The Classic Car Database

This dictionary is reproduced here just as it was published in 1921. It was an appendix to Dyke’s Encyclopedia of Automotive Terms.

Dyke’s 1921 Dictionary

A  |  B  |  C  |  D  |  E  |  F  |  G  |  H  | I  |  JKL  |  M  |  NO  |  P  | QR  |  S |  T  |  UV  | WXYZ

A
Absorption dynamometer	See dynamometer.
Accelerator	A type of throttle control. Usually a foot throttle on an automobile.
Accessory	A subsidiary part of an engine, such as the parts required for ignition, carburetion, lubrication and starting.
Accumulaters	A set of secondary cells, also called storage batteries, containing positive and negative plates, and filled with electrolyte.
Actual horsepower	The amount of power that would be available if there was none ab­sorbed by friction within the engine itself, and the total energy of the explosion was trans­mitted without friction or other losses to the engine shaft.
Advance spark	The distance usually measured in degrees of arc, that the spark occurs in advance of the dead center.
Air-cooled motor	See engine, air-cooled.
Air gas	See gas.
Air starter	A device for starting an engine with compressed air.
Airplane motor	See motor, automobile.
ALAM	Associated Licensed Automo­bile Manufacturers.Now known as SAE (Society of Automotive Engineers).
Alternating current	A current changing its di­rection of flow, or alternating backwards and forwards.
Aluminum	This metal, the chief characteristic of which is its lightness, is not generally used in its pure state, but is alloyed with a small proportion of zinc; sometimes, for special re­quirements, a small quantity of copper and manganese are added.
Ampere	The practical unit denoting the quantity of electricity.
Ammeter	An instrument that indicates amperes or rate of current flow.
Ampere-hour capacity of a battery	A term used to express the amount of current that can be gotten out of battery of a given size. An actual 50 ampere-hour accumulator should be capable of giving 1 ampere for 50 hours, 2 amperes for 25 hours; but the ratio becomes disproportionate as a higher rate of current is taken from the cell.
Annealing	Softening of iron. By placing it in a fire and getting it red hot and then permitting it to cool without water it softens.
Anti-friction metal	See white metal.
Artificial gas	See gas.
Asbestos	This material is of mineral origin (large quantities come from Canada). In its natural state it is fibrous and somewhat brittle. As it resists great heat, it finds considerable ap­plication in motor work for engine jointing in the form of packing washers (of copper sheet and asbestos). Asbestos cord is used for cov­ering exhaust pipes where these pass through woodwork, etc. Worked up into a fabric with brass wire, it is largely used for brake-band linings and clutch covering, as it cannot be burnt out by excessive friction.
Automatic valve	Also called suction valve. An inlet valve held to its seat by a light spring and opened by atmospheric pressure due to the suction of the piston. In a carburetor a valve opened by the vacuum in the carburetor.
Auxiliary port	In a four-cycle engine, an exhaust port, uncovered by the piston at the end of the stroke; in a two-cycle engine, an intake port leading to the crankcase.
Axis	A line passing through the center as the center line of a crankshaft or the center line of a cylinder.
Axle, dead	See Dead axle.
B	Back to top
Back fire	An explosion in the intake passages of an engine. See Base Explosion.
Back-pressure	Term applied to restricted exhaust discharge. Unless muffler is of sufficient size there will be back pressure, and the exhaust will not be discharged as rapidly as it should.
Baffle, baffle plate	An obstruction in the path of a fluid for the purpose of either changing its direction or retarding its velocity. See deflecting plate.
Balance, running	Any part of a machine is in running balance when the arrangement of particles in the rotating part is such that there is no tendency for it to be deflected from its prescribed path by unbalanced centrifugal forces. Static balance - A part such as a flywheel is in a static balance when, being free to roll, it will remain in any position on a level surface. Balance weight - A weight either a part of or attached to the crankshaft to counter-balance the effect of the reciprocating parts and the crank pin and the crank arms. Balance wheel - Frequently, but erro­neously, used for flywheel.
Balance weight	See balance, running.
Balance wheel	See balance, running.
