubrication, trough system.

Lubrication, Double — A system of lubrication in which two
independent means of oiling each working surface are pro-
vided, so that, in event of the failure of one means the other is
still effective, e. g., a gas engine all principal parts of which are
oiled by individual feeds from a lubricator and in the crankcase
of which is maintained an oil supply sufficient to oil all parts
by the splash method.

Lubrication, Flooding System — See lubrication, circulating
system (pump type), and lubrication, pressure feed.

Lubrication, Force Feed — See lubrication, pressure feed.

Lubrication, Force Feed Non=splash — A system of lubri-
cation in which oil is supplied under pump pressure to the
motor main bearings (q. v.), a part of the oil from the bear-
ings entering channels formed in the crankshaft, passing there-
through to the crank pins (q. v.), lubricating them, and thence
through channels in the connecting rods, through the hollow
piston pins, lubricating their hearings and the cylinder walls.
All important bearing surfaces are thus oiled directly and
splash lubrication (see lubrication, splash) is not depended upon.
The excess of oil returns to the oil reservoir and is recirculated.
(See lubrication, circulating system, pump type.)

Lubrication, Gas Pressure Feed — A system of feeding oil
to the working surfaces of a gas engine, in which gaseous pres-
sure derived from the exhaust or the compression in a closed
crankcase is caused to act upon a body of oil in a reservoir
and forces it to delivery points within the motor, so long as the
motor which sets up the pressure is in operation.

See lubricator, gas pressure.

Lubrication, Gravity — A form of gas engine lubrication
in which the flow of oil from an elevated reservoir, under the
influence of gravity, is depended upon to feed the various
bearing surfaces or to replenish the supply in the crankcase of a
splash lubricated motor.

Lubrication, Hand — Lubrication in which the oil supply in
the crankcase of a splash lubricated motor is replenished at

197

Intervals by means of a hand operated purrip. The term is
applied to all lubrication which is non-automatic, such as the
oiling of parts with a squirt can.

Syn. : Manual lubrication.

Lubrication, Individual Feed — A system of engine lubrica-
tion in which oil is supplied from a common supply, directly to
each bearing surface which requires it, instead of being supplied
to the motor as a whole (as to a pool in the crankcase) from
which it is distributed by splash or other means. The feeding
and distributing functions are combined, by providing each of the
main working surfaces with an individual oil lead through which
oil is supplied to it from a lubricator (q. v.).

Lubrication, Mixture Method — A method of lubrication ap-
plied to gas motors which take their fuel charges through the
crankcase, in which a certain proportion of cylinder oil, usually
about one part in twenty by volume, is mixed with the gaso-
line in the fuel tank. The oil passes through the carburetor
with the gasoline and is there broken into a fine spray and
enters the erankcase, settling upon the working surfaces and
lubricating them.

Lubrication, Pressure Feed — A system of lubrication in
which oil is automatically supplied to the working surfaces of an
cngir.e under a positive pressure, usually created by a pump or
series of pumps.

Lubrication, Self Contained — A system of gas engine lu-
brication in which the supply of oil and the means for supplying
and distributing it are embodied in the engine itself, no auxiliary
or external parts, such as a separate lubricator, being required.
The term is specifically applied to circulating systems.

See lubrication, circulating system.

Lubrication, Single Pump System — See lubrication, cir-
culating system (pump type).

Lubrication, Splash — A method of distributing lubricant to
the working surfaces of motors of the enclosed crankcase type
and to the working surfaces of any mechanism which is housed
in a tight case. A supply of oil is maintained in the lower por-
tion of the case at such a height that some moving portion or
portions of the mechanism dips into it and, when in motion,
splashes the oil into a mist which fills the case and settles upon
the working surfaces, holes being drilled in the bearing caps to
permit its entrance to the bearings. In a motor, the large ends

TROUGH SYSTEM
LUBRICATION.

oi the connecting rods or special splashers attached thereto effect
the splashing, and in a gearset or gear driven axle, a gear, usu-
ally that of largest diameter, effects the splashing action.

Lubrication, Trough System — A method for maintaining
an exactly constant splash level for the connecting rod ends

to dip into. Under each rod is a trough
of the required, depth and set at the
correct height, to which oil, in con-
siderable excess, is constantly sup-
plied by an engine driven pump,
drawing from a reservoir or sump
usually formed in the engine base.
Oil is constantly overflowing back
into the sump from the troughs,
which are thus always full to the
brim and a constancy of splash level
is thus attained.

Lubrication, Vacuum Feed —
See lubrication, constant level.

Lubrication, Variable Level
System — A system of splash lu-
brication applied to gas engines oiled by circulating systems
of the pump type, in which the oil level may be raised when the
motor requires more oil, as when being driven at full output,
and vice versa. This may be accomplished by raising the
mouths of the standpipes (see lubrication, constant level), or by
the use of a pivoted trough (see lubrication, trough system)
under each connecting rod, the troughs being raised when a
greater splashing effect is required and vice versa. The level
may be raised manually or there may be provided an inter-
connection with the throttle mechanism which acts automati-
cally to raise the level as the throttle is opened and vice versa.
The system is designed to prevent a smoky exhaust and still to
insure copious lubrication when heavy work is required of the
motor.

Lubricator, Force Feed — An automatic device for forcing
oil to the working surfaces of a machine, such as a gas en-
gine. It usually consists of a reservoir which is kept filled
with oil, located in proximity to the motor which it is to lubri-
cate, through which runs a shaft slowly rotated by the motor.
The shaft operates a series of small pumps immersed in the

199

oil, each of which draws oil from the reservoir and forces it
at a predetermined rate through a metal tube to some working
surface of the motor or to the crankcase. All the pumps make
a working stroke for a given number of motor turns, and the
rate of feed per pump stroke through each oil lead (usually
from one to several drops) can be regulated by adjusting the
pump stroke or in some similar manner. The feed to each
lead can be observed through an individual sight feed glass.
In some lubricators two pumps are used for each lead, one
a measuring pump and the other a force pump. Such lubri-
cators are largely used in individual feed systems and some-
what in constant level splash systems. Syn. : Mechanical lubri-
cator, mechanical oiler.

Lubricator, Gas Pressure — A reservoir filled with oil,
provided with outlets, each controlled by an adjustable needle
valve, and feeding an oil pipe leading to some delivery point
within a gas motor. A pipe, usually connected into the ex-
haust pipe at one end and at the other into the reservoir above the
oil level, causes a gaseous pressure to be maintained upon the
oil while the motor is in operation, and forces oil through the
several delivery pipes to the motor. A small vent is usually
provided in the cover of the reservoir to permit the pressure
to escape and cause the cessation of the oil flow soon after the
motor is stopped. A sight feed is usually included in each
lead. Syn : Exhaust pressure oiler.

Lubricator, Gravity Feed — A reservoir of oil placed at a
level higher that the motor or other mechanism which it is
to supply with lubricant, and provided with one or more outlets
controlled by adjustable needle valves, which supply oil by
gravity, drop by drop, through sight feeds, to oil pipes leading
to the various bearings and other points of friction or to the
crankcase of the motor. A shut-off permits the supply to all
the leads to be started and stopped at will. Syn : Oil cup,
magazine oiler.

Lubricator -Drive — The mechanical connection by means of
which motion is transmitted from a vehicle motor to the pump
operating shaft of its force feed lubricator. This may be a
direct connection between -an auxiliary shaft (q. v.) and the
lubricator shaft; by a train of gears operated from an auxiliary
shaft; by a belt or chain from a motor shaft; by a connecting

200

rod and crank, or an eccentric rod operated from a motor shaft
which operates the lubricator shaft directly or through a ratchet
and pawl mechanism or by other means.

Magnet — A mass of iron or steel or of certain other less
common materials which is endowed with the property of attract-
ing to it pieces of these metals, and which, when freely suspended,
tends to place itself in a definite relation to the direction of the
earth's magnetism.

Magnet, Horseshoe — A magnet formed of a straight bar
bent into a U shape, thus bringing its ends or poles rather
close together and concentrating the magnetic
influence in the relatively narrow gap thus
formed between the poles.

Magnet, Permanent — A magnet which re-
tains its magnetic properties indefinitely after
the magnetizing influence is withdrawn. Such
a magnet is formed of special steel (usually
tungsten steel), tempered to a glass hard con-
dition and magnetized by contact with a pow-

.. , HORSESHOE

erful electromagnet or by means of an electric ,,

current circulated through a coil of wire

placed about it. Permanent magnets are used to produce the

magnetic fields of magnetos.

Magnetic Field— See field, magnetic.

Magnetic Leakage — The passage of lines of magnetic force
(see field magnetic) from pole to pole of a magnet through paths
which do not permit of their useful effect being realized, e. g.,
when they pass outside of the conductors of a magneto armature
and are therefore not cut by them. Leakage reduces the effective-
ness of the magnetic fields of dynamos, magnetos and induc-
tion coils.

Magnetic Polarity — See polarity, magnetic.
Magnetic Spark Plug — See ignition, magnetic plug.

Magnetic Vibrator — An automatic device for producing
rapidly recurring makes and abrupt breaks in the primary cur-
rent of an ignition induction coil in order to create a close sue-

201

cession of high tension impulses in the secondary coil capable of
producing igniting sparks. It consists of a small, soft iron arma-
ture, supported close to one end of the mag-
netic core of the coil, upon the free end of
a light flat spring, to the stationary end of
which is connected one end of the primary
winding. An adjustable, platinum pointed
screw is supported by a statioiiary metal MAGNETIC VIBRATOR.

arch spanning the spring and its point A> Soft -Jrot? Arma-
ture; B, Soft Iron
touches a platinum contact fixed upon the Core; C, Platinum

spring. A wire connected to the arch forms Arch^E^pS/num
one terminal of the primary circuit. When Contact,
current is applied to the primary circuit it passes through the coil
and vibrator and the core of the coil becomes magnetized. The
armature is then attracted and draws down the spring, separating
the platinum contacts and abruptly interrupting the primary circuit.
The magnetism in the coil thereupon dies away and the resiliency
of the spring returns it to its initial position, bringing the plati-
num points again into contact and re-establishing the primary
circuit. The above described actions are repeated rapidly and
continuously so long as current is applied to the circuit, and a
succession of sparks in the secondary results. (See coil, induc-
tion). Syn. : Buzzer, magnetic make and break, trembler.

Magneto — A mechanical generator of electricity, consisting
of a permanent magnetic field (see magnet, permanent) between
the poles of which is rotated by external
power an armature (q. v.) or an induct-
or (see magneto, inductor type). The
cutting of the magnetic lines of the field
by the working conductors located there-
in generates in them by induction an
electromotive force (q. v.), and in the
operation of the machine mechanical
energy is converted into energy in the
electrical form. The magneto is almost
universally used as a source of ignition
current and occasionally in vehicle light-
ing, the vehicle motor driving the mag-
neto.

Syn. : Magneto electric generator.

MAGNETO.

202

DIAGRAM ILLUSTRATING ACTION

OF ALTERNATING CURRENT

MAGNETO.

Magneto, Alternating Current — A magneto which delivers
to its external circuit an alternating current (q. v.). Such a

magneto has no commutator
(q. v.),one end of its inductive
winding usually being grounded
or electrically connected to the
frame of the machine, and the
other being brought out
through an insulated bushing
to a contact upon which bears
a brush (q. v.), from which
the current is led to the live
side of the working circuit.
In its most common form the
armature core is a shuttle or
H-shaped mass of soft iron
stampings, mounted upon the
shaft and rotated thereby in
close proximity to the pole
pieces (q. v.) of the field. The inducing coil is of insulated wire,
wound in the slot of the core. The action of a two-pole machine
of this type is shown in the accompanying diagrams. In a lines
of magnetic force passing through the core, magnetize the same
and thread through the winding. In b the armature has been
rotated, so as to cease to form a magnetic path from pole to
pole, the core demagnetizes and the lines cease to thread through
the winding, and in so doing cut the conductors, and a rapidly
rising electromotive force is produced therein which dies away
after its maximum is reached. In. c the armature has been
rotated so that the conditions depicted in a are reproduced, ex-
cept that the magnetic lines thread through the winding in the
opposite direction. In d the condition depicted in b is again at-
tained, except that, on account of the reversed position of the
winding the electromotive forces produced lies in the opposite
direction. For each rotation of the armature two electrical im-
pulses, alternating in direction and separated by periods of in-
activity, are produced. Most magnetos used in ignition and
lighting are of the alternating type.

Magneto, Automatically Timed — A magneto in which is
embodied means for automatically advancing (see advance) and
retarding (see retard) the timing of its sparks in proportion 35

203

the speed of the motor which it ignites increases or decreases,
manual adjustment of spark position thus being obviated. See
timer, automatically advanced.

Magneto, Direct Current — A magneto which delivers to its
working circuit a direct current (q. v.), its shaft carrying a
commutator (q. v.), which translates the alternating electromo-
tive forces developed in its windings into a direct current at
the brushes to which the external circuit is connected. Such
a magneto is sometimes used as a substitute for a battery in
the operation of ignition systems of the battery type and oc-
casionally in vehicle lighting. It is usually provided with a
governor (see governor, dynamo) to keep its voltage con-
stant irrespective of speed changes in the vehicle motor which
drives it.

Magneto, Double Spark — A magneto capable of producing
two simultaneous sparks at two separate spark plugs in each
cylinder of a gas motor, to effect double spark ignition therein
(see ignition, double spark). Such a magneto is usually con-
structed with a single primary winding and make-and-break de-
vice (see magneto make-and-break) but with two separate
secondary windings and distributors (see magneto distributor)
and separate secondary wiring to the two sets of spark plugs.

Syn. : Twin spark magneto.

Magneto, Flywheel Type — A magneto not constructed as a
separate machine, but having its moving part built into and
rotated by the flywheel of a gasoline motor.

Magneto, High Tension — An ignition magneto which de-
velops within itself a high tension current suitable for jump
spark ignition. In addition to the inducing winding, consisting
of a relatively small number of turns of comparatively coarse
wire, the armature carries a coil consisting of a very large
number of turns of a very highly insulated, very fine wire, wound
upon the coarse wire coil. The coarse wire coil has included in
its external circuit a mechanical make and break device (see
magneto, make and break), which is operated by the magneto
shaft and which alternately acts to permit current to flow through
the coarse winding, magnetizing the armature core, and to
abruptly break this current, through a condenser. When the
current is broken, the armature core loses its magnetism and a
high tension electrical impulse, capable of producing a spark, is
caused in the fine winding. One terminal of the fine wire or

204

secondary coil is grounded within the machine, and the other
is led out through an insulated collector ring and brush to the
rotating brush of the distributor (q. v.), from which the sparks
produced are distributed to the cylinders of the motor in the
proper sequence. A very commonly used type of magneto.

Magneto, Ignition and Lighting — A magneto of the direct
current, constant voltage type (see dynamo, constant voltage)
employed to charge a storage battery, used both for ignition
and lighting service and embodying the timing and distributing
mechanism of an ignition system which is an integral part of
and driven by the magneto itself.

Magneto, Inductor Type — A
magneto, the inducing conductors
of which, instead of being rotated
through the field upon the driving
shaft, are stationary windings
placed within the field. The cut-
ting of them by the field is ef-
fected by the rotation, upon the
magneto shaft, of a properly
shaped mass of soft iron, which
causes the lines of magnetic force
to be alternately threaded through
and removed from the winding.
Since the windings do not move,
no brushes or collector rings are
required to lead the current from
them to the external circuit.

Magneto, Lighting — See magneto, direct current and mag-
neto, non-synchronous.

Magneto, Low Tension — A magneto which delivers to the
external circuit a low electromotive force of the magnitude
of that furnished by ignition batteries. Such a machine may
be of the alternating, non-synchronous type (see magneto,
non-synchronous), used to supply current to an ignition sys-
tem of the vjbrator coil type or for lighting. It may be
of the alternating current, synchronous type, used to supply
current to a contact spark ignition system (see ignition, con-
tact spark); or it may be of the direct current type, used to
furnish current to an ignition system as a substitute for a
battery, or for lighting purposes.

INDUCTOR TYPE MAGNETOS.

A, Magnet; B, Rotor; C,
Primary Winding; D, Secondary
Winding.

205

Magneto, Low=high Tension — A type of alternating cur-
rent, synchronous magneto for use in jump spark ignition,
which develops within itself a low tension current only (see
magneto, alternating current). In connection with it is
used a separate, plain induction coil (see coil, plain), through
the primary of which the low tension is led and transformed
in its secondary into a high tension current, which latter cur-
rent is conducted back to the magneto and distributed by the
distributor, which forms a part of the machine. One side of
the coil primary is grounded and the other side is connected,
through the magneto make and break (q. v.) device, to the
live side of the magneto winding, a condenser being con-
nected around the make and break device. One side of the
secondary winding of the coil is grounded and the other is
connected to the rotating brush of the distributor (q. v.).
A very commonly used type of magneto.

Magneto, Rotating Armature — A magneto the wire wound
armature of which is the rotating part. (See magneto, alternat-
ing current for a description of this, the most common type
of magneto). The term is used in contradistinction to mag-
neto, inductor type (q. v.).

Magneto, Non=synchronous — An alternating current mag-
neto driven in such a manner from the vehicle motor that
the periods of occurrence of its current impulses bear no
predetermined and sustained time relation to the instants at
which ignitions are required by the motor. An alternating
current magneto, operated by a non-positive drive, such as
a belt or friction wheel, comes within this class. Such mag-
netos are used to energize ignition systems employing vibrator
coils and to operate electric lights.

Magneto, Synchronous — An alternating current magneto,
usually of the two impulse per rotation type (see description
under magneto, alternating current), which is driven from
its motor at such a speed relation therewith that each cur-
rent impulse produced by it corresponds in time to the in-
stant at which an ignition is required by the motor. This
result is attained by driving the magneto from the motor by
some positive means, such as a train of gears, producing the
desired speed ratio between the magneto and the motor. All
high tension and low-high tension magnetos and all low ten-
sion magnetos used with contact spark system are of this type.

206

Magneto Boot — A waterproof and dustproof protective cov-
ering designed to be placed around a magneto.

Magneto Bracket— A shelf-like base, generally formed in-
tegrally with the upper portion of a gas motor crank case, of such
size "and so positioned that a magneto may be mounted upon it
so as to be conveniently driven from the motor. The magneto is
usually positioned upon such a base by dowel pins (q. v.) and
clamped thereupon by means of an adjustible, readily removable
steel strap, passing over the tops of the magnets.
Magneto Breaker=Box,
Magneto Breaker=Cam,
Magneto Breaker=Bar,
See magneto, make and break.

Magneto Coupling — A means for attaching the shaft of a
magneto to and in driving relation with the shaft which ro-
tates it. It usually is some form of slightly flexible coupling
such as the Oldham (q. v.), and thus allows for slight dis-
crepancies in the alignment of the two shafts, and is usually
so constructed as to allow of the convenient removal of the
magneto. In some instances the coupling permits of angular
adjustment between the magneto and driving shaft, and thus
permits of altering the timing of the magneto.

Magneto Distributor — The distributor (q. v.) used in con-
nection with a high or low-high tension magneto. It usually
forms a part of the machine, being gear driven from the mag-
neto shaft. In magnetos of the two impulse per rotation
type, used with four and six cylinder motors, the distributor
is geared to rotate at one-half the speed of the magneto shaft.
Highly insulated cables with snap terminals lead from the
stationary contacts of the distributor directly to the respect-
ive jump spark plugs, the order of connection being such
that the required firing order (q. v.) is secured in the motor.
Magneto Distributor Gears — In a synchronous magneto
the pair of gears, one upon the armature shaft and the other
upon the distributor shaft, which drive the latter from the former
at such a rate that the contact arm of the distributor (q. v.)
makes one complete rotation for each two rotations of the four-
cycle motor which it serves.

Magneto Drive — The means by which motion is communi-
cated from a driving shaft to a magneto shaft. Synchronous
magnetos of the two impulse per rotation type, used with

207

four cylinder, four cycle motors are usually direct driven
from a geared auxiliary shaft running at crankshaft speed.
Such magnetos when used with six cylinder, four cycle mo-
tors are gear driven at one and a half times crankshaft speed.
When used with two cycle motors the magneto is driven at
twice the speed, relatively to the crankshaft, required for a
four cycle motor of the same number of cylinders. The
drive is usually so adjusted that the magneto delivers its
sparks not later than at the upper dead centre when the full
retard is in use.

Magneto Induction Coil — The plain induction coil used in
connection with a low-high tension magneto. It is generally
mounted upon the dash in a coil box which carries the igni-
tion switch, and contains the condenser, and often the safety
spark gap and arrangements for a dual ignition system, but
is sometimes contained in a waterproof, tubular casing, also
containing the condenser, and designed to be located under
the dash or at the magneto itself in the U-shaped space within
the field magnets.

Syn.: Transformer, step-up coil.

Magneto, Make=and=Break — The means for alternately per-
mitting current generated by a synchronous, alternating cur-
rent magneto to flow in its pri-
mary circuit and charge the
magnetic core and of abruptly
breaking this current, discharg-
ing the magnetism of the core
and thus inducing a high tension
current in the secondary coil.
A typical form of this device,
applied to a two impulse per
rotation magneto, is constructed
as follows: The end of the mag-
neto shaft carries a cam hav-
ing two high spots diametrically
opposite (the breaker cam), and

within a relatively stationary, insulated shell, supported upon
the shaft (the breaker box) is mounted a lever, pivoted at one
end (the breaker bar or arm), so positioned that it is slightly
oscillated by the cam twice in each rotation thereof. The
breaker bar carries a platinum contact point, which can make

MAGNETO, MAKE-AND-BREAK.

A, A, Cams; B, Breaker Box;
C, Breaker Bar; D, Spring.

208

contact with an insulated, adjustable, fixed, platinum pointed
contact screw. These contacts are together so long as the
low portions of the cam are acting upon the breaker arm, but
when, twice in each rotation, the high parts of the cam strike
the arm the latter is oscillated and the contacts are abruptly
separated. The breaker bar is held against the cam by a
spring and is grounded, and the mechanism is so set that the
breaks occur only when current is flowing in the inducing
winding.

Syn.: Interrupter.

Magneto Spark Advance — The means for altering the
cyclical period in the operation of a motor at which the sparks
produced by a synchronous magneto, take place in its cylinders.
(See ignition, point of). Among these are the following: (i)
The non-rotating portion of the make-and-break device may
be rotated through an arc upon the magneto shaft, by the
spark control lever, thus altering the angular position of the
armature and hence the cyclical period of the engine at which
the cam causes the current to be broken. (2) The magneto
shaft may be coupled to its drive shaft by means of a key and
spiral keyway arrangement, or by some equivalent construction
by means of which the angular position of the armature and
breaker cam may be altered at will, by movements of the timing
lever, thus varying the cylindrical period at which the cam acts
to break the circuit. (3) The magneto and the non-rotating
portion of the make-and-break mechanism may both be rotated,
in respect to the magneto shaft, thus securing sparks of maxi-
mum intensity at all angles of advance.

Main Bearing — A principal shaft bearing. Specifically one
of the bearings which support the crankshaft of a motor.
(See bearing.)

Malleable Iron — Cast iron of a good grade which, after
being cast into the desired form, is annealed by being heated
and cooled very slowly, by which process the metal is ren-
dered comparatively soft, malleable and flexible. Sometimes
spoken of as "semi-steel." Used mostly for small fittings not
required to possess great strength or rigidity.

Manganese Bronze — A bronze of high strength and tough-
ness, castings of which are sometimes used, for example, for the
portions of crank and gear cases which are most severely stressed.
A specification for this me/v>i 'alls for copper 60 per cent., zinc

209

40 per cent, and iron and manganese in small variable pro-
portions.

Manifold — See intake manifold, exhaust manifold, water mani-
fold.

Manifold Clamp — See exhaust manifold clamp.
Manograph — A form of indicator especially adapted to ex-
hibit the operative peculiarities of a high speed heat motor.
Its essential part consists of a mirror, delicately suspended in
such a manner that there may be simultaneously imparted to
it angular deflective movements in two planes at right angles
one to the other. A reducing mechanism, driven by the mo-
tor crankshaft, deflects the mirror back and forth on an axis
in one plane, in correspondence to the back and forth motion
of the motor piston, while a diaphragm, acted upon by the
pressure in the motor cylinder, acts to deflect the mirror
about an axis in a plane at right angles to the former one to
one or to the other side of a zero position (that of atmos-
pheric pressure), in proportion as the pressure acting upon
the motor piston is greater or less than atmosphere. The
plane occupied by the mirror is thus determined by the re-
sultant of two deflective motions acting at right angles. A
beam of light is directed upon the mirror, and is reflected
upon a darkened ground glass, and thus describes, as the
plane of the mirror varies, a luminous figure from which may
be determined the pressure acting at any point in the motor
cycle. The reflected beam may be received upon an other-
wise darkened photographic
plate, and a permanent record
of the motions of the reflect-
ed beam thus be obtained,
from which prints, known as
manograph records or cards,
may be obtained. Used in
testing vehicle motors.
Syn. : Optical indicator.
Manograph Record — The
photographic record of the
performance of a heat motor,
made with a manograph. In
the somewhat idealized record,
from a 4-cycle gas engine, re-

MANOGRAPH RECORD.

210

produced herewith, A B represents the atmosphere line; G C
the admission line, showing a negative pressure and the area
enclosed by it representing negative work; C D the compres-
sion line, the area under which represents negative work ; D E
the combustion line; E F the expansion line, the area under
which represents useful work ; F G the exhaust line, the area
under which represents negative work. Pressures above atmos-
phere are indicated by the height of the perpendicular, let fall to
line A B from the point in question upon the curve, and negative:
pressures are indicated by the height of the perpendicular erected
at the point in question to line A B.

Master Clutch — A principal clutch in contradistinction to a
subsidiary one, e. g., the clutch which controls the transmis-
sion of power to a change speed gear of the individual, jaw-
clutch type, as distinguished from the separate clutches which
act to engage the gears appertaining to each particular speed
ratio.

Master Gears — The principal gears of a device, such as a
differential gear (q. v.)-

Master Link — A specially constructed link of a driving
chain, the connection or disconnection of the parts of which
connects or disconnects the ends of the chain and permits it
to be secured upon or removed from its sprockets.

Master Vibrator — See ignition, master vibrator.

Mean Effective Pressure — The average useful pressure act-
ing upon the piston of a steam or gas motor during a cycle
of its operation. It is obtained from a manograph record
(q. v.) by dividing the length of the same (the length repre-
senting the stroke) into a considerable number of equal parts
and drawing at each division point a perpendicular to the
atmospheric line. The length of each perpendicular from the
atmospheric line to its point of intersection with any one of
the lines of the diagram represents a pressure. The effective
pressure at each division point is the algebraic sum of the
pressures acting thereat, pressures which represent useful
work accomplished by the fluid upon the piston being taken
as positive and pressures (either above or below atmosphere)
which represent work done upon the fluid by the piston being
taken as negative. When the effective pressures acting at all
the division points are obtained, they are averaged by finding
their sum and dividing it by the number of division points,

211

the result being the mean effective pressure. Abbreviation:
M. E. P. See manograph record. See also planimeter. For
the relation of M. E. P. to H. P. see horse power, indicated.

Measuring Pump — See gasoline measuring pump. A simi-
lar pump is used for dispensing lubricating oil. The term is
also applied to the small individual pumps of mechanical lu-
bricators, which measure a predetermined quantity of oil to
be forced through a lead to a bearing.

Mechanical Lubricator — See lubricator, mechanical.

Mechanical Make and Break — A device for mechanically
closing and opening at predetermined periods, a primary ig-
nition circuit, as distinguished from one electromagnetically
operated.

Mercury Arc Rectifier — See rectifier.

Mesh (v.) — To position a pair of gears in correct driving
relationship, so that the teeth of one act upon the teeth of
the other with a minimum of sliding friction and do not bot-
tom (q. v.). In most common forms of gears, correct mesh is
obtained when their pitch surfaces are in tangency. See
under "pitch." Used also as a noun.

Mirror — A. slightly concaved mirror supported upon an auto-
mobile in front of the operator, in which are reflected, in
miniature, objects behind the car, thus enabling him to observe
traffic to the rear, without turning around.

Miss (v.) — In the operation of an internal combustion motor,
the failure of an explosion to occur, as intended, in each cycle
of operations, resulting in reduced output, irregular turning
effort and usually in loss of fuel. It is generally caused by
the failure of the igniting spark to pass through the charge
or by the absence from the cylinder of a combustible fuel
charge. Used also as a noun.

Syn. : To misfire, to sk-ip, to miss explosions.

Misalignment— The failure of parts to be in alignment (q. v.).

Mixing Chamber — The part of a carburetor in which the
fuel and air come together with the vaporization of the
former and the mixture of the resulting vapor with the air
required for its combustion. See carburetor.

Syn.: Vaporizing chamber.

Mixing Tube— In the burner of a steam vehicle, the tube
in which the sprayed fuel becomes mixed with the air re-
quired for its combustion. See burner; burner jet.

Mixture — The aeriform fuel of an internal combustion motor,
consisting of air mingled with a certain proportion of an in-
flammable gas or vapor. In automobile practice, the mixture
consists of air impregnated with gasoline vapor. See fuel,
gasoline; lean mixture; overrich mixture.

Mixture Pipe — See intake pipe.

Monobloc Casting — A single casting in which are included
all the cylinders of a gas motor. See cylinder, block cast.

Motor — The headings under this general term refer to in-
ternal combustion motors or engines of the four cycle type,
unless otherwise specified.

Motor, Air=Cooled — A motor, the cylinder walls of which
are maintained at a temperature sufficiently low to permit of
effective lubrication and to prevent binding of the parts, self-
ignition (see ignition, self) and too great reduction of the
charge weight taken into the cylinders, by means of the con-
vective influence of currents of cool air directed upon the
cylinders and attached heated parts. See air-cooling; blower-
cooled.

Motor Ball Bearing — A motor, the crankshaft of which
rotates upon ball bearings, the cam shaft and the large ends of
the connecting rods being sometimes thus supported. See crank-
shaft, ball bearing; bearing, annular ball.

Motor, Block — A motor, the cylinders of which are cast
en bloc. See cylinder, block cast.

Motor Compound — A motor in which the exhaust gases from
a cylinder in which combustion occurs is directed into a
closely adjacent secondary or low pressure cylinder of larger
diameter in which the final expansion of the gases to atmo-
spheric pressure does work upon a piston acting upon the
same crankshaft upon which the primary cylinder acts. Two
four-cycle cylinders, firing at intervals of 360 degrees, may
be used, their exhausts acting upon the piston of the same
large diameter low pressure cylinder upon each down stroke
thereof, all three cylinders acting upon the same three throw
crankshaft.

Motor, Double Cylinder — A motor consisting of two cylin-
ders acting upon a common crankshaft. The two cylinders
may be arranged (i) upon the same side of the crankshaft,
with their axes parallel and perpendicular to the crankshaft.
(2) They may be arranged upon opposite sides of the crank-

213

shaft with their axes in the same plane and perpendicular to
the crankshaft (see motor, opposed cylinder). (3) They
may be arranged with their axes making an acute angle one
with the other and perpendicular to the crankshaft. In (i)
a double throw crankshaft is used (see crankshaft, double
throw) and the cylinders fire at 180 degrees apart, or the two
throws are placed upon the same side of the shaft and the
cylinders fire at 360 degrees apart. In (2) a double throw
crankshaft is used and the cylinders fire at intervals of 360
degrees, four cycle cylinders here being assumed. In (3) both
cylinders act upon a single crank (see crankshaft, single
throw). See also motor V type. Syn. : Two cylinder motor
Type (3) and occasionally type (i) are sometimes known as
twin motors, type (2) as a double opposed motor.

Motor, Double Diameter Piston Type — A motor with a
double diameter cylinder (see cylinder, double diameter),
within which reciprocates a double diameter or two-stepped
piston. Such a motor may be a two-cycle motor (q.. v.) or a
four-cycle motor. In the latter case, the annular space be-
tween the large diametered portion of the piston and the step
in the cylinder forms one combustion space and the space
between the head of the small piston and the cylinder head
another combustion space. Each of these combustion spaces
is fitted with the usual valves and spark plug, and the com-
bination constitutes two power
cylinders acting upon the same
piston and crankshaft, which al-
ternately produce power im-
pulses at intervals of 360 de-
grees of crank angle.

Syn. : Differential piston motor.
Motor, Double Piston — A
motor in the cylinder of which
reciprocate, in opposite direc-
tions, two pistons, one acting
through an ordinary connecting
rod and the other through a
suitably designed yoke, upon the
same crankshaft. The charge is
admitted, compressed and fired in
DOUBLE; PISTON MOTOR. the space between the heads of

214

the two pistons, the working pressure acting upon them simul-
taneously and forcing them toward their respective ends of the
cylinders. Superior running balance is claimed for this construc-
tion which is, however, little used.

Motor, Eight Cylinder — A motor, usually of the V type
(see motor, V type) with four pairs of cylinders, each pair
acting upon one of the cranks of a four throw crankshaft. (See
crankshaft, four-throw.)

Motor, Electric — See electric motor.

Motor, Explosion — An internal combustion motor (q. v.)

Motor, Forced Induction — A motor operated upon the
forced induction (q. v.) principle.

Motor, Four Cycle — A motor which operates upon the
four stroke cycle (q. v.).

Motor, Four Cylinder — A motor with four cylinders, act-
ing upon a common crankshaft, (i) The four cylinders may
be arranged with their axes parallel and perpendicular to the
crankshaft and act upon a four-throw crankshaft (see crank-
shaft, four-throw), the power impulses occurring at intervals
of 180 degrees of crank angle, (see firing order) four cycle
cylinders being assumed, (2) The cylinders may be arranged
in two V placed pairs, the two cylinders of each pair acting
upon one crank of a double-throw crankshaft (see crankshaft,
double-throw), producing power impulses as in (i). (See motor,
V type.) (3) The cylinders may be arranged in two opposed
pairs (see motor, opposed cylinder), each pair acting upon one
crank of a two-throw crankshaft, the power impulses being
spaced as in the two other types.

Motor, Gasoline — A motor using gasoline (q. v.) for fuel.

Motor, High Compression — A motor employing a compres-
sion pressure higher than the average adopted in motors other-
wise similar. The term is purely a relative one, but motors carry-
ing more than about 75 pounds compression pressure per square
inch may be so considered. See compression.

Motor, High Speed — A motor, in the output of which ro-
tative speed is relatively a larger factor than torque — the ac-
cepted type in automobile practice on account of its large out-
put per unit of weight.

Motor, Horizontal — A motor, the axes of the cylinders of
which lie in a horizontal plane. Such motors are mostly of the
opposed type and are placed either under a car body, with

215

the crankshaft transverse to the car length or under a hood with
the crankshaft longitudinally with respect to car length.

Motor, L Head — A motor constructed with L type cylinders
(see cylinder, L type).

Motor, T Head — A motor constructed with T type cylinders
(see cylinder, T type).

Motor, Long Stroke — See long stroke motor.

Motor, Low Compression — A motor employing a compres-
sion pressure lower than that of the average of motors other-
wise similar. The term possesses a relative significance only,
but a motor employing a compression pressure less than 70
pounds per square inch may be so called.

Motor, Low Speed — See low speed motor.

Motor, Multicylinder — A motor constructed with more
than one cylinder, the several cylinders acting upon the same
crankshaft.

Motor, Non=Poppet valve — A motor in which valves other
than poppet valves are employed. (See motor, rotary valve;
motor, sliding sleeve, and motor, piston valve.)

Motor, Opposed Cylinder — A two or four cylinder motor
in which the cylinders are located upon opposite sides of the
crankshaft with their axes in the same plane and perpendicular
to the crankshaft. (Two cylinder type..) The cylinder axes are
usually slightly displaced from a straight line to enable their
connecting rods to act upon the two throws of the crankshaft
(see crankshaft, double throw). Such a four cycle motor
gives two equally spaced power impulses in each two rotations.

