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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.
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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.
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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.
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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.
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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.
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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.
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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>
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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,
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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.
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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.
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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.
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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.
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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