Base	That part of an engine containing the crankshaft. A term usually employed for engines in which the crankshaft is enclosed. Compare frame.
Base explosion	An explosion in the crankcase or base. Usually employed in reference to a two-cycle engine.
Battery, electric	A combination of two or more electric cells.
Battery, primary	See primary battery.
Battery, secondary	See secondary battery.
Battery ignition	See ignition.
Bearing, coil	A spark coil, usually of the high tension type, enclosed in a wooden box.
Bearing, piston	A hollow piston closed at both ends.
Bed, engine	See frame.
Benzene	A liquid hydrocarbon, with a formula (C6H6). Formerly derived exclusively from coal tar, but now obtainable from petroleum. Compare benzine. Benzene group - Hydrocarbons of the formula (C6H2n6).
Benzene group	See benzene.
Benzine	A distillate of petroleum between gasoline and the petroleum ethers.
Benzol	Crude benzene. Chiefly a mixture of benzene and its homologues.
Benzoline	Benzene.
Berline	A body of the same general description as the sedan, except that there is a partition at the rear of the driver’s seat that makes it an enclosed two-compartment body. Generally one glass window in the partition is made so that it can be moved horizontally or vertically.
Berline-Landaulet	A body that bears the same relation to the berline that the sedan-landaulet bears to the sedan.
Bezel	The groove in which the glass cover of speedometer of clock is fitted.
BHP	Brake horsepower.
Blast furnace gas	See Gas.
Bore, of cylinders	Inside diameter.
Boss	A projection, usually cylindrical, of a machine part.
Box	See bearing. Strictly speaking, box is the frame containing the anti-friction part of a bearing. Sometimes called bearing shell.
Brake, emergency	See emergency brake.
Brake, external contracting band	See external contracting band brake.
Brake, foot	See foot brake
Brake, hand	Also called emergency brake. See emergency brake.
Brake horsepower (BHP)	Measurement of horsepower of an engine of actual net work of the engine or horsepower delivered at the crankshaft. So-called because the power is. usually determined in a test by means of a prony brake or other form of absorption dynamometer. See also horsepower.
Brake, internal expanding band	See Internal expanding band brake.
Brake load	See load, brake.
Brake, service	Also called foot brake. See foot brake.
Brake shoe	A band that may either be drawn around the outside of a drum (external band) or expanded within so that it bears agains the inside wall of the drum (internal expanding).
Brass bearing	The bronze shells of a bearing which are in contact with the rotating shaft. They may or may not be faced with babbitt.
Breech	The closed end of a piston or a cylinder.
British Thermal Unit (BTU)	The amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit (at its maximum density, which is at 89.1 degrees Fahrenheit.) This expression is much referred to in the study of the value of various fuels for engines: thus gasoline ranges about 19,000 to 20,000 BTU per pound. A pound of gasoline of 58 s.g. is ap­proximately 8/10 of a pint. 1 BTU is equivalent to 778 foot-pounds of work.
Brougham	A body of the same general description as the limousine, except that the non-collapsible roof extends only over that portion of the body that is entirely enclosed.
Brougham-Landaulet	A body that bears the same relation to the brougham as the sedan bears to the sedan-landaulet.
BTU	British Thermal Unit.
Built-up flywheel	A flywheel comprised of two or more pieces.
Bulb, hot	In certain forms of oil engine an unwater-jacketed cup or pocket employed for the purpose of ignition.
Butterfly throttle	A thin disk similar to the damper in a stove pipe rotated on a spindle passing at right angles through the axis of the inlet pipe.
By-pass	See transfer port.
C	Back to top
Cable, ignition	An insulated electric conductor, or a combination of several insulated conductors.
Cabriolet	A body similar in appearance to the brougham and having the general characteristics of the condoled, except that the falling pillar-hinge is set back from the pillar-line and shows the curved parting line through the leather. The rear section is therefore longer than that of the landaulet.  The body has one fixed cross-seat for two or three, and folding seats on the partition for two additional passengers.
Calorific value	This term is used with reference to various fuels, such as gasoline, benzol, paraffin, etc., and represents the effective heating power per pound. in terms of British Thermal Units.  One pound of gasoline contains about 19,000 BTU's.