(Four cylinder type) — The four four-cycle cylinders are ar-
ranged in two opposed pairs, the two cylinders of each pair
acting upon the same throw of the double throw crankshaft.
Such a motor delivers four equally spaced power impulses in
each two turns of the crankshaft.

Motor, Overhead Valve — A motor, the valves of which are
located in its cylinder heads. (See valve, overhead.)

Motor, Piston Valve — A motor, the valves of which are of
the piston type. (See valve, piston.)

Motor, Pocketed Valve — A motor, the valves of which
are located in pockets or chambers communicating with the
cylinder spaces. (See valve, pocketed.)

Motor, Poppet Valve — A motor, the valves of which are
of the poppet type. (See valve, poppet.)

210

Motor, Revolving Cylinder — A motor, the cylinders of
which revolve as a unit, while the crankshaft remains stationary,

power being transmitted from
the shaft of the cylinder unit,
which is revolved by the reac-
tion of the pistons, transmitted
through their connecting rods
to the fixed crankshaft. The
axes of the cylinders are on
equally spaced radii from, the
crankshaft and may be three,
four, five or more in number,
joined to a central crankcase.
Such engines are frequently
air-cooled, exhaust directly in-
to the atmosphere and receive
ROTARY CYLINDER MOTOR. their charges from the station-
ary carburetor through piping,
including a rotating joint. No

flywheel is usually provided, as the cylinders themselves act in
this capacity.

Motor, Rotary Valve — A motor fitted with a valve or valves
of the rotary type. (See valve, rotary).

Motor, Short Stroke — See long stroke motor.
Motor, Single Cylinder — A motor with one cylinder act-
ing upon a single throw crankshaft (see crankshaft, single
throw) delivering one power impulse in each two rotations.

Motor, Six Cylinder — A motor with six cylinders ar-
ranged upon the same side of the crankshaft, with their axes
in the same plane and perpendicular to the crankshaft, acting
upon a six-throw crankshaft. (See crankshaft, six-throw.)
In such a motor, power impulses are delivered at intervals of
\2o degrees of crank angle. (See firing order.) Also a motor
of the V type (see motor, V type) with six cylinders in three
pairs, each pair acting upon one throw of a three throw crank-
shaft (see crankshaft, three-throw) delivering power impulses
spaced as in the other type.

Motor, Truck Piston Type — A motor in which the upper
end of the connecting rod is directly connected to and pivots
in the piston, it being secured thereto by the piston pin (q. v.),

217

no piston rod, crosshead (q. v.) or crosshead guides being
required. The lower end of the piston is necessarily open,
and the connecting rod angularity (q. v.) is so proportioned
with regard to the inside diameter of the piston that the
former clears the latter. The piston performs the crosshead
function and the cylinder the guiding function. (See piston,
trunk.) This is the accepted type of internal combustion motor
for vehicle use.

Motor, Sliding Sleeve — A motor, the valve action of which
is effected by sliding sleeves. (See valve, sliding sleeve).
Syn. : Knight type.

Motor, Three Cylinder — A motor with three cylinders ar-
ranged upon the same side of the crankshaft with their axes
in the same plane and perpendicular to the crankshaft. (See
crankshaft, three throw.) Such a motor delivers a power im-
pulse in each 240 degrees of crank movement.

Motor, Twin Cylinder — A motor of the double cylinder
V-type. The term is occasionally applied to a double cylinder
motor of the type first described under motor, double cylinder.
Motor, Two Cycle — See two-cycle motor.
Motor, Two Cylinder — See motor, double cylinder.
Motor, V Type — A motor the cylinders of which are arranged
in two equal sets, the axes of the cylinders of one set converg-
ing toward the axes of the
other set and nearly or ex-
actly intersecting at the
crankshaft axis, perpen-
dicularly thereto. The
angle between the axes of
the two sets is most com-
monly go degrees. The cyl-
inders of one set are near-
ly opposite the respective
V TYPE MOTOR. cylinders of the other set,

and each two oppositely

placed cylinders act upon the same throw of the crankshaft.
Referring to V motors of the 90 degree type : The two cylinder
(twin) motor delivers to its single throw crankshaft two power
impulses in each two rotations spaced at angles of 270 degrees
and 450 degrees.

218

Motor, Vertical — A motor the cylinders of which are placed
with their axes in a vertical position. The accepted type in
automobile construction in which the motor is located under a
hood, with its crankshaft lengthwise of the vehicle.

Motor, Water Cooled — A motor the cylinder walls of
which are maintained at a temperature sufficiently low to permit
of effective lubrication and to prevent self-ignition, by the cir-
culation of water about them through jackets enveloping them.
See water cooling, water jacket.

Motor Air Compressor — An air compressor, operated by
a motor, usually electric, used in garages for charging a tank
with compressed air to be used for inflating tires. The motor
is usually started and stopped automatically as the pressure in
the tank rises above or falls below a predetermined amount.

Motor Buggy — See high-wheeled car.

Motor Generator — An apparatus for transforming electri-
cal energy in the alternating form into electrical energy in

the continuous form or vice
versa, or for transforming
electrical energy at one volt-
age into that at another or
for accomplishing both re-
sults simultaneously. It con-
sists of an electric motor
operated by electrical ener-
gy of the character which
is to be converted, which
drives a dynamo capable of
generating electrical energy
of the desired character, the

two machines usually being arranged upon the same bedplate
and direct connected.

It is used in garages for converting alternating into direct
current or high voltage into low voltage current adapted to
charging vehicle and ignition batteries.

Syn. : Generator set

MOTOR GENERATOR.

Mud Guard — See fender.

210

Mud Hook — A traction increasing device intended for tempor-
ary use in very deep mud or snow, consisting of a narrow pad-
dle-shaped piece of metal applied cross-
wise of the tire tread and securely fastened
to the wheel felloe so that when the wheel
rotates the edge of the mud hook cuts
deeply into the road surface and secures a
hold thereupon. Several such hooks arc
usually applied to each driving wheel and
are removed as soon as a firm road sur-

MUD HOOK. face is reached'

Mud Pan — See sod pan.

Muffler — A device for suppressing the noise of the escape
of the exhaust gases from an internal combustion motor, con-
sisting of means for permitting
said gases gradually to expand
in confined spaces, with resulting
decrease in their pressure and
temperature, so that they are final-
ly emitted into the outside air at
a pressure but little above atmos-
phere. Its construction may com- MUFFLER.
prise a series of closed, concentric,

cylindrical chambers communicating from one to the other by
somewhat devious passages. Gases from the engine exhaust
pipe are usually first admitted to the largest chamber and then
successively to the progressively smaller chambers, expanding
and cooling in each until they are emitted from the last cham-
ber, through the final escape pipe, in a greatly expanded condi-
tion and without explosive violence. The muffler is usually sup-
ported under the rear of the vehicle frame, with the escape
pipe in a horizontal or slightly upcurved position.

Syn. : Silencer.

Muffler Cut Out— A valve opening into the outside air
from the exhaust pipe of an internal combustion motor at
a point between the muffler and the motor, which, when
open, permits the exhaust gases to escape directly into
the air without passing through the muffler. Opening
the valve allows the sound of each explosion to be

220

heard, and enables the operator to detect any irregularity there-
in. If the muffler develops back pressure (q. v.), opening the
valve eliminates it and thus adds to the effective output of the
motor. The cut-out valve is usually operated by a linkage con-
trolled by a pedal set in the footboard or by a hand lever located
upon the heelboard.

Muffler Explosion — An explosion produced by the accidental
ignition of combustible gases contained in a muffler. When a
motor rotates without burning its charges, they are exhausted
into the muffler, rilling it and the exhaust pipe so that when,
subsequently, a cylinder fires its charge, its burning exhaust
gases, meeting the explosive mixture in the piping and muffler,
may explode it.

Multiple Battery — A battery, the cells of which are ar-
ranged in multiple series connection (q. v.), the number of
series groups used being proportioned to the capacity of the
cells and the severity of the service demanded. For a given
draft of current by the external circuit, the larger the number
of series groups, the smaller the current demanded from each
cell, and the longer the life of the battery and the greater its
freedom from polarization.

Used in ignition and in vehicle lighting on a small scale.

Multiple Coil Ignition — See ignition, multiple coil.

Multiple Connection — In an electric battery, that method of
connecting cells in which the positive poles of all cells are
connected to the same lead wire and the negative poles of all
cells to the other lead wire, producing a battery, the voltage of
which is that of a single cell and the internal resistance of which
is equal to the internal resistance of a single cell divided by the
number of cells in the battery. In the case of electric lamps,
electric motors or other electrical translating devices, that method
of connection in which one lead wire from the source of supply
is conducted to one terminal of each device, and the other lead
wire to its other terminal, thus dividing the current supplied
among the devices in circuit. Syn. : Parallel connection.

The opposite of series connection.

Multiple Series Connection — In an electric battery, the com-
bination of a number of groups of cells, the cells of each group
being in series connection (q. v.), and equal in number. The
positive terminal of each group is connected to one lead wire
and the negative terminal of each group to the other lead wire.

221

The voltage of such a battery is that of one cell multiplied by
the number of cells in each group and its internal resistance is
equal to the internal resistance of one series group, divided by
the number of groups.

Multiple Threaded Screw — A screw which is cut with a
number of uniformly spaced parallel helices instead of with a
single helix, a thread of very coarse pitch being thus produced,
while, at the same time a sufficient number of threads are
always in engagement with those of the nut. Such a screw
provides for a rapid rate of motion, relatively to its multiple
threaded nut in proportion to their relative rotation and may
be so designed that reversibility of action between the screw
and nut may be obtained in almost any desired degree. Used
in steering devices (q. v.) of the worm and sector and screw and
nut type and in worm drives.
Mutilated Thread— See breech-block joint.
Needle Valve — A valve for controlling the flow of a fluid,
usually consisting of a stem provided with a more or less
tapered point, adapted to tightly fit in a
somewhat conical seat. When the stem is
thus seated the flow of fluid is cut off, and,
as the tapered end of the stem is gradually
withdrawn from its seat, a passage is pro-
gressively opened, the area of which is capable
of close regulation. Used in carburetors, lu-
bricators, gasoline shut-offs, gas tanks, etc.

See carburetor needle valve and carburetor
float valve.

Negative Plate— That plate of a battery
cell into which the current seems to flow from
the external circuit. In a primary cell this is
the carbon or copper plate and in an accumu-
lator the spongy lead or iron-oxide plate.
Negative Terminal — That terminal of any electrical apparatus
into which current seems to flow from the external circuit.

Neutral Position — That position of the mechanism of a
sliding pinion change speed gear in which no driving effort is
transmitted from the rotating motor to the wheels, although the
clutch is in engagement, for the reason that no gears are in
engagement. Also the position of the gear shifting lever, which
corresponds to the above described condition in the gearset.

NEEDLE VALVE.

222

That condition of a planetary or individual clutch change speed
gear in which no clutch is in engagement and the position of the
control devices which correspond therewith.

Neutralize: (v.) — To place a change speed gear in the neutral
position.

Nickel Babbitt — A white metal of which bushings (q. v.) for
bearings are made and for which the following is a specification :
Copper, 64 per cent.; tin, 5 per cent; lead, 30 per cent., and
nickel, i.o per cent.

Nickel Steel — See steel, nickel.
Nickel Chrome Steel — See steel, nickel-chrome.
Nipple — A term specifically applied to the points of attach-
ment of the branches of an intake or exhaust manifold (q. v.),
which are properly formed to fit in their respective port open-
ings, the joints being either ground tight or packed by gaskets
and held in place by clamps or otherwise. Also a pipe fitting
consisting of a short length of pipe threaded externally at both
ends.

Non=Conductor — Electric — A substance through which elec-
tricity cannot appreciably flow at ordinary electrical pressures.
Used in electrical devices to prevent the escape of electricity
from the wires or other conductors to which it should be con-
fined. Glass, porcelain, rubber, mica, vulcanized fibre and silk
are among the best non-conductors. Syn. : Insulator, dielectric.
Non=Fluid Oil— See grease.

Non=Freezing Solution — See anti-freeze solution.
Non=Return Valve — See check valve.

Number Plate — A plate, usually of sheet steel, conspicuously
inscribed with the registration number of 'a car and the name
of the State in which it is reg-
istered, two of which are
usually required by law to be
carried at all times affixed re-
spectively upon the front and
rear of a car so that the own-
ership of the car may be read-
ily ascertained by reference
to a list of registrations. The
rear number plate must be il- NUMBER PLATE.

luminated at night by the tail
lamp, according to most automobile laws. Syn.: Number Pad.

223

ODOMETER.

Odometer — An instrument for continuously recording the
distance traveled by a vehicle. It is essentially a mechanical
counter and recorder of road wheel revo-
lutions, which automatically, by means of a
suitably designed clockwork train converts
wheel revolutions into miles and fractions
thereof, and indicates the same upon a suit-
able dial. It is usually combined with a
speedometer (q. v.) and is driven by suit-
ably proportioned gearing from a non-driv-
ing (usually front) wheel through a flex-
ible shaft (q. v.), the instrument itself
generally being mounted upon the vehicle dashboard.

Odometer, Hub — An odometer con-
tained within the hub cap of a non-driving
road wheel of a vehicle, and thus requiring
no special driving mechanism. A suitable
connection of the indicating mechanism to
a part, such as a knuckle, which does not
rotate, is provided, so that the instrument
is positively driven. By sealing the hub
cap in place, tampering with the indica-
tions of the instrument can be prevented. HUB ODOMETER.

Odometer, Trip — An odometer which can be set back to
zero at will, so that the distance traveled by the car to which
it is attached from the time of resetting to any later time
can be read off directly, no subtraction of readings being
necessitated. It is usually combined in the same case with
an ordinary totalizing or season odometer.

Offset (n.) — In general, a bend or angle in a generally
straight mechanical part, which causes a portion of it to lie out
of alignment with, but generally parallel to, the remainder of
the part. Specifically: In a motor, the perpendicular distance
from the axis of a crankshaft to the extended 'axis of its
cylinder, frequently expressed as a fraction of the stroke length.
See crankshaft, offset.

The perpendicular distance from the axis of a camshaft to
the extended axis of its cam follower.
See camshaft, offset.

Offset (v.) — To adopt an offset construction, as in the posi-
tioning of a crankshaft or camshaft.

224

Offset Camshaft — See camshaft, offset.

Offset Crankshaft — See crankshaft, offset.

Offset Screwdriver — A special form of screwdriver with an
offset in its blade, used to turn screws which are inaccessible
to an ordinary screwdriver.

Ohm — The unit of electrical resistance, being the resistance
offered by a column of pure mercury 106.3 centimetres
long and one square millimetre in cross section when at the
temperature of melting ice.

Ohms Law — The law connecting a steadily impressed elec-
tromotive force (E) (q. v.), the resulting current flow (C)

and the resistance (R), namely E=CR, R=?and C— -?• The

C R

first equation means that the electromotive force in volts acting
between any two points in such a closed circuit is the product
of the current in amperes and the resistance of the circuit, in
ohms, between the two points chosen. The second equation
means that the resistance in ohms between any two points
of such a closed circuit is the quotient of the electromotive force,
in volts, acting between those two points by the current flowing
in amperes. The third equation means that the current, in am-
peres, flowing in such a circuit is the quotient of the total im-
pressed electromotive force, in volts, by the total resistance of
the circuit in ohms.

This law applies to steady currents only and not to alternating
or pulsating currents.

OiJ, Castor — The oil expressed from the castor bean and
used as a cylinder lubricant in internal combustion engines
which operate at high speed and temperature for considerable
periods of time, as in racing.

Also used to treat the facings of leather lined clutches.

Oil, Cylinder — See cylinder oil ; cylinder oil, gas engine
and cylinder oil, steam.

Oil, Neatsfoot — An animal oil especially adapted to preserve
the qualities o'f leather and hence used to render soft and pliable
the facings of leather lined clutches.

Oil, Non=Fluid — See grease.

Oil Bath — A body of oil contained in a tight case in which
mechanical parts operate in such a manner as to be flooded
with the oil and lubricated thereby.

See lubrication, splash.

225

OIL CABINET.

OIL CUP.

Oil Cabinet — A stationary case con-
taining a supply of one or more grades of
oil with means for drawing the same and
often with means of measuring the amount
drawn. Used in garages for conveniently
handling oil without waste.

Oil Cup — A cup of metal or of metal with
glass sides, filled with oil
and arranged to .feed a
bearing into which the out-
let of the cup is inserted.
Generally an adjustable
needle valve permits the
flow of oil to be started
and stopped and regulated

and a sight feed (q. v.) is often provided below
the cup to permit the rate of feed to be ob-
served.

Oil Gauge — See gauge, oil, and gauge, oil
pressure.

Oil Groove — A special form of oil way, con-
sisting of a continuous spiral or circular groove cut in the
working surface of a motor, piston rather near the crank end
thereof, to aid in distributing lubricating oil evenly about the
whole of the piston surface and sometimes so designed as to
prevent excess oil from reaching the combustion space.

Oil Gun — A syringe used to handle lubricating oil. Similar
to a grease gun (q. v.).

Oil Lead (pron. leed) — A small diameter tube, usually of
copper, used to convey oil from the point of supply to a de-
livery point, e. g., from the reservoir of a force feed lubricator
to an oil-hole in a bearing cap. Also a cored passage in a motor
crank case through which the oil in a circulating system of lubri-
cation is distributed. An oil duct.

Oil Level — The depth at which the oil available for splash
'lubrication is maintained in the bottom of a crank case or other
housing. See lubrication, constant level and lubrication, splash
Oil Pan — A name appled to the lowest section of the crank-
case of a vertical internal combustion motor, the function of
which is to retain lubricating oil and not to support the crank-

226

shaft. It is usually readily removable to permit the bearings to
be inspected.

Oil Pocket — A depression formed in the bottom of the crank
case of a splash lubricated motor, directly under each connect-
ing rod and which holds a supply of oil into which the rod tip
dips at each revolution,- with resulting splashing about of the
lubricant. Syn. : Oil well.

Oil Pump — A pump, used to force or lift lubricating oil. It
may be of the plunger, gear or vane type driven usually through
gears from the motor to the lubrication system of which it
supplies oil, and is sometimes an integral part of the same.
See lubrication, circulating system, pump type. The term is
also applied to the individual pumps of a lubricator (force feed)
(q. v.), to a hand pump, used to replenish the oil supply in a crank
case, to transfer oil from an auxiliary oil tank to the reservoir
of a circulating system, or to lift oil from a stationary oil tank.
Oil Retainer — A device to prevent the escape of lubricating
oil from a bearing, consisting of a felt washer (q. v.) secured
in the outboard end of the bearing and
fitting tightly about the shaft or an ex-
pansible metal ring similarly fitted. It may
also consist of a metal ring fastened to
the shaft in such a manner as to throw off
any excess of oil, centrifugally, into a
pocket formed in the bearing support from
which it is returned to its source.

The term is also applied to a small
self closing oil tube adapted to be screwed
into a part requiring lubrication so that oil
fed into it from a squirt can flows into the oil hole of the bear-
ing and is prevented from escaping, while dust is at the same
time excluded.'

Oil Ring — A ring loosely fitted about
a shaft within a bearing standard,
adapted by its rotation to distribute oil
over the bearing surfaces. See ring oiler.
A more or less sharp edged ring fitted
upon a shaft, adapted to throw off ex-
cess oil centrifugally in such a manner
as to prevent its escape from the housing
of the bearing. See oil retainer. A cir- A, Oil Ring.

OIL RETAINER.

A, Felt Washer.

B, Roller Bearing.

C, Shaft.

227

cular groove cut around the lower end of a motor piston to aid
in distributing the oil. See oil groove. A hollow ring of hook
shaped cross-section, fastened in the cheek (q. v.) of a crank-
shaft so as to closely encircle the adjacent end of the neighbor-
ing main bearing (q. v.) and adapted to catch oil escaping from
the bearing and to guide it to a channel in the crankshaft cheek
through which it is forced, centrifugally, to the adjacent crank
pin (q. v.) bearing.

Oil Strainer — A filter of fine metal gauze, employed in circu-
lating lubrication systems (see lubrication, circulating system) to
remove sediment from the oil. It is made of large area and
readily removable for cleaning and is usually placed in the path
of the oil returning from the crank case to the sump (q. v.) or
oil reservoir. Synx Oil filter.

Oil Trough — A small metal trough sometimes formed in or
affixed to the inside of a motor crank case for the purpose of
collecting and conducting splashed oil from one part of the case
to another, as from one compartment to another or from a
portion of the inside surface of the case to a bearing.
See lubrication, trough system.

Oil Way — A groove or channel formed in a bearing cap or
in the bearing surface of a bushing adapted to conduct oil
from the point of supply to the frictional surfaces and to
permit of its distribution thereupon.
Oil Well— See oil pocket.

Oildag — The trade name applied to defloeculated graphite
(q. v.) in a form suitable to be added to oil and used as a
lubricant. Somewhat used in the lubrication of vehicle motor
cylinders.

Oiler — See lubricator.
Oiling — Lubrication (q. v.).

Oldham Coupling — A device for connecting in driving re-
lationship two shafts which are approximately in the same straight

line, so as to provide a slight de-
gree of flexibility at the junction
and thus prevent binding due to
accidental misalignment. It usu-
ally consists of two circular
flanges, fixed respectively to the
two shaft ends, in the abutting
OLDHAM COUPLING. faces of each of which is a dia-

228

metral groove, the grooves in the two flanges being located at
right angles one to the other. A disc-like floating member, car-
rying upon its two faces diametral projections placed at right
angles one to the other, is so held between the two shaft flanges
that the projection on one of its sides engages with the groove
of one flange, and the projection on its other side engages in the
groove in the other flange. A slight sliding action of the pro-
jections in the grooves corrects binding effects due to faulty
alignment.

Syn. : Hookham coupling. See flexible coupling.

Oscillate (v) — With reference to a mechanical part, to
swing to and fro upon a point which is fixed relatively to the part
in question as, for example, the connecting rod (q. v.) on the
piston pin (q. v.)

Otto Cycle — See four-stroke cycle.

Output — The rate at which energy is given out by a prime
mover or by a machine used to transform energy from one form
to another. Mechanical output, as from a gas or steam engine, or
an electric motor, is expressed in horse power (q. v.), and elec-
trical output, as from a dynamo or magneto, is expressed in
watts (q. v.) or kilowatts. In the case of a storage battery,
it is the average rate at which energy is given out by it during
discharge multiplied by the time occupied by the discharge.
Antonym : Input.

Ovalization — In the case of the cylinder bore of a gas or
steam engine, the departure from a truly cylindrical form to a
more or less elliptical form, occasioned by the greater wearing
action of the piston in the plane of the connecting rod move-
ment as compared with the wearing action in" other planes. This
action, to which the piston is also subject, tends to increase
leakage between the piston and the bore, (v.) Ovalize.

Overcharge (v.) — To pass charging current through an ac-
cumulator cell, after the reversible chemical changes in the
plates, which are effected by charging, have been practically
completed. It results in loss of electrical energy, excessive evolu-
tion of gas and spraying of the electrolyte, with an excessive rise
of temperature and often in shedding of the active material.
Also used as a noun.

Overflow Dam — In a circulating system of lubrication (see
lubrication, circulating system) of the constant level type, a
raised portion of the metal of the crankcase bottom, over which

229

oil flows back from the crankcase to the sump, the height of
which regulates the depth at which oil is carried in the oil
pockets (q. v.).

Overhead Camshaft — See camshaft, overhead.
Overhead Valves — See valve, overhead.

Overhead Washer — A device used in washing vehicles, con-
sisting of a horizontally placed arm of pipe, hung from the ceiling
. of a garage over the washstand,

so arranged as to swing upon a
vertical axis and connected to a
water supply. A flexible hose is
connected to one end of this swing-
ing arm and its nozzle may thus
conveniently be carried to any side
of the vehicle to be washed, the arm
following the motions of the hose.
Overheat — In reference to an
automobile part, to rise in tem-
perature to such an extent that it
fails to function properly or
may become damaged. An over-
heated bearing may run hard
from failure of lubrication and
may become melted or may cut

its shaft. An overheated motor cylinder may become cut from
failure of lubrication and may self-ignite its charges. An over-
heated dynamo or motor may destroy its insulation and burn out.

Overload (v.) — To demand from a prime mover or other
machine an output in excess of that which it is intended to
afford (nominal overload), or of that which it can give out
without danger of failure or undue wear and tear. To impose
upon a structural part a load greater than that which it can
repeatedly withstand without permanent deformation or liability
of early failure. A gasoline motor may be considered over-
loaded when the resistance against which it is working becomes
so great that, with full gas supply and most advantageous igni-
tion, its speed falls greatly below normal. An electric motor
is overloaded when the resistance against which it is working is
so great that the current called for is capable of dangerously
overheating it.

OVERHEAD WASHER

230

Overload Capacity — In an electric motor, the difference be-
tween its nominal or rated output and the output which it can
deliver, temporarily at least, without damage. Overload capacity
is usually expressed as a percentage of the rated output.

Overrich Mixture — A fuel mixture containing a larger pro-
portion of combustible vapor and a smaller proportion of air
than are present in a mixture of normal quality. See gasoline.
Packing — See gasket and stuffing box.
Pasted Plate— See plate, pasted.

Pedal, Adjustable — A pedal, so constructed that its length
and sometimes its inclination and that of its footpiece (pad)
may be adjusted to suit the convenience of operators of widely
differing stature.

Peen (v.) — To change the form of a malleable metal by caus-
ing it to flow slightly under repeated, rather light blows of a
hammer with a specially formed head. The process is used in
expanding metal parts and is related to the processes of up-
setting and riveting. Peening tends to make a metal more
dense. Spelled also pern.

Peen Hammer — A hammer with a spherical or otherwise
specially formed head used in peening or riveting.

Petcock — A small cock or valve, which, when opened, per-
mits the escape of a fluid from a chamber, e. g., the compression
cock (q. v.) inserted into the cylinder of a
gas or steam engine.

Petrol — The English equivalent of the
American term gasoline (q. v.).

Phosphor Bronze — A reddish metal of
excellent wearing qualities principally used
for bearing bushings, but, when rolled or
drawn into wire often used for small
PETCCCK springs, for which the following is a speci-

fication : Copper, 80 per cent. ; tin, 10.0

per cent. ; lead, 10.00 per cent. ; phosphorus, 0.05 to 0.25 per cent.
Pick Up (v.) — When applied to the action of a vehicle motor,
to increase in speed under load. When applied to the action of a
clutch, to accelerate the mechanism driven thereby to the speed
of the prime mover.

Picric Acid — A substance of acid nature, explosive by heat,
which is sometimes dissolved in gasoline with the intention of
increasing the rapidity of combustion of the charge in vehicle

231

motors, and hence of securing increased output, as in racing.
Tri-nitro-phenol, C6H3 NsOi.

Pilot Light — A small flame of fuel vapor and air employed
in connection with the burner (q. v.) of a steam vehicle to
initially heat the vaporizer of the main burner so that it can
gasify the fuel; to keep the main burner hot enough to enable
it at once to start into action after being turned off and also
to ignite the gas issuing from the main burner. The pilot light
of a steam vehicle is usually kept burning so long as the car
is likely to be called into service at any moment.

Pilot Light Valve— The valve, usually located within reach
of the operator of a steam car, which controls the supply of fuel
to the pilot light.

Pin — Specifically, a small metal pin used to hold together two
related parts by being tightly driven into a hole drilled through
bofh the parts after they are put together in their proper rela-
tive positions, the ends of the pin often being slightly upset to
prevent its loosening. Used to fasten cams, small gears and
such parts upon their shafts and to hold together parts which
are to be united by brazing.

Pin (v.)— To fasten together by pins.

Pin, Split — See cotter pin.

Pin, Taper — A pin of a slightly conical form, which can be
driven very securely into its hole.

Pinch (v.) — With reference to the air tube of a pneumatic
tire: To catch a portion of its wall between other parts of the
tire or of the rim, thus preventing the tube from assuming its
normal shape when inflated and producing sharp creases there-
in at which breakage may finally occur with consequent de-
flation.

Pinion — The smaller of a pair of gears (q. v.). In change
speed gears (q. v.) a pinion is known by the function it per-
forms, e. g., the smaller of the two gears which are meshed
to secure the low speed being known as the "low speed pinion"
and the "reverse pinion," "intermediate speed pinion," etc., being
similarly designated. .

Pinion, Driving — Specifically, the pinion forming a part of
the final drive of a gear driven car. Usually of the bevel type
in cars with longitudinally olaced shaft drive and of the spur

232

or herringbone type in cars the wheels of which are driven from
a transverse shaft.

Pinion Frame — A part of a differential gear (q. v.) or a
planetary gear (q. v.).

Pinion Shaft — A term specifically applied to the shaft of a
gear driven car, which carries the final drive pinion. In a bevel
gear driven car this is a longitudinal shaft, the rear end of
which at least is supported in the axle housing.

Piston — The member which reciprocates (q. v.) within the
cylinder of a gas or steam motor or a pump and is directly acted
upon by and directly acts upon the working fluid. It fits closely
and slides freely in the cylinder bore (q. v.). The piston of
a motor imparts reciprocating motion to the connecting rod
(q. v.) or piston rod (q. v.), the outward end of which is
made fast to it, and during the working portion of the cycle
(q. v.) the useful pressure of the fluid acts upon the head of
the piston, and the resulting motion thereof is converted, by
means of the other reciprocating parts, (q. v.) into rotation of the
crankshaft. During the remainder of the cycle the piston head
acts upon the working fluid.

Piston, Double Diameter — A piston the external surface of
which is stepped or formed with two superposed, coaxial, cyl-
indrical portions of different diameter, which respectively re-
ciprocate in the two appropriately diametered bores of a double
diametered cylinder.

Syn. : Differential piston. See cylinder, double diametered.
Used in some two cycle engines.

Piston, Ported — A form of piston, occasionally used in two
cycle motors, through the wall and 'head of which are cut ports,
which, when they register with corresponding ports in the cylin-
der wall, permit the transference of the charge from the pump
chamber to the combustion space.

Piston, Steam Engine Type — A piston into which is rigidly
fastened the upper end of the piston rod. (q. v.).

Piston, Spherical Head — A piston, the head of which is
inwardly concaved, taking somewhat the form of a spherical
arc and sometimes used in motor cylinders of the dome head type
in order to attain a nearly spherical compression space:

233

TRUNK PISTON.

Piston, Trunk — A piston, which not only performs the usual
functions of transmitting the working pressure to the other
reciprocating parts, but also that of a cross-
head (q. v.), the cylinder wall acting as
the crosshead guide (q. v.). No piston rod
is used with this type, the piston being
hollow, open at its crank end and quite
long in proportion to its diameter and the
piston pin (q. v.) being secured in its walls.
The accepted type in internal combustion
vehicle motors.

Piston Barrel — The side wall part of
a piston, which forms its working surface
in distinction to the head portion. The

barrel is usually made very slightly less in diameter near the
head end than at the crank end, to allow for the greater ex-
pansion of the former in service, and occasionally the central
portion of the barrel is made very slightly less in diameter than
either end portion so as to confine the bearing to the end por-
tions.

Piston Boss — One of the two diametrically opposite pro-
jections formed upon the inside of the barrel of a trunk piston
(see cut under piston, trunk) to form supports for the ends of
the piston pin (q. v.). See boss.

Piston Displacement — In a steam or gas engine, the total
volume swept by the piston or pistons thereof in a single full
stroke. It is usually expressed in cubic inches and is the product
of the area of the cylinder bore in square inches, the stroke
in inches and the number of cylinders. Piston displacement
may be used as a factor in estimating motor output.

Piston Head — The closed end of a piston which forms the
surface upon which the pressure of the working fluid acts.

Piston Pin — The pin, inserted diametrically through the
walls of a trunk piston, in a position
parallel to the crankshaft, to which is
secured the head end of the connecting
rod, and which transmits the motion
of the piston to and from the same. The
connecting rod may be free to oscillate
upon the piston pin, in which case the
ends of the latter are fastened in two PISTON PIN AND LOCK

234

diametrically opposite bosses formed in the inside of the piston
barrel or the connecting rod may be rigidly fastened upon the
pin, the ends of which oscillate in the piston bosses.
Syn. : Wrist pin.

Piston Pin .Lock — The device employed to prevent acci-
dental endwise movement of the piston pin in the piston walls,
which might cause the obtruding end of the pin to score the
cylinder wall. A set screw in each piston boss, clamping one end
of the pin, with the screws wired together to prevent their
turning out, is one of many forms of this device.

Piston Ring — A form of metallic packing employed to render
a motor piston gas tight in its cylinder. Such a ring is cut
from a hollow cylinder of cast iron of
about the same external diameter as that
of the cylinder bore and is severed or split
at one point so as to permit it to be sprung
into a circumferential groove formed in
the working surface of the piston in which
it fits closely, laterally. The ring being
free to open at the point where it has been

cut, is capable of expanding and filling any slight space be-
tween the piston and its bore. Three or four such rings are
commonly placed in parallel grooves between the piston pin and
head of a gas motor piston, and an additional one is often
placed in a similar groove on the crank side of the piston pin.
The rings are usually prevented from rotation in their grooves
by loosely pinning them to the piston wall, and the cuts in the
several rings are so located as not to be in the same straight
line.

Piston Ring, Compound — A piston packing composed of
more than one ring in each groove, for instance of a wide ring
in the bottom of the groove and two rings of one half its width
placed side by side over it in the outer part of the groove, the
splits in the three rings being spaced at equal angular intervals
around the groove and so held by pins.

Piston Ring, Diagonally Cut — A piston ring which is split
by cutting it through in a plane usually making an angle of
about 45 degrees with the plane of the ring and passing through
the ring's centre. When such a ring expands in service, a less
wide passage for the escape of gases is formed between its ends
than were the cut made squarely across the ring.

235

Piston Ring, Eccentric — A piston ring, the inside and out-
side circumferences of which are slightly eccentric, giving it a pro-
gressively varying thickness. It is usually split at its thinnest
point, and, in use, produces a more even expanding action than
does a concentric ring.

Piston Ring, Lap Ended — A piston ring, which is split, by
sawing half way through its width from one edge, and half way
through its width from the other edge, the two cuts being a
slight distance apart and their inside ends being connected by
a longitudinal cut in the plane of the ring. The ends of the
ring thus lap one past the other. This method of cutting is
adopted to reduce the escape of gas at the split.

Piston Ring Groove — A circumferential groove, usually of
rectangular section, formed in the working surface of a motor
piston to receive and hold an expanding packing ring.

Piston Rod — The reciprocating rod which transmits the mo-
tion of a motor piston to and from its crosshead (q. v.) one
end of the rod being secured in the piston and the other in the
crosshead. A part of some steam vehicle engines.

Piston, Side=thrust — The pressure between a piston and its
cylinder walls, acting at right angles to the direction of piston
motion, and in the plane of the connecting rod movement, when
the connecting rod is inclined to the cylinder axis. In a gas en-
gine, it is mainly due to that component of the reaction of the
connecting rod upon the piston, which acts during the power
stroke (q. v.), forcing the piston against one wall of the cylinder
and to that component of the reaction of the piston upon the
connecting rod which acts during the compression stroke (q. v.),
forcing the piston against the opposite wall of the cylinder. Its
ultimate effect is to wear the piston and cylinder out of round.
See ovalization. See crankshaft, offset.

Piston Speed — The rate of travel of the piston of a steam
or gas motor, generally stated in feet per minute. It is ob-
tainable by the use of the following formula : L =—r- , or

0.166 Sn, where L is the piston speed in feet per minute, n the
number of revolutions of the crank shaft per minute and ^ is the
piston stroke in inches.

Piston Stroke — The range of motion of the piston of a steam
or gas motor measured from its extreme position in one direction

236

to its extreme position in the opposite direction. Expressed in
inches or millimeters.

See long stroke motor ; short stroke motor.

Piston Travel — That portion of the working surface of a
motor cylinder which is swept over by its piston and equal in
length to the piston stroke, plus the length of the piston.

Piston Valve — See valve, piston.

Pit — A vault or depression built in the floor of a garage, over
which a car can be driven when inspection or repair of its under
parts is required and in which a workman can stand upright
while doing the required work. It is usually built of brick or
concrete and drained.

Pit (v.) — Referring to the working surface or seat of a gas
engine valve ; to become covered with minute rough depressions
caused by the scaling off of particles of the metal under the
action of hot gases. Pitting tends to prevent perfect tightness
between a valve and its seat.

Pitch (v.) — To so adjust the operative relationship of two
meshed gears that they run together most advantageously, with
a minimum of noise, wear and loss of energy, being neither too
deeply nor too lightly meshed. Theoretically this condition is
attained when their pitch surfaces are tangent one to the other.

Pitch, Chain — In a sprocket chain, the length of a complete
link, that is, the linear distance from a certain point on a link
to the corresponding point on the next link, expressed in inches.
The pitch of a sprocket is the straight line distance from the
point of intersection of the pitch circle with the centre line of
one tooth to the corresponding point of the next tooth, expressed
in inches.

Pitch, Circular — In a spur gear, the linear distance from the
centre of one tooth to the centre of the next tooth or the dis-
tance from one side of one tooth to the corresponding side of the
next tooth, measured as an arc of the pitch circle. Usually ex-
pressed in inches.

Syn. : Circumferential pitch.

Pitch, Diametral — Li a gear, the quotient obtained by divid-
ing the number of teeth by the diameter of the pitch circle, in
inches; being thus the number of teeth per inch of pitch diameter.
Diametral pitch is expressed by numbers e. g. A 40 tooth gear
having a pitch circle of 8 inches diameter is one of 40 -=-8= 5 pitch.
Automobile gears are known by their diametral pitches,

237

Pitch Circle — In a spur gear, the imaginary circle, which,
if rolled without slippage upon the pitch circle of a mated gear,
would produce the same relative angular velocities as are real-
?ed in the two gears when they work together in practice.

Pitch Diameter — The diameter of a pitch circle.

Pitch Surface — In a gear, the imaginary surface which, if
rolled without slippage upon the pitch surface of a mated gear
would give rise to the same angular velocities as are realized when
the two gears run together in practice. It is a cylindrical sur-
face in spur gears and a conical surface in bevel gears.

FIG. i.

PLANETARY GEAR.

FIG. 2.

Planetary Gear — A form of change speed gear (q. v.) usu-
ally affording two forward speeds and a reverse motion and
embodying the epicycle or sun-and-planet movement. In prin-
ciple, it consists of a spur gear D, fast to the motor shaft, a
number of symmetrically disposed spur pinions C, supported
upon studs in a frame rotatable on a sleeve upon the motor
shaft and in mesh with gear D, and an internal gear cut upon
the inside of a drum K, also rotatably sleeved upon the motor
shaft, which gear is also in mesh with pinions C. See Fig. I. If
the motor shaft and gear D is rotated while drum K is held from
turning, pinions C will simultaneously roll on D and the in-
ternal gear, but, on account of the teeth of D being less numerous
than those on K, they and the pinion frame will revolve around
D in the same direction with it but at a less angular velocity,
dependent upon the tooth ratios. If, on the other hand, the
motor shaft be rotated as before, and the pinion frame be held

238

from rotation, K will be rotated by the pinions in the direction
opposite to that of D, but at a fraction of D's speed determined
by the tooth ratios. If there be loosely mounted upon the
motor shaft, the sprocket of a chain final drive or its equivalent,
the low gear will be secured when, by suitable mechanism, oper-
ated by the control devices, the sprocket is made fast to the
pinion frame and drum K is held from turning. The reverse
will be secured when the sprocket is made fast to drum K
and the pinion frame is held from turning and the sprocket
will be directly driven at motor speed and the high gear se-
cured when it is made fast to the motor shaft and the gear-
combination is locked from turning and permitted to rotate as
a unit. In practice, two separate combinations of gears as above
described are employed, one for the low speed and one for the
reverse motion. See Fig. 2. The planetary gear is employed
upon some cars which are likely to be roughly handled, for
its operation requires no meshing of gears.

Syn. : Epicyclic gear, sun-and-planet gear.

Planimeter — An instrument for mechanically measuring plane
surfaces, however irregular in contour, and used in determining
the areas of manograph cards (q. v.), when the mean effective
pressure (q. v.) of a motor is to be calculated.

PLANIMETER.

Plate — One of the elements of a voltaic or storage cell. See
negative plate, positive plate.

Plate, Formed — An accumulator plate or element consisting
of a metallic grid or frame, usually of lead alloy, upon the surface
of which the active material (q. v.) of the cell is gradually pro-
duced by the electrochemical actions consequent upon the passage
of electric current into and out of the cell.

Syn. : Plante type plate.

230

Plate, Ironclad — A form of positive accumulator plate con-
sisting of a number of vertical metal rods, united at their upper
and lower extremities, respectively by a metal frame, each rod
having molded about it a cylinder of active material about
the outside of which is fitted a perforated hard rubber tube.
Freedom from shedding of active material under heavy charges
and discharges is the principal advantage secured by this con-
struction.

Plate, Pasted — An accumulator plate or element consisting of
a metal supporting grid or frame affording interstices in its struc-
ture into which the active material (q. v.) is forced in the
form of a paste applied under pressure.

Syn. : Faure type plate.

Point — In reference to an electric vehicle controller. One of
the several operative positions or notches in which it may be
placed by the operator, corresponding to one of the forward or
reverse speeds, the "off" position, etc.

Points of Carbon — The number of hundredths of one per
cent, of carbon which is present in a steel. Thus 30 point car-
bon steel is steel containing 0.30 per cent, of carbon.

Polarity, Electric — The direction in which an electric current
ts considered to flow, which is from the positive (+) to the
negative ( — ) pole of an electrical device. When the poles are
identified the polarity of the current is known.

Polarity, Magnetic — In the case of a magnet, that pole
thereof which attracts the south-seeking end of a compass needle
is called the north (N.) pole and vice versa.

Polarity Test — A test to determine which pole or conductor
of an electric circuit is positive and which is negative, made
use of in determining how to connect a storage battery to its
charging circuit.

If the ends of two wires attached respectively to the two poles
of the circuit be held somewhat apart in a glass filled with slightly
salted or acidulated water, that wire at which the most gas is
given off is connected to the negative pole and vice versa.

Polarization — The reduction of output occasioned in a
primary electric cell by the collection of hydrogen gas upon the
carbon or copper plate, the effect being due not only to the
development of a counter electromotive force (see electromotive
force, counter) but to an increase in the internal resistance.

240

In storage cells a very high rate of discharge sometimes so
coats the plates with gas that they do not make a good con-
tact with the electrolyte and a sort of polarization results. See
depolarizer.

Pole, Electric — See negative terminal, positive terminal.

Pole Magnetic — One of the two ends of a magnet where
free magnetism exists and between which magnetic force acts.
See polarity, magnetic.

Pole Piece — A piece of soft iron fixed to the pole of a mag-
net and adapted to conduct magnetic force into an armature
(q. v.) with a minimum of loss. In the case of a horseshoe
magnet, the pole pieces attached to the two poles respectively are
so shaped as partly to surround, and very closely to approach the
part upon which the magnetic force is to act, e. g., the arma-
ture of a magneto, dynamo or electric motor.

Poppet Valve — See valve, poppet.

Popping in the Carburetor — See backfiring.

Port — In general, a passage for the flow of a fluid. Specifically,
a valve controlled passage, through which gases enter or leave
the cylinder of a gas motor. They are usually cored out in the
process of casting the head of the cylinder and communicate
from the combustion space through the cylinder wall to the
outside thereof. See exhaust port and inlet port.

Positive Plate — That plate or element of a battery cell out
of which the current seems to flow to the external circuit. This
is the zinc plate in a primary cell, the peroxide of lead plate
in a lead accumulator and the nickel oxide plate in an alkaline or
Edison type' accumulator.

Positive Terminal — The terminal of any electrical device
out of which the current seems to flow. In a battery cell it is the
terminal attached to the positive plate.

Syn. : Positive pole.

Potential, Electrical — See electromotive force, with which it
is generally synonymous in practice.

Pound (v.) — In a motor or other mechanism to produce in
operation a series of abnormal blow-like sounds, usually caused
by looseness or lost motion (q. v.), between related parts which
is alternately developed and taken up as they operate together,
causing the striking together of the parts. A crankshaft loose
in its bearings is likely to pound.

241

Power Stroke— That stroke in the cycle (q. v.) of a gas
motor during which the working fluid imparts useful energy to
the piston. In a four cycle (q. v.) gas motor, it is considered
the third stroke of the cycle and is an outward piston stroke
(downward in a vertical motor). Shortly before the com-
mencement thereof, the spark occurs and the gaseous charge, just
previously compressed by the piston (see compression stroke), is
ignited and reaches its maximum pressure at the beginning of the
power stroke, expanding during its progress and doing work
upon the piston until the exhaust valve (q. v.) opens.

In a two cycle motor each outward stroke (downstroke in a
vertical motor) is a power stroke, and is simultaneous with the
compression of the charge by the lower face of the piston, or
by a separate piston, preparatory to its being transferred to the
combustion space.

Syn. : Working stroke, expansion stroke.
Power Tire Pump — See tire pump, power.
Pre=expansion — The expansion of the charge while entering
a gas motor cylinder caused by heat derived from the cylinder,
ports and valves. It reduces the weight of charge which a cyl-
inder of given dimensions will draw in and thus reduces the
output of the motor. Its effect is especially noticeable in motors
which run very hot.

Preheating — The practice of warming the air used to form
the charge of a gas motor before it reaches the carburetor, by
means of a hot jacket placed around the air inlet pipe or by
drawing the air from around the hot exhaust pipe (see hot air
intake). It is adopted in order to compensate for the heat
absorbed in the vaporization of the fuel and thus to facilitate
complete evaporation.

The term is also applied to the practice of supplying heat to
the charge while it is being formed in the carburetor passages
and while it is passing through the intake pipes, hot air and hot
water jackets around these parts being resorted to. See car-
buretor, exhaust jacketed; carburetor, water-jacketed; Intake
pipe, jacketed.

Pre=ignition — Premature ignition. (See ignition, premature.)
Pressed Steel — Sheet steel which is pressed into the de-
sired shape while hot, by means of powerful dies. Generally used
for vehicle frames and extensively employed for crank cases,
housings of various kinds and other parts in preference to thin

242

castings on account of its superior strength for a given weight.
Pressed steel housings are usually made of two or more parts,
the edges of which are united by autbgeneous welding (q. v.) to
form the desired finished shape.

Pressure of Explosion— The maximum pressure attained
by the burning gases in a gas motor cylinder usually amounting
to from 250 to 350 pounds per square inch in a motor working
at full power.

. Pressure Feed — See fuel feed, pressure and lubrication, pres-
sure feed.

Pressure Gauge — See under gauge.

Prime (v.) — In a carburetor, to supply an excess of liquid
fuel to the air passages, so that an ignitible mixture may be
drawn by the motor when cranked at a speed too low to cause
sufficient fuel to be atomized by the carburetor spraying nozzle
(q. v.). Priming is usually effected by temporarily raising the
fuel level (q. v.) so that fuel spills out of the spraying nozzle
into the air passages.

Syn. : To flood the carburetor ; to tickle the carburetor.

In a motor, to supply liquid fuel directly to the combustion
spaces of the cylinders so that an ignitible mixture may be
formed by it and the entering air and explosions be obtained,
although a sufficiently rich mixture cannot be delivered to the
cylinders by the carburetor at practicable cranking speed.

Primer — A device for priming a carburetor, usually by raising
the level in the float chamber. See carburetor float depressor.
A device for furnishing liquid gasoline to the intake manifold
or cylinders consisting of a small reservoir filled with gasoline,
fitted with a hand pump and a delivery pipe leading to the in-
take manifold or branched piping leading to the combustion
spaces of the cylinders, check valves (q. v.), or stopcocks usu-
ally being inserted in the delivery pipes. The pump and tank
are usually attached to the dashboard and a few pump strokes
serve to prime the motor and to facilitate starting by the crank
or on the spark.

Priming— The fuel supplied to prime a carburetor or motor.
Gasoline or a mixture of gasoline and sulphuric ether.

The name given to drops of unvaporized water present in
wet steam, as steam from a foaming or over full boiler. The

243

presence of excessive priming causes loss of efficiency in a
steam engine, and the collection of excessive water in its
clearance spaces may cause knocking or possible damage to the
cylinder.

Priming Cock — A small cock with a cup shaped top, inserted
into the clearance space of a gas motor cylinder. The cock
when opened permits gasoline poured into the cup to enter the
clearance space as priming. The same cock may act as a com-
pression cock.

Syn. : Priming cup.

Progressive System — See sliding gears, progressive.

Propeller Shaft— The drive shaft (q. v,) of a shaft driven
car.

Protected Terminals— See spark plug, protected terminal.

Pump — See air pump, oil pump, gasoline measuring pump,
water pump, tire pump.

Pump, Centrifugal — A form of rotary, non-positive pump,
dependent for its action upon centrifugal force. It consists of
a narrow, somewhat ring-
shaped housing with an inlet
near its axis and an outlet ar-
ranged tangentially to its out-
side edge. The ring-shaped
portion of the housing is usu-
ally of increasing cross-section
toward the outlet. On a trans-
verse, power-driven, axial shaft,
within the housing is rotated a
wheel (the runner or im-
peller), composed of a hub
and several radiating blades,
usually concaved in the direc-
tion of rotation, which when
in operation, draws in liquid
through the inlet which is

forced centrifugally toward the outside of the housing and ex-
pelled through the discharge. Used as a circulating pump (q. v.)
in water cooling (q. v.) systems, being driven from the motor
through an auxiliary shaft (q. v.).

SECTIONAL VIEW OF CENTRIF-
UGAL PUMP.

244

GEAR PUMP.

Pump, Gear — A pump consisting of a liquid-tight housing
so formed as to enclose two meshed gears with practically no
clearance between their faces and the hous-
ing wall. The inlet is placed in a space pro-
vided where the gear faces come out of en-
gagement, when running, and the outlet is
placed in the corresponding space where the
teeth engage. When the shaft supporting
one of the gears is rotated, the other gear
also rotates and a partial vacuum is formed
at the inlet where the teeth recede, liquid
being drawn thereinto. As the teeth of the
two gears unmesh, liquid is carried along between them and the
casing and is delivered by them into the discharge outlet as they
mesh.

Used as an oil pump in lubricating systems (see lubrication,
circulating system) and occasionally as a water pump in water
cooling systems.

Pump, Plunger — A pump identical in principle with the com-
mon domestic force pump, used to pump oil in lubricating sys-
tems, to pump air in fuel feed systems, etc.

Such a pump is usually operated by an eccentric (q. v.) upon
one of the engine shafts.

Pump, Sliding Vane — A form of positive rotary pump in
which one or more sliding vanes perform the function of pis-
tons. . One form consists in principle of a
somewhat disc-shaped liquid tight housing
A, within which rotates on a power driven
shaft G, a disc B, of practically the same
thickness as the inside of the housing.
Shaft G is somewhat eccentric with the cen-
tre of the housing, and the diameter of B
is such that it moves with very slight clear-
ance over the housing at H. A crescent-
shaped water space / is thus formed. A
vane E, of practically the same width as
the thickness of the housing, is inserted in a
radial slot in B, and is pressed outwardly

by a spring F, so that its end is always in contact with the hous-
ing, causing it to act as a piston sweeping the space /. When

SLIDING VANE
PUMP.

245

R is rotated, as shown by the arrow, liquid is drawn in through
inlet D and kept in motion by vane E until it is discharged at
outlet C. Such pumps are used in lubricating systems. (See
lubrication, circulating system, pump type.)

Pump Bracket — A support, usually formed integrally with the
upper part of a gas motor crankcase, to which the water pump
(q. v.) is secured so as to be conveniently driven from the motor.

Pump Drive — The mechanical connection by means of which
a circulating pump (q. v.) is driven from a vehicle motor. It is
usually by means of a flexible coupling (q. v.) connecting one of
the auxiliary shafts (q. v.) of the motor with the pump shaft.
See water pump.

Pump Lubrication — See under lubrication.
Puncture — The accidental piercing of the wall of the air
tube (inner tube) of a pneumatic tire allowing the air to es-
cape and the tire to deflate. It is usually occasioned by some
sharp object in the roadway being forced through the tire casing
and tube when the tire rolls over it.

Push Rod — In general, a rod which transmits a pushing
effort from one part of a mechanism to another. Specifically,
a guided rod which transmits the opening
motion from a cam (q. v.) to the poppet
valve stem of a gas motor having pocketed
valves (see valve, pocketed), or from a cam
to the rocker arm (q. v.) of an overhead
valve (q. v.) motor. A means for adjust-
ing the length of the pushrod is usually
provided to permit of regulating the clear-
ance (q. v.) in the valve operating
mechanism.

PUSH ROD

Pushrod Guide — A slide, usually fixed
in the upper surface of a cam shaft hous-
ing, directly over a cam, in which a valve
pushrod reciprocates.

Pushrod Guide Yoke — A removable yoke secured to the
upper surface of a gas motor crankcase over a cam shaft, which
acts as a clamp to hold the pushrou guides (q. v.) in place. Such
a yoke is usually two armed and each arm bears upon a guide.

246

Pushrod and Spring Housing — A thin, readily removable,
tubular housing, usually of aluminum, which encloses an indi-
vidual ptishrod (q. v.) and the valve spring (q. v.) of the poppet
valve (see valve, poppet) which it operates, thus muffling the
valve noise, excluding dust and retaining lubricant. (See valve
gear, enclosed.)

Quadrant — A sector shaped stationary part, consisting of a
portion of a circle with radial supporting arms, employed to
guide the motion of a control lever and to hold it in any de-
sired position. See gear shifting quadrant, brake latch, throttle
lever and spark lever.

Quartz Powder — Finely pulverized quartz or silica used as
an abrasive in grinding motor valves to their seats.

Quill — A sleeve (q. v.).

Race (v.) — In a gas motor : To rotate at excessively high speed
unloaded ; all the mechanical energy developed being dissipated in
friction among the parts and in internal losses in the parts re-
sulting from abnormally severe inertia stresses.

Race— In a ball bearing, a single line of balls and the parts
they roll upon.

Rack and Pinion — A mechanism for transforming rotary
into straightline motion or the reverse, usually consisting of a
small spur gear (the pinion) the
teeth of which are in mesh with
corresponding teeth cut upon one
edge of a straight bar (the rack)
guided so as to move in its axis of
length. Rotation of the pinion
produces rectilinear motion in the
rack, which motion may be trans-
mitted to some other part as in a
steering gear. (See steering de-
vice, pinion and rack.) RACK AND PINION.

Radiation — Specifically, the area of the heat dissipating sur-
faces exposed in a radiator. Usually expressed in square inches.

Radiator — A device for dissipating into the surrounding air
the excess heat imparted to the cylinder walls of a gas motor.
(See water cooling.) It consists of an arrangement of pas-
sages, the exposed surface of which is very large in propor-
tion to their cross section, through which water from the water

247

jackets (q. v.) of a motor is caused to circulate so long as the
motor is in operation. The water in the jackets becomes heated
by contact with the cylinder walls and flows through piping to the
radiator, through the numerous small passages of which it
circulates. The external surfaces of these are exposed to a
draft of relatively cool air (see fan and flywheel, fan-spoked),
which abstracts the heat from the water within by convection,
which then circulates back to the jackets through piping to again
become heated.

Syn. : Cooler.

Radiator, Cellular — A form of radiator in which the water
to be cooled trickles through thin passages among tubes through
which cool air is caused to pass. Such
a radiator is built up of a large num-
ber of short, thin walled copper tubes,
usually of square or hexagonal sec-
tion, parallelly arranged to form a
construction of the desired shape.
The ends of the tubes are usually
slightly enlarged and the aggregation
of tubes is secured together by solder
at both ends, or the respective ends
of all the tubes are sweated into a
stamped metal frame. Narrow spaces
are left between adjacent tubes
through which the water passes from
a tank or header at the top of the

radiator to another header at the bottom, from which it is re-
turned to the jackets. The side walls of the outside tubes are
soldered to the frame of the radiator.

Syn. : Honeycomb radiator.

Radiator, Coil— A radiator consisting of a close coil of thin
walled copper or brass tubing, usually provided with radiating
flanges (see radiator, finned tubular) through the convolutions
of which the jacket water is circulated and which is exposed
to the air. The coil is generally of somewhat rectangular form
and may be simply held together by clamps or may be mounted
in a frame of conventional shape.

Radiator, Continuous Flange Type— A radiator of the finned
tubular type in which a series of continuous pieces of thin metal
form the cooling flanges for all the parallel tubes, each continuous

CELLULAR RADIATOR.

248

flange being threaded around and soldered to all the tubes. A
multiplicity of small separate flanges is thus avoided.

Radiator, Dashboard Mounted— A radiator mounted verti-
sally upon the vehicle frame close to the front surface of the
dashboard and to the rear of the motor,
the cooling air being drawn in through
apertures in its sides and expelled back-
wardly and downwardly under the foot-
board. Generally used with motors cov-
ered by hoods of the sloping type (see
hood, sloping).

Syn. : Renault type radiator.
Radiator, Finned Tubular — A radiator
constructed of thin walled (usually copper)
tubing, the external surface of which is
very greatly increased for the purpose of

DASHBOARD MOUNTED radiating and convecting the heat of the

RADIATOR. jacket water passing through them, by

closely spaced sheet metal flanges, fins

or gills soldered, at short intervals,

to the outside of the tubing. The fins are usually of thin sheet
copper, sometimes corrugated, threaded around the tubing, and
may be circular or square or of the continuous type (see radiator,
continuous flange type).

Syn. : Flanged tube or gilled tube radiator.
Radiator, Flat Tubular— A form of radiator built up of thin
walled tubing the external surface of which is made very large
as compared with its sectional area, for the purpose of heat dis-
sipation, by flattening it so that the passage within it is quite
narrow.

Radiator, Front Mounted — A radiator which is mounted
upon the extreme front of a chassis frame, forward of its motor
and forms the forward end of the hood space. (See hood,
straightline.)

Radiator, Honeycomb — A name applied to radiators of the
cellular type (q. v.), especially to those in which tubes of hexa-
gonal section are used.

Radiator, Tubular — A radiator consisting of a combination
of tubes surrounded by cooling air, through which the jacket
water is circulated, in contradistinction to a radiator of the cellu-

240

RADIATOR BRACKET.

lar type (q. v.) in which the cooling air passes through tubes,
around which the jacket water flows.

Radiator, Underhung— A radiator carried attached to the
under side of the vehicle frame. Usually of the coil type.

Radiator Bracket — A bracket attached to each side of the
bottom of the frame of a vertical, front mounted radiator, by
which it is secured, respectively, to the
two side members of the vehicle frame.
Sometimes the brackets are of the trun-
nion type, thus relieving the radiator of
stresses.

Radiator Casing — The ornamental sheet
metal casing surrounding the essential parts
of a radiator.

Radiator Draw=off — A cock or tap in-
serted in the bottom of a radiator through
which the water may be drawn off.

Radiator Fan — See fan.

Radiator Filler Tube— A tube, inserted in the tank at the
top of a radiator, and closed by a cap (the filler cap), through
which water is supplied to the cooling system.

Radiator Frame — The structural part of a radiator which
holds together the tubes and headers and by which the whole
radiator is mounted upon the vehicle.

Radiator Overflow — A means for providing for the .escape of
steam and the excess volume of water created by expansion
from the tank of a radiator, usually consisting of a pipe in-
serted into the tank and terminating below the radiator.

Radiator Spreader — A device placed in a radiator tank
(q. v.) to distribute the circulating water evenly among the
radiator passages.

Radiator Tank — A tank, usually forming the upper portion
of a radiator, from which water is distributed to the cooling
passages and which holds a supply of water to compensate for
that lost by evaporation or otherwise.

Radiator Tie Rod — The rod commonly used to give support
to the top of a front mounted radiator, one end of which is se-

250

cured to the dashboard and the other to the top of the radia-
tor frame, a turnbuckle being generally provided to permit the
length of the rod to be adjusted.

Radius Rod — See distance rod.

Rake — Upward and backward inclination of a vehicle part,
as of the steering post.

Rating Formula— A mathematical formula, by the applica-
tion of which the output of a gas motor may be calculated when
such data as' its cylinder bore, piston stroke and number of

cylinders are known. E. g., The formula H. P.— ,d* s n

10

where d is the bore in inches, S the stroke in inches and n the
number of four cycle cylinders, is an example of such a -formula.
See horsepower A. L. A. M.

Reach Rod — A structural member of the running gear of
some motor vehicles, the function of which is to connect the
rear axle with the front axle.

Syn. : Perch.

Ream (v.) — To finish a hole to size by means of a reamer
(q. v.). Some motor cylinders are reamed after being bored. •

Reamer — A metal working tool, consisting of a fluted cylin-
drical bar carrying longitudinally arranged cutting edges upon
its cylindrical surface which, when inserted in a bored hole and
forced therethrough with a rotary motion, enlarges the diam-
eter thereof very slightly, by taking a light chip from the
walls of .the hole, leaving it nearly true and of approximately
the same diameter as the reamer itself, which is usually of a
standard size. If the reamer is slightly conical (taper reamer)
instead of cylindrical, it produces a taper hole, such as required
for the reception of a taper pin, for instance.

Rebound Check — See shock absorber, recoil strap.

Reciprocate (v.) — With reference to a mechanical part.
To move alternately backward and forward.

Reciprocating Parts — Strictly, parts which reciprocate (q. v.)
only, such as a motor piston, piston rod and crosshead, but the
term is often applied to parts which not only reciprocate but
oscillate (as a motor connecting rod).

251

RECOIL STRAP.

Recoil Strap — A continuous strap or loop, generally of leather,
used to check the recoil of vehicle springs. Two such straps
are often used, passed around the rear
of an automobile frame, respectively, at
or near the two sides thereof, and also
loosely looped, respectively, around the two
ends of the rear axle casing. The body is
free to lower relatively to the axle, but
if it tends to rise far above its normal
position the straps are tightened, and the
rebound of the body away from the axle
is stopped. Sometimes applied to act be-
tween the upper and lower members of
a full elliptic spring to prevent their sep-
arating abnormally.
Syn. : Rebound strap, jump strap, limit strap.
Rectifier, Alternating Current — A device for converting al-
ternating current (q. v.) into direct current (q. v.) to permit the
charging of storage batteries by electrical energy derived from
an alternating current supply. The electrical arrangements are
usually such that the flow of current in both directions is utilized,
but matters are so ananged that the flow in the battery to be
charged is in a constant direction.

Syn. : Alternating current converter. See motor generator.
Rectifier, Aluminum Cell — A form of rectifier making use
of the property possessed by an electrolytic cell employing alumi-
num plates of permitting current to flow through it in one di-
rection only ("electric valve" action), to convert an alternating
into a pulsating direct current.

Syn. : Chemical rectifier or converter.
Rectifier, Mercury Vapor — A form of
rectifier making use of the property pos-
sessed by the electric arc in mercury vapor
of permitting current to pass through it in
one direction only ("electric valve" action),
to convert an alternating into a direct cur-
rent.

Syn. : Electrolytic rectifier, electrolytic
converter, mercury arc converter.

Rectifier, Vibrating Armature Type—
A form of rectifier consisting of a vibrat-

WWWVWWWMA

DIAGRAM OF
MERCURY VAPOR
RECTIFIER.

252

ing armature (q. v.) under the control of an alternating current
electromagnet, which automatically reverses the circuit connec-
tions of a storage battery under charge from an alternating
current supply each time the current reverses its direction, and
thus causes a pulsating direct current to be supplied to the battery.
Used to charge ignition and lighting batteries.

Syn. : Commutating rectifier.

Relief Cock — See compression cock.

Relief Valve — A valve the function of which is to auto-
matically open and relieve the pressure in a fluid containing
system, when it exceeds a predetermined value, by allowing the
excess of fluid to escape or to be sent through a by-pass (q. v.)
to the low pressure side of the system. The point of action
of such a valve is usually regulated by the tension of the spring
which seats it.

A relief valve is sometimes employed in pressure fuel feed
systems which make use of exhaust gas or air pressure, it
being arranged to act when the desired pressure in the system
is exceeded.

Reserve Tank — See auxiliary fuel tank, auxiliary oil tank.

Reserving Valve — See fuel valve, reserving.

Resistance, Electrical — The hindrance offered by a substance
forming part of an electric circuit to the flow of electricity
through it. It may be regarded as similar to the frictional re-
sistance offered by a pipe to the flow of water. Good con-
ductors (q. v.) offer comparatively little resistance, while in-
sulators on non-conductors (q. v.) are of extremely high re-
sistance. The resistances of rods or wires of a given material
are directly proportional to their lengths and inversely propor-
tional to their sectional areas. The unit of electrical resistance
is the ohm (q. v.). For the mathematical relations of current,
electromotive force and resistance in direct current circuits,
see Ohm's law.

Resistance, External — The resistance offered by an electric
circuit (see circuit, closed) not including that of the current
source (battery or dynamo).

Resistance, Internal — The resistance offered by a current
source, e. g., the resistance of the plates and electrolyte (q. v.)
of a battery or that of the armature winding (q. v.) and other
parts of a magneto or dynamo which are included in the main
circuit.

253

Resistance Control — A method for controlling the speed of
an electric vehicle (see controller) in which the voltage applied
to the motor is varied by means of resistance inserted into or
withdrawn from the motor circuit by the controller. Other things
remaining the same, the greater the resistance in circuit the lower
the voltage at the motor, and the lower its speed and vice versa.
Resistance control is wasteful and is used only as an auxiliary
method in connection with more economical methods. See field
commutation control and controller, series parallel.

Syn. : Rheostat control.

Retard (v.) — In reference to ignition timing: To so arrange
matters that the spark occurs later in the cycle (q. v.) of the
motor. The opposite of advance. See ignition, delayed.

Retread (v.) — With reference to pneumatic tires. To re-
place the tread (see tire tread) of a tire which has been worn
out or damaged in service or which has proven defective.

Reverse Band — The friction band, acting upon the reverse
drum (q. v.) of a planetary gear, which, when tightened by the
control mechanism, secures the reverse motion of the car.

Reverse Clutch — In an individual clutch change speed gear,
the clutch which, when engaged, secures the reverse motion of
the car.

Reverse Drum — In a planetary gear (q. v.) the drum which,
when held from turning by the reverse band, secures the reverse
motion.

Reverse Gear — The mechanism by means of which backward
motion of a motor car is secured. In gasoline cars the direction of
rotation of the motor being constant, the reverse mechanism is
embodied as a part of the change speed gear, and when in action
causes the final drive shaft thereof to rotate in a direction oppo-
site to that in which it rotates wlien forward speeds are in use.
As steam engines and electric motors can rotate in either direc-
tion, reversing their directions of rotation reverses the direction
of car movement. See planetary gear and friction drive for the
principles involved in their reverse actions. In gearsets of the
sliding gear, (q. v.) direct drive (q. v.) type, reverse motion is
generally secured by sliding one of the gears on the final drive
shaft (commonly the low speed gear) into mesh with an idler
(q. v.) or intermediate gear, which is in mesh with a gear car-
ried by the layshaft (q. v.). The inclusion of the idler in the gear
train causes the final drive shaft to rotate in the same direction

254

as the layshaft, while on forward speeds the opposite is the case.
In individual clutch systems a separate gear and clutch, usually
on the driven shaft and a gear on the motor shaft, with an idler
in mesh between them, are put into operation to secure the
reverse. In steam vehicles the reversal of the direction of rota-
tion of the motor and hence reverse motion of the vehicle, is
usually obtained by manipulation of the valve gear by the link
motion (q. v.). In electric vehicles the motor is reversed by
reversing the direction of current, either through the fields or
through the armature.

Reverse Idler — The pinion which, in sliding gear and indi-
vidual clutch gear sets, by acting as an intermediate rotating
member between two main gears, causes the reversal of rotation
of the final drive shaft. See idler.

Reverse Latch — A safety device designed to prevent a slid-
ing gear (q. v.), change speed gear, from being unintentionally
placed in the reverse position. It consists of means for normally
blocking the reverse slot or position of the gear changing quad-
rant (q. v.), so that the gear shifting lever cannot be made to
enter it until the operator presses a button or thumb-piece upon
the lever handle, which releases the latch.
Syn. : Reverse gate.

Reverse Lever — A lever, the operation of which causes a
car to back. In some electric vehicles the reverse lever performs
the reversing function in conjunction with the controller handle,
and in some steam cars a reverse lever is employed which acts
upon the link motion and varies the point of cut-off (q. v.) as
well as reversing the engine.

Reverse Pedal — A pedal the operation of which causes a
vehicle to back, as in some planetary geared cars and some steam
and electric vehicles.

Rheostat — A device for introducing resistance into an elec-
tric circuit for the purpose of varying the current flowing therein.
It usually consists of a frame contain-
ing coils of rather high resistance wire,
such as iron or German silver, and pro-
vided with means by which the current
may be passed through the whole or any
part of the coils, and much or little re-
sistance thereby be introduced. Used in
regulating the charging current supplied
RHEOSTAT. to storage batteries, in regulating the

255

current in the field coils (q. v.) of dynamos and hence the voltage
produced, and as an auxiliary in the speed control of electric
vehicles. (See resistance control.)

Rib — A thickened portion of a casting, usually rather nar-
row, extending over portions thereof where the stresses acting
are severe and serving as a reinforcement to make the part more
rigid. In castings which must be light, such as crank and gear
cases, the walls are cast rather thin', and strength and stiffness
are secured by providing ribs along lines where failure might
otherwise take place.

Ride (v.) — Faulty action of a sprocket chain. See climb.

Rim — A ring shaped channel secured around the outside of
the felloe of a vehicle wheel and designed to secure thereto a
solid rubber or pneumatic tire.

Rim, Clincher — A rim of somewhat cres-
cent shaped section, with incurved edges
adapted to hold the shoulders or beads of
a tire casing of the clincher type (see tire,
clincher. It may have several equally
spaced holes through it to receive the re-
taining bolts, which assist in holding the
tire to the rim.

SECTION OF
CLINCHER RIM.

Rim, Demountable — A form of rim upon which is mounted
a fully inflated pneumatic tire and which can quickly be substi-
tuted for another similar rim, the tire
upon which has becomed damaged.
One or more demountable rims, with
their inflated tires, are carried upon
a car, and in event of tire trouble it
is only necessary to loosen the fas-
tening devices which secure the rim
to be changed to its wheel, take it
off and attach in its place one of the
spare rims and tires. The labor of
changing tires and inflating them

upon the road is thus avoided. The demountable rim is bolted
to a steel band shrunk upon the felloe or fastened thereto by some
equivalent device, and the tire is held thereupon by either the
clincher or quick detachable method.

DEMOUNTABLE RIM.

256

Rim, Quick Detachable — A rim built up of several ring-like
parts, so arranged that the part holding one edge of the tire may

readily be detached, allowing the
tire to be slipped off for repairs
or replacement. The parts of the
rim are held together by some
form of locking device, and in
event of tire trouble it is only
QUICK DETACHABLE RIM. . necessary to release the locking

device and remove the ring which
holds the outside edge of the tire

when the tire can be removed without the use of force which
the removal of a clincher shoe from a solid rim entails. The tire
being repaired, it can be replaced upon the rim without the
use of great force, the outside ring put in position and the lock-
ing device tightened.
Syn. : Separable rim.
Rim, Separable — See rim, quick detachable.