Cam	A rotating part of a machine having a projection designed to give variable motion to another part bearing against it.
Camshaft	The shaft running through the engine which has the cams placed upon it at certain fixed positions.
Cap bolt, cap screw	A bolt used without a nut to screw into one of the parts which it is used to hold together.
Cap stone	A flat stone sometimes employed for the top of a foundation.
Carbon	One of the well-known non-metallic elements. It is an excellent conductor of electricity. As applied to the automobile, it refers to the carbon deposit which accumulates in the combustion chamber of an engine. In a hard state it works well as a contact medium in conjunction with copper or brass. It is, therefore, largely used for the brushes of the magneto, and also for the brushes of car-lighting dynamos. Carbon in its natural form of graphite is used as a lubricant for gearing. It is generally mixed with grease, and is supplied ready prepared by lubricant manufacturers.
Carbonize	The deposit of carbon upon the points of the spark plugs and the various internal portions of engine cylinder and exhaust pas­sages.
Carburetor	A device by means of which the air entering a liquid fuel engine is caused to pick up and atomize a small quantity of the liquid fuel.
Catalytic ignition	See ignition.
Cell, electric	An electric couple comprised of two dissimilar metals or a metal and a metalloid surrounded by a salt of an acid solution which will produce a difference of potential between the solid elements. The liquid is known as the electrolyte. Dry cell - An electric cell in which the electrolyte is contained in some absorbent material.  Storage cell - An electric cell in which electrical energy is transformed into chemical energy and stored until some future time when it may again be obtained in the form of electrical energy.
Cellular radiator	Consists of tubes and cells place horizontally through which the air passes and the water flows downward around these cells or tubes.
Celluloid	A compound of camphor and gun-cotton. Its transparency and flexibility are its chief characteristics. Non-inflammable celluloid is now made for windshields.
Centrifugal governor	See governor.
Chamfer	A small channel or groove cut in metal or wood; corner beveled off.
Charge	In a gas engine, that quantity of mixture taken into a cylinder at one suction stroke.
Chassis	Derivation, French; a frame in wood or metal; the frame work of a wagon; later the term was applied to the frame-work of a locomotive; then to the longitudinal and transverse frame members of the motor car. By extension it also designates the whole of the mechanical portion of a motor ear. More correctly, however, the word chassis should only apply to the metal framework receiving the engine gearset and controlling mechanism.
Chauffeur	Derivation, French - chauffeur, to heat. A chauffeur is a man in charge of a furnace or boiler fire.  The first use of the word chauffeur was dur­ing the revolution of 1789, when bands of brigands heated "chauffeur" the feet of their victims in order to make them reveal the place where their money was hidden. The "chauffeurs" were stamped out during the Consular period. The word chauffeur was first applied to motor car drivers under the popular supposition that they had to tend a fire. On the French railroads the chauffeur is the fire­man; the engine driver is the mechanician.
Chauffeuse	A woman chauffeur.
Check-valve	A stemless valve; one which permits the passage of a fluid or gas in one direction only.
Circuit	The path of the electrical current; the conducting material, or wires.
Circulating pump	Pump used to circulate the cooling-water, operated by the engine.
Circulating lubrication system	Systems having continuous circulation of oil, sometimes termed the ‘pump over’ system. For example, a system using a force pump for pumping the oil from the lower part of the crankcdase to the upper part, with a drain back to the lower part again, would be termed a circulating system.
Circulating pump cooling system	The gear type consists of 2 small gears with large teeth, the 2 being in mesh, and placed in a casing that fits a s snugly as possibly.  The water enters at one side where the teeth separate and is carried around to the opposite side in spaces between the teeth where it escapes through an outlet. The rotary type consists of a ring-shaped casing, within which a dsik revolves, the disk being “eccentric”, or to one side of the center of the casing.  Through a slot across the disk are 2 arms, their ends being pressed against the casing by a spring.  As the disk revolves, the water is forced from the inlet to the outlet by the arms.  The centrifugal pump type acts on the principle of an air blower, and has blades projecting from a hub, which revolve at high speed inside of a casing. The water enters at the hub, and is thrown outward by the blades to the outlet in the casing.