Rim, Universal — A rim of the quick 'detachable type, adapted
to hold any standard make of pneumatic tire casing, whether of
the clincher or straight bead type (see tire bead), an easily
effected rearrangement • of the parts permitting either style of
casing to be utilized.

Rim. Cutting — The penetration of the edges of a rim into the
outside wall of a pneumatic tire caused by continued pressure
between them. It is usually caused by underinflation, by some
defect in the rim or by the use of a casing and rim not adapted
one to the other. Its effect is to weaken the wall of the casing
so that a blowout ultimately occurs.

Ring Oiler— A device for oiling shaft bearings, consisting
of a small, oil filled reservoir formed in the bearing stand and
a metal ring, loosely threaded around and resting upon the
shaft and dipping into the oil. As the shaft rotates the ring
is also rotated by friction with the shaft, and carries up oil
from the reservoir, which it distributes over the shaft. Used
in electric vehicle motors and elsewhere. See oil ring.

Road Resistance — See tractive resistance.

Road Test — A test to determine the operative condition of
a motor car by driving it upon the highway under service

257

conditions. A road test generally forms a part of the factory
testing routine, and develops and permits the rectification of
defects which might otherwise come to light only after the
car was in a customer's hands.

Roadster — A body somewhat resembling the runabout, but

usually fitted with a single
or double rumble seat. A
hooded dash is ordinarily
used.

Robe Rail— A metal rod
or leather strap, supported
upon the back of the front
seat of a motor car, upon

ROADSTER.
which carriage robes, coats, etc., are intended to be hung.

Rocker Arm — In general a lever pivoted near its centra
and given a rocking motion by a rod or other device, acting
upon one end, which motion is
imparted by the other end of
the lever to some other mechan-
ical part. Specifically a part of
the mechanism generally em-
ployed to open overhead valves
(see valve, overhead), the rocker
arm being pivoted in a bracket
affixed to the cylinder head, a
push rod (q. v.) communicating
the cam movement to one end
thereof, and the other end of the
rocker arm acting directly upon
the stem of its valve.

Syn.: Walking beam.

Roller Bearing — See bearing, roller.

Root Circle — In reference to a gear: An imaginary circle
drawn through the bottoms of the tooth spaces*.

Rubber Cement— Pure rubber or rubber compounded with a
small proportion of sulphur, dissolved in a volatile liquid such as
benzene, used in applying a coating of pure or vulcanizing rubber
to surfaces, as in the manufacture and repair of tires.

ROCKER ARM (A).

RUMBLE SEAT.

Rumble Seat — A small seat, usually single but occasionally
for two, located to the rear of the principal seat and ordinarily
intended for casual rather than regular
use. Mainly used upon cars of the run-
about and roadster types.

Run In (v.) — To operate a mechanism
for the purpose of smoothing up the work-
ing surfaces of its moving parts by their
mutual frictional action. Motors are "run
in" and inaccuracies of adjustment and
manufacture, smoothed out by operating
them for a considerable period by ex-
ternal power or their own power, a plentiful supply of oil being
provided. The same treatment is applied to gear sets, rear
axles and other parts.

Runabout — A body primarily intended to accommodate two
persons upon a single seat which is usually located considerably

further to the rear of the
chassis than is the front
seat of a touring car. A
rumble seat, an artillery
box, a trunk platform or
gasoline and oil tanks may
occupy the space to the
rear of the seat or a slop-
ing back enclosing luggage
space may be used.

Running Board — A continuous step, extending horizontally, at
a convenient height, between the front and rear fenders (q. v,) on
each side 'of a motor car, usually made of pressed steel or
aluminum or of steel or wood, covered with linoleum or some
similar .material and supported by irons from the frame. It
is useful not only as a step, but as a protection to the passengers
from flying mud and as a support for tool and battery boxes and
gas tanks or generators.

Running Gear — A term applied collectively to the combina-
tion of motor car parts which is common to all wheeled vehicles,
such as the frame and other structural parts, wheels, springs,
axles and their immediate attachments.

Rush (v.) — To speed up a car, thus increasing its momentum,
in order that the energy of motion thus imparted to it may be

RUNABOUT.

259

expended in assisting the motor to overcome a temporarily in-
creased road resistance, such as a short hill or a short stretch
of mud or sand.

Safe Starting Position — That position of the timer (q. v.)
and spark lever (q. v.) of an ignition system corresponding
to a timing of the spark sufficiently retarded so that the danger
of the operator's receiving a back kick (q. v.), when cranking
the motor, is obviated.

Safety Loop — A metal loop attached to and extending down
from the frame of a shaft-driven car so as to encircle the drive-
shaft at a slight distance below
it. Should the driveshaft break
away at its forward end it would
be caught by the safety loop and
prevented from falling and catch-
ing in the roadbed with the pos-
sibility of damaging the mechan-
ism or of overturning the car.

Safety Plug— A circuit closing
plug which can be removed from
a socket upon an electric vehicle,
when it is to be left unattended,
thus breaking the electric circuit
from the battery to the motor and
thereby preventing the starting of

the vehicle until the plug 'is replaced. The term is also some-
times applied to the fusible plug (q. v.) used in steam vehicle
boilers.

Safety Spark Gap— A pair of discharge terminals (q. v.)
irranged at a suitable distance apart, connected respectively to
the two ends of the secondary coil (see
coil, secondary) of an ignition induction
coil (see coil, induction), or of a high
tension magneto armature (see mag-
neto, high tension), so that, in case the
high tension wires leading from the coil
become detached from their spark plugs,
the discharge can take place harmlessly
at the safety spark terminals, rather than
destructively through the insulation of the coil. The safety spark

SAFETY LOOPS.

SAFETY SPARK GAP.

260

gap is usually housed or enclosed in wire gauze, so that the
spark thereat cannot ignite stray gasoline vapor.

Safety Spark Retarder — An automatic device for prevent-
ing the starting crank of a motor car from being used unless
the spark timer is set in the safe starting position (q. v.).

Safety Starting Crank — See crank, safety starting.

Safety Valve — A valve, which, when opened, permits the
escape of steam from a boiler when the pressure within it
exceeds a predetermined point, thus preventing
further increase of pressure, and obviating the
danger of an explosion. Such a valve is nor-
mally held to its seat by an adjustable spring
and automatically opens when the steam pres-
sure acting against it overbalances the spring
tension.
Syn. : Pop valve ; escape valve.

Saturate (v.) — To completely or nearly
completely charge with magnetism a mass of
iron or steel, such as the field or armature
core of a dynamo.

Saturated Mixture — Air which has taken
up all the fuel vapor which it can retain. In
certain forms of carburetor (see carburetor
vaporizing tube) a saturated, or at least a very
greatly overrich mixture is first formed, which
is diluted with air before reaching the cylinders.

SAFETY VALVE.

A, Connec-
tion to Engine;
B, Outlet to At-
mosphere.

Scale (v.) — With reference to a gas motor valve: To loosen
thin portions thereof or of the seat, under the oxidizing action
of the hot gases, lack of tight seating being the result.

Scale (n.) — An adherent substance which gradually forms
upon the inside surfaces of the water spaces of steam boilers
and of gas motor water jackets and radiators, and which is
the result of the action upon the metal of mineral and organic
impurities in the water. Scale retards the passage of heat to
and from the water and thus reduces the efficiency of the appara-
tus, and in the case of steam boilers sometimes causes their
burning out. Caustic alkali solutions are often used as scale
removers.

261

Scavenge— In the operation of a gas motor, to expel the
products of combustion from the cylinders prior to the entrance
of a fresh fuel charge. In four-cycle motors this is accomplished
by the inward stroke of the piston, known as the exhaust stroke
(q. v.), and the tendency for the burned gases to leave the cylin-
ders is sometimes augmented by the use of an exhaust manifold,
ejector type (q. v.). In two-cycle (q. v.) gas motors the in-
coming charge is generally depended upon to displace the burned
gases, thus scavenging them out of the cylinder through the ex-
haust port, which is located opposite to the admission port.
See deflector plate. In some two-cycle motors a special charge
of fresh air, admitted ahead of the fuel charge, is depended
upon to scavenge the cylinder.

Scavenging Stroke — See exhaust stroke.
Score (y.) — With reference to the action of one moving part
upon another, to cut or abrade their working surfaces, e. g.,
a motor piston sometimes scores its cylinder walls, forming
grooves in their respective surfaces and destroying the tightness
of their fit. Scoring is usually caused by lack of lubrication, or
by the accidental protrusion of some moving part against a
smooth surface, as of the wrist pin against the cylinder bore.

Scrape (v.) — To finish the working surface of one part into
perfect fit with that of another related part by removing, by
means of a hand tool (scraper), the inequalities of the surface
of the part which is not true, e. g. Bearing bushings are often
scraped until they fit the shafts which run in them.

Seat, Divided — A motor car front seat, which is divided
into two seating compartments for the operator and a passenger
respectively, by a central upholstered parti-
tion, which gives support to the occupants'
bodies and prevents their jostling together.
Second Gear — That arrangement of a
change speed gear which secures a speed
ratio between the final drive and the mo-
c tor next higher than that secured by the

iJIVIDED oEAT. ,

low gear (q. v.). In three speed gearsets
this is synonymous with the intermediate gear (q. v.).
Syn. : Second speed.
Secondary Battery — See accumulator.
Secondary Coil — See coil, secondary.
Secondary Commutator — A distributor (q. v.).

262

Secondary Gears — Synonymous with half-time gears (q. v.)
and cam gears (q. v.).

Secondary Shaft — Synonymous with cam shaft (q. v.) and
half-time shaft (q. v.).

Secondary Wiring — Wiring used to convey a secondary or
high tension current (q. v.). See high tension wire.

Sector — A portion of a gear, consisting of an arc of its toothed
circumference, its hub and spokes; which is used, in mesh with
a worm or spur pinion, in steering devices (see steering device,
worm and sector) and in other gear combinations in which one
of the gears does not perform a complete rotation. The term is
also applied to control lever guides. (See quadrant.)

Seize (v.) — In reference to bearing surfaces, to adhere
together so that they cannot be moved one upon the other. If
no film of lubricant is maintained between the surfaces and they
are operated together under pressure, heat is developed and metal
particles of one surface enter superficially into the metal of the
other surface and the surfaces stick together, leaving them
rough and in an inoperative condition when they are separated.
Selective System — See sliding gears, selective.
Selector — In a sliding gear change speed device of the selective
type, a fork carried upon the end of a crank which rotates one of
the gear shifting shafts (q. v.), and with which the gear
shifting lever (q. v.) engages when it is moved out of its
neutral position. Two selectors are commonly employed, located
upon opposite sides of the neutral position, each selector con-
trolling the movement of the shaft which shifts its respective
pair of sliding gears.

In a self-starting device, an indicator which shows which cyl-
inder is in the firing position.

Self=Contained — With reference to a mechanism : Capable of
performing its functions without the co-operation of apparatus
external to it, e. g. The self contained lubrication system, re-
quires no piping, reservoirs, pumps, etc., external to the motor
in which it is used. (See lubrication, circulating system.) The
term is sometimes used in the sense of "compact" merely.

Self=Stwter — A device designed to obviate the necessity of
cranking a gas motor in order to set it into operation, consisting
of means for turning over the motor by mechanical instead of
human energy, until it commences to fire its charges and oper-
ate normally.

263

Self Starter, Electric Motor Type— A self starter, which
starts a gas motor into rotation by means of an electric motor

supplied with current from
a storage battery carried
upon the car. When start-
ing is to be effected the
armature pinion (q. v.) of
the electric motor is thrown
into mesh with a large gear
upon one of the gas motor
shafts and current is turned

ELECTRIC TYPE SELF STARTER.

A, Motor Generator; B, Flywheel
with Teeth cut on its .Periphery; C,
Intermediate Shift Gears.

on to the electric motor
and, when the gas motor as
in normal operation the
armature pinion is thrown

out of gear. The electric motor and storage battevy usually
act as parts of the vehicle lighting and ignition system when
not in use as parts of the self starting system.

Self Starter, Gas Pressure Type — A self starter in which
gaseous pressure, admitted from a storage tank carried upon
the car, through a hand operated cock, a distributing valve
(see valve, distributing) and check valves to the compression
spaces of the several cylinders, successively, when on their work-
ing strokes, causes the motor to rotate and to draw its charges,
which are fired by the spark, thus causing the regular operation
of the motor to commence, when the self starting pressure is
cut off by closing the cock. Either air pressure created by a

GAS PRESSURE TYPE SELF STARTER.

264

power driven air pump or exhaust gas pressure obtained from
one cylinder, through a check valve, is used. The distributing
valve is gear driven at one-half engine speed.
Syn. : Compressed air starter.

Self Starter, Ignition Type — A selfstarter which charges
with a combustible fuel mixture the cylinders of a gas motor
either (i) by introducing it into each cylinder individually, or
(2) into the intake pipe, at the moment after ignition has been
interrupted and the motor is stopping. In (i) a hand operated
distributor valve (see valve, distributor), controlling the flow
of acetylene from a gas tank, delivers a measured quantity of
gas through a separate pipe and check valve to the combustion
space of each cylinder, and in (2) the act of the operator, which
interrupts the ignition, also opens a valve permitting acetylene to
enter the intake pipe and to be sucked into all the cylinders
during the final rotations of the motor. After the cylinders are
thus charged, the motor may be set in operation by starting on
the spark (q. v.). Syn.: Spark self-starter, acetylene self
starter.

IGNITION TYPE SELF STARTER.

E, Acetylene Tank; C, Foot Button, which, on being pushed down when
the Motor is stopped, opens the Valve A, allowing a charge of Acetylene
Gas to be drawn into the Cylinders during the last few strokes of the
. Motor, and at the same time short circuits the Magneto at K. A manipula-
tion of the Spark Lever will start the Motor.

Self Starter, Spring Type— A self starter which starts the
motor into rotation by utilizing the mechanical energy stored in
a coil spring, which can be made to act upon the crankshaft.
The spring is automatically rewound by the power of the motor
when it is operating normally. '

Semi=SeIective System — See sliding gears, semi-selective.

265

Separator — A thin sheet of perforated, non-conductive ma-
terial, such as hard rubber, celluloid or wood placed between
neighboring positive and negative plates of a storage cell to
keep the plates out of contact and to prevent the space between
them from being bridged by active material (q. v.) shed (q. v.)
from the plates.

A device to prevent water accidentally present in gasoline from
reaching the carburetor. See filter.

A device for removing cylinder oil from the water collected in
the condenser of a compound steam vehicle motor, the difference
in specific gravity of the two liquids being made use of to
effect the separation.

In a ball bearing, a thin metal cage in which the balls are
loosely held so that they cannot roll one upon another.

Series Connection — The connection of several electrical de-
vices in circuit so that the same current passes through them
successively. Battery cells are connected in series when the
positive terminal of one is joined to the negative terminal of a
second, and the positive terminal of the second cell to the nega-
tive terminal of a third cell, and so on, until all are connected.
The electromotive force (q. v.) of such a series connected bat-
tery is equal to the electromotive force of one cell, multiplied by
the number of cells and its internal resistance (see resistance,
internal) is equal to the internal resistance of one cell multi-
plied by the number of cells.

Syn. : Tandem connection.

Series wound — See dynamo, series wound and electric motor,
series wound.

Set Screw — A means for locking in fixed relative position
two parts which are capable of sliding or rotating one within
the other. It consists of a screw with a hardened and some-
times cup-shaped or otherwise specially formed point, which is
threaded in a hole drilled in the outside part and which can
be screwed down tightly against the surface of the slidable or
rotatable inside part so that it cannot move,- a small depression
or "spot" being made in the surface against which the screw is
set to receive its end. •

Settling Pocket— A depression, formed in the bottom of a
liquid containing chamber, in which collects relatively heavy
foreign matter present in the liquid and from which it can be

2G6

drawn off through a cock or plugged opening. Used in gasoline
tanks, oil tanks and gasoline separators (see filter).

Shaft Drive— A method of transmitting the power of a
motor to the driving wheels of a car in which a shaft, rotated
by the motor, drives the wheels by means of gears.

In cars propelled by front mounted motors, with their shafts
longitudinal of the car, the drive shaft (q. v.) is longi-
tudinally placed; connected at its front end to the clutch or final
shaft of the change speed gear and driving the rear axle by
bevel or worm gearing (see bevel gear drive; gear, worm;
driveshaft, single jointed; drive shaft, double jointed.) In
a few commercial vehicles the drive shaft is transversely placed,
and each end thereof carries a spur pinion which meshes with
a large internal gear bolted upon one of the driving wheels.

Shed (v.)— With reference to the active material (q. v.) of
storage battery plates, to fall away from the grids (q. v.), to
which it is attached, with the result of reducing the capacity of
the cell and possibly of shortcircuiting (q. v.) it. The action
is caused by deformations of the grids occurring when very heavy
currents are passing.

Shield — A continuous guard, usually of sheet steel, filling the
space between the running board (q. v.) and fenders (q. v.)
and the body of a car, designed to prevent road splash from
reaching the body and the passengers.

Syn. : Splash apron.

Shift Gears (v.) — To change gears (q. v.).

Shim — A piece of thin material, usually sheet metal, placed
between two parts of a mechanism to adjust their distance apart,
e. g., shims are used between bearing caps (q. v.) and bearing
brackets (q. v.) to regulate their distance apart when they are
bolted together, and thus to adjust the pressure of their bear-
ing surfaces upon the shaft which they hold. When a shaft has
worn its bearings, by taking out one or more shims under each
side of the bearing cap, the looseness may be corrected.

Shock Absorber — A device designed to reduce the severity of
the road shocks communicated from the running gear to the
body of a vehicle by regulating the action of the springs — es-
pecially by checking the violence of their recoil.

267

Shock Absorber, Dashpot Type— A type of shock absorber
in which sudden and extensive movements of the springs are

resisted and retarded by
fluid pressure, acting in
a dashpot (q. v.), the
cylinder and piston of
which are respectively

SECTIONAL VIEW OF DASHPOT TYPE
SHOCK ABSORBER.

attached to the vehicle
frame and the axle.

Gradual movements of the springs are permitted by the
escape of the fluid from the cylinder (if air is used) or by
its being by-passed (q. v.) around the piston (if oil or glycerine
are used), but abrupt movements are checked by the pressure of
the fluid acting upon the dashpot piston.

Shock Absorber, Friction Type — A type of shock absorber
which dampens the action of the springs, preventing their ex-
cessive movement and vibratory action
by imposing a constant or progressively
increasing friction which resists their
movement. In a common form of this
type the friction is applied between ad-
justably spring pressed discs placed at
the pivot of a toggle joint, formed by
two arms, one end of one of which is
pivotally attached to the vehicle frame,
and one end of the other to the axle,
their other ends being united at the FRICTION TYPE SHOCK
friction joint. As the vehicle body ABSORBER.

raises and lowers, relatively to the axle, A' Framei B> Axle-
the toggle joint opens and closes and the friction at its pivot
gives the desired dampening action.

Shop Test — A test to which an automobile and its component
elements are subjected to determine its fitness for use, before
it is delivered to the purchaser by its manufacturer. Such a
test may include any or all of the following operations or others:
The running of the motor upon a test stand with a dynamometer
(q. v.) to measure its output, a test of the efficiency and quiet-
ness of operation of the change speed gear and rear axle unit,
and a test of the completed chassis, under power, the output
at the wheels being measured by a dynamometer.

Syn. : Factory test.

268

Short=Circuit — The passage of an electric current by a path
shorter than that over which it is intended it should normally
flow, thus withdrawing from the circuit a portion of the con-
ductor through which it should pass. An accidental short-
circuit is usually caused by the failure of the insulation between
some of the conductors forming the circuit, as by the action of a
high electromotive force, the current thus being afforded a short
path from one conductor to another through the ruptured in-
sulating material. A short-circuit may be intentional, as in the
act of shutting off a high-tension magneto, a short path being
afforded from one terminal of the low tension winding to the
other around the make-and break, thus preventing the interrup-
tion of current by the latter and stopping the production of
sparks.

Short Stroke Motor — See long stroke motor.
Shoulder — An abrupt increase in the size of a mechanical
part, especially an abrupt increase in diameter of a shaft, used to
limit the endwise motion thereof or for some other purpose.
Shunt Wound — See dynamo, shunt wound.
Shutter — See air damper.

Shuttle Wound — A term applied to magneto and dynamo
armatures, the conductors of which are wound in two longi-
tudinal, diametrically opposite slots, of somewhat rectangular
section around a shuttle shaped or H section armature core (see
core, magnetic), as thread is wound upon a shuttle.

Side Member — One of the two members of a vehicle frame
which form the sides thereof. See frame.
Side Curtains — See top, cape.
Side Slip— See skidding.

Side Sway — The two-and-fro motion of a car upon its springs,
in a horizontal plane, sometimes experienced at high speeds.

Sight Feed — A visual indicator used to demonstrate the
flow of a liquid, usually of oil, in a lubricating system, consist-
ing of a small chamber into which are
connected a pipe through which oil is de-
livered from the source of supply, and
another pipe through which the oil flows
to a bearing or other point of application.
The chamber is provided with a transparent
window through which the flow of oil may

be observed. The sight feed is usually
SIGHT FEED.

located within view of the operator, as upon the dashboard, and
there is sometimes incorporated with it an adjustable needle
valve to regulate the rate of flow of the oil. Syn. : Telltale.

Silicon Steel,

Silico Manganese Steel,

Silico Vanadium Steel — See steel.

Sill — One of the main members of a vehicle frame, particu
larly when of wood.

Simpling Device — A term applied to the piping and valves
used in connection with a compound steam engine (see steam
engine, compound) to permit the temporary admission of live
steam to the low pressure cylinder to increase the output of the
engine. When the simpling device is in use the engine operates
as a two cylinder simple engine.

Single Coil Ignition — See ignition, single coil.

Single Motor Equipment— In an electric vehicle, the use
of a single motor driving the traction wheels through a dif-
ferential gear (q. v.) and suitable reduction gearing in contra-
distinction to double motor equipment (q. v.).

Single Spark Ignition — See ignition, single spark.

Siren — A kind of alarm or signaling device sometimes used
upon automobiles. It consists of a perforated, hollow cylindrical

member rotatably fitted
within a stationary cyl-
indrical housing pro-
vided with corresponding
perforations. As these
parts rotate relatively
their perforations pass
each other and sound waves, the pitch of which varies with the
rotative speed, are produced which are directed by a horn shaped
resonator. The rotating member may be driven by a small bat-
tery energized electric motor or by means of a friction pulley
which is pressed into contact with the flywheel of the vehicle
motor.

Skidding — The abnormal sidewise movement and unintentional
change of direction of a motor vehicle caused by one or both
pairs of its wheels moving upon the roadway in directions other
than those in which they are being steered — that is, slipping
sideways. It is occasioned by lack of adhesion of the wheels to
the roadway, due to the slippery condition of the latter and

270

may be brought about by changing a vehicle's course too sharply
at too high speed, by applying the brakes or power too suddenly
when the two traction wheels are upon unequally slippery footing
or by driving upon the sloping side of a crowned road. The
liability of skidding can be reduced by driving very slowly over
slippery roads, by avoiding sharp turns of the steering wheels
and sudden and powerful brake applications, by keeping to the
flat portion of the roadway, and by the use of anti-skid devices
(q. v.), tire chains (q. v.), and anti-skid tires (q. v.).
Syn. : Side Slip.
Skip (v.) — To miss (q. v.).

Sleeve — A hollow internally cylindrical member fitted closely
around another cylindrical member, the two members being
capable of sliding or rotating relatively to each other.
Slide — The crosshead guide (q. v.).

Slide Valve — A valve commonly used in double acting steam
vehicle engines of a somewhat D shape, and arranged to slide

over the two admission ports, and
the single central exhaust port in
the inside wall of the steam chest
(q.v.). It is given a reciprocating
motion by means of the valve stem
(q. v.) and a link motion (q. v.).
In the accompanying diagram A is
the steam chest, C the slide valve.
D and E the ports of the head and
crank ends of the cylinder re-
spectively, F the exhaust port, G
the cylinder, and B the piston ; the
valve being represented in its ex-
treme right hand position, steam

SECTIONAL VIEW OF STEAM
ENGINE, SHOWING SLIDE
VALVE C.

being admitted to the head end through port D; and being ex-
hausted from the crank end through ports E and F. As it moves
toward the left, steam is cut off from the head end by the
closing of port D (see cut-off, point of), and thereafter acts
expansively therein until exhaust occurs. Exhaust from the
crank end is terminated by the closing of port E, and compression
takes place at that end of the cylinder. As the valve moves
still further to the left, steam is admitted to the crank end
through port E, and exhaust takes place from the head end
through ports D and F. The valye then commences to move back

271

toward the right, causing cut off in the crank end, compression in
the head end, exhaust in the crank end, and admission in the
head end. Syn. : D valve.

Sliding Gears— A type of change speed gear (q. v.) in which
the several speed ratios between the motor and the final drive
shaft are obtained by throwing into mesh, at will, any one of
several pairs of spur-gears, the ratio of the number of teeth of
the two gears of each pair being different and so chosen as to
provide the required series of gear ratios (q. v.). One gear of
each pair is carried upon a shaft driven by the motor, and the
other gear of each pair is carried upon the parallelly located
final drive shaft of the gearset. One gear of each pair is arranged
to be meshed with its mate by sliding it along its shaft so that
the sides of its teeth enter the tooth spaces of the other. See
gear case, and headings under gear shifting.

Syn. : Clash gears. Sliding gear transmission. Sliding pinion
system.

Sliding Gears, Direct Drive Type — A type of sliding gear
change speed device, a common three speed form of which
consists of a short shaft (the primary shaft) driven from the
motor 'through the clutch and carrying a gear which is in con-
stant mesh with another gear upon a parallel shaft (the lay-
shaft) (q. v.) which latter is thus constantly rotated so long as
the primary shaft is in motion. In alignment with the primary
s'haft and having one of its bearings upon the inner end thereof,
is a shaft (the final drive shaft of the gear-set) which is squared
or feathered (see squared shaft and keying, multiple), upon
which are mounted and held from turning thereon two gears of
different diameters, which can be slid along the shaft — the larger
being the low and reverse gear and the smaller the intermediate
gear. Upon the layshaft are secured two forward speed gears,
the larger the intermediate gear and the smaller the low gear,
so located that the corresponding sliding gears can be meshed
with them. Upon the inside face of the primary shaft gear is
fixed one member of a jaw clutch (see clutch, jaw) or internal-
external gear clutch (q. v.), and the other clutch member is
carried upon the neighboring side of the sliding gear next to
the end of the final drive shaft (usually the intermediate gear).
The low and intermediate speeds are secured by meshing one
or the other of these pairs of gears, the drive being from the
primary shaft, through the constantly meshed gears, to the lay-

272

shaft and therefrom, through the meshed pair of gears to the
final shaft. The reverse motion is usually secured as described
under reverse gear (q. v.). The direct drive (q. v.) is secured
by sliding .the two members of the above described clutch into
engagement, when the final drive shaft rotates as a unit with
the primary shaft, the layshaft then rotating idly or, in some
designs, being entirely disconnected and remaining motionless.
In some gear sets of this type the sliding gears are on the lay-
shaft and their mates upon the final drive shaft.

Sliding Gears, Indirect Drive Type — A type of sliding
gear change speed device, in which two gears are in action on
all forward speeds, consisting of a primary shaft, rotated by the
motor, upon which are secured as many spur gears of differ-
ing diameters as there are forward speed ratios to be secured
and a parallel shaft (the final drive shaft of the gearset) which
is squared or feathered (see keying, multiple) upon which are
mounted, so that they cannot rotate upon it but can be slid
along it, an equal number of corresponding gears. The gears
are so spaced upon their shafts that only those two correspond-
ing to one particular speed can be meshed at any one time. By
meshing the largest gear on the final shaft with the smallest
gear on the primary shaft the lowest gear is secured and by
meshing the smallest gear on the final shaft with the largest
gear on the primary shaft the highest gear is secured; the inter-
mediate speeds being secured by the meshing of gears of inter-
mediate tooth ratios. The reverse is secured as described under
reverse gear. In some gearsets the sliding gears are carried
on the primary shaft and the fixed gears on the final shaft.
Syn. : Panhard system.

Sliding Gears, Progressive— A type of sliding gear change
speed device, the sliding gears of which are all moved simultane-
ously when gear changes
are made, and starting
from the neutral position
(q. v.) the several speeds
are engaged in a fixed
succession as the com-
bination of sliding gears
is progressively shifted
It is thus necessary when
PROGRESSIVE TYPE CHANGE GEAR. passing from one speed

273

to a speed not next to it in order, to momentarily mesh the
gears of intervening speeds. The whole set of sliding gears is
shifted by a gear shifting fork (q. v.) and gear shifting shaft
(q. v.) or equivalent devices by means of a gear shifting lever
(q. v.) moved over a gear shifting quadrant (q. v.).
Syn. : Progressive transmission.

Sliding Gears, Selective — A type of sliding gear change
speed device the sliding gears of which are moved in pairs,

the movement of a pair
in one direction engag-
ing one of its gears with
its mate, and its move-
ment in the opposite di-
rection from the neutral
positon (q. v.), engaging
d the other gear with its
mate. Each sliding pair
is moved by a separate
gear-shifting fork (q. v.)
and gear-shifting shaft
(q. v.) actuated by the
gear-shifting lever (q.v.)
SELECTIVE TYPE CHANGE GEAR. operating in a gear-shift-

ing gate (q. v.) in con-
junction with a selector (q. v.)- In three speed selective
gearsets of the direct drive type, one sliding pair usually
comprises the low and reverse sliding gears and the other pair
the intermediate sliding gear and the direct drive clutch. The
selective system permits any speed to be engaged or disengaged
without the necessity of meshing and unmeshing the gears be-
longing to any other speed.

Sliding Gears, Semi=selective — A type of sliding gear
change speed device in which the forward speeds are secured
upon the progressive system (see sliding gears, progressive)
while the reverse is secured on the selective system (see slid-
ing gears, selective) by moving the gear-shifting lever from
the neutral position of the quadrant into a special slot which
causes it to engage a selector (q. v.) through the action of
which and a shaft and fork the reverse gears are meshed.

This arrangement is designed to obviate the danger of en-
gaging the reverse speed when the engagement of a forward

274

speed is intended, the reverse slot being usually guarded by a
reverse latch (q. v.).
Syn. : Semi-selective transmission.

Sliding Key Gear System— A modification of the individual
clutch system (q. v.) of gear changing in which, instead of
employing a separate clutch to fasten one gear of each pair to
its shaft, each of these gears is secured to its shaft at will by
sliding a key, movable in a slot in the shaft, into a keyway in
the hub of the gear to be made fast.

Sliding Sleeve — See valve, sliding sleeve.

Sliding Shaft — The squared or feathered shaft of a sliding
gear change speed device along which the gears are slid. See
sliding gears; squared shaft; keying, multiple.

Slip Cover — A covering of durable fabric which can be
fastened closely over the upholsteiy of a car to protect it from
dust and wear. The fabric cover which fits around the top,
when it is folded down, is sometimes also so called.

Slip Joint — An arrangement designed to prevent the undue
stressing of a member, the ends of which are attached to
points, the distance apart of which may alter The mem-
ber ' is divided at some point in its length, and the end of
one part is arranged to telescope within the end of the other
part, and thus alter its length by the required amount. In the
drive shafts (q. v.) of some cars such a joint is sometimes used
(generally incorporated with a universal joint q. v.)-to permit
the shaft to change its length and still maintain its driving
effect, as its support upon the frame and the rear axle approach
and recede under spring action. There may also be a slip
joint in the drive shaft housing.

Slow Speed — See first speed. See also headings under "low
speed."

Smooth=0n — A kind of cement used to unite iron parts and
to fill cracks therein or to replace small parts of the same, which
have been broken away.

Snap Gauge — See limit gauge.

Sod Pan — A protective covering, fitted under the engine,
clutch, gearbox, and other parts of an automobile to prevent
water and road dirt from being splashed upon them,
usually consisting of sheet metal so formed as to fill the space
between the front and side members of the frame, from which
it is supported, and to extend to the rear of the frame supported

275

mechanism just clearing the under sides of the parts to be
protected. Sometimes the pan is a thin casting, forming a
web between the supporting arms of the power plant.

Syn. : Pan, underpan, under protection.

Soot (v.) — With reference to the end of a spark plug within
a cylinder, to become covered with carbon or carbonized material,
deposited from the fuel or the lubricating oil, with the result
that the sparking current leaks across the insulation of the
plug, through the carbon coating, instead of passing as a spark
between the points of the plug.

Sootproof Spark Plug— See spark plug, protected terminal.

Spacer — A distance piece used in journals which contain
two ball or roller bearings, as in wheel hubs, to keep the two
bearings in correct position.

Spare Wheel— A road wheel, fitted with a fully inflated tire,
adapted to be carried upon a car and quickly and readily to be
substituted for one of the wheels of the vehicle, the tire of
which, or the wheel itself has become damaged.

Spark — See ignition.

Spark, Early, Late — See advance; retard; ignition, prema-
ture; ignition, delayed.

Spark Coil — An induction coil used to produce sparks for
ignition purposes. See coil, induction; coil, self induction, and
other headings under coil.

Spark Gap — The space between the discharge terminals
(q. v.) of a spark plug (q. v.) of the jump spark type, through
which the spark passes in the surrounding gas. The width of
the spark gap varies from slightly less than 3*2 to rather over
3s inch, depending upon whether a magneto, high tension (q. v.)
or a coil, vibrator type (q. v.) supplies the sparking current.

Syn. : Sparking distance.

Spark (timing) Lever — The small lever, usually mounted
upon the steering post, by means of which and a suitable link-
age connecting it with the timer (q. v.), the magneto make
and break (q. v.) device or the igniter mechanism of a contact
spark system (see ignition, contact spark), the point of igni-
tion (see ignition, point of) can be adjusted. The lever usually
moves over a notched quadrant by which it is held where it is
set.

See advance, retard.

276

Spark Linkage — The mechanism which transmits the advanc-
ing and retarding movement of the spark (timing) lever (q. v.)
to the timer (q. v.) or magneto make and break (q. v.).

Spark Plug — A device adapted to be inserted, gastight, into
the compression space of a gas motor cylinder, through
a hole provided for the purpose in the cylinder wall, and support-
ing, within the cylinder, two spark points or discharge terminals
(q. v.), insulated from each other, between which the electric
spark passes in the midst of the compressed gaseous charge
and ignites the same. Upon the outside of the plug is provided
a binding post to which the live wire of the ignition circuit is
connected.

Spark Plug, Jump Spark Type — A type of spark plug
used in all high tension ignition systems (see ignition, high
tension) consisting of a threaded iron plug
of such size as to screw gastight into a
threaded hole in the cylinder wall and bored
with a central, shouldered, axial hole. To
its inside rim is affixed the grounded (q. v.)
discharge terminal and within the should-
ered hole is placed a hollow, generally cyl-
indrical, shouldered insulating bushing of
porcelain, mica or other non-conductive
heat-resisting substance, which is made gas-
tight in the iron plug by a gasket clamped
by a ring nut. Its outer end extends for
some distance outside the iron plug and its
inner end is not more than flush with the
inner end thereof. In an axial hole in
the bushing is a metal stem or wire, bearing upon its inner end
the live discharge terminal (q. v.), the end of which is brought
into sparking distance with the end of the grounded discharge
terminal, and upon the end of this stem as it emerges from the
outside end of the bushing is provided a binding post. The
sparking current enters at the binding post, passes down the
central stem to the live discharge terminal, jumps across the
spark gap (q. v.) to the grounded discharge terminal and thence
into the iron part of. the plug, to the cylinder and to ground
(q. v.). Syn. : High tension spark plug.

Spark Plug, Low Tension — An igniter (q. v.). See ig-
nition, contact spark.

JUMP SPARK TYPE
SPARK PLUG.

277
Spark Plug, Magnetic— See ignition, magnetic plug.

Spark Plug, Magneto Type— A form of jump spark
plug, the discharge terminals of which are more* massive than
those used in battery ignition systems in order that they may
not be rapidly fused and volatilized by the very hot spark pro-
duced by the current from high tension magnetos. See arc
flame.

Spark Plug, Protected Terminal— A jump spark plug so
constructed that the internal end of the insulating bushing is
somewhat protected from lubricating oil
and soot (q. v.) by being located in a recess
formed by the extended shell-like inside end
of the iron portion of the plug.
Syn. : Sootproof plug.
Spark Plug Hole— A threaded hole in
the cylinder wall of a gas motor, usually
in the wall of the compression space, into
which the spark plug is screwed. It is gen-
erally a hole drilled and tapped in a valve
PROTECTED TERMINAL caP (Q- v-).

SPARK PLUG. Spark Shaft— The shaft, within or at-

tached to the steering column, which trans-
mits the movements of the spark (timing) lever to the rest of
the spark linkage.

Sparking Points — See discharge terminals and contact point.

Speedometer — An instrument for indicating, at any instant,
the rate of motion of a vehicle, usually reading in miles per
hour. It consists of some kind of rotary mechanism, driven
from one of the road wheels of the vehicle (usually a front
wheel), at a speed always bearing a constant relation to
the road .wheel speed. By means of the rotary mechanism, an
indicator, which is returned to zero by a spring or gravity
when the vehicle stops, is caused to assume a position upon a
graduated scale dependent upon the rate at which the rotary
mechanism and, hence, the vehicle is moving at any instant. The
indicating portion of the speedometer is placed within view of
the operator and an odometer is generally combined therewith.
It is driven by means of the speedometer gears and speedometer
shaft (q. v.).

278

SECTIONAL VIEW OF

CENTRIFUGAL TYPE

SPEEDOMETER.

A, Centrifugal Ring;
B, Spring; C, Pointer.

Speedometer, Centrifugal Type — A speedometer, the rotary
portion of which comprises a pair of rotating weights which are
drawn toward one another .by a finely
adjusted spring. Centrifugal force, act-
ing upon the rotating weights, causes
them to overcome the spring, and move
apart in proportion to their speed of
rotation and hence in proportion to the
speed of the vehicle, and, as they move
apart, under increasing speed, they act
to move a needle over a scale gradu-
ated in miles per hour.

Speedometer, Magnetic Type — A
speedometer in which the mechanism
operated by the road wheel rotates a
magnetic field (see field, magnetic) with-
in the inductive influence of which is a
light and delicately pivoted metal cyl-
inder in which is" developed electrical
eddy currents that tend to cause the cylinder to rotate in propor-
tion to the rate of rotation of the magnetic field and in the same
direction therewith. The tendency of the metal cylinder to rotate
is resisted by a delicately adjusted spring, and, in action, the
cylinder rotates through a certain angle and takes up a position
dependent upon the speed of the mag-
netic field and of the vehicle at any
particular instant. A scale, gradu-
ated in miles per hour, is carried by
the cylinder and a stationary pointer
indicates upon it the vehicle speed.

Speedometer Gears — The gears
which give motion to a speedometer
shaft and speedometer. As usually
arranged, a relatively large spur gear
is bolted to a front wheel hub Hange MAGNETIC"SPEEDOMETER.

and a smaller gear or pinion is held

, M f. , , A, Permanent Magnet; B, Metal

in mesh with this upon the end of a 'cup; C, Hair Spring; D, Scale
short horizontal shaft, originating on Rotating Cup; E, Arma-
in a housing supported upon the

steering knuckle arm of the road wheel. Upon the inside end of
this shaft, within the housing, is a bevel or spiral gear in mesh

279

SPEEDOMETER GEARS.

with another similar gear on a
short horizontal shaft at right an-
gles with the first named shaft,
and to the outer end of which the
speedometer shaft is connected.

The spur gears are usually of
fibre or other non-sonorous ma-
terial, and their tooth ratio can be
altered to enable the same spee-
dometer to give correct indications
when used with road wheels of
differing diameters.

Speedometer Shaft — The
flexible shaft (q. v.) which is con-
nected at one end with the speedometer gears and at its other end
with the rotating member of the speedometer itself, constituting
the driving connection between them. Its flexibility is required
to allow for the motion of the vehicle springs and for the turning
of the front road wheels in steering.

Spider — A construction consisting of a central hub and several
radiating arms upon which operative parts are fastened. See
brake spider, clutch spider, steering wheel.

Spin (v.) — With reference to the driven member of a clutch,
to continue to rotate after it has been disengaged from the driv-
ing member, rotating with it the primary and lay shafts of a
sliding gear change speed device, and thus rendering the meshing
of gears noisy and difficult. The greater the weight and diameter
of the driven member and attached parts, the greater the ten-
dency to spin, which is overcome in some cars by the use of a
clutch brake (q. v.).
Spiral Gear — See gear, helical.
Splash Basin — An oil pocket (q. v.).

Splash Lubrication — See lubri-
cation, splash.

Splash Plate— A baffle plate (q. v.)
used in the lubricating system.

Splasher — A scoop-like projection
attached to the end of a moving part,
such as a connecting rod tip, designed
to dip into a pool of oil and to splash
it over adjacent parts. Connecting rod
splashers are often tubular, oil being

SPLASHER (A)

B, Oil Trough.

280

supplied through them to the rod hearings as well as heing

splashed over cylinder walls, etc. Syn. : Scoop.
An extension of the fenders, usually of enameled leather, hung

from their lower ends nearly to the ground, and intended to cut

off road splash. Also other extensions of the mud guards around

the front of the car to protect the radiator and elsewhere.
Spline — A key (q. v.).
Split Pin — See cotter pin.
Spoke, Bossed — A wheel spoke which is of enlarged cross

section at that part of its length where the bolt holding a brake

drum or sprocket passes through it.

Spot — The slight depression formed in a shaft to receive the

point of a set screw (q. v.).

Sprag — A form of emergency brake, designed to prevent an

automobile from running down hill backward, should the regu-
lar brakes prove ineffective. Syn. : Drop brake.

Sprag, Drop Type — A sprag, consisting of an iron rod

pivoted at its front end upon one of the rear cross members

of the frame, and with its rear

end pointed and normally held up

by a cable, out of contact with the

road. When it is required, the

cable is released by the operator.

and the pointed rear end falls into

contact with the roadway. If the

vehicle starts to back, the pointed

end catches in the surface of the

road and forms a prop, which

prevents further backward movement of the vehicle.

Sprag, Ratchet Type— A
sprag consisting of a ratchet
toothed drum fastened upon the
jackshaft, rear wheel hub flange
or upon the final drive mech-
anism at some point, and a
pawl or detent, securely fast-
ened to some stationary part,
which can be dropped upon the
ratchet drum by the operator.
The pawl is so placed as to
catch the teeth and hold the

SKETCH SHOWING DROP
SPRAG A.

SPRAG, RATCHET TYPE.

281

drum, and hence the car, from backward motion, but so as not
to resist forward motion. When ascending a dangerous hill the
operator may drop the pawl, as a precaution, raising it again
when level ground is reached. Syn. : Hill pawl.

Spray (v.) — With reference to a storage cell, to throw out
electrolyte in the form of minute drops, carried by bubbles of
gas which burst at the surface of the liquid. See gas (v).

Spraying Carburetor — See carburetor, atomizing.

Spraying Nozzle— See carburetor spraying nozzle.

Spring — See clutch spring, brake spring, accelerator.

Spring — One of the elastic members by which the frame, its
attached mechanical parts and the body are supported upon the
axles of a motor car, in order to prevent jolts arising from rough
roads from being transmitted to these parts and the passengers.
Four springs of the leaf type (see spring, leaf type) are com-
monly employed, generally arranged parallel to the frame side
members, and supporting each side of the front and rear of the
frame upon the respective ends of the front and rear axle. Or
three springs may be used, two supporting the respective sides
of one end of the frame upon the ends of one axle and the third
supporting the centre of the other end of the frame upon the
other axle.

NOTE. — The following definitions under "spring" refer to vehicle
springs unless otherwise stated.

Syn. : Vehicle spring, body spring.

Spring, Cross — A leaf spring arranged crosswise of a ve-
hicle, its ends being shackled to the ends of the rear or occasion-
ally of the front axle, and its middle point being secured to the
centre of the rear cross member, or occasionally of the front
cross member of the frame.

Spring, Eccentrated — A spring of the half elliptic type, the
point of attachment of which to the axle is not midway between
its ends.

Spring, Full Elliptic — A compound spring, consisting of two
half-elliptic leaf springs arranged with their concave sides facing

one another, and with their
corresponding ends secured to-
gether, thus forming an ap-
proximate ellipse. The centre
of one spring member is fast-
FULL ELLIPTIC SPRING. ened to the vehicle frame and

282

the centre of the other spring member to the axle. In the
ordinary full elliptic spring the ends of the two spring members
are simply pivoted together by means of an eye-bolt (q. v.), but
in the double scroll ended full elliptic spring (see spring, scroll
ended) one of the members is a double scroll ended half-elliptic
spring and the other an ordinary half-elliptic spring, the ends of
the two members being secured together by means of shackles.
In the double shackle type of full elliptic spring, two single
scroll clliptics are used, the scroll end of one being shackled to
the plain end of the other.
Syn. : Double elliptic spring.

Spring, Half Elliptic — See spring, leaf type. Syn. : Semi-
elliptic spring.

Spring, Inclined— A vehicle spring the ends of which are not
in the same horizontal plane, the front end being higher than
the rear end, thus rendering it capable of deflection under back-
ward as well as upward forces transmitted to it by the axle when
the wheels strike road obstructions.

Spring, Leaf Type — A composite spring in the shape of an
arc of rather large radius, built up of a number of long, flat,

slightly curved, relatively thin and
narrow strips or leaves of highly
elastic steel of graduated lengths,
LEAF TYPE SPRING (SEMI- superposed and fastened together
ELLIPTIC). in alignment at or near their cen-

tres of length, the longest or main

leaf being upon the concave side and the shortest leaf upon the
convex side of the assemblage. The thickness of each leaf is
usually reduced toward its ends. Such a spring is supported by
the two ends of its main leaf and through the point at which its
leaves are fastened together, and is so mounted upon the vehicle
that its load tends to straighten it, the longer leaves yielding first
and the shorter leaves successively deflecting as the load is in-
creased, a progressively increasing resistance to its deflection thus
being developed. A spring constructed as above is a semi-elliptic
or half-elliptic spring, and the joining together of two or three
such springs produces the various types of compound spring.
Syn. : Laminated spring.

Spring, Offset — A spring which does not lie directly under
a frame member, but slightly outside thereof, being fastened
thereto by spring-hangers or irons extending outward from the

283

OVERLOAD SPRING (A).

frame, and which are sometimes up-curved so as to bring the
frame lower relatively to the axle than it would otherwise be.

Spring, Overload — A spring arranged as an auxiliary to a
regular spring, and which is normally out of action, but which
j— — j comes into play when extreme

deflections of the regular
springs are caused by excessive
loads and rough roads. Such
a spring may be attached to
J the frame and arranged to bear
upon the axle only under over-
load conditions, thus relieving
the regular springs. Used upon
some commercial vehicles. Syn. : Auxiliary spring.

Spring, Platform — A compound spring, consisting of three
half-elliptic members, viz., a cross spring and two longitudinally
arranged springs, the three members being shackled together at
their ends, thus forming a hollow square. The centre of the cross
member is fixed to the middle of a frame cross member, and the
free ends of the side springs are pivoted to the respective side
members of the vehicle frame, while their centre points are made
fast to the two ends of the axle.

Syn. : Three point spring suspension.

Spring, Scroll Ended — A leaf spring the
form of which departs from a uniform curve
in that one or both ends are sharply bent, in the
general direction of curvature, into the form
of a scroll, hook or C shape, the acute curva-
ture being confined mainly to the principal leaf.

Spring, Side — A long. leaf spring, arranged longitudinally
under a side frame member with its front and rear ends se-
cured to the front and rear axles, respectively, and its centre
point fastened at or near the middle of one of the frame side
members, a similar spring being used under the other side mem-
ber. A nearly obsolete type.

Spring, Spiral Type — A spring of the coiled, helical or spiral
type wound of highly elastic steel wire, occasionally used instead
of a spring of the leaf type, such springs acting between the ends
of the frame members and the axles.

Syn. : Coil spring, helical spring.

SCROLL- EN BED
SPRING.

284

Spring, Supplementary — A spring employed to supplement
the cushioning action of a vehicle spring. It may be a spring or
combination of springs of the spiral type,
acting between the axle and the frame, or
a spring or pair of springs of the spiral
type, or a combination of a scroll and spiral
springs interposed between one end of the
regular vehicle spring and its point of sup-
port upon the frame or between the adja-
cents ends of two members of a compound
SUPPLEMENTARY vehicle spring.

SPRING (A). Syn. : Equalizing spring, spring shock

absorber, auxiliary spring, secondary spring.

Spring, Three=quarters Elliptic — A type of compound spring
intermediate between the half-elliptic and the full-elliptic types,
consisting of a half-elliptic
member fastened at about
its centre to the axle and at
one end to a frame side
member. Its other end is
connected, usually by a
shackle, to the thin end of
one-half of a semi-elliptic
spring member, usually of THREE-QUARTER ELLIPTIC SPRING.
the scroll type, the thick end
of which is rigidly secured to the frame side member.

Spring, Underslung — A spring which is secured to the
under side of the axle instead of to the upper side thereof, this
method of attachment being adopted in order to lower the frame
relatively to the axle.

Spring, Valve — See valve spring.

Spring Centre Bolt — The bolt 'which passes through and
secures together the leaves of a leaf spring, generally at or near
centre of the length thereof. Its use is not necessary when
nibbed or dented leaves are employed. (See
spring leaf, nibbed.)

Spring Clip — A device for fastening the
fixed point of attachment of a leaf spring to its
support upon the axle or frame, generally con-
sisting of a U-shaped steel forging, with
SPRING CLIP. threaded ends, of a spread equal to the width"

285

of the spring. Two such U-shaped fittings are straddled over the
spring and their threaded ends are passed through holes in the
spring seat (q. v.) of the axle or in the support on the frame, and
i tits are turned onto the threaded ends until the spring is firmly
clamped in place.

Syn. : Spring saddle.

Spring Drive — An elastic member consisting of a combina-
tion of springs, through which the turning effort acts, some-
times introduced into the transmission system of a motor car
to cushion the shocks to the mechanism occasioned by sud-
den clutch engagements or by irregularities in the action of
the motive power, or interposed between a magneto or other
auxiliary and its drive to lessen noise and shock.

Spring Eye — A hole formed in each end of the main leaf
of a spring, in a direction perpendicular to the plane of move-
ment thereof, through which the spring eye-bolt (q. v.) passes, and
which forms the point of attachment of the spring to a spring
hanger (q. v.), to a spring shackle (q. v.) or to another spring.
The ends of the main leaf are enlarged, in forging, to permit
of the drilling of the hole, in which is usually fitted a bronze
bushing within which the eye-bolt rotates.

Spring Eye=bolt — A bolt used to secure the end of a leaf
spring to a spring hanger, or to secure together the connected
ends of two members of a compound
spring, and upon which the spring end
rotates as the spring deflects. It is
passed through the spring eye and suit-
able holes in a spring hanger or
SPRING EYE-BOLT. through the eyes of two connected

spring members, and is usually drilled

with grease or oil ways and provided with a grease cup or spring
oiler.

Spring Hanger — One of the fittings attached to a vehicle
frame or formed integrally therewith, which act as supports
for the vehicle springs. The hangers
supporting the front ends of the front
springs and the rear ends of the rear
springs (spring horns) are usually the
specially formed, forged ends of the
frame side members, while other hangers SPRING HANGER
are suitably formed fittings riveted to the

286

frame members, adapted to receive a spring eye-bolt and to
support a spring eye or a spring shackle, or adapted to form
a spring seat and to receive a spring clip.

Spring Leaf, Nibbed — A spring leaf, in the metal of whicli
are formed a series of indentations which raise a portion ot
the metal on one side and form a corresponding concavity
upon the other. In assembling a series of such leaves to
form a spring, the projections of one leaf are fitted into the
dents in the next leaf, and the leaves, when clipped together,
are thus prevented from moving out of alignment or sliding
one upon another, and the use of a spring centre bolt, with
its weakening effect upon the leaves, is obviated.
Syn. : Dented spring leaf, fishbacked spring leaf.
Spring Leaf Retainer— A small clip clamped around a leaf
spring to prevent its leaves from un-
duly separating or moving out of
alignment. Several such retainers are
used, distributed along the length of
the spring.

Spring Oiler — See oil retainer.
Spring Perch — See spring seat.
Spring Saddle — See spring clip.

Spring Seat — A flat surface, formed upon an axle or axle
casing or on a spring hanger, upon which a spring fits and to
which it is secured by spring clips (q. v.)
and containing the holes to receive the
clip ends. The spring seat on an axle is
usually formed integrally therewith, but
may be formed upon a special fitting se-
cured around the axle, but free to rotate
thereon.

Syn. : Spring perch, spring pad.

Spring Shackle— A link employed to flexibly attach one
or occasionally both ends of a leaf spring to a frame mem-
ber, or to attach one or both
ends of one member of a com-
pound spring to the end or ends of
another member. It is used to
compensate for the variation in dis-
tance between the ends of a spring
as it is deflected more or less. A SPRING SHACKLE

A, SPRING LEAF
RETAINER.

A, SPRING SEAT.

287

shackle is ordinarily a simple link with a hole through each end to
take the eye-holts (shackle bolts) of two spring members or to re-
ceive an eye-bolt and the pivot bolt of a spring hanger. A
compound, universal or double shackle is used to join spring
members which deflect in planes at right angles one to the
other (platform spring), and may consist of two links pivoted
together at their ends so as to act in perpendicular planes, or a
ball and socket link device may be used.

Spring Stop — A rigid extension of a spring hanger, so lo-
cated in proximity to a spring as to limit the deflection
thereof.

Spring Washer — A lock washer (q. v.).

Sprocket — See chain and sprocket gear.

Squared Shaft— A shaft the end of which, instead of being
of circular section, is formed into a square section, the
squared end portion fitting into a square hole in the member
which drives it or is driven by it. This construction obviates
the use of keys (q. v.). Sometimes the corners of the shaft
are somewhat rounded off at its end, and its end is fitted into
the squared hole in such a manner that, while a positive driv-
ing connection is secured, slight angular deviations are per-
mitted in the alignment of the two parts.

A shaft which, for a portion of its length, is of square cross
section, and upon which are carried members, such as gears,
which are to drive or be driven by it, but which require to be
slid along it. See sliding gears. Sliding shaft.

Stall (v.) — To accidentally stop a vehicle motor, usually
by overloading it (see overload), as by a too sudden clutch
engagement.

Standpipe — See carburetor standpipe and lubrication, con-
stant level.

Starting Button — In a dual or battery system of ignition a
button which, when pressed and suddenly released, makes and
breaks a battery current through the primary of the transformer
coil and produces a high tension current in the secondary winding
which is delivered by the distributor to the spark plug of the
cylinder that is ready to fire. It is used in starting on the spark.
In some systems the pressing of the starting button or the throw-
ing of a switch to the starting position closes the battery circuit
and introduces thereinto a magnetic vibrator the make-and-break
action of which produces a succession of sparks.

288

Starting Crank — See crank, starting; crank, safety starting.
Starting Crank Bracket— A bracket attached to the front of
a vehicle frame or to the forward end of the motor base, which
forms the bearing of the starting crankshaft.

Starting Crank Latch — A latch which holds a starting crank
in position when it is not in use, and prevents it from swinging.
A leather strap, attached to the vehicle frame and looped about
the crank handle is sometimes used.

Starting Crank Shaft — The slidable shaft to which the start-
ing crank is secured, the free end of which engages the motor
crankshaft.

Starting Gear — The lowest gear of a gasoline motor vehicle,
mainly employed in starting it from rest.

Starting Ratchet — See crank, starting.

Starting Shutter — See air damper.

Starting on the Spark— A method of starting a multi-
cylinder gas motor without cranking it. A battery generated
spark is produced in the cylinder, which happens to have
stopped on its power stroke (q. v.), by throwing on the switch
and manipulating the spark lever, and if the motor has not
stopped on dead centre (q. v.), and if the fuel charge, which
was left in the cylinder at stopping, has not escaped or con-
densed, it will be ignited, an explosion will occur, and the
motor will commence to rotate. It will continue to rotate
if the force of the initial explosion brings the next cylinder in
firing order (q. v.) to the firing point, and if its cylinder and
successive cylinders contain sufficient ignitible charge. See
self-starter, ignition type.

Syn. : Switch starting, spark starting.

Steam Boiler — See boiler.

Steam Chest — The closed space adjoining the cylinder of
a steam engine, and communicating with the boiler through
the steam pipe, and with the cylinder through the steam ports.
Within it and controlling the port openings are the valves.

Steam Engine, Compound — An engine with two cylinders-
one, the high pressure cylinder, of relatively small bore, and
the other, the low pressure cylinder, of considerably larger
bore, the moving parts of the two cylinders acting upon the
same crankshaft. Steam from the boiler is admitted to the
high pressure cylinder, partially expanded therein and ex-
hausted into the steam chest of the low pressure cylinder,

289

where it is further expanded, and from which it is finally ex-
hausted into a condenser (q. v.) or into the air. The com-
pound engine is capable of utilizing the energy in steam more
efficiently than the simple engine.

Steam Engine, Condensing — An engine which exhausts
into a condenser (q. v.) instead of directly into the air, as
does a non-condensing engine.

Steam Engine, Double Acting — An engine in which the
steam performs useful work both upon the inward and the
outward strokes of its piston, steam being admitted to the
head end of .'the 'cylinder near the beginning of the outward
piston stroke, and to the crank end of the cylinder on the
inward piston stroke. The common type of vehicle engine.
See slide valve.

Steam Engine, Horizontal — An engine, the axis of the cyl-
inder or cylinders of which is horizontal. Such an engine is
usually arranged under the car body, with its crankshaft cross-
wise of the vehicle and directly geared to the driving axle.
Steam Engine, Piston Valve — See piston valve.
Steam Engine, Simple — An engine in which the steam
entering one of its cylinders receives its full expansion there-
in. The opposite of compound steam 'engine.

Steam Engine, Single Acting — An engine in which the
steam performs useful work on the outward stroke only, steam
being admitted at the head end of the cylinder. Its \ alves
are usually of the cam operated, poppet type, and its design
is similar to that of a gas engine. Occasionally used in multi-
cylinder forms, for vehicle propulsion.

Steam Engine, Slide Valve Type— See slide valve.
Steam Engine Vertical — An engine, the axis of the cylinder
or cylinders of which is vertical. Such an engine is usually ar-
ranged with the crankshaft lengthwise of the car, and power is
transmitted to the rear axle through a shaft drive (q. v.).
Steam Gauge — See gauge, steam.

Steam Pipe — A pipe leading from the steam space of a
boiler to the steam chest or chests of an engine, through
which steam is supplied thereto. The throttle valve (q. v.)
is located therein.

Steam Pocket — Any portion of the space within a water
jacket (q. v.) which accidentally becomes filled with steam
instead of water. Its effect is to prevent the proper cooling of

290

that portion of the cylinder or valve pocket wall which it includes,
and overheating thereof may result. Faulty design of the
water spaces, leading to a sluggish circulation at certain parts
thereof, is usually the cause.

Steam Separator — See separator.

Steam Siphon — A device used to fill the water tank of a
steam vehicle, consisting of an ejector and length of flexible
hose connected thereto, carried upon the car. The free end
of the hose is placed in a roadside supply of water, steam
from the boiler is turned into the ejector and water is lifted
through the hose and forced into the tank. The ejector con-
sists of a small chamber, furnished with an inlet and outlet,
and with a steam jet located in a contraction therein. When
in action, a part of the energy in the steam is converted into
energy of motion of the water, which is drawn into the cham-
ber to fill the vacuum formed therein, the water being deliv-
ered through the outlet.

Steel — Purified pig iron containing less than 2.2 per cent,
of carbon, which is malleable between certain temperatures,
and which, furthermore, is either capable of being cast into
an initially malleable mass, capable of being hardened by sud-
den cooling or possesses both these properties. The material
principally used for structural and moving parts of automo-
biles because of its high strength for a given weight and its
ability to be formed into the most diversified shapes.

Steel, Acid Open Hearth — Pig iron which has been con-
verted into steel by the burning out of its excess of carbon
and impurities by the excess of oxygen contained in a flame
of intensely preheated gas and air which plays over it while it
lies upon a hearth lined with siliceous material, the action usu-
ally being hastened by adding iron ore and scrap steel to the
charge. It is sometimes preferred to basic open hearth steel
as being more uniform and less likely to contain oxygen, and
on account of its usually being made from higher grade ma
terials; but it is less used in the automobile industry than basic
open hearth steel.

Steel, Basic Open Hearth — Steel produced similarly to
acid open hearth steel except that lime is added to the pig
iron of the charge, the hearth is not lined with siliceous but
with basic material, such as iron oxide and less pure pig iron

291

and scrap steel are generally used for the charge. Steel so
produced is very largely used in the automobile industry.

Steel, Bessemer — Pig iron which is practically freed of
carbon, manganese and silicon by forcing cold air through it.
while melted, in a Bessemer converter and to which, while-
still molten, the proper amount of carbon, manganese and
silicon are added to give it the required composition. It is
much less used than open hearth steel for automobile parts
on account of its inferior quality, due to lack of homogeneity,
liability to brittleness from too high phosphorous content and
its high content of gases.

Steel, Carbon — Steel which depends mainly upon the pres-
ence of a closely regulated proportion of carbon to give it its
strength, malleability, ductility and ability to be hardened.
Automobile carbon steels usually contain from 0.08 per cent,
to 1.05 per cent, of carbon, from 0.25 per cent, to 0.80 per
cent, of manganese and not over 0.04 per cent, of phosphorus
nor over 0.04 per cent, of sulphur. Low carbon steels may
be considered as those containing from 0.08 per cent, to 0.40
per cent, of carbon, and high carbon steels as those contain-
ing from 0.40 per cent, to 1.05 per cent, of carbon, but there is
no definite line of demarcation between them. In a very gen-
eral way, an increase of carbon renders steel stronger and
harder but less malleable and ductile and more brittle. Car-
bon steel is the steel most largely used in the automobile
industry, but alloy steels (q. v.) are taking its place for many
parts of high grade cars.

Steel, Cast — A trade name for crucible steel (see steel,
crucible).

Steel, Casting — Steel which can be formed into the desired
shape, like cast iron, by pouring it, while molten, into molds. A
specification for such steel is as follows : Carbon, 0.30 to 0.40 per
cent.; manganese, 0.60 to 0.80 per cent.; silicon, o.io to 0.30 per
cent.; phosphorus and sulphur not over 0.06 each.

Steel, Chrome — An alloy steel, usually containing 0.80 to
2.00 per cent, of carbon and i.oo to 2.00 per cent, of chro-
mium, which is extremely hard, without brittleness and pos-
sesses a very high elastic limit. Occasionally used for auto-
mobile gears, but the use of chrome-nickel steel for this purpose
is much more usual.

292

Steel, Chrome Nickel — An alloy steel, usually containing
from o.io to 0.50 per cent, of carbon. 1.50 to 3.75 per cent, of
nickel, 0.50 to 1.75 per cent, of chromium, 0.30 to 0.60 per
cent, of manganese, o.io to 0.30 per cent, of silicon and not
over 0.04 per cent, each of phosphorus and sulphur, possess-
ing great hardness and strength and thus used for automobile
gears, shafts, engine parts, frames, etc. Nickel chrome steels,
low in carbon, are chiefly used for structural and case-hardened
parts and those higher in carbon for moving parts, such as
shafts, that highest in carbon being mainly used for gears.

Syn. : Nickel chrome steel.

Steel, Chrome=Vanadium — An alloy steel of high strength
and superior resistance to repeated and reversed stresses and
thus largely used for the vital parts of cars where extreme
reliability and light weight are required, such as crankshafts,
connecting rods, gears and gear shafts, drive shafts, axles and
springs. Specifications for various grades call for from o.io
to 0.18 per cent, of vanadium, 0.80 to 1.30 per cent, of chrom-
ium, 0.15 to 0.45 per cent, of carbon. 0.40 to 0.90 per cent, of
manganese, o.io to 0.30 per cent, of silicon and not over 0.04
per cent, each of phosphorus and sulphur. Such steel, low in
carbon, is used for case-hardened gears, that moderate in car-
bon for shafts and other moving parts, and that higher in
carbon for important structural parts and hardened gears.

Steel, Crucible — Steel made by melting pieces of wrought
iron in an hermetically sealed crucible, the required amount
of carbon being placed on top of the iron before closing the
crucible. The finest quality of steel is the result, all gases
being excluded and the process being under good control.
Crucible steels are usually rather high in carbon and are used
for springs. Alloy steels are often made by the crucible
process, the alloying materials being added with the carbon.

Syn.: Cast steel.

Steel, Electric — Pig iron refined to the condition of steel
in some form of electric furnace, and of a grade comparable
with crucible steel.

Steel, High Carbon — See steel, carbon.

Steel, Low Carbon — See steel, carbon.

Steel, Manganese — A steel containing 12.00 to 13.00 per
cent, of manganese and 1.50 to 2.00 per cent, of carbon, which
is extremely hard and wear-resisting and which possesses

293

about three times the tensile strength of ordinary steel. It is
difficult to machine or otherwise work, but improvements in
its manufacture and treatment may render it important in the
automobile industry.

Steel, Molybdenum — An alloy steel containing from 2.00
to 2.50 per cent, of molybdenum and similar in its properties
to steel, tungsten (q. v.).

Steel, Open Hearth— See steel, acid open hearth, and steel,
basic open hearth.

Steel, Nickel— An alloy steel usually containing from 3.25
to 375 Per cent, of nickel, 0.15 to 0.35 per cent, of carbon, 0.50
to 0.80 per cent, of manganese and not over 0.20 per cent, of
silicon nor over 0.04 per cent, of phosphorus. The addition
of nickel raises the elastic limit of the material about 50 per
cent, and decreases its ductility only slightly, increases its
ultimate strength, renders it harder and tougher and better
able to resist blows, and, moreover, confers upon it about six
times the resistance to repeated and reversed stresses. It is
one of the most useful of all alloy steels, as parts may be
made of it considerably lighter than of carbon steel and still
show superior life. Nickel steel, low in carbon, is mainly used
for structural and case-hardened parts and that higher in car-
bon for moving parts, such as crank, gear and driving shafts.

Steel, Nickel (valve metal) — A metal used for the heads of
poppet valves and possessing great resistance to corrosion by
hot gases. It contains from 28.00 to 35.00 per cent, of nickel,
not over 0.50 per cent, of carbon, not over 1.50 per cent, of
manganese, not over 0.04 per cent, of sulphur and not over
0.06 per cent, of phosphorus, the remainder being iron.

Steel, Pressed — See pressed steel.

Steel, Silicon— An alloy steel, capable of higher temporary
magnetization than pure iron and in which the magnetic
losses are low. It is therefore used for the cores of ignition
and lighting apparatus where high efficiency and light weight
are important. It contains about 2.75 per cent, of silicon and
the percentages of carbon, manganese, sulphur and phos-
phorus are kept as low as possible.

Steel, Silico=Manganese — An alloy steel specially adapted
for vehicle springs, frames and gears, containing from 1.90 to
2. 20 per cent, of silicon, 0.60 to 0.70 per cent, of manganese.

294

0-45 to 0.55 per cent, of carbon and not over 0.04 per cent, of
either sulphur or phosphorus.

Steel, Titanium — A steel which, in the process of manu-
facture, is treated with titanium, which nearly frees it of
oxygen and other gases. A trace of titanium is usually found
in the finished product. It is coming into use for vehicle
springs, etc.

Steel, Tool — Steel, usually that produced by the crucible proc-
ess (see steel, crucible), of a quality suitable for cutting tools,
containing approximately one per cent, of carbon and thus
capable of a high degree of hardening. Used for parts which
are called upon to resist extensive wear but are not heavily
stressed, such as piston pins and steel bushings. Also used for
springs.

Steel, Tungsten — An alloy steel of very high magnetic
retentivity. used for the permanent magnets of magnetos,
ampere hour meters and other electrical measuring instru-
ments. It contains from 4.00 to 5.00 per cent, of tungsten,
0.50 to 0.70 per cent, of carbon and occasionally 0.50 per cent,
of chromium.

Steel, Vanadium — See steel, chrome vanadium.

Steering — The act of guiding a motor car, performed by the
hands of the operator applied to a wheel or lever and connected
mechanism which simultaneously deflects one or more of the road
wheels of the car into the direction which it is desired it should
take.

Steering Arm — The crank or arm, pivoted at one end within
the steering device on the steering arm
shaft (q. v.), the other end of which
moves through an arc, and thus transmits
the steering effort from the steering de-
vice to the drag rod. See drag link.

Steering Arm Shaft — The horizontal
shaft, secured in bearings within the hous-
ing of a steering device, which carries the
steering arm upon its external end, and re-
ceives the steering effort upon its inside end.

Steering Column — The column or post
which carries at its upper end the steer-
ing wheel, and usually the spark and
throttle levers and quadrants, and at its

A, STEERING ARM.

295

lower end the steering device. It is usually inclined upward and
to the rear, and its lower and forward end is secured to the
vehicle frame at a point under the bonnet, the column itself pass-
ing through the dash or the front floor boards. In right hand
drive cars it is located directly -in front of the right hand front
passenger, and in left hand drive cars (q. v.) on the opposite
side. The column comprises the steering shaft (q. v.), and
the shafts which operate the spark and throttle linkages, and
it is usually enclosed in a tubular ornamented casing. In
lever steered cars the column is usually vertical, and carries
the steering lever at its top.

Syn. : Steering post, steering mast.

Steering Column Jacket — The ornamental casing which sur-
rounds the steering column.

Steering Device — The mechanism by which the movement
imparted by the operator's hand to the steering wheel and
shaft is altered in direction and rate before being transmitted
by the steering arm (q. v.) to the drag rod (q. v.). It con-
sists of some form of reduction gearing which gives the end
of the steering arm a movement relatively small as com-
pared with that of the operator's hands, and in a plane nearly
at right angles to the plane of movement
of the hand wheel. It is usually located
at the lower end of the steering column,
and encased in an oil and dust tight
housing.

Steering Device, Cam and Pushrod
Type — A steering device in which the steer-
ing shaft carries cam surfaces which act
upon the upper ends of two vertically
guided pushrods, the lower ends of
which bear upon the respective ends of a
rocking lever, fast upon the steering arm
shaft. When the wheel is turned in one
direction one pushrod is actuated and
moves the rocking lever and the steering
arm in one direction, and when the wheel
is turned in the other direction the other
pushrod is actuated and the direction of
motion of the rocking lever and steering arm is reversed.
It may be made perfectly irreversible.

CAM AND PUSHROD
STEERING DEVICE.

A, Cam; BB,
Pushrods; C,
Rocking Arm;
D, Steering
Shaft.

296

DIFFERENTIAL
SCREW AND NUT

DEVICE.

A, Steering Shaft;
B, Rocking
Lever.