Circulating splash lubrication system	This system could also be termed a ‘pump over’ system and is the true constant level, circulating splash system because the oil troughs are kept at a constant level by a pump. It could also be termed a ‘force feed and splash’ system.
Clerk-cycle	A form of two stroke cycle invented by Dugald Clerk and having a separate charging cylinder.
Clover Leaf	An open car seating three or four. Ther rear seat is close tot he divided front seat and entrance is only through doors in front of the front seat.
Clutch pedal	The foot pedal which connects and disconnects the clutch.
Clutch	A device for connecting and disconnecting the engine from the transmission - usually placed in or on the inner face of the fly wheel rim.
Clutch, cone	See cone clutch.
Clutch, disk	See disk clutch.
Clutch, plate	See plate clutch.
Clutch, single plate	See single plate clutch.
Coal gas	See gas.
Cock, drain	An ordinary pet cock used for letting surplus oil out of the base or water out of the water jacket.  Relief cock - A valve or pet cock connected to the cylinder, usually to the compression space, to relieve the compression. Priming cock or cup - A small pet cock of special form with the cup on the outer end which is screwed into the cylinder and is employed for the purpose of admitting a small quantity of gasoline to the cylinder for starting.
Cock, relief	See cock, drain.
Cock, priming	See primer. See also cock, drain.
Coefficient	A known quantity. That which cooperates with another variable or unknown quantity.
Coefficient of unsteadiness	The allowable variation of the speed from the normal speed of the engine, used in flywheel design.
Coil	See spark coil and jump spark coil.
Coil, secondary	See secondary coil.
Coil, spark	See spark coil.
Coil and battery system of ignition	In a battery the electricity is obtained by chemical means instead of mechanical means, as when a dynamo is used. The coil has nothing to do with the generation of the electric current, its function being to "gear up," intensify, or increase the pressure or transform the low-voltage primary current into a high voltage secondary current to enable a spark to be produced across the air gap of the plug points.
Coil link suspension	A coil spring suspension with the ‘links’ being the different pivot points on the frame.
Combustion space	The space between the end of piston (when on upper dead center) and head of cylinder. That portion over the valve is also included.
Compensating air valve	Also called compensating valve and auxiliary air valve.  A valve which counteracts the tendency of an over rich mixture as the speed increases. (In a carburetor, a valve whose function is to retain the proper proportions of the mixture at all speeds.)
Compensating valve	See compensating air valve
Compression	A term implying that the explosive charge of gas and air drawn into the cylinder on the suction stroke is subjected to a strong squeezing effect on the next stroke. The charge is pressed into a space about one-fifth the volume or space of that occupied by it on the suction stroke, equaling 55 pound to 90 pound pressure per square inch. Compression pressure - The pressure in pounds gage secured by the inward movement of the piston. Compression space - The space in the cylinder back of the piston when the piston is at the end of its inward stroke. Compression stroke - The second stroke of the four-stroke cycle in which the charge, already drawn in is compressed before ignition.
Compression curve	See curve, compression.
Compression pressure	See compression.
Compression relief cock	See cylinder priming cock.
Compression space	See compression.
Compression stroke	See compression.
Compression tap or cock	A small tap placed at the upper end of the cylinder, which can be opened to relieve the compression, to make cranking easier.
Concentric	The opposite of eccentric.
Condenser	An important part in a spark coil or high tension magneto.
Conductor	A material along which electricity will readily flow, such as copper, platinum, steel, and, in fact, all metal silver is the best conductor, but copper is only very slightly inferior. Carbon is a non-metallic element, but an excellent conductor much used in magneto construction for the brushes. The wires or cables of the ignition circuit are sometimes referred to as conductors or "leads."
Cone clutch	This type of clutch is built into the flywheel, and the flywheel forms one of its parts. The rim of the flywheel is broad and the inside of the rim is made slightly funnel-shaped, forming the surface against which the cone part of the clutch presses.  The surface of the cone that bears against the flywheel rim is often covered with leather. Some manufacturers use fabric material, running in oil.