Steering Device, Differential Screw and Nut— A form of

steering device in which the steering shaft carries a left-handed
and a right-handed screw, each of which is in
mesh with a separate nut, which can slide
along the column, but cannot rotate. Turning
the hand wheel in one direction moves one nut
up and the other nut down, and reversing the
direction of motion of the wheel reverses the
directions of motion of the nuts. Downward
projections of each nut bear respectively upon
the ends of a rocking lever fixed to the housed
end of the steering arm shaft (q. v.) and the
nut, which at any particular instant is being
turned down, rocks the lever and gives the
steering movement. An irreversible type.

Steering Device, Irreversible — Any steer-
ing device which is so constructed that road
shocks communicated to it from the road
wheels by the steering linkage are not trans-
mitted through it at all to the hand wheel, or
not to an extent sufficient to turn the wheel,

against the will of the operator.

Steering Device, Pinion and Rack — A form of steering

device in which a spur pinion mounted upon and rotated by

the lower end of the steering shaft,

meshes with and gives a straight line

motion to a guided rack, to which one

end of the drag link (q. v.) is con-
nected. The rack may be replaced by

a spur sector pivoted upon a shaft on

which the steering arm is secured

(pinion and sector steering device).

These forms are reversible, and are

used mainly upon light cars.

Steering Device, Planetary — A

form of steering device in which

the gearing down between the hand

wheel and the steering arm is ef-
fected by means of a planetary

gear (q. v.) mechanism, the central

pinion of which is turned by the Steering' Shaft.

PLANETARY TYPE STEERING
DEVICE.

A, Pinion on Steering
Wheel Spindle; B, Plane-

297

SCREW AND NUT TYPE
STEERING DEVICE.

hand wheel, the internal gear being held from rotation by the
stationary portion of the column, and the pinion frame (q. v.)
communicating its rotation to the steering shaft, and thence to the
steering arm. The planetary mechanism is enclosed in a housing
located just under the hand
wheel. A reversible type, and
mainly used upon light cars.

Steering Device, Screw and
Nut — A type of steering device
in which the gear reduction be-
tween the hand wheel and the
steering arm is effected, and ir-
reversibility is secured by means
of a screw (usually multiple
threaded), formed upon and ro-
tated by the steering shaft, and
working in a nut which it moves
upward and downward, but
which is prevented from rotat-
ing. The motion of the nut is usually communicated to the
steering arm shaft and steering arm through a rack, cut upon
one side of the nut, which meshes with a spur gear on the
steering arm shaft.

Steering Device, Worm and Sector— A form of steering
device in which a worm (usually multi-
ple threaded) (see worm gear), carried
upon and rotated by the lower end of
the steering shaft, is in mesh with and
rotates a worm wheel or a sector thereof,
secured upon the horizontal steering arm
shaft.

Steering Drag Rod — See drag link.
Steering Gear — A term applied to the
entire mechanism concerned in the steer-
ing operation.

Steering Head — The specially formed
portion of each end of the front axle, to
which the front road wheels are pivoted.
WORM AND SECTOR The steering heads may be formed inte-
STEERJNG DEVICE. graUy with the axle or they may be sep-

298

arate forgings, one of which is secured to each end of a tubular
axle 'by pinning and brazing (q. v.), by welding or in some
similar manner.

Steering Head, Elliott Type — A steering head of a forked or
yoke shape, with the arms of the fork in a nearly vertical
plane and their ends nearly in
vertical alignment. The steer-
ing knuckle (q. v.) and steer-
ing knuckle spindle (q. v.)
used with this type are a sin-
gle forging, the hollow verti-
cal member of which is held
in the head by the steering
knuckle pin (q. v.), which
is passed through it and

through holes drilled in the
ends of the two arms of the
head.

ELLIOTT TYPE STEERING HEAD.

Steering Head, Lemoine
Type — A steering head formed by
enlarging or spreading the axle
end in a vertical plane. A
nearly vertical hole is drilled in
this portion to receive, from
below, the vertical member of
the L-shaped steering knuckle,
upon the horizontal member of
which the road wheel is jour-
LEMOINE TYPE STEERING HEAD, naled.

Steering Head, Reversed El=
liott Type — A steering head
used with a forked knuckle, the
ends of the arms of which are
secured to the head by the verti-
cal knuckle pin, which is passed
through holes in the ends of the
knuckle arms and through the
hollow, vertical member of the
Steering head.

REVERSED ELLIOTT TYPE
STEERING HEAP,

299

STEERING KNUCKLE.

A, Steering Knuckle Arm; B,
Steering Knuckle Pin; C, Steering
Knuckle Spindle; D, Steering
Knuckle Thrust; E, Tie Rod.

Steering Knuckle— That part of the steering gear which

pivots on a nearly vertical
axis fixed in the steering head
and carries a front road wheel
journaled upon a nearly hori-
zontal projection thereof (the
steering knuckle spindle, q
v.). the swinging of which,
in a horizontal plane, permits
the deflection of the road
wheel, in steering.

Steering Knuckle Arm — A

nearly horizontal arm, by means
of which the knuckle and the
road wheel which it carries are
deflected, in the act of steering.

One end of it is secured in the vertical portion of the knuckle,
and to its other end is pivotally secured one end of the steer-
ing tie rod (q. v.), and also, in some instances, one end of the
drag rod. The knuckle arm may be an integral part of the
knuckle forging or a separate forging secured in the knuckle.
In some instances one knuckle of a pair is provided with two
knuckle arms for the attachment of the tie rod and the drag
rod respectively.

Steering Knuckle Pin— The nearly vertical pin or bolt upon
which the steering knuckle pivots in or upon the steering head.
It is usually drilled with greaseways, carries a grease cup upon
its upper end and turns in a bushing secured in the knuckle.

Syn. : Steering yoke bolt.

Steering Knuckle Spindle — The nearly horizontal portion
of a steering knuckle, which is swung in a horizontal plane in
the act of steering, and upon which is carried the bearings of
one of the front road wheels.

Syn. : Steering stub ; stub axle.

Steering Knuckle Thrust— A thrust bearing (see bearing,
ball thrust), interposed between the steering knuckle and the
steering head at the point where the pressure due to the vehi
cle weight acts. By reducing friction between the knuckle and
the head, the force required in the act of steering is reduced.

300

A-

Steering Lever — A lever, used instead of a wheel, in steer-
ing light cars. Its free end is grasped by the operator and
the other end is attached to and imparts rotation to the upper
end of a nearly vertical steering shaft, in a column located in
front of or to one side of the operator. The lower end of the
shaft usually carries a steering arm that moves the drag rod.
Steering Linkage — The general term applied to the rods

and levers of a steer-
ing gear, not includ-
ing the steering de-
vice or the mechan-
ism in and upon the
column.

Steering Lock —
See lock, angle of,
and turning radius.

Steering Shaft—
The shaft, in the
steering column,
which transmits the
rotation imparted to
the steering wheel

by the operator to the steering device. It is usually hollow,
with the steering wheel keyed to its upper end and with the
screw, worm, pinion or other driving member of the steering
device secured near its lower end. The shafts which operate
the spark and throttle linkages are usually within the hollow
steering shaft.

Steering Shaft Thrust— A ball thrust bearing, usually of the
double type, located within the steering device housing and
adapted to resist the end pressure of the steering shaft which
is created by the action of the screw, worm or cam which it
carries.

Steering Stop — A projection formed upon a steering knuckle,
or upon some other part of a steering linkage, which strikes
a stationary part of the running gear when the front wheels have
been deflected as far as advisable from the straight ahead posi-
tion, in either direction, thus limiting the extent of their deflection
and preventing the tires from rubbing upon any part of the car.
Steering Tie Rod— See tie rod,

STEERING LINKAGE.

A. Drag Link; B, Tie Rod; C, Steering Gear;
D, Steering Knuckles.

301

Steering Wheel— The hand wheel which is fast to the upper
end of the steering shaft and is turned by the operator in steering.
It consists of a metal hub, keyed to the shaft and carrying a
number of radial arms (the spider), and a
rim, usually of laminated wood or molded
composition.

Steering Wheel Switch — An ignition
switch (q. v.) mounted upon the steering
column so that the driver may operate it
without removing either hand from the
vicinity of the steering wheel.

Step Up Coil-An induction coil. (See A> STEERING WHEEL
coil, induction.) SWITCH.

Stethoscope — An instrument similar in principle to that used
by physicians, but known by various trade names, used tc locate

the source of abnormal operative
sounds emitted by a motor, con-
sisting of a sound transmitting
rod or tube, one end of which
may be placed successively in con-
STETHOSCOPE. tact with different parts of the

motor and a sound receiving ap-
paratus attached to its other end which is applied to the opera-
tor's ears. Only those sounds that are produced in the immediate
vicinity of the point at which the instrument is applied are heard
in the instrument.

Stock Car — A term used in automobile racing, signifying a
racing car, the chassis of which is identical with those of standard
pleasure cars sold in commercial numbers, in contradistinction to
a specially designed racing car.

Stonebruise — A contusion sustained by a tire casing, due to
forcible contact of the same with a stone or other blunt road
obstruction, which results in the complete or partial breakage of
the tread, and of the canvas and rubber of the tire carcass (q. v.),
so weakening the same as to predispose to a blowout (q. v.) at
the point of injury.

Storage Battery, Storage Cell — See accumulator.

Storm Front— See top, Cape.

302

Straight Line Body — A motor car body, the contour of which
is defined by straight rather than by curved lines, the horizontal
line of the top of the hood being continued by the upper edges
of the doors and side panels. Fore door, flush sided, gunboat and
torpedo bodies are generally of the straight line type. See body

Straight Line Drive — A shaft drive (q. v.) in which the
drive shaft (q. v.) is nearly in a straight line with the crank
shaft of the motor and
the final drive shaft of
the change speed gear, at
least when the vehicle is
normally loaded, and thus
but slight relative motion STRAIGHT LINE DRIVE.

of the parts of the uni-
versal joints (q. v.) in the drive shaft is required in the opera
tion of the vehicle.

Strip (v.)— To break off the teeth of meshed gears. Stripping
of permanently meshed gears is usually caused by the too
sudden application to them of an abnormally heavy load and
the stripping of sliding gears by attempting to mesh them when
their tooth velocities are widely different.

See chassis, stripped.

Stroke — See piston stroke and long stroke motor.

Strut Rod — In general, a structural rod, the function of which
is to resist compressive stresses. Specifically, a distance rod
(q. v.) or radius rod.

Stud— A bolt-like rod of metal threaded at both ends, one
or more of which are employed to hold together two related
parts. One end of the stud is permanently screwed into a hole
in one of the members and the free end is passed through a
correctly positioned unthreaded hole in the other member. A
nut is then screwed down upon the free end of the stud, and
against the surface of the second member, drawing the two
members tightly together. E. g., studs, fixed in the crank case,
are used to position and secure thereto the cylinders of a motor.

Stuffing Box — A device to prevent the escape of fluid from
a chamber around the bearing surface of a rod or shaft which
enters and moves therein, consisting of a
recess, formed in the wall of the chamber,
surrounding the rod or shaft, and adapted
to confine a compressible packing (often of
asbestos-rubber fabric), usually arranged
spirally around the shaft or rod, within the
recess. A stuffing nut or gland (q. v.) is
arranged to be screwed into the outside
end of the stuffing box, around the rod or
shaft and to compress the packing so that

STUFFING Box.

A, Cylinder; B, it bears tightly against the walls of the

Piston Rod; C, Pack- „

ing; D, Gland. stuffing box and the shaft or rod, thus

preventing leakage. Used in connection

with steam engines, around the piston rod and valve stem; in
housings which contain oil, around the shafts entering them and
around the drive shafts of water pumps.

Subframe — A subsidiary supporting frame attached to the
main frame of a motor car and designed to hold the motor,
change speed gear or
other part which cannot
conveniently be supported
directly upon the main
frame. A subframe is
generally constructed of
channel (q. v.) or angle
steel (q. v.) riveted to
the main frame and is
often dropped below the general level of the main frame.

Suction Pipe — See intake pipe.

Suction Stroke — See aspirating stroke,

Sulphatation — The conversion of a portion of the active
material (q. v.) of an accumulator (q. v.) of the lead type into
lead sulphate, by the action of the sulphuric acid of the electro-
lyte. If this action becomes excessive, the sulphate prevents
the proper entrance of the electrolyte into the active material, and
loss of capacity, buckling (q. v.) and reduced efficiency result,
the internal resistance of the cell is increased and the plates
tend to shed (q. v.) excessively. Excessive sulphatation is
generally caused by overdischarging a cell, by allowing it to

A, SUBFRAME.

304

stand discharged for a considerable time, by a too high discharge
rate (q. v.)> by too high temperature of the electrolyte or by
its too high density or by local action among plates or parts
of plates.

If not too far advanced, oversulphatation may be corrected
by overcharging a cell at a low rate, with the electrolyte at a
low temperature, but, if the plates are completely sulphated,
they are generally irreclaimable.

Sump — A reservoir located at the lowest point in a circu-
lating lubrication system (see lubrication, circulating system,
pump type), into which the oil supplied to the moving parts, by
the pump, returns by gravity, and from which the pump draws
it to be recirculated. It is usually a specially formed depression
in the bottom of the engine crank case.

Superheated Steam — Steam to which has been imparted
more heat than that required to maintain it in the condition
of dry or saturated vapor at its existing pressure. A given
weight of water in the condition of superheated steam thus
possesses a greater capacity for doing work than does the same
weight of water in the form of saturated steam and its tempera-
ture is higher. It is employed in fhe engines of steam vehicles
because of the water economy thus effected and the less dense
exhaust created.

Superheater — A device used in connection with steam ve-
hicle boilers, for superheating steam by subjecting it, as pro-
duced, to a temperature higher than its normal saturated tem-
perature at its existing pressure. It consists of passages, often
a coil of piping, through which the steam is passed, the outside
walls of which are exposed to the hot gases from the burner, by
being located in the uptake or chimney. In some boilers, steam
is superheated by passing through the upper portions thereof,
which are maintained at a sufficiently high temperature.

Syn. : Superheating coil.

Supplementary Air Valve — See auxiliary air valve and car
buretor, automatic.

Supplementary Spring — See spring, supplementary.

Surrey — A body similar to the tonneau form, except that the
side entrances to the rear seat are open and not provided with
doors and that the rear seat does not overhang the side lines
of the vehicle, and usually seats two instead of three passengers

305

Switch, Ignition — See ignition switch, kick switch, lock
switch, steering wheel switch.

Switch, Lighting— A switch, usually of the multiple push
'button type, used to separately control the electric current flow-
ing to the headlights, sidelights and tail lamp in an electric
vehicle lighting system. It is usually placed upon the dash or
upon the heelboard of the front seat.

Switch Plug — A removable circuit controlling plug which,
when in position in the socket provided for it in an ignition
switch, closes the circuit from the switch to the rest of the
ignition apparatus and when removed opens the circuit and
prevents the operation of the ignition system. In many switches
the handle is removable when in the "off" position, and when so
removed performs the function of the switch plug.

Switch Starting — See starting on the spark.

Synchronized Ignition — See ignition, synchronized.

Tachometer — A device for continuously indicating speeds
of rotation. Its principle is identical with that of the speed-
ometer (see speedometer, centrifugal type, and speedometer, mag-
netic type). It reads, however in revolutions per minute in-
stead of in miles per hour, and its drive shaft is usually directly
connected to the shaft the speed of which is to be measured.

Tail Lamp — A small oil or electric lamp, carried upon the
left hand side of the rear of an automobile, to warn following
traffic of the presence of the vehicle and
to illuminate the rear number plate. It dis-
plays a red light to the rear, a green light
to the left, and a white light to the right,
which is directed upon the number plate.

Tail Shaft — The rearward extension of
a gas engine crankshaft, beyond the flywheel
flange or other mounting, upon which the
driven member of the clutch is supported,

and upon which it rotates when the clutch ELECTRIC TAIL LAMP.
is disengaged.

Talc — Finely pulverized soapstone (French chalk), which is of
a slippery nature and is thus used to prevent rubber surfaces from
sticking together. It is rubbed upon the surface of inner tubes
and upon the insides of tire casings for this purpose and to reduce
the friction between them.

306

Taper — A somewhat conical portion of a mechanical part, such
as a shaft, usually upon an end of the same. E. g., one end of a
shaft may be tapered and intended to receive a gear or similar
part, the hub of which is bored out correspondingly conical and
fitted upon the tapered end of the shaft. A nut is then screwed
down upon the projecting, threaded end of the shaft against the
surface of the hub, forcing the tapered surfaces into tight contact.
A key (q. v.) may be employed to prevent rotation of the gear
upon the shaft.
See pin, taper.

Tappet — A rocker arm (q. v.).
Tappet Rod — A push rod (q. v.),

Taxicab — A public motor vehicle, with a closed or convertible
body, operated for hire and fitted with a taximeter (q. v.), by
which the charges for its use are automatically computed.

Taximeter — An instrument installed upon a public passenger
automobile, that is operated for hire, which automatically in-
dicates the fare which the passenger is
expected to pay, at any instant, while the
vehicle is in his service. It is a com-
bination of a trip odometer mechanism
(see odometer, trip) and a clock, which,
respectively, measure the distance trav-
eled and the time consumed, these fac-
tors being combined in such a manner
by the mechanism that a continuous indi-
cation is given in dollars and cents of
what the service has cost the passenger
at any instant after the vehicle is hired.
TAXIMETER. Telescope Joint — See slip joint.

Telltale— A sight feed (q. v.).

Terminal — One of the points of attachment through which
an electric current is led into or out of a piece of electrical ap-
paratus. It is generally a binding post (q. v.).

A specially formed piece of metal soldered or otherwise elec-
trically connected to the end of a wire or cable and adapted to
be conveniently and securely attached to a binding post or terminal
of a piece of electrical apparatus. It may be in the form of a
spring clip arranged to be snapped over or upon a binding post.

Terminal Pressure — The fluid pressure existing in an engine
cylinder at the instant of the opening of the exhaust valve.

307

Testing Block — A stand or framework, suitably equipped with
apparatus, upon which a motor, change speed gear or other power

transmitting part of
an automobile, or in-
deed, a complete chas-
sis, may be quickly and
conveniently mounted
to enable a dynamo-
meter test (q. v.) or
other form of shop
test (q. v.) to be

TESTING BLOCK. made uP°n *•

Syn. : Testing stand.

Testing Body — A rude, skeleton body which is mounted upon
a completed chassis while it is being given its road test (q. v.),
wear and tear upon the highly finished body, which is to be
delivered upon the chassis, thus being obviated. Special test-
ing wheels are generally used upon the chassis, during the
road test, instead of the highly finished wheels which belong
with it.

Testing Track — A course, laid out upon privately owned
land, upon which motor cars can be tested under road condi-
tions without interference from other traffic or legal restric-
tions.

Thermal Efficiency — See efficiency, thermal.

Thermo=siphon — See water cooling, gravity system.

Thermostat — A device which is sensitive to temperature
changes, and which when the temperature to which it is ex-
posed changes material-
ly from a predetermined
value, is capable of set-
ting into action mechan-
ism which tends to re-
adjust the temperature
to its normal value. Its
action is usually depend-
ent upon the differential
expansion and contrac-
tion, by temperature
changes, of two sub-
stances (usually dissimi-

THERMOSTAT.

A, Steam Inlet; B, Copper Tube; C, Iron
Rod Jointed to B at D; E, Bell Crank
Operating Valve F; G, Fuel Feed.

308

lar metals.) Used in flash boilers to regulate the fire (see auto-
matic fire regulator) and in electric vulcanizers (see vulcanizer,
electric).

Third Gear — The highest gear ratio obtainable from a three
speed change speed device (its high gear), and the next to the
highest gear ratio obtainable from a four speed change speed de-
vice.

Syn. : Third speed.

Three Point Suspension — A method of supporting a motor
crankcase, gearcase, unit power plant (q. v.) or the like upon a
vehicle frame, by the employment of which the part so mounted
is substantially insured against being stressed by the accidental
warping of the frame. The part thus mounted is secured to the
frame at three points, usually as follows : By an arm extending
from each side of the front or the rear thereof to the adjacent
frame side member, and by a third arm extending backward or
forward from the middle of the rear or front end thereof to the
middle portion of a frame cross member, this last mentioned sup-
port often being of trunnion (q. v.) construction. The principle
involved in this method of suspension is that three points, no
matter how located, are always in the same plane, and that no
matter how the vehicle frame distorts in service, and although
the plane of the mounted part may be altered as a whole, there is
practically no tendency to change the position of one supporting
arm relatively to another and thus no tendency to stress the ma-
terial of the part. Since four points may be so located as not to
lie in the same plane, a part secured to a frame by four or more
arms must necessarily be subjected to a warping tendency when-
ever the frame so distorts as to tend to move the parts of it
which act as supports out of the same plane.

Throttle Valve — In connection with a gas engine, the valve
which controls the passage of the gaseous charge from the car-
buretor to the cylinders, in response to the suction existing there-
in, by contracting or enlarging, at the will of the operator, the
effective area of the gas passage. Its degree of opening deter-
mines the weight of fuel vapor drawn into each cylinder, and
thus the explosion pressure therein and the amount of work done
by the motor, per cycle. It is generally a part of the carburetor
(see diagram carburetor, automatic) and generally located close
to its point of attachment to the intake pipe (q. v.),and is most

309

commonly a butterfly valve (q. v.), but may be a piston valve
(see valve piston), a sliding valve or the like.

In connection with a steam engine, the valve in the steam pipe
which controls the flow of steam from the boiler to the engine.
It may be a slide valve with self-adjusting seat, a form of globe
valve moved by a multiple threaded screw or the like.

Throttle (v.) — To restrict the rate at which steam or gas
is received by a steam or gas engine and thus to reduce its out-
put. To throttle down.

Throttle, Auxiliary — A valve in the steam pipe of a steam
car, additional to the regular throttle valve, arranged so as com-
pletely to close the same and thus to prevent the starting of the
car upon the unintentional or malicious opening of the regular
throttle and to prevent its accidental starting in case the regular
throttle leaks. It may be provided with a removable handle or a
locking device, as a precautionary measure.

Syn. : Safety throttle.

Throttle, Clutch Operated — In connection with a gas vehicle
motor, a mechanism which automatically nearly closes the throttle
valve, when the operator disengages the clutch and the load is
consequently removed from the motor, the throttle valve being
permitted to return to its set degree of opening upon the re-
engagement of the clutch. It acts to reduce the speed of the
motor to a safe idling rate and thus to prevent racing when the
clutch is thrown out.

Throttle, Foot — See accelerator.

Throttle, Governor Controlled — A throttle valve which, in
some commercial vehicle gas motors, is entirely distinct from
the hand or foot controlled throttle valve, and which is auto-
matically opened and closed by a governor (q. v.), its func-
tion being to limit the speed of the motor to a predetermined
maximum value. (See Governor. Maximum Speed.)

Throttle Lever — The hand operated lever, by means of which
the throttle valve is opened and closed. On gasoline and many
steam cars, it is located upon the steering column and moves ovei
a stationary sector (the throttle quadrant or segment) so de-
signed as to retain it in whatever position thereon it is set bj
the operator.

Syn.: Hand throttle,

310

Throttle Linkage — The mechanism which transmits the open
ing and closing movement of a throttle control device (lever,
pedal or otherwise) to the throttle valve itself.

Throttle Shaft— The shaft, within or attached to the steering
column, which transmits the movement of the throttle lever to
the rest of the throttle linkage.

Throttle Spindle — The spindle or shaft, in a carburetor, upon
which the throttle valve rotates.

Throttle Wheel — The wheel, located upon the steering col-
umn, under the steering wheel on some steam cars, which acts
as the throttle valve control device.

Through Bolt — In a gas motor, one of a number of long bolts
passed through the cylinder flanges (q. v.), the upper wall of
the crank case, and the main bearing hangers and caps, so as
to themselves assume the stresses acting between the cylin-
ders and the bearings, and thus relieve the material of the crank
case from these stresses.

Thrust Bearing — See bearing, ball thrust. Not necessarily a
ball bearing, however, roller bearings being sometimes used and
plain stepped bearings with washers between the shoulder of the
shaft and the end of the bearing being sometimes employed.

Tickler — The device employed to prime (q. v.) a carburetor.
See carburetor float depressor.

Tie Rod — The rod forming a part of the steering gear, located
transversely of and at the front of a motor car, the ends of
which each bears a clevis (q. v.) by which they are pivotally
connected respectively to tihe ends of the right and the left hand
steering knuckle arms (q, v.). Its function is to interconnect the
two front road wheels so that they are at all times maintained in
the straight ahead or in correspondingly deflected positions. Its
length is usually slightly variable so that the front wheels can
be adjusted to parallelism.

Time (v.)— To adjust the period of occurrence of the igni-
tion spark with relation to the cycle of an internal combustion
motor. (See ignition, point of; advance; retard). (See also
valve timing).

Tinier — In an ignition system, the device which auto-
matically closes and opens the primary circuits at such
periods as to produce sparks at the instants when they are

311

TIMER.

A, Contact Roller; B,
Metallic Segment;
C, Insulated Hous-
ing; D, Connection
to Spark Lever.

required by the gas motor with which it i?
used. It usually consists of a grounded
(q. v.) contact-carrying arm, rotated by one
of the motor shafts (at one-half the speed
of the crankshaft for a four stroke cycle
(q. v.) motor and at crankshaft speed
for a two stroke cycle (q. v.) motor, and a
number of equally spaced, metallic contact
segments (one for each engine cylinder)
fastened upon the internal surface of a
stationary, cylindrical, insulating shell which
is carried (usually on a ball bearing) upon
and concentric with the contact arm shaft in
such a manner that the contact arm, when rotated, successively
makes and breaks connection with the segments. The timer shell
with its contact segments is capable of being rotated through an
arc, by means of the spark lever (q. v.) and linkage so that the
period in the engine's cycle at which the contacts are made and
broken may be varied and the desired angle of advance (q. v.)
can be secured. A primary wire from one of the spark coils
(q. v.) is connected to each segment, and, as the contact arm
rotates, it touches each contact segment in succession and ener-
gizes each ignition circuit successively, the connection being such
that sparks are produced in the cylinders in the proper firing
order (q. v.). A timer of this type is used with multiple vibrator
coils (see ignition, multiple coil), and in the master vibrator
system (see ignition, master vibrator). A timer is employed
in connection with a" distributor (q. v.), usually being
built integrally therewith in battery systems, all the con-
tact segments of such a timer being electrically connected
together, so that the primary circuit of the single spark
coil (see ignition, single coil) is closed at the instant each
cylinder requires a spark. In timers used in single spark
systems (see ignition, single spark), the contact arm of the
timer is usually replaced by a cam (see cam, ignition) with as
many projecting faces as there are cylinders to be ignited. The
cam projections, as they pass them, successively close a pair of
spring opened, platinum tipped contact points which are in cir-
cuit with the primary of the single coil used in the system. A
magneto make and break (q. v.) is essentially a timer,
Syn. : Commutator,

312

Timer, Automatically Advanced — A timer so devised as
automatically to advance (q. v.) the spark with increasing motoi
speed, and to retard it with decreasing motor speed, so that
ignition always takes place at the most advantageous point
(see ignition, point of) in the cycle of each cylinder and
manual adjustment of the spark is obviated. A centrifugal
device, similar to that used in an engine governor (see governor,
centrifugal), rotated by the timer shaft, is mechanically so con-
nected with the timer as to alter the angular relation of the timer
arm or cam to the timer shaft, or to alter the angular position
of the timer shell and contact segments as to secure the spark
position demanded by each change in engine speed. Automatic
timing is applied to magnetos, usually automatically varying the
angular relation to the magneto driving shaft of the cam which
operates the make and break device.

Timer, Ball Contact — A timer the contact arm of which car-
ries a spring pressed steel ball, which makes successive electrical
connection with the contact segments, which are usually of hard-
ened steel, a rolling action between the contact parts thus being
secured.

Timer, Brush Contact — A timer the rotating arm of which
bears a spring pressed brush (q. v.), which makes a sliding con-
tact with the segments or one in which each segment is re-
placed by a pair of spring contacts between and in rubbing con-
tact with which the timer arm passes, or any timer in which a
sliding rather than a rolling electrical contact is employed.

Timer, Roller Contact — A timer, the rotating arm of which
terminates in a spring pressed, hardened steel roller, which suc-
cessively runs over the hardened steel contact segments with a
minimum of wearing action.

Timer Shaft — The shaft which operates a timer. Such a
shaft runs at one-half engine speed in the case of a four stroke
cycle (q. v.) motor, and thus may be identical with a cam
shaft (q. v.). In the case of a two stroke cycle (q. v.) motor it
runs at crankshaft speed and may be identical therewith. Very
often the timer is driven by a special shaft arranged vertically
or slightly inclined on one side of the motor and driven by
spiral or bevel gears from a camshaft or otherwise.

Syn. : Commutator shaft.

Timing Gears — See half-time gears.

313

Timing Marks — See flywheel markings.

Timing Range — The total angle through which the occurrence
of the spark can be varied by moving the spark timing mechan-
ism from its most advanced to its most retarded position. It
may be measured as the total angular movement produced in
the adjustable member of the timer or as the total angular move-
ment of the motor flywheel between its position when the spark
occurs under full advance and that at which it occurs when fully
retarded ; the angle as measured upon the flywheel being twice
that measured at the timer, in the case of a four cycle motor.

Tire— A coninuous circular band, fastened around the periph-
ery of a road wheel outside the felloe, the external surface of
which forms the actual surface of contact between the wheel and
the roadbed. Its function is to resist the wearing effect of the
road surface, and, in automobile practice, to protect the struc-
ture of the wheel, the car mechanism and the passengers or load
against road shocks and to reduce the noise of the vehicle's
operation, to attain which results the material of the tire is

usually of a somewhat yielding and
•^£-gf^S>» resilient nature, such as rubber.

^jjfk^^**1*? Tire, Anti=Skid — A tire, the tread

of which is so constructed as to grip
the road surface more securely than
does a smooth tread. The treads of
pneumatic tires of this class may be
provided with a multiplicity of
molded knobs of rubber arranged in
various patterns ; the tread may con-
sist of a leather band, studded ex-
ternally with a multiplicity of steel rivets, or it
may be othewise roughened so as to tend to
indent the road surface and thus to offer extra
resistance to the tractive effort and to side slip.
Tire, Block — A form of solid rubber tire,
mainly used upon commercial vehicles, built up
of closely spaced blocks of rubber, usually of
somewhat rectangular section and thus possess-
ing a tread which is not continuous, but scal-
loped. The specially constructed bases of the
rubber blocks may be held in rectangular
sockets in a retaining band (either continuous

T

ANTI-SKID TIRE.

BLOCK TIRE.

314

or sectional) which is bolted to the wheel felloe, or they may be
secured in a channel rim by means of side wires. Two parallel
series of such blocks are frequently used upon the same wheel,
the blocks of the two series being "staggered." Such tires possess
excellent tractive and anti-skid properties, on account of the ten-
dency of the separate blocks to cling to or to indent the roadway.
Individual blocks of such tires which have become damaged
can be separately replaced.

Tire, Clincher — A tire of the pneumatic or solid rubber type,
adapted to Ic held in a clincher rim (see rim, clincher) mainly
by the tendency of its base forcibly to ex-
pand transversely under inflation or by its
own elasticity. Such a tire is made with
a continuous bead (see tire bead) upon
each side of its base, which is forced under
the respective incurved edge of the rim.
In pneumatic tires of this type a number of
retaining bolts (staybolts) are employed,
which pass thiough the felloe and rim and
the appropriately shaped beads of which (on
the outside of the rim) bear against the in-
side edges of the base of the tire casing,
when the bolts are tightened, drawing it

against the rim and forcing the edges of the beads into the
clinchers, thus resisting any tendency to creep (q. v.) and to
leave the rim.

Tire, Cushion — A tire depending for its resiliency upon the
elasticity of rubber, and differing from a solid rubber tire (see
tire, solid rubber) in that the rubber
is so distributed as to impart to the
tire peculiar yielding qualities.

Such a tire may be constructed with
a continuous hollow centre or core,
or with a hollow centre divided into
cells by rubber bridges ; holes or cells
may be provided in its tread or sides ;
the sides may be hollowed or notched ;
the tread may be provided with sev-
eral continuous ridges which yield under pressure, or any ex-
pedient may be adopted to secure a greater freedom of bending of
the tire under load than is obtainable in a rubber tire of solid Q

CLINCHER TIRE.

CUSHION TIRE.

315

shaped section. In resiliency, the cushion tire is intermediate be-
tween an ordinary solid tire and a pneumatic, and is used upon
some commercial vehicles and- upon some pleasure vehicles,
chiefly electrics and high wheel cars.

Tire, Dual — The combination of two like tires, either of the
solid or pneumatic type, side by side, in suitable rims, upon the
same wheel. Dual solid tires are more successful than a single
tire of equal width upon heavily loaded wheels, for the reason
that there is secured a more uniform distribution of driving
and braking stresses over the tire base. Dual pneumatic tires
are used upon the wheels of heavy vehicles which cannot be
economically operated upon single tires of the largest sizes
commercially obtainable.
Syn. : Twin tires.

Three tires are sometimes applied in a similar manner to ex-
ceedingly heavily loaded wheels of commercial vehicles. (Triple
tires.)

Tire, Flat Tread — A pneumatic tire the cross-section of the
central portion of the tread of which is a straight line instead
of the arc of a circle and which thus presents to the road a
flat surface of considerable width, even though no flattening of
the tire takes place. Such treads are sometimes employed with
the idea of obtaining superior road adhesion, greater security
from puncture, greater immunity from skidding and superior
wearing qualities.

Tire, Mechanically Fastened— A
pneumatic tire the inflation of which
plays no part in holding it to its rim, as
it does in the case with clincher and most
quick detachable tires.

Positive mechanical holding devices
are provided which secure it in place
whether it is in an inflated or deflated
condition.
Syn. : Bolted-on tire.

Tire, Pneumatic — A tire which owes
its resiliency to air, confined under pres-
sure, between the rim of the wheel and
the tire tread. In its usual form it
consists of a continuous circular, tubu-
lar casing (see tire casing), fastened

MECHANICALLY
FASTENED TIRE.

AA, Clamp; BB, Ring
Retainers; C, Rim.

by the edges of its base, upon the wheel rim, within which is fitted
an endless circular, air-tight tube, the inner tube (q. v.), which,
when inflated with air to a considerable pressure distends, presses
against the rim and the inside walls of the casing, thus giving
the tire a rotund shape under load, and confining a highly elastic
body of air between the roadway and the rim of the wheel. The
casing and inner tube are capable of bending, without large waste
of energy, to conform to irregularities of the road surface, partly
or wholly "absorbing" them and thus preventing jolts which would
otherwise be communicated to the wheel and the vehicle.

Tire, Puncture Proof — A pneumatic tire in or on the casing
of which is provided an armor of steel or other impervious
plates which deflect puncturing objects before they reach the
inner tube, or any pneumatic tire in which the inner tube is
protected against external damage.

Tire, Quick Detachable — A pneumatic tire adapted to be
mounted upon a quick detachable rim (see rim, quick detachable)
so that it can readily be put on and taken off.

Tire, Single Tube — A pneumatic tire, in which the casing and
inner tube are intergral, the latter being .merely the air-tight
inner layer of nearly pure, lightly vulcanized rubber, the whole
forming an endless closed tube of circular section. Equally
spaced metal lugs, vulcanized into the inner face of the tire, re-
ceive screws driven through the felloe and rim and hold the
tire in place, cement also sometimes being used. Occasionally em-
ployed upon electric vehicles, a special light-walled and highly
resilient form being usually chosen. (High duty tire.)

Syn. : Hosepipe tire.

Tire, Solid Rubber — A tire the resiliency of which is due
to the yielding quality of compounded rubber in the form of a
band of somewhat Q shaped section, applied to the periphery of
a wheel in a rim of somewhat channel shape. Such tires are
generally used upon commercial vehicles and occasionally upon
high wheel pleasure cars and others,
as they deaden the noise of the wheel
contact with the roadway, absorb vi-
bration to quite an extent and possess
good road adhesion.

Tire, Solid Rubber, Internally
Wired — A solid rubber tire, which is INTERNALLY WIRED SOLID
held in its rim by the constrictive ac- RUBBER TIRE.

317

ti( ni of one or more continuous wires which are embedded in the
base portion of the tire throughout its entire length. The wires
are stretched, by a special machine, after the tire is on the rim
and the two ends of each are united by welding or otherwise so
that each wire forms a complete band, under heavy tension.

Tire, Solid Rubber, Metal and Hard Rubber Base—
A solid rubber tire with a base
made up of a steel band externally
provided with circumferential dovetail
projections, upon which is molded a
layer of hard rubber, the external sur-
face of which is vulcanized to the rubber
body of the tire. Such tires are es-
pecially intended for use upon demount-
able rims, the inside surface of the steel
band being held upon the rim by wedge
like rings, one of which is usually
clamped to the wheel by bolts.

SOLID RUBBER TIRE,

METAL AND HARD

RUBBER BASE.

SOLID RUBBER TIRE, SIDE
WIRED.

Tire, Solid Rubber,
Mesh Base — A solid rubber tire,
in the base of which is embedded
a meshwork of wires which pre-
vents it from stretching and
forms an unyielding base. It is
secured in a channel shaped rim,
one flange of which is removable,
and which when bolted on, com-
presses the 'base transversely and
holds the tire from creeping.

Tire, Solid Rubber, Side Wired

— A solid rubber or similar tire
which is secured in a somewhat
channel-shaped rim by two steel
wire bands drawn tightly around
between each edge of the rim and
the neighboring edge of the tire base.
The base of the tire is given rigidity
by numerous cross wires vulcanized
into it upon the ends of which the
two side wires bear.
Wire

SOLID RUBBER TIRE, WIRE
MESH BASE.

318

Tire, Wood Block — A tire, built up of blocks of hard wood
secured in and filling a channel rim with the
grain of the wood perpendicular thereto, the
faces of the blocks being turned down to a
true circle. Such a tire is much less noisy,
somewhat more resilient and less likely to slip
than a steel tire, and is occasionally used upon
heavy commercial vehicles.

Tire Base — That portion of a tire which is
immediately in contact with the rim and by
which it is held in position thereon. The term
is especially applied to solid rubber and cushion

WOOD BLOCK
TIRE.

tires, the bases of which are usually of special rigid construction,
in order that they may be securely held, while the tire proper
is of a yielding nature.

Tire Bead — The two edge portions of the base of a tire which
are grasped by the sides of the rim (see tire, clincher). The
bead of pneumatic tire casings is formed of a strip of hard
rubber around which the rubberized fabric of the tire carcass
(q. v.) is built up to give the required shape. In clincher
pneumatic tires the bead is hooklike, and adapted to fit under
the incurved edges of the rim. In some pneumatic tires for use
on quick detachable rims the bead is not hooklike but straight-
sided (straight or Dunlop bead) and in the bead is enclosed a
continuous elastic wire cable (cable base tire) which prevents
the base from stretching and, by contracting under inflation, holds
the casing tightly upon the rim.

Tire Breaker Strip— In a pneumatic tire casing a strip of
iheavy fabric applied between the cushion (q. v.) and the
rubber of the tread.

Tire Carcass — The structural or stress resisting portion of a
pneumatic tire casing to which the tread and other parts are ap-
plied. It is built up of rubberized cotton fabric, wound diagonally
around a core of the required shape
and size and compacted into a solid
mass by pressure and vulcanization.

Tire Carrier — A support attached
to a car in which extra tires or de-
mountable rims are carried. The tires
are frequently strapped at three points
to forked irons, two of which extend TIRE CARRIER.

319

out from the car body and one from the running board, or they
may be held in suitable supports attached to the rear of the body.

Syn. : Tire holder. Tire irons.

Tire Case — A waterproof and dustproof envelope of the shape
and size of a pneumatic tire, designed to be fitted around a spare
tire to protect it from deterioration while it is carried on a car.
It is usually made of enamel cloth and is held. tightly about the
tire by a contracting wire spring sewed ino the fabric.

Syn. : Tire cover.

Tire Casing — A pneumatic tire exclusive of its inner tube.
The wear and stress resisting external portion or envelope,
which is secured to the wheel rim. Syn. : Tire shoe. For parts
thereof see tire bead, tire carcass, tire tread, tire cushion, tire
flap, tire breaker strip.

Tire Chain — A traction increasing and anti-skid device (q. v.),
consisting of two steel chains which fit entirely around a tire
on each side thereof near its
base. These two side chains
are united by a series of short,
uniformly spaced cross chains
of hardened steel, the ends of
which are hooked into links of
the side chains so that they lie
across the tread of the tire.
The two ends of each side
chain are held together by a
snap hook which is released
when the tire chain is put on or
taken off. In use, the .cross
chains indent a yielding road-
way, and increase the adhesion TIRE CHAIN.
of the wheel thereto and, on

hard road surfaces, wedge between it and the tire and reduce
the slipping 'tendency.

Tire Cushion— A layer of nearly pure rubber applied, in the
manufacture of a pneumatic tire casing, between the tire carcass
(q. v.) and the breaker strip (q. v.) or strips, to act as a buffer
between the tread and the body of the tire.

Tire Filling — A composition sometimes used to completely
fill the air space within a pneumatic tire, thus rendering it im-
mune to puncture without entirely destroying its resilient

qualities. Such compositions consist of mixtures of somewhat
resilient, spongy or jelly-like materials, such as glucose, glue,
glycerine, etc., which are introduced into the air tube, when in
a melted condition, by means of air pressure, and assume, upon
cooling, a resilient solid condition.

Tire Flap — A fabric lip or band, so attached, by one edge,
as to lie around the inner circumference of a quick detachable
pneumatic tire casing, and which, after the inner tube is placed
in position, is so adjusted that it intervenes between it and the
rim, thus protecting it from pinching and rusting.
Syn. : Tire chafing strip.
Tire Gauge — See gauge, tire.
Tire Inflater— See air bottle.

Tire Inner Shoe — A circular band of leather, strong fabric
or other material of such shape as to fit between the inside
of a pneumatic tire casing and the inner tube and thus to rein-
force the former against the outward pressure of the latter, thus
assisting in preventing blowouts and in resisting punctures. Prin-
cipally used with casings which have become weakened in use.
See blowout patch. Syn. : Inside tire protector.
Tire Inner Tube — See inner tube.

Tire Patch — A prepared piece of rubber of such quality, size
and shape as to be conveniently cemented or vulcanized over a
puncture in an inner tube to close the same. The edges of the
patch are usually beveled off and one side of it is often pre-
pared with a rubber cement.

Tire Protector— A band of highly resistcnt and impenetrable
material applied to the tread of a pneumatic tire to relieve the
tread from road abrasion, to resist the
attacks of puncture producing objects
and to strengthen the casing against
blowouts. It may be a band of leather
cemented or otherwise permanently af-
fixed to the tread and studded with steel
rivets or a detachable endless band con-
sisting of layers of leather externally
bearing steel rivets or containing over-
lapping steel plates, which is held upon
the tire by the outward pressure of its
inflation and by a series of contrac-
TIRE PROTECTOR. tile springs acting to hold its edges

321

in tension and closely against the tire. Such protectors are gen-
erally designed to act as anti-skid devices (q. v.)-

Tire Pump — An air pump or compressor used to inflate pneu-
matic tires by forcing air into their inner tubes. See illustration
under air pump.

Tire Pump, Power — A tire pump operated by mechanical
1 lower. Portable pumps for use upon automobiles may consist
of a combination of one or more pump cylinders, the pistons of
which are driven from a crankshaft which is, in turn, rotated by
being thrown into gear with a shaft of the vehicle motor, or by
means of a friction pulley forced into contact with the motor
flywheel or by suitable mechanical connection to a jacked-up road
wheel. Another type (impulse pump) is operated by motor cyl-
inder pressure and consists of a double diameter piston (see pis-
ton, double diame-
ter) and cylinder
arrangement which
is screwed into a
spark plug hole of
the motor. The
alternating c o m-
pression pressure

ENGINE DRIVEN TIRE PUMP.

A— Cylinder; B— Piston; C— Connecting Rod;
D— Crank Shaft; E— Driving Pulley; F— In-
take Valve; G — Delivery Valve.

and suction, with-
in the motor cyl-
inder, acting upon
the larger of the

pump pistons reciprocates it and causes the smaller piston and
its cylinder to reciprocate as well and it and its cylinder to act as
an air pump.

A stationary power tire pump, such as used in garages, usu-
ally consists of a multicylinder air pump, operated by an electric
motor or from shafting, which maintains a predetermined air
pressure in a tank from which air can be drawn for tire inflation.

Tire Shoe — A tire casing (q. v.).
Tire Sleeve — See blowout patch.

Tire Staybolt— See tire, clincher.
Syn. : Tire lug.

Tire Tape — See friction tape.

322

Tire Tool— A hand tool employed to facilitate the removal
from and replacement upon their rims of pneumatic tire casings.

Such tools are stiff steel levers,
of a variety of shapes, adapted
to act, to the utmost advantage,
between the beads of the tire and
the rim.

TIRE TOOL.

Tire Tread — The part of a tire which is in actual contact with
the road surface and thus has to resist the abrasion and cutting
action thereof. In pneumatic tire casings, it is the outside layer
of specially compounded rubber adapted to resist wear and cut-
ting by sharp objects and, at the same time, to prevent water
from entering the fabric portion of the tire. It is of consider-
able thickness along the line of contact of the tire with the
road and. thinner along the sides of the casing, and a portion of
it is often deeply embossed into various shapes for anti-skid
(q. v.) purposes.

Tire Valve — An inwardly opening, spring closed valve, through
which air is forced into the inner tube of a pneumatic tire and
by which it is confined therein. The valve
is placed in position by screwing it into its
seat in the valve stem (q. v.).

Tire Valve Stem— The externally
threaded metal tube, one end of which en-
ters, airtight, through the wall of an inner
tube and through which air passes into and
out thereof. It contains the seat for the
tire valve (q. v.), and its free end is pro-
vided with an internal thread to receive a
pump connection and an external thread
upon which an airtight cap is normally

screwed. The stem is of such length that, when the inner tube
is in place, its free end protrudes accessibly through a hole in the
rim and felloe, a ring nut being screwed down upon the stem so
as to bear against the felloe and draw the inner tube tightly
against the inside of the rim, and a dust cap (q. v.) is usually
screwed down upon this nut.

Tonneau — An unenclosed body used especially in touring, with
a front seat for two passengers about midway of the chassis and
a seat for three nearly over the rear axle, somewhat overhanging
the general side lines of the vehicle. Entrance to the rear seats

TIRE VALVE.

is by a door on each side, which when shut entirely encloses the
tonneau space. Chair seats for two passengers are sometimes
added between the two main seats.
Syn. : Touring body.

Tonneau, Baby — A small tonneau accommodating two in-
stead of three passengers upon the rear seat, and with no
space for extra seats between the front and rear seats.

Syn.: Toy tonneau, miniature tonneau, pony tonneau, demi-
tonneau.

Tonneau, Detachable — A tonneau body of which that por-
tion to the rear of the front seat-backs and comprising the
rear seating accommodations (the tonneau proper) is remov-
able, as a unit, from the vehicle frame upon the loosening
of bolts. When so removed the rear portion of the car be-
comes a flat deck or trunk platform, upon which a truck box
or similar attachment may be mounted, thus permitting the
same car to be used as a two passenger car, a four passenger
car or for light commercial purposes.

Tool Box — A box in which automobile tools are carried, usu-
ally constructed of pressed steel and generally mounted upon
one of the running boards of a car.

Tool Steel— See steel, tool.

Top, Cape — A folding top of waterproof fabric attached
to inverted H shaped bows which, when extended, forms a
rain and sun proof protective
covering over a car, extend-
ing from the extreme rear to
a point slightly forward of
the dash, the fabric being-
brought down for a short dis-
tance along its edges, but
"leaving the sides and ends of
the car practically open. The
lower ends of the bows are
supported upon two top irons
on each side of the body, one

pair being located close to the rear and the other pair nearly
in line with the front seat. Two bows are generally used at
the front and either .two or three at the rear. The top is
kept tightly extended by means of two pairs of adjustable top

324

straps attached respectively to the two sides of the front and
of the rear thereof, the other ends of the front straps being
hooked into eyes fastened to the front of the car frame and
the other ends of the rear straps to the rear portion of the
body. In putting down the top, the front straps are un-
hooked, and the front bows are detached from the front irons
and attached to the rear irons and the top collapsed rear-
wardly, the bows being closely strapped together with the
top fabric folded among them. Detachable, waterproof cur-
tains, with celluloid windows, which button onto the top and
onto the body at the sides and rear of the car (side curtains),
may be attached to completely close in the passengers, in
inclement weather, and a curtain with celluloid windows, or-
dinarily carried rolled up on the front bow, may be let down
and buttoned to the dash, to close in the front of the car (storm
front).
Syn. : Cape cart top.

Top Cover — A waterproof fabric cover, so shaped as to slip
over a top when it is folded and to button securely about it,
thus hiding it from view and protecting it against soiling.

Syn. : Slip cover, envelope.

Top Circle — With reference to a gear wheel, the imaginary
circle drawn through the points of its teeth.

Torpedo Body — See body, gunboat.

Torque — The turning or twisting effort exerted by or upon
a rotating part, such as a shaft, and measured by the mo-
ment of the forces acting. It is the product of the turning
force and the perpendicular distance of its point of applica-
tion from the axis of rotation. If the force is expressed in
pounds and the distance in feet or in inches, the torque is
expressed in pounds-feet or pounds-inches, respectively.
Knowing the horse power P being transmitted by a rotating
part, the torque T acting in pounds-feet, is

33,000^ 25.2,g

- N

where Af = the revolutions per minute of the rotating part. See
horse power and dynamometer.
Syn.: Turning moment.

325

Torque Rod— A rod, generally tubular or of I-section, em-
ployed to resist • the tendency of an automobile driving axle
housing to rotate under the reaction of the driving and braking
forces. It is located lengthwise of the vehicle, its rear end being
secured rigidly into some part of the axle structure, usually

the driving gear
housing, and its front
end secured to a
frame cross member,

this end usually bem§
confined between two

spiral springs, held in
TORQUE ROD (A). a su}table fitting> with

the intention of per-
mitting slight deflections of the rod to cushion starting and
braking shocks. Sometimes two tubes are used, their rear
ends being bolted, respectively, to the upper and lower edges
of the drive gear housing, and their front ends united at the
spring support on the frame, a triangular structure thus being
formed. A torque rod is used upon most shaft driven cars
having drive shafts of the double jointed type (see drive shaft,
double jointed), although in some small cars, the rear springs,
which are tightly clipped to the axle housing, act to resist its
rotation. In cars with drive shafts of the single jointed type, the
drive shaft housing (q. v.) is often arranged to act as a torque
rod, its front end being secured to a frame supported part so that
it can pivot thereon at a point concentric with the universal
joint and its rear end being rigidly secured to the drive gear
housing. Under such conditions the housing also acts as a
distance rod (q. v.).

Touring Car — A motor car, usually of the five or seven
passenger tonneau type, especially intended for use in making
long, continuous runs over all kinds of roads at speed, and
with comfort to its passengers, in contradistinction to a runa-
bout intended for use in making short, local trips. It is usually
rather highly powered, with large 'capacity for supplies and lug-
gage, a long wheelbase, specially easy riding springs and luxu-
rious seats, and specially fitted with conveniences tending to
make its occupancy comfortable during long periods.

Town Car — A motor car with a closed or convertible body,
usually hung rather low to afford easy access and egress, pri-

326

marily intended for city use, such as shopping and calling. Such
a car is usually not especially high powered, but is designed with
a small turning radius (q. v.) and a capacity for rapid accelera-
tion to facilitiate its being manoeuvred handily in crowded traffic.
Limousine, landaulet, coupe and other similar bodies are em-
ployed.

Track — The gauge of a vehicle (q. v.).

Traction — The adhesion of the wheels -of a vehicle to the
roadway; that is, the frictional force acting between them and
the road, which furnishes the reaction against which the tractive-
effort acts in moving the vehicle and against which the braking
effort acts in stopping it. It is the product of the coefficient of
friction of the tires on the roadway and the weight supported
upon the driving wheels. When the tractive effort or braking
effort exceeds the traction, the driving wheels slip and the vehicle
fails to move or fails to stop promptly. Imperfect or diminished
traction results from icy, muddy or otherwise slippery roads,
unsuitable tires or too lightly loaded driving wheels.

Traction Increasing Device — See mud hook, tire chain and
tire, anti-skid.

Tractive Effort — The force applied, tangentially, at the point
of contact of a driving wheel with the roadway which tends to
move a self-propelled vehicle. Knowing the horse power P being
applied to a pair of driving wheels, the tractive effort in pounds

p
is F = 5025.2 TT^ f where R is the wheel radius in feet and N is

the speed thereof in revolutions per minute.

Tractive Resistance — The resistances acting at the points
of contact of the wheels of a vehicle with the surface of a level
roadway, which opposes the rolling of the wheels over it and
thus the movement of the vehicle. Such resistance varies with
the load carried, the kind and width of tires used and their
condition, the character and condition of the road surface, the
wheel diameter and vehicle speed and other factors. It is usu-
ally expressed in
pounds per ton of
weight moved.

Syn. : Road re-
sistance.

Tractor — A mo-
tor car designed to
draw t r a M e r s TRACTOR (A) AND TRAILER

327

(commercial vehicles without motive power) or to drag agricul-
tural or other similar machinery. Syn. : Traction engine.

Also a motor-car mechanism adapted to be attached to the for-
ward end of a horse drawn vehicle and thus to convert the latter
into a self-propelled vehicle. Syn. : Forecarriage. One type of
tractor consists of a power chassis with a single front wheel for
steering purposes, the rear of this chassis being made fast to the
fifth wheel of the horse-drawn vehicle, the front wheels of the
latter receiving the power from the tractor and supporting its
rear portion, the whole constituting a five wheel vehicle. Deflec-
tion of the front wheel deflects the tractor portion and turns the
fifth wheel and the two driving wheels, thus permitting the whole
vehicle to be steered and manoeuvred in a small space.

Transfer Passage — In a two (stroke) cycle motor, the
passage through which the fuel charge, which has been com-
pressed in a separate chamber, is allowed to expand and flow
into the working cylinder. Its point of entrance into the crank
case or other chamber in which the charge is compressed is
called the transfer port and its point of entrance into the working
cylinder is called the inlet port. The transfer passage is usually
cast in the cylinder wall from the crank case to the working
cylinder space, but, in multiple cylinder engines, it may be a
passage extending from the pumping space of one engine to
the working cylinder of the adjacent engine. See diagram under
two cycle engine, three port type.
Transformer — See coil, induction.
Transmission — A change speed gear (q. v.).
Transmission Axle — A driving axle to the front side of
the gear housing of which is bolted the rear end of the case

(gear case) con-
taining the change
speed gear (q. v.)
of a gasoline au-
tomobile, the front
end of the drive
shaft (q. v.)
(either single or
double jointed)
being connected
directly to the

TRANSMISSION AXLE (A).

clutch shaft, and

323

its rear end to the primary shaft of the change speed gear, upon
the final drive shaft of which is directly mounted the driving
pinion of the bevel gear drive (q. v.). In this construction there
are but two units to be mounted upon the frame: the engine-
clutch unit at front and the change speed gear-axle unit at the
rear.

Transmission Brake — See brake, transmission.
Transmission Efficiency— See efficiency, transmission.
Transmission Line— A term applied to all the elements con-
cerned in the transmission of power from the motor to the driv-
ing wheels of an automobile, including the clutch and its shafts,
the change speed gears and their shafts, the universal joints, dif-
ferential gear, axle shafts and drive shaft or chains and sprockets
of the final drive.

Tread — The gauge (q. v.) of a vehicle.
Tread — See tire tread and tire, anti-skid.
Trembler — See magnetic vibrator.

Truck Box — A box adapted to be mounted upon the rear
of an automobile for commercial purposes. The term is usually
applied to a box which can be attached and detached at will, in
place of a tonneau or rear deck, to enable a car to be used for
several classes of service.

Trunk Rack — A folding rack, usually of steel construction,

attached to the rear of an auto-
mobile body and adapted to
hold a trunk or other luggage
and to be folded into small
compass when not in use.

Trunnion — A projection at-
tached to a movable structure,
which fits into a suitable socket
in a stationary p.art and forms
a pivot upon which the sup-
ported structure may rotate

TRUNK RACK. ,. , . , ... . .

slightly (usually in a vertical

plane). The end support of

a motor or other mechanism which is on a three point sus-
pension (q. v.) is often a trunnion, and a trunnion is sometimes
used upon each side of a radiator to give it a slight freedom of
motion in the radiator brackets.

329

Truss — A construction designed to give transverse stiffness
to a structural member. See axle, trussed, and frame, trussed.

Try Cock — A gauge cock (q. v.) or a cock set horizontally
into a housing containing oil, the opening of which indicates by
the outflow of oil therethrough, or its failure so to outflow,
whether the oil level is or is not above the point of insertion of
the cock.

Tungsten Lamp — A form of electric incandescent lamp the
filament of which is of tungsten wire and which is highly efficient
as compared with the carbon filament lamp, consuming from i.o
to 1.25 watts, per mean horizontal candle power. It is generally
used in all automobile electric lighting systems.

Tune Up (v.) — To make such adjustments upon a motor car
mechanism as to cause all parts to work together with the utmost
harmony and efficiency.

Tungsten Steel — See steel, tungsten.

Turnbuckle — A device for adjusting the length of a structural
or control rod. In one common form, the rod is divided at
some convenient point in its length
and the adjacent ends are threaded
respectively right and left handed-
ly. A long nut, with its two ends
threaded correspondingly right and

left handedly, is screwed onto the TURNBUCKLE.

two threaded ends of the rod.
Turning the nut in one direction

draws both ends of the rod into it, thus reducing the
rod's length, and turning the nut in the opposite di-
rection screws both ends of the rod out of the nut, thus in-
creasing the rod's length. A check nut is sometimes applied to
one end of the nut to retain the adjustment. It is used to ad-
*just the lengths of spark, throttle and brake linkages, the tension
rods of trusses, distance rods, etc.

Turning Moment — Torque (q. v.).

Turning Radius — The radius of the circle which the outside
wheels of a car describe when it is turned completely around
with the front wheels deflected, by the steering gear, into one
or the other of their extreme positions. The greater the angle
of lock (see lock, angle of) and the shorter the wheelbase (q. v.)
the smaller the turning radius and the less space required in
which to manoeuvre a car,

330

Turntable — A device for turning cars around in a garage,
consisting .of a circular platform, flush with the floor, which is
supported beneath upon anti-friction bearings, generally several
series of balls, so that it and a car which has been run onto it
can readily be rotated by hand, and the car be left pointing in
any desired direction.

TURNTABLE.

Two Cycle Engine— A gas engine operated upon the two
stroke cycle (q. v.). Most such engines are without valves in the
common acceptation of the term, gases leaving and entering the
working cylinder and pump chamber through ports in the cylinder
wall, which are closed a*nd opened by being covered and uncov-
ered by the working surface of the .piston in its travel. In some late
designs, however, mechanically operated and automatic valves are
adopted. The charge to be admitted to the working cylinder,
through the transfer passage (q. v.), is usually precompressed in
the gas-tight crank case by the lower face of the piston or in a
special pump chamber acted upon by an extension of the working
piston. The displacement of remanent burnt gases from the cyl-
inder and the distribution of the fresh charge therein are facili-
tated by a deflector plate (q. v.)- Mechanically and as to their
ignition (see timer), carburetion, cooling and Lubrication (see
lubrication, mixture method), they are similar to four cycle
engines. They are built in multicylinder types and in the four
cylinder type the cranks are usually set at angular intervals of
90 degrees, thus providing for an overlapping of power impulses
and a constant torque. The details of the manner in which the
cycle is carried out is susceptible of considerable variation, and
much diversity of design exists. The most common types in
commercial use are denned under the following heads:

Two Cycle Engine, Differential Piston Type — A type of
two cycle engine equipped with differential pistons and cylinders
(see piston, double diameter, and cylinder, double diameter).

331

The larger bore and piston of each cylinder acts as a pump, pre-
compressing the charge for transfer to the combustion space of
another cylinder, the crank of which is set at 180 degrees with
that of the pumping cylinder.

Two Cycle Engine, Distributor Valve Type — A type of two
cycle engine, built with two cylinders or a multiple thereof, in
which the transfer of the precompressed charges to the working
cylinders is effected through transfer passages which, as well as
the suction passages to the pumping chambers, are controlled by
a rotary distributor valve (q. v.), rotated at crankshaft speed by
the engine. In a typical form of four C}4inder engine of this
type, in which the cranks of each pair of cylinders are set in
opposition, double diameter pistons are employed (see two cycle
engine, differential piston type). The distributor valve alter-
nately establishes communication between the carburetor and the
precompression space of a particular cylinder, during the entire
downward stroke of its piston and between the said precompres-
sion space and the tranfer passage to the adjacent working cyl-
inder when the piston of the same is near its downward dead
centre. The angular relation of the distributor valve to the crank-
shaft can be varied at the will of the operator so as to delay
the instants of transfer of the charges to the working cylinders,
when high fuel economy but not maximum power is required.

Two Cycle Engine, Fuel Injected — A form of two cycle
engine in which pure air is supplied the working cylinder from
the crank case or other source of transfer pressure, and fuel is
injected into -the combustion space at the correct instant to form
the combustible mixture (see fuel injection). Not in commer-
cial use.

Two Cycle Engine, Rotary Valve Crank Case Admission
Type — A type of two cycle engine in which the third port (see
two cycle engine, three port type) is dispensed with and in which
the charge is admitted from the carburetor to the crank case,
previous to its compression therein, and transfer to the working
cylinder, through a rotary valve carried by the crankshaft, which
opens the passage during nearly the whole upward stroke of
the piston and closes it during the down stroke. A disc, with a
sector shaped port, is carried by the crankshaft, which registers
during the appropriate part of its revolution with a port in the
end of the crank case, which gives communication with the
carburetor,

332

Two Cycle Engine, Three Port Type — A two cycle engine,
the cylinder wall of which is pierced with three ports, extending
around it through considerable arcs, viz. : The
mlet port B on one side thereof, forming one
termination of the transfer passage (q. v.)
and, upon the other side, the exhaust port C,
the outward edges of these ports registering
with the inward edge of the piston when at
its outward dead centre. The exhaust port is
wider than the inlet port. On one side of
the cylinder is the third, or crank case admis-
sion port A, the inward edge of which regis-
ters with the outward edge of the piston when
it is at its inward dead centre. This port
is piped to the carburetor. The cycle is as
follows : Considering first the outward face of
THREE PORT TYPE, the piston acting upon the gases in the tight
Two CYCLE MOTOR crank case, in moving inwardly, nearly to
its inward dead centre, the piston has rari-
fied the gases in the crank 'case by increasing its volume, and, as
its outward edge passes the outward edge of port A, gas rushes in
therethrough from the carburetor, filling the crank case. As the
piston reverses and begins to move outward, port A is closed and
the charge, trapped in the crank case, is slightly compressed, which
action continues until, late in the outstroke, the inward edge of the
piston uncovers inlet port B and the somewhat compressed charge
rushes into the working cylinder through the transfer passage,
being diverted into a proper direction by deflector plate (q. v. )
D, the exhaust gases meanwhile escaping through exhaust port
C, partly under the scavenging (see scavenge) action of the in-
coming charge. As the piston commences its inward move-
ment, its inward edge closes inlet port B, and, somewhat later,
exhaust port C, and the charge trapped in the working cylinder
is compressed therein, back of the piston, until the inward dead
centre is reached, when the spark is passed, ignition and expan-
sion occur and the piston is forced outward on the working
stroke. When its inward edge registers with the inward edge
of ex'haust port C, the burned gases commence to escape, and
a little later, when its inward edge registers with the inward
edge of inlet port B, the new charge, previously compressed in
the crank case, begins to enter the cylinder.

most generally used type of two cycle engine.

333

Two Cycle Engine, Two Port Type — A type of two cycle
engine in which the crank case admission port (see two cycle
engine, three port type) is dispensed with, gas being drawn into
the crank case from the carburetor, through an inwardly opening,
suction operated, spring closed poppet valve (see valve, auto-
matic), which opens when the instroke of the piston has suffi-
ciently rarefied the gases in the crank case and closes when the
rarefaction ceases, at or near the beginning of the outstroke.
This type is not well fitted for automobile use, but is common in
marine practice.

Two Stroke Cycle — The cycle upon which a two (stroke)
cycle internal combustion motor is operated, comprising one in-
ward and one outward piston stroke. At the beginning of the
outward stroke, the fuel charge, previously compressed behind the
piston in the working cylinder, is ignited, expands and does use-
ful work upon the piston, forcing it outward, the products of
combustion escaping during the later portion of this stroke and
the earlier portion of the inward stroke. During the last part
of the outward stroke and the first part of the inward stroke,
the next fuel charge, which has meanwhile been somewhat
compressed in a communicating pump cylinder, is allowed to
expand into the working cylinder, its entrance thereinto assist-
ing in displacing the remanent exihaust gases therefrom and
charging the working cylinder for the next combustion. During
all but the earlier portion of the inward stroke the charge thus
admitted is trapped behind the working piston and is compressed
preparatory to being ignited at the end of this stroke. An en-
gine operating upon this cycle does useful work on each outward
stroke instead of on each alternate outward stroke, as does a four
cycle engine. The outward stroke is primarily a power stroke
and the inward stroke a compression stroke, exhaust and ad-
mission occurring practically simultaneously during the period
when the piston is near its outward dead centre. The charge is
always forced into the working cylinder by external energy and
not by the suction of the working piston as in a four cycle engine.

Underpan — See sod pan.

Unit Coil— See coil, unit.

Unit Power Plant — The combination as a single rigid struc-
ture of a vehicle motor and all transmission parts other than
the final drive mechanism. To the rear end of the motor
crank case is bolted the front end of a yoke or housing sup-

334

porting the clutch and the change speed gear case, so that the
three elements constitute a unit which is readily mounted upon

UNIT POWER PLANT.

and dismounted from the frame and in which the liability of any
failure of alignment of parts is minimized. The control levers
and pedals and all engine auxiliaries are usually attached to
this structure.

Universal Joint — A form of joint adapted to transmit rotary
motion from one shaft to another located at an angle there-
with. Principally used to connect
the ends of the driving shaft of
shaft-driven cars respectively, to
the clutch or gearshaft and to the
driving pinion shaft which rotates
the rear axle, and required be-
cause the angular relation of the
drive shaft to the other shafts is
constantly varying as the vehicle
springs act. A common form is
constructed as follows : The ends
of the connected shafts terminate

in U-shaped yokes A C, yoke A, on one shaft, lying in a plane
perpendicular to yoke C of the other shaft. The two yokes are
held in driving relation by a cross-shaped piece B, the ends of
the two pair of arms of which are journaled respectively in

UNIVERSAL JOINT.

335

the ends of the two yokes. A dust and lubricant tight housing is
usually fitted over the whole joint.
Syn. : Cardan joint, Hooke's joint
Universal Rim — See rim, universal.

Upset (v.) — To expand or rivet over the end of a part which
protrudes through a hole in another part, so as to prevent its
loosening therefrom.

V=BeIt — A leather or fabric belt of blunt V-section, adapted
to run upon pulleys with V-shaped grooves. The belt is either
notched upon its working face or built up of overlapped layers
of leather to give it flexibility. Such a belt may be run quite
loose without serious slipping and is sometimes used to drive
radiator fans. Syn. : Trapezoidal belt.
V=Type Motor — See motor, V-type.

Valve — Any device for controlling the flow of a fluid through
a passage, such as a pipe, or through an opening from one cham-
ber to another, consisting of means for opening or closing such
passage or for enlarging or contracting its cross section at will,
as, for instance, by the insertion into or withdrawal from it of
a movable member, such, for instance, as a slide or damper or
by the seating or unseating of a tightly fitting part in the
entrance or exit space of the passage.

The entrance and exit of the working fluid from the cylinders
of gas and steam engines is effected through valves, automati-
cally opened and closed by the engine mechanism and most of the
definitions here given refer to engine valves, although valves
are also used in fuel systems, lubrication systems, etc.
Valve, Admission — See inlet valve.

Valve, Automatic — Specifically, a valve, usually of the poppet
type (see valve, poppet), which is opened automatically by the
difference in pressure of the fluid acting
upon the two sides of its disc and which is
closed by a spring. Such valves were for-
merly used as gas engine inlet valves open-
ing inwardly by atmospheric pressure, and
admitting the fuel charge to the cylinder
when the rarefaction therein, caused by pis-
ton movement, became sufficient to over-
come the closing spring pressure. Such
valves are used as the crank case inlet
valves of two cycle engines (two port type)

AUTOMATIC VALVE.

336

(q. v.) and as the auxiliary air valves (q. v.) of carburetors and
similar ones, as suction valves of air, oil and gasoline pumps and
water feed pumps.

The term is used in contradistinction to mechanically operated
valve. Syn. : Suction operated valve, clack valve.

Valve, Caged — In gas engine practice, a valve usually of the
poppet type, which, together with its seat, its spring and the
valve stem guide, can be removed from
the cylinder in which it is used. Such
valves are used in overhead valve gas mo-
tors (see valve, overhead), the cage usu-
ally being cylindrical, provided with a
gas passage by which it connects with the
manifold, and arranged to be screwed into
a threaded hole or clamped in an un-
threaded hole in the cylinder head, seat-
ing gas-tight upon an annular gasket (q. v.).
Valve, Concentric — A combination of
two valves arranged concentrically, so that
intake and exhaust can take place through
the same cylinder port and space thus be
economized so that valve openings of large

area as compared to the cylinder bore can be secured. In one
form, which has been used in an air-cooled motor, the intake valve
is hollow and annular and its external edge closes upon a seat
formed in the cylinder head, and the exhaust valve is an or-
dinary poppet valve, coaxial with the inlet valve and within it,
seating upon the internal periphery of the head of the latter.
Both valves are lifted as a unit during intake and the exhaust
valve only during exhaust.

Valve, Distributor — A valve, usually rotary in its action, the
function of which is to control the flow of fluid from a com-
mon source of supply to
several points of delivery
in regular succession.
Such valves are used to
distribute the fuel charge
from the carburetor to
the pump chambers and
working cylinders of two

CAGED VALVE.

DISTRIBUTOR VALVE.

cycle motors (see two

33?

cycle motor, distributor valve type) ; to deliver oil to a series of
leads; in self-starters (q. v.) of the spark type to distribute acety-
lene gas to the motor cylinders, and in self-starters (q. v.) of the
gas pressure type to furnish gas pressure to the motor cylinders in
their firing order. In the latter application the distributor valve
consists of a rotating disc, provided with an arc shaped port,
operated at one-half crankshaft speed (for a four cycle motor),
which disc contacts with and moves over a flat surface in which
equally spaced holes deliver the gas from the gas-tight valve
housing through tubes to the several cylinders.

Valve, Exhaust — See exhaust valve.

Valve, Inclined — A gas engine valve of the poppet type, the
axis of which makes an acute angle with the cylinder axis.
Overhead valves are often so placed, as very large valve diam-
eters and a domed form of cylinder head may be employed
when the valves are so placed.

Valve, Inlet — See inlet valve.

Valve, Interchangeable — A gas engine poppet valve which
can be used either as an exhaust or inlet valve in any particular
engine. The valves of the two sets being identical, one spare
valve serves to replace any one of the valves of the engine which
may have broken.