Connecting rod	A mechanical link connecting the piston to the crankshaft.
Consumption, fuel	See fuel consumption.
Contact breaker	The interrupter on a magneto. Also applied to the interrupter arrangement on the "make and break" igniter.
Contact ignition	See ignition.
Contact maker	See maker, contact.
Contact sector	One of the sectors in a timer or distributor.
Contact points	In a make-and-break ignite the two small pieces of metal at the point of contact between the insulated and the grounded electrode, and between which the spark is made.  Frequently made of a nickel alloy.
Contact-screw	The small screw, having a platinum point, against which the trembler vibrates.
Continuous or direct current	This implies that the current flows in one direction.  The direct opposite of alternating current.
Convertible Coupe	A roadster provided with a detachable coupe top.
Convertible Sedan	A salon touring car provided with a detachable sedan top.
Cooling tank	A tank of comparatively large capacity connected to the water jacket of an engine.
Cooling system	Consists of radiator, water pipes, ciruclating pump and fan. The object of the colling system is to keep the engine from getting too hot when the explosions take place inside the cylinders.  See also circulating pump cooling system and thermo-syphon,
Counter balance	See balance weight.
Counter bore	An enlargement of the diameter of the cylinder in the compression space.
Counter weight	See balance weight.
Coupe	An enclosed single-compartment body, with one fixed cross-seat.  This seat may be straight and accommodate two persons, or be staggered and accommodate three persons.  With the latter arrangement, a folding seat may be placed beside the driver’s seat, thus making it a four-passenger body. The conventional body has two doors and two movable glass windows on each side; the roof is permanent;  and there is a luggage compartment at the rear.
Coupe-Landaulet	A body that bears the same relation to the coupe and the sedan-landaulet bears to the sedan.
Coupelet	Seats two or three. It has a folding top and full-height doors with disappearing panels of glass.
Crank case or chamber	See base. Crank arm - That part of the crankshaft connecting the crank pin to the main shaft. Crank pin - That part of the crankshaft to which the outer end of the connecting rod is attached. Sometimes but erroneously called wrist pin. Crank pit - Practically synonymous with crank case, but usually referred to the lower part of the base. Crankshaft - An axle or shaft carrying a cylindrical portion offset from the main shaft and connected thereto by means of arms for transposing the reciprocating motion of the piston into rotating motion. Starting crank - A bent lever with a handle for turning an engine when starting. Crank web - See crank arm.
Crank arm	See crank case or chamber.
Crank pin	See crank case or chamber.
Crank pit	See crank case or chamber.
Crank web	See crank case or chamber.
Crankshaft	See crank case or chamber.
Crosshead	A guiding member, usually employed in a double-acting engine, located at the connection of the piston rod and the connecting rod.
Crude oil	Unrefined oil as it comes from the well. The term is frequently, but erroneously, applied to the residuums of the refinery
Cup, priming	See primer. See also cock, drain.
Cup, grease	A device for supplying lubricating grease to a bearing. Oil cup - A device for supplying oil to a bearing or similar surface. Priming cup - See primer. See also cock, drain.
Current, induced	See induced current.
Current	The flow of electricity.
Curve, compression	The line on the indicator diagram denoting the rise of pressure during the compression stroke. Expansion curve - A curve on the indicator diagram showing the drop of pressure during the expansion stroke. See also expansion.
Cut-off (valve closure)	A term usually applied in a steam engine to the closing point of the admission valve. Sometimes used in the internal combustion engine to indicate the time of closure of the inlet valve.
Cut-out, muffler	A valve opening into the exhaust pipe at a point between it and the muffler. When opened it permits the exhaust gases to escape through it directly into the atmosphere instead of being forced through the muffler.
Cycle	The complete series of operations required for the functioning of a heat engine. Four cycle, properly four-stroke cycle - A cycle requiring four strokes or two revolutions of the engine for its completion as follows: suction stroke, outward; compression, stroke inward; expansion stroke, outward; exhaust stroke inward.  Six cycle, properly six-stroke cycle - A cycle requiring six strokes of the engine for its completion. The strokes are as follows: suction, compression, explosion, exhaust, suction of a charge of air, or scavenging charge, and expulsion of scavenging charge.  Two cycle, properly two-stroke cycle - A cycle requiring two strokes of the piston for its completion. The suction stroke and the exhaust stroke of the four-cycle are eliminated, the outward stroke is always the expansion stroke. About 1/5 of the expansion stroke is used for exhaust and approximately 1/10 of the same stroke for receipt of a fresh charge from a special source of supply, as the crank case or a charging pump outside of the cylinder. The inward stroke is always the compression stroke.
Cylinder	The hollow cylindrical portion of an engine in which the functions of the cycle take place.  Cylinder head - The closed end of the cylinder. Cylinder jacket - An annular space about the cylinder containing the cooling medium.  Cylinder bore - The inner diameter of the cylinder. Cylinder studs - Studs for holding the cylinder to the base or frame. Cylinder bolts - Bolts to hold the cylinder to the base or frame.
Cylinder bolts	See cylinder.
Cylinder bore	See cylinder.
Cylinder head	See cylinder.
Cylinder jacket	See cylinder.
Cylinder en bloc	The cylinders cast together in one piece.
Cylinder priming cock	Same as compression relief cock. Usually placed in the head of the cylinder for injecting gasoline.
D	Back to top
Dead center	The extreme end of the stroke both inward and outward. So-called because the piston comes to a "dead" stop for a small fraction of time before it starts in the opposite direction.
Dead rear axle	A rear axle that does not turn. It is usually used on double chain driven cars.
Deflecting plate, deflector	In a two-cycle engine a projection on the piston to direct the incoming charge towards the cylinder head.
Delivered horsepower	The horsepower delivered to the driving shaft or to the belt or other driving means exterior to the engine itself. See also horsepower.
Delivery Wagon	The distinction between the Delivery Wagon and Truck is in size and weight. The delivery wagon is usually a shaft-driven solid, or pneumatic-tired car, whereas, the truck is a double-chain or shaft-driven solid or pneumatic-tired, heavier machine.
Demountable rim	A form of rim that can be taken off the wheel without deflating the tire.
Diagram, indicator	The trace drawn by the pencil or stylus of the indicator.
Diameter of cylinder	See bore.
Die-cast bearing	Bearing cast in metal dies.
Diesel motor	See motor, automobile.
Diesel cycle	A high pressure cycle of either the two-cycle or the four-cycle type in which pure air only is compressed, and the fuel is injected, usually by air, at or near the end of the compression stroke. The term is usually applied to engines depending entirely upon the heat of the compression to ignite the fuel without the aid of any other ignition means.
Differential	Also called Compensating Gear. Its purpose is to allow the rear wheels to turn at different speeds when turning a corner, while at the same time both are being driven by the engine. This gear is automatic, and operates according to the resistance of the road against the wheels
Differential piston	A piston having two or more portions of different diameters.
Direct current	Electric current where the current flows continuously in one direction, unlike alternating current.
Discharge, water	Water outlet.
Disk clutch - (or Multiple disk - more than 3 disks)	Consists of a number of disks which are pressed together when the clutch is “in”. The friction between them causes one to drive the other. This type of clutch is very compact and is frequently built inside a metal housing cast to the engine. They can be either lubricated or dry. A lubricated disk clutch runs in an oil bath. Its disks are usually alternate steel and bronze or all steel disks. A dry disk clutch usually has steel disks, one set of which is faced with a friction material of woven asbestos fabric.
Disk brakes	Brakes which use a revolving disk instead of a drum. The brake shoes are applied against the disk to slow or stop the vehicle.
Distillate	A liquid petroleum derivative with a specific gravity between gasoline and kerosene. The term is usually applied to a product of Pacific coast petroleum.
Distributor	Virtually a commutator for the high tension spark in jump spark ignition. Usually made to operate synchronously with the circuit breaker.
Distributor or Distributer	A special form of rotary switch, which directs the high tension cur­rent to the various spark plugs.