Valve, Mechanically Operated — A valve which is operated
by power driven mechanism and not by suction or manually.
Specifically, a gas engine valve which is operated by mechanism
driven by the motor of which it is a part, in contradistinction
to an automatic valve (see valve, automatic). The valves of
practically all gas engines are mechanically operated. (See valve
gear.)

Valve, Mushroom — See valve, poppet.

Valve, Needle — See needle valve and carburetor needle valve.

Valve, One Piece — A gas engine poppet valve, the head and
stem of which are integral, being a single forging, in contradis-
tinction to a valve whose head and stem are separate parts
screwed together or united by welding — the more usual practice.

Valve, Overhead — A gas engine valve, generally of the caged
type (see valve, caged), which is placed directly in the cylinder
head, in contradistinction to one which is located in a pocket
or valve chamber communicating with the cylinder (see valve
pocket), and which thus permits gases to enter or leave the
cylinder directly, avoiding the friction and transfers of heat inci-

338

dent to their movement through any intervening passages. Such
valves are practically universally used upon air cooled motors.
For method of operation see camshaft, overhead; push rod and
rocker arm. Syn. : Valve in the head.

^ Valve, Piston — A type of gas engine valve, consisting of a
piston, similar to a motor piston, which fits in and is caused to
reciprocate (q. v.) in a cylinder (the valve cylinder) in the
wall of which is a port communicating with the working cylinder
(the exhaust or inlet port, q. v.). When the valve piston is so
moved by the valve gear (q. v.) that its end begins to pass off
from this port, gases may pass therethrough to or from the
valve cylinder and out of or into the working cylinder, and
when the end of the valve piston has again covered the port, gas
movement is prevented. Instead of employing the end of the
valve piston to effect the valve action, a port may be cut in the
piston wall, which permits gas flow when it registers with the
port in the valve cylinder. Piston valves have lately been applied
to four cycle gas motors in order to secure silence of operation
and improved filling and evacuation of the cylinders, a separate
valve generally being used for exhaust and intake. Such valves
are sometimes used in steam vehicle motors.

Valve, Pocketed — A gas engine valve, especially a poppet
valve, which is located in a chamber or pocket (see valve
pocket) attached to and communicating with the working cyl-
inder, in contradistinction to one which is located directly in the
cylinder wall. (See valve, overhead.)

Valve, Poppet — A disc valve, borne upon a guided stem and
having a reciprocating motion in the line of its axis. When
closed, the edge of its disc or head rests,
fluid-tight, upon an annular seat formed
in a partition which separates a chamber

nf from which fluid is to be transferred

from a chamber into which it is to be
transferred. In opening, the valve moves
POPPET VALVE. away from its seat and the fluid flows

through the passage formed between its

head and its seat. This is the type most generally used for gas
engine inlet and exhaust valves, being generally mechanically
opened by cam action and closed by a spring. See valve,
mechanically operated; valve head, valve stem, valve spring;
• *"•. . ^ Svn. : Mushroom valve, mitre valve.

1

Valve, Poppet (Flat Seated) — A poppet valve the seating
surface of the head of which is flat or in a plane at right angles
to its axis and contacts with an annular seat which is also flat
or in a plane at right angles to the valve axis.

Valve, Poppet (Taper Seated) — A poppet valve, the seat-
ing surface of the head of which is beveled or conical and
which contacts with an annular seat which is correspondingly
beveled or conical. The angle of the conical surfaces of head
and seat is usually about 45 degrees with the plane of the head.
The most commonly used type of gas engine poppet valve.

Syn. : Conical seated valve, bevel seated valve.

Valve, Rotary — A valve which is rotated upon a shaft and
in so rotating alternately permits and cuts off the flow of a
fluid, the valve being pierced with a
passage which, when it registers with
the inlet or exit passages provided
for the fluid, allows the flow thereof.
Such valves as applied to four cycle
gas engines, in order to secure quiet
action and complete filling and evacu-
ation of the cylinders, are of various
forms, mechanically operated by
gearing. In one type the single valve
employed is a disc on a vertical shaft

operated at' one-half engine speed, seated against the inside of
the cylinder head and pierced with a sector shaped opening
which alternately registers with the exhaust and inlet ports cut
in the cylinder head. In another type the single valve is a cyl-
inder rotated at one-quarter engine speed, in a cylindrical hous-
ing formed upon the cylinder head. The valve is pierced by a
diametral passage, each end of which registers alternately with
the inlet and exhaust ports cut from the housing into the cyl-
inder. Instead of a single valve, separate valves may be used
for inlet and exhaust, each valve consisting of a hollow cylinder
with a port in its wall, fitting in a housing formed in the cylinder
head. When the port registers with a port cut in the cylinder
wall, gas movement is permitted, the hollow valve acting as a
gas passage.

. Valve, Slide — See slide valve.

ROTARY VALVE.

340

Valve, Sliding Sleeve— A type of gas engine valve, con-
sisting of a thin cylindrical sleeve, or a pair of concentrically
arranged sleeves, fitted between the
cylinder wall and the piston and
pierced with ports which control the
transfer of gases to and from the
cylinder through ports in its wall, the
sleeve or sleeves being reciprocated
parallel to the cylinder axis or given
a combined reciprocatory and rotary
motion by suitable valve gear. In the
Silent Knight sliding sleeve motor two
concentric sleeves are employed, which
are independently reciprocated by two
crank and connecting rod mechanisms
at a frequency one-half that of the pis-
ton. The inlet and exhaust ports in the
cylinder wall are at opposite sides
thereof, above piston travel (q. v.),
and each extends about one-third
around the cylinder. Each side of
each sleeve is pierced toward its in-
ward end with a correspondingly ar-
ranged port, and the reciprocatory
motions of the two sleeves are so
timed that, during intake, the intake
ports of both sleeves simultaneously register with the intake port
in the cylinder wall and the charge enters, while, during exhaust,
the exhaust ports in both sleeves simultaneously register with
the exhaust port in the cylinder wall. At all other periods in the
cycle the sleeves prevent gas movement. In this construction the
rate of valve opening is high, the area of the passages is large,
and their resistance is slight; there are no valve pockets to add to
the surface exposed to the charge, and the valve action is quiet
and capable of permanent adjustment.

Valve Cap — A plug which screws into a valve pocket (q. v.)
and closes the same, the removal of which permits the with-
drawal of the poppet valve which is located therein. The cap
usually seats upon a ring-shaped gasket, and a spark plug is
commonly located in a hole drilled and tapped in the cap.
Syn. : Valve plug.

SLIDING SLEEVE VALVE
MOTOR.

341

Valve Chamber — See valve pocket.
Valve Clearance — See clearance.

Valve Cover Plate— A readily detachable plate used to pro-
tect poppet valve gears from dust and to retain lubricant upon
the parts. (See valve gear, enclosed.)

Valve Diameter — The diameter of the passage in which
a poppet valve is seated. It is usually the same as the smaller
diameter of the head of a conical or taper poppet valve.
Syn. : Clear valve diameter.

Valve Gear — The term applied to all the mechanism con-
cerned in operating engine valves. In gas engines of the poppet
valve type, it includes the cam mechanism, push rods, rocker
arms, valve springs, valve guides, etc. ; and in rotary valve, piston
valve and sliding sleeve gas motors it includes the gears, shafts,
cranks, connecting rods, rockers, etc. In steam engines it in-
cludes the eccentrics, eccentric rods, valve stems, etc.

Valve Gear, Enclosed— A valve gear in which the parts that
operate outside of the engine structure, such as the valve stems,
push rods, valve springs, etc., of a poppet valve gas engine, are
protected from dust and so housed as to be susceptible of con-
tinuous lubrication, by some such device as a tightly fitted plate
covering them in and bolted to suitable projections cast upon the
outsides of the cylinders. Syn. : Valve gear housing.
Valve Grinding — See grind.

Valve Grinding Tool— A tool similar to a bit stock, pro-
vided with a screwdriver-like point adapt-
ed to rotate a poppet valve upon its seat
in the process of grinding the same, and
to facilitate the occasional separation of
the valve from its seat to cause the redis-
tribution- of the grinding material there-
upon. Syn. : Valve grinder.

Valve Head — The disc-like portion of a
poppet valve (see valve, poppet) which per-
forms the valve function. It is usually
made of nickel steel (see steel, nickel) or
of cast iron, and is slightly convex on its
outward surface and concaved upon its
inner surface to form a fillet (q. v.). The
VALVE GRINDING stem (see valve stem) is either electrically
TOOL. welded into an axial hole therein or is

342

screwed and riveted thereinto. Its outer surface is slotted to
receive a screwdriver point.

Valve Housing — Any stationary part which encloses a valve.
In gas engines it may be an integral part of the cylinder or a
part attached thereto. It usually forms a gas passage to or
from the valve, a pipe branch from a manifold being connected
to it.

Valve Lap — See lap.

Valve Lead — See lead.

Valve Lift — The distance through which a poppet valve moves
in passing from its closed to its full open position.

Valve Lifter — See pushrod.

Valve Location — The positions occupied by the valves of a
gas engine with reference to the working cylinder. Poppet valves
may be located in pockets at the sides of the head (see valve,
pocketed). Both inlet and exhaust valve may be so placed, side
by side, or one over the other on the same side of the cylinder
(see cylinder, L type), or the inlet valve may be pocketed upon
one side of the cylinder and the exhaust valve upon the opposite
side (see cylinder, T type). One valve may be pocketed upon one
side of the cylinder and the other valve may be in the cylinder
head (see valve, overhead). Both valves may be located in the
head (see valve, overhead) with their stems parallel to the cyl-
inder axis; inclined thereto (see valve, inclined) or in the side
of the head with their stems perpendicular to the cylinder axis.

Syn. : Valve position, valve arrangement.

Valve Plunger — See push rod.

Valve Pocket — A chamber, usually cast integral with the
cylinder head of a gas engine upon the side thereof, communi-
cating with the cylinder and with the inlet or exhaust piping,
respectively, through ports, with a valve, usually of the poppet
type, seated in a dividing partition within the pocket. Access
to the pocket is secured by removing a valve cap (q. v.).

Syn. : Valve chamber, valve housing.

Valve Seat — The surface with which a valve is in contact
when closed and upon which it forms a fluid-tight joint. The
seat is usually finished by grinding the valve upon it. The seats
of gas engine poppet valves are annular, with flat or conical
surfaces (see valve, poppet), and are formed in the metal of the
valve pocket (q. v.), or of a valve cage (see valve, caged),

Valve Setting — See valve timing.

343

Valve Spring — The spring which returns a valve to position.
The springs used with gas engine poppet valves are usually
of the spiral type, wound of high carbon or vanadium steel
wire, threaded around the valve stem (q. v.) and compressed
between the end of the valve stem guide (q. v.) and the valve
spring washer (q. v.) and valve spring key (q. v.). They act
to promptly close the valve upon its seat after it has been opened
by the push rod (q. v.) or rocker arm (q. v.)- A light spiral
spring is sometimes used in a poppet valve operating mechanism
to keep the push rod in constant contact with its cam, and thus
avoid the tapping noise otherwise caused by the hamm-i." like
action of these parts.

Valve Spring, Shear Type — A type
of valve spring (q. v.) consisting of
a loop of wire with spiral convolutions
at its closed end, the free ends of
which act respectively upon a fulcrum
and upon a valve to close it. Springs
of this type stand further away from
the hot parts of the motor than spiral
springs, and, being thus less likely to SHEAR TYPE VALVE
lose their temper by heat, are used upon
some air cooled motors.

SPRING.

Valve Spring Key — A pin which is passed through and se-
cured in a hole drilled in a poppet valve stem, the function of
which is to resist the reaction of one end of the valve spring
(q. v.) and to hold it in place.

Valve Spring Remover — A tool, consisting of a lever, adapted

to be adjustably fulcrumed
upon some part of a motor, the
short arm of which is engaged
under the valve spring washer
(q. v.) and the long arm moved
by the hand, compressing the
valve spring away from the
valve spring key (q. v.), thus
permitting the removal of the
latter and the freeing of the

1OT

VAI.VE SPRING REMOVER,

spring and valve.
Syn. : Valve spring tool

344

Valve Spring Washer— A cup shaped washer which is
threaded upon a poppet valve stem and receives the end of
the valve spring, and which is held in place by the valve spring
key (q. v.).

Valve Stem — The rod-like part of a gas engine poppet valve
(see valve, poppet), to which is axially attached the valve head
(q. v.), and which guides the motion of the valve. It is usually
made of carbon steel rod and its free end is case hardened (q. v.)
to resist the wear of the push rod or rocker arm impact, and
near this end is drilled a hole for the reception of the valve
spring key (q. v.). In a steam vehicle motor, the rod which
operates the slide valve (q. v.) from the eccentric rod (q. v.)
and eccentric (q. v.).

Valve Stem Guide — The specially formed part of a valve
pocket (q. v.) or of a valve cage (see valve, caged), in which
is drilled a hole, coaxial with the valve seat, in which slides the
stem of a poppet valve, and by which its motion is guided. The
hole is usually provided with a replaceable bushing (q. v., the
valve guide bushing). One end of the valve spring acts against
the external end of the valve stem guide.

Valve Timing — The adjustment of the valves of an engine
so as to open and close at such periods in its cycle as to give
the best operative results, such as maximum output or maximum
fuel efficiency. See lap; lead; cut-off, point of. For approxi-
mate periods of opening and closing of gas engine poppet valves,
see exhaust valve and inlet valve. The timing of such valves
is primarily dependent upon the form and angular relations of
their cams (q. v.) and by the mesh of the camshaft gears (q. v.),
but is influenced by the adjustment of the push rods (q. v.).

Syn. : Valve setting.

Valve Tool Fulcrum— A small projection or ledge, cast upon
the outside surface of a gas motor cylinder in such a position as
to form a convenient fulcrum for the lever of a valve spring
remover (q. v.).

Vanadium Steel — See steel, vanadium.

Vaporization — In general, the change of a liquid into an aeri-
form or vaporous state (vapor), brought about by the application

345

of heat and facilitated by the reduction of the pressure which acts
upon the liquid. This change of state involves the absorption
of a large amount of heat (latent heat of vaporization). In auto-
mobile practice, that form of vaporization known as evaporation,
or the change of a liquid into a vapor at the liquid's surface, at
ordinary air temperatures, is of chief interest. All internal com-
bustion vehicle motors make use of gaseous fuel consisting of
suitably proportioned mixtures of air and the vapor of some
volatile combustible liquid, which are produced by evaporation
in a carburetor (q. v.), and all steam vehicle boilers, which are
fired with liquid fuel, make use of similar mixtures formed in a
vaporizer (q. v.) and mixing tube (q. v.). Gasoline (q. v.), de-
natured alcohol (q. v.), benzol (q. v.), evaporate at ordinary
temperatures, and are thus available for the formation of fuel
mixtures, little -or no application of artificial heat being required,
the evaporation of such fuels in carburetors which are unjack-
eted being accomplished by the heat in the air and liquid used,
and in carburetors, exhaust jacketed (q. v.), and in carburetors,
water jacketed (q. v.) partly by heat artificially applied. In all
carburetors evaporation is facilitated by the reduced pressure act-
ing therein caused by the engine suction, by the rapid removal
of the vapor from the liquid surfaces by the moving air, and by
the practice of finely dividing the liquid at the spraying nozzle
(see carburetor, atomizing), so that a very large liquid surface
is exposed to the passing air.
Syn. : Gasification, evaporation.

Vaporizer — In a steam vehicle burner (q. v.), an arrangement
of piping through which the liquid fuel is passed, and which is
exposed to heat, for instance, by being placed across the face of
the burner plate (q. v.), so that the fuel may be warmed and may
readily vaporize when it is sprayed into the mixing tube (q. v.)
at the burner jet (q. v.). The pilot light (q. v.) is usually so
placed as to keep the vaporizer warm when the main burner is
shut off. The term vaporizer is sometimes applied to the carbu-
retor (q. v.).

Vaporizing Chamber — See mixing chamber.

Vaporizing Tube Carburetor — See carburetor, vaporizing
tube.

346

Ventilator — An arrangement for admitting air for purposes
of ventilation into the body of a closed
car or of a car of the fore-door type (see
body, fore-door), consisting of an adjust-
able slide or register closing or uncovering
perforations in the body, doors or dash or
a deflector plate and orifices answering the
same purpose, by the adjustment of which
more or less air can be admitted to the
body or to the front seat compartment.

Venturi Tube— A tube for the flow of
fluids, of somewhat hour-glass shape, which
may be considered as formed by the junc-
tion at their smaller ends, of two tubes,
each of which is the frustum of a circular
cone, the junction where the cross section

is the least being known as the throat or waist. The mixing
chambers (q. v.) of carburetors are quite often Venturi tubes,
as this design secures a very decided increase of suction at the
spraying nozzle (see carburetor spraying nozzle),
which is located at the throat, and hence a
very energetic action thereof and a tendency
toward homogeneity of mixture, without excess-
ive contraction of the air flow through the mix-
ing chamber, the effect of the flared outlet of the
Venturi, being to facilitate the delivery of air.
A large gas output, together with low frictional
resistance, is thus secured.

VENTILATOR.

VENTURI
TUBE.

Vibrator — See magnetic vibrator.

Vibrator Coil — See coil, vibrator.

Viscosity — That property of a liquid dependent upon the degree
of cohesion among its particles, in virture of which it is sluggish
in its flow. The term is chiefly used in reference to lubricating
oils, oils of considerable viscosity being better suited to the
maintenance of continuous lubricating films between surfaces
acting under heavy pressures than those of slight viscosity, but
giving rise to increased liquid friction. Viscosity is increased by
reduction of temperature (see cold test). It is measured by the
viscometer, the indications of which depend upon the weight of
liquid which is discharged in a given period of time at a given

34?

temperature and constant known head through a small tube of
standard area. The opposite of fluidity.
Syn. : Body (q. v.).

Visor — A forwardly and downward-
ly sloping extension formed upon the
forward ends of a front fender (q. v.),
shaped like a cap visor and designed to
catch the road splash from the front
wheel.

Volt — The practical unit of electro-
motive force (q.* v.). That electromo-
tive force which, steadily applied in a

closed electric circuit of a total resistance of one ohm (q. v.),
causes a current of one ampere to flow therein is one volt.

Voltage — Electromotive force expressed in volts.

Voltammeter — An electrical measuring instrument, consist-
ing of a voltmeter (q. v.) and ammeter (q. v.) combined, for
convenience, in the same case.

Voltmeter — An instrument, similar in most respects to an
ammeter (q. v.), but used for the measure-
ment of electromotive force and giving in-
dications expressed in volts. The wire coil
of a voltmeter is of extremely high resist-
ance (q. v.), and thus the current which
flows through it is practically proportional
to the electromotive force applied to it.
The electromagnetic effect which moves
the pointer, being proportional to the cur-
rent flowing in the coil, the indications of
the instrument are proportional to the elec-
tromotive force being measured.

Volumetric Efficiency — See charge ratio.

VOLTMETER.

Vulcanization — A process for rendering rubber more highly
elastic, stronger, more durable and less liable to the attacks of
solvents, by adding to it a carefully proportioned amount of sul-
phur and "curing" it, usually under pressure, for a short time,
at a temperature of about 300° Fahr. The rubber of vehicle tires
is all vulcanized more or less highly, dependent upon the character

348

o£ the service required of it. Vulcanization is employed to effect
the permanent adhesion of the fabric and rubber layers of pneu-
matic tire casings, and in joining to the tire structure the rubber
or rubberized fabric used in making repairs.

(v.) : To vulcanize.

Vulcanizer — The apparatus in which vulcanization is ef-
fected. In this connection, the apparatus employed to perform the
vulcanization required in the repair of pneumatic tire casings and
inner tubes, consisting of an iron mold or plate fitting around or
upon the portion of the tire to be repaired, and means for clamp-
ing the mold or plate thereon and for applying heat from the
mold to the rubber to be vulcanized. Such vulcanizers may be
stationary and capable of making extensive repairs quickly, or
portable and intended for smaller repairs, which may be per-
formed, if desired, without removing the tire from the wheel.

Vulcanizer, Electric — A type of vulcanizer in which the heat
required is developed electrically in conductors embedded in the
metal of the iron or aluminum plate
or mold. The temperature of the
vulcanizing surfaces is indicated by a
thermometer, and is automatically
maintained at the correct point by
means of a thermostat (q. v.) within
the apparatus, which interrupts the
heating current when the proper tem-
perature is exceeded and re-estab-
lishes it when the temperature is too
low. In some vulcanizers a rheostat
(q. v.) is adjusted by hand to main-
tain the required current strength
and temperature. Portable vulcan-
izers of this type, which may be oper-

ated in connection with any commercial electric circuit, are pro-
vided with means for clamping the vulcanizing surfaces to the
tire, even though it is still upon its wheel, and the surfaces are
so formed as to enable repairs upon both casings and inner
tubes to be accomplished.

ELECTRIC VULCANIZER.

349

Vulcanizer, Steam— A vulcanizer, the molds or plates of
which are set into the external sur-
face of a closed chamber containing
water, to which the heat from a gas,
gasoline or alcohol flame is applied
to raise steam, which brings the vul-
canizing surfaces to the required tem-
perature, a steam gauge or thermom-
eter being used to measure the same.
Such vulcanizers may be stationary
or portable, the latter type usually
burning alcohol and being adapted to
the repairing of tires on or off their
STEAM VULCANIZER. wheels.

Vulcanizing Cement — A rubber cement used in making tire
repairs which are to be vulcanized.

Vulcanizing Rubber — Rubber compounded with sulphur and
capable of vulcanization.
Walking Beam — See rocker arm.

Warp (v.) — With reference to the heads of gas engine pop-
pet valves (see valve, poppet), to distort under the expansive
influence of the heat to which they are subjected, so that they
no longer fit gastight upon their seats.

Wash (v.) — With reference to the elements (q. v.) and
separators (q. v.) of accumulator cells, to clean them of all shed
(q. v.) active material (q. v.) which may cause internal short-
circuits (q. v.).

Water Column A vertical chamber, the upper end of which

is connected into the steam space and the lower end into the
water space of a steam boiler. Water rises in the column to
the same height at which it stands in the boiler and this
height is approximately indicated by opening the gauge cocks
(q- v.).

Water Cooling — A method of maintaining the internal walls
of a gas motor cylinder at a sufficiently low temperature to per-
mit of their lubrication by oil and to obviate the overheating of
the fuel charges, by the continuous circulation about the external
walls of the cylinder of water contained in a water jacket (q. v.)
enveloping these parts. The moving water abstracts heat from
the cylinder walls, maintaining their temperature below the boil-
ing point, and in its circulation, carries away the heat thus ab-

350

stracted and dissipates it to the air in a radiator (q. v.) from
which the water is returned, in a cooled condition, to the jackets,
to be heated again, this action going on continuously.

The ordinary method of cooling gasoline vehicle motors.

Water Cooling, Gravity System— A system of water cooling
in which no pump is employed, the circulation of the water being
effected, as in a domestic hot water heating system, by takiny
advantage of the head produced by the difference of specific gravi
ty of the water in the hot and cool portions of the system. The
bottom of the radiator is connected, through very large area
piping, to the bottoms of the water jackets and the tops of the
jackets to the top of the radiator. The water which is heated
in the jackets rises and flows to the top of the radiator, where
it is cooled in flowing down therethrough and returns to the
bottoms of the jackets to be heated again, this action going on
continuously during the operation of the motor.

Syn. : Natural circulation, thermo-siphon system.

Water Cooling, Pump System— A system of water cooling
in which the circulation of water is maintained by a pump (see
water pump), driven by the motor -to be cooled. The pump
usually delivers water through suitable piping (see water mani-
fold) to the water jackets (q. v.) at points near the exhaust
valves, which leaves them at points in their cylinder head por-
tions, and is conducted through piping to the top of the radiator
(q. v.), downward through which it. passes and out of the bot-
tom of which it flows, through piping, to the intake connection of
the pump. A closed path of flow is thus formed, through which
the same water is forced so long as the motor is in operation.

Syn. : Forced water cooling.

Water Glass — See gauge, water.

Water Hammer — The shock and noise occasioned by the pis-
ton of a steam engine when, in approaching the end of its
stroke, water, which has condensed in the cylinder, more than fills
the clearance space and thus impedes further piston movement.
Under these conditions there is danger of the breakage of the
cylinder head or other parts. See drain cock.

Water Jacket — A water tight casing or envelope provided
around those portions of the outside cylinder walls of an in-
ternal combustion motor which are most exposed to the heat de-

351

veloped therein ; between which and the walls of the cylinder itself
is a closed space, in which is circulated water which is delivered
to and conducted away from the space through pipes. The water
space usually includes not only that around the cylinder barrel
or the head portion of the same, but that around the cylinder
head itself, the valve chambers or cages (especially the exhaust
valves) and the valve stem guides. The water intake to the
jacket is usually at a point near the exhaust valve and the outlet
in the head portion and baffle plates are sometimes used within
the water space to insure an active flow in all parts thereof. See
water cooling.

Water Jacket, Applied — A water jacket, the barrel portion
or the whole of the walls of which are not formed integrally with
the cylinder itself, but are of sheet metal (usually copper), so
formed and applied as to envelop the parts of the cylinder requir-
ing cooling, water tight joints being formed ~t the junctions of
the sheet metal and the cylinder.

Syn. : Sheet metal water jacket.

Water Jacket, Integral — A water jacket, the walls of which
are cast of the same metal and as an integral part of the cylinder
itself, the water spaces being cored out in the operation of found-
ing. The most common type. (See diagram under cylinder, L
type.)

Water Jacket Cover Plate — A detachable plate which, when-
fastened into place with screws, forms a part of the wall of a
water jacket which is not cast complete as a part of its cylinder
or block of cylinders. This method of casting jackets incomplete
and using cover plates enables the water spaces to be inspected
for defects and gives access to the water spaces at any time. The
cover plates being of thin, somewhat yielding material, the burst-
ing of the jacket casting by freezing is rendered less likely.

Water Jacket Plug — A plug screwed into a threaded hole
in a cast water jacket — for instance, in the centre of the cylinder
head to give access to the cylinder plug (q. v.), or at other
points in a water jacket to close holes left in the process of
founding.

Water Level— With reference to a steam boiler of other than
the flash type, the height at which the water stands within it.
(See gauge, water and gauge cock.)

352

Water Level Indicator — A device other than the water
gauge, which gives a continuous (usually visual) indication of
the height of the water in a steam vehicle boiler.

Water Manifold — The main pipe into or out of which water
flows, through branches, to or from the jackets of multi-cylinder
gas motor. Two such manifolds are used, one, the water outlet
manifold, which receives the heated water from the jackets and
conveys it to the radiator, and the other, the water inlet mani-
fold which delivers cooled water from the pump or bottom of
the radiator to the jackets. These manifolds are usually of
branched copper or brass tubing, of cross section, varying with
the flow of water therethrough, the junctions of their branches
with the jacket ports being by flanged couplings or tapered nip-
ples. In motors with pair cast cylinders (see cylinder, pair cast)
there is usually but one inlet and outlet from each double jacket
to the manifolds, and in block motors (see cylinder, block cast)
there may be but one water inlet and one water outlet and no
manifold required.

Syn. : Water header.

Water Pump — With reference to a gas motor, the pump
which circulates the water in a forced water cooling system
(see water cooling, pump system). Such a pump may be of the
centrifugal type (see pump, centrifugal), the gear type (see pump,
gear) or sliding vane type (see pump, sliding vane) and is usu-
ally direct driven from a gear driven auxiliary shaft (q. v.) by
the motor which it serves, through a somewhat flexible coup-
ling:. ( i ten including a member designed to break in case the
pump is frozen or otherwise obstructed and thus to prevent any
injury to the pump itself. The pump inlet is usually piped to
the bottom of the radiator and its outlet to the water intake
manifold.

With reference to a steam vehicle, the feed pump (q. v.).

Water Tank — The reservoir in which is carried the water
which is to be fed to the boiler of a steam vehicle.

Watt — The unit by which is measured the rate at which
electrical energy is delivered to an electric circuit. If a current
of one ampere (q. v.) is delivered to a circuit or an electrical
device at an electromotive force of one volt, electrical energy is
being expended therein at the rate of one watt, and the rate of
expenditure of electrical energy in any circuit or electrical de-
vice, in watts, is equal to the product of the current flowing

353

therein, in amperes, by the electromotive force acting thereupon in
volts. E. g., a tungsten lamp requires 1.25 amperes at 6 volts. It
therefore absorbs 6 X 1.25 = 7.5 watts. The rate of expenditure
of electrical energy in electrical horse power (see horse power,
electrical) is obtained by dividing the rate of expenditure in
watts by 746.

The above statements apply to direct currents only.

Weak Mixture — See lean mixture.

Weave (v.) — In reference to a vehicle frame, to distort from
its normal form under the stresses imposed by rough roads, tend-
ing to throw the mechanical parts mounted upon it out of correct
relationship.

Web — A comparatively thin portion of a mechanical or struc-
tural part, formed integrally therewith and serving to connect
portions thereof of greater cross section or extending out from
a part of larger cross section. In castings and forgings, those
portions where the stresses acting are slight are often made
in the form of thin webs, for purposes of weight reduction, such
webs connecting portions of greater cross section where the
stresses acting are severe; e. g., in an I-section axle (see
axle, I-beam) such a web joins the two flanges.

Weight Efficiency — See efficiency, weight.

Wheel, Artillery — A wheel with wooden spokes and felloe,
which differs in the following respects from the ordinary horse-
drawn vehicle wheel, in which the inside
ends of the spokes are mortised into a
wooden hub : The inner ends of the spokes
are wedge or sector shaped and so pro-
portioned and formed that when the spokes
are assembled in the felloe and on the
metal hub or box, their sloping sided ends
fit tightly together, filling the entire angular
space and forming a compact wooden disc
with a hole in its centre filled by the metal
hub. The compactly arranged inner ends ARTILLERY WHEEL-
of the spokes are clamped between two

steel flanges, one integral with the hub and the other separable,
by means of bolts passing through both flanges, and through
each of the spokes. A wheel of very great strength and that
most commonly used upon motor vehicles.

Wheel, Cast— A type of wheel which is cast as a unit— hub

Disc WHEEL.

spokes and felloe — out of steel or iron. It is used upon very

heavy commercial vehicles and tractors.
Wheel, Disc — A form of metal wheel, without spokes, the

hub and felloe being connected by two shallow saucer shaped or

very flatly conical discs, usually of

heavy pressed steel, placed with

their concave faces together, and

with their external edges bolted to

the felloe and their centres secured

to flanges at the respective ends

of the rather long metal hub. Such

wheels, are sometimes used upon

heavy commercial vehicles, espe-
cially those of the electric type, the

space within the wheel, between

the two concave discs, being util-
ized to house the electric motor

which drives the wheel and which

is geared to a large internal gear

fixed to the inside periphery of the felloe.

Wheel, Dished— A wheel the axes of the spokes of which

are not exactly in the plane of the felloe, but are the elements
of a very flat cone, the complete wheel being
of a very shallow saucer form. Such wheels
are generally used upon axles the spindles of
which are cambered (see axle, cambered), and
the camber and degree of dish are so chosen
that the spokes which support the vehicle
weight are vertical and thus are subjected to
compression only.

Dished construction gives a wheel great re-
sistance to transverse stresses, especially those
acting against the felloe inward toward the
vehicle; such as met with in running against
a curb.

Wheel, Elastic— A wheel between the hub
and felloe of which is provided a resilient
elastic medium of some kind so that road
shocks sustained by the rim are partially absorbed before reach-
ing the axle. The elastic medium may be a series of metallic
springs acting radially along the spokes or in an equivalent man-

DISHED WHEEL.

055

ner, or may be cushions of rubber performing a similar func-
tion. The spring wheel is designed to obviate the necessity of
using rubber tires, but has thus far met with very limited com-
mercial application.

Wheel, Spare — See spare wheel.

Wheel, Tubular Steel — A wheel, the rim, spokes and hub
of which are made of steel tubing. A type formerly quite largely
used upon automobiles.

Wheel, Wire — A wheel in essential respects like the familiar
tangent spoked bicycle wheel, but made larger and stronger for
automobile purposes. It is con-
sidered to be lighter for a given
strength than an artillery wood
wheel, and is therefore extensive-
ly used upon racing cars. It is
also used upon ordinary motor
cars in countries where wood suit-
able for artillery wheels is difficult
to obtain.

Wheel Base — The straight line
distance from the point of road
contact of a rear wheel of a ve-
hicle to the point of road contact
of the front wheel upon the same

side of the vehicle, the front wheels being in their straight ahead
position.

Wheel Puller — A sort of screw press used to remove a
wheel from the end of a shaft upon which it is a tight fit,

consisting of means for holding
the puller to the wheel hub or
spokes and a screw capable of be-
ing turned in the body of the
puller and of exerting pressure
upon the end of the shaft to force
the shaft out of the wheel hub.
Used for removing road wheels
from axle shafts, fly wheels from
crank shafts, etc.

White Bronze — A kind of
bearing metal of qualities some-
WHEEL PULLER. what similar to babbitt (q. v.) for

WIRE WHEEL.

la

O O O COO

o

i

i

which the following is a specification : Copper, 3.00 to 6.00 per
cent. ; tin, not less than 65.00 per cent, and zinc, 28.00 to 30.00 per
cent. Extensively used Jn gas engine bearings.

Wick Oiler— A means of supplying oil to a bearing, consist-
ing of a reservoir containing oil which is supplied to the shaft
by the capillary action of a wick, or of cotton waste placed in
the reservoir and in contact with the shaft. A common means
of oiling the armature shafts of electric vehicle motors.

Wind Resistance — See air resistance.

Wind Shield— See glass front.

Windage — The energy expended by a rotating part in beat-
ing the surrounding air.

Winding, Primary and Secondary— See coil induction and
magneto.

Wing Nut— See butterfly nut.

Wirebar — A bar of insulating material in which is embedded
or through channels in which are threaded the ignit-ion wires re-
quired by a vehicle motor, the wirebar being so supported and
placed as to enclose the wiring as far as possible and to protect
it against mechanical injury and the action of oil and water.
Ignition wiring is quite commonly enclosed in copper or fibre
tubing suitably supported from the motor.

Wiredrawing — The reduction in pressure sustained by a
fluid, such as steam or the vaporous fuel mixture of an internal
combustion motor, as a result of friction incident to its move-
ment through restricted passages or ports or through piping with
rough inside walls. Wiredrawing results in the reduction of the
effective pressure acting in steam engines and limits the charge
which enters the cylinder of an internal combustion motor, and
hence reduces the output of both types of engine.

Wireless Battery Box — See battery box.

Wiring, Primary — The ignition wiring used in connection
with a gas motor, in which flows a low tension current (q. v.).

Wiring, Secondary— The ignition wiring, used in connection
with a gas motor, in which flows a high tension current (q. v.).

Wood Alcohol— Methyl alcohol (CH3OH) produced by
the destructive distillation of wood, which is used in the prepara-
tion of denatured alcohol (q. v.) and, in mixture with water, as
an anti-freeze solution (q. v.). Such an aqueous solution con-
taining 20 per cent, of wood alcohol freezes at about 5 degrees

35?

Fahr. above zero, and one containing 40 per cent, at about 21
degrees Fahr. below zero.

Syn. : Methyl alcohol.

Working Fluid — The gas or vapor which, by acting expan-
sively, at a relatively high temperature, upon the piston of an
engine, causes the conversion of heat energy into mechanical
energy and operates the engine. Steam and air are the working
fluids of steam and gas engines, respectively.

Working Stroke— See power stroke.

Worm Drive — See gear, worm.

Wrist Pin — See piston pin.

Yoke — A forked or U-shaped operative or structural part,
e. g., that part of a clutch operating device (q. v.) which acts
against the clutch collar and clutch spring to effect disengagement.

Yoke End — See clevis.

[THE END.]

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