Double-acting	Applied to either an engine or a pump in which functions of the cycle are performed on both sides of the piston.
Double chain drive	A method of power transmission to the rear axle, requires a dead rear axle. Each chain runs along a side of the car from the jack shaft to the rear axle. (The jack shaft being driven by the transmission.)
Drain cock	See cock, drain.
Drawbar horsepower	See horsepower.
Drip lubrication system	Also called splash system. Consists of a drip or gravity-feed oil cup placed over bearings and also on the side of the cylinder. Special oil cups are required for the cylinder which will prevent the compression interfering with oil entering the side of the cylinder wall. See also splach lubrication system.
Drop, in two cycle ports	The distance measured along the axis of the cylinder between the opening of the exhaust and the opening of the inlet from the transfer port.
Dry battery	Called dry cells or primary cells. A series of primary cells which do not contain liquid electrolyte.
Dry cell(s)	See dry battery. See also cell, electric.
Dry plate clutch	A dry disk clutch which usually has steel disks, one set of which is faced with a friction material of woven asbestos fabric. See also disk clutch.
Dual ignition	An arrangement whereby a magneto may be used for battery ignition, usually temporarily for starting.
Duplex engine	Occasionally applied to a two-cylinder engine with the cylinders parallel.
Duplex ignition	A system of ignition whereby two spark plugs may be used simultaneously.
Dynamo	A generator of electricity. The dynamo is usually used on a motor car to light the electric lights and to recharge storage batteries and in some instances furnishes current for the ignition.
Dynamometer, electric	See electric dynamometer.
Dynamometer	A device for measuring the horsepower of an engine or motor. Absorption dynamometer - A dynamometer in which the power is absorbed in the dynamometer itself. Transmission dynamometer - One in which the power is measured during its transmission to power driven apparatus.
E	Back to top
Earth connection	Also called ground. An inaccurate term when applied to the electric circuits of a motorcar. The car is insulated from the road by the tires, hence the "earth" is not used at all. What is meant is that the framework of the car is used as a return conductor so as to dispense with some of the wires.
Economy, fuel	The amount of fuel required per horsepower hour. See fuel consumption.
Effective port area	That area which gives the required speed of the gases as computed on the assumption that the valve or port is fully open when open at all.
Efficiency	The ratio between actual performance and theoretical perfection. Thermal efficiency - The ratio of the delivered to the indicated horsepower. Thermal efficiency - The ratio between the amount of heat transformed into work and the heat value of the fuel required to perform that work. Volumetric efficiency - The ratio of the actual volume of the charge, measured at atmospheric pressure, to the piston displacement of the engine.
EHP	Electric Horsepower. 746 Watts.
Electric battery	See battery, electric.
Electric governor	See governor.
Electric horsepower (EHP)	See horsepower.
Electric dynamometer	A form of dynamometer of which an electric generator forms the principal part.
Electric ignition	Any form of ignition depending upon electric current for its functioning.
Electric starter	An electric motor for turning an internal combustion engine to start it.
Electro-magnet	Any piece of metal (usually iron or steel) that is magnetized electrically. The opposite of a permanent magnet.
Electrode, of the spark plug.	The terminal wire of the plug inside the cylinder through which the spark passes. Generally, the terminals of conductors performing any function. Movable electrode - In a make-and-break igniter the rocking contact arm. Stationary electorde - In a make-and-break igniter the insulated contact rod.
Electrode	The insulated part placed in the igniter of a low tension system of “make and break" ignition. The center rod of a spark plug.
Electrolyte	An acid solution used in an electric cell. When placed between two dissimilar metals (or a metal and a metalloid) a difference of potential (voltage) is produced.
EMF	Electro Motive Force, voltage, pressure, tension.
Emergency brake	Also called hand brake. Usually applied by a lever at the side or center of the drivers seat. Normally, it is of the internal expanding band type, but occasionally it is a contracting band over a drum mounted on the main transmission shaft.
En-bloc	Cast in one piece.
Engine, air-cooled	An engine with cylinders cooled by direct contact with air. Diesel engine - Any engine using the Diesel cycle. Gas engine - An internal combustion engine using gas for fuel. Oil engine - An internal combustion engine using oil for fuel. Hot bulb engine - An internal combustion engine using a hot bulb or unjacketed pocket for ignition. Internal combustion engine - An engine wherein the fuel is entirely consumed inside the working cylinder. Two-cycle engine - See cycle. Four-cycle engine - See cycle. Portable engine - An engine mounted on a wheel truck. Semi-Diesel engine - A popular term for a hot bulb engine. Six-cycle engine - See cycle.
Engine bed	See frame.
Engine, duplex	See duplex engine.
Entropy	A function of heat change. It is the quotient of the heat change divided by the absolute temperature at the instant of change.
EPM	Explosions per minute of a gasoline engine.
Exhaust (verb)	The act of discharging material, such as waste gases from the cylinder or water from the water jacket.
Exhaust manifold	See exhaust, water.
Exhaust passage	See passage, inlet.
Exhaust pipe	See pipe, exhaust. See also exhaust, water.
Exhaust pit	See pit, exhaust.
Exhaust port	See exhaust, water.
Exhaust stroke	See exhaust, water.
Exhaust timing	See exhaust, water.
Exhaust valve	See exhaust, water.
Exhaust, water	Water discharged from the water jacket. Exhaust manifold - That part of the exhaust passages immediately connected to the cylinder. Exhaust pipe - A pipe connected to the exhaust manifold or to the muffler for carrying the exhaust gases to the point of discharge into the atmosphere. Exhaust port - An opening in the cylinder wall for the discharge of the exhaust gases. Exhaust stroke - The fourth stroke of a four-stroke cycle, during which the exhaust gases are discharged from the cylinder. Exhaust timing. Points measured in circular degrees at which the exhaust valve or exhaust port opens and closes. Exhaust valve - The valve closing the opening into the cylinder through which the exhaust is discharged.
Exhaust n	Gases discharged from the cylinder, usually the products of combustion.
Expansion	Increase in volume. Expansion curve - The line on the indicator diagram indicating the pressures in the cylinder in relation to the various points in the stroke. Expansion stroke - The third stroke of a four-stroke cycle during which the gases expand and perform work upon the piston.
Expansion curve	See expansion. See also curve, compression.
Expansion stroke	See expansion.
Explosion	A sudden increase in pressure or volume usually caused by combustion. Explosion line - The line of the indicator diagram showing the increase in pressure after ignition. Premature explosion - An explosion caused by too early ignition during the compression stroke. Explosive mixture - A mixture of combustible fuel and air in such proportions that explosion will result on ignition.
Explosion line	See explosion.
Explosive mixture	See explosion.
External contracting band brake	Also called external band. A flexible steel band faced with an asbestors composition. Setting the brake causes friction between the brake drum and the linings.
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Field	The seat of magnetic flow, between the pole pieces of a generator or motor.
Fixed-hub axle	See semi-floating axle.
Flame ignition	Ignition by exposure of the charge to a naked flame. Flame propagation - The advance of combustion throughout the charge following ignition.
Flame propagation	See flame ignition.
Float	A part of the carburetor lighter than the fuel and employed to regulate the height of fuel in the nozzle. Float chamber - That part of the carburetor containing the float.
Float chamber	See float.
Flooding	Excess of liquid fuel in the intake passages or in the cylinder.
Flux, magnetic	Lines of magnetic force, that pass or flow through a magnetic field.
Fly wheel	A heavy wheel rotating without contact with anything save its axle, by the momentum of the periphery of which, an even running of the engine is obtained.
Flywheel	A heavy wheel attached to the crankshaft of the engine to prevent excessive fluctuation in speed.
Foot brake	Also called service brake. Applied by pressing on a foot pedal. It is usually an external contracting band.
Force cooling system	In the force system, the engine drives a pump which keeps water in constant circulation.  The pump forces the water from the bottom of the radiator to the inlet at the bottom of the the water jacket through which it flows to the outlet at top, whence it goes to the top of the radiattor and flows through the radiator tubes to the bottom.  As it passes through the radiator tubes, it is cooled, after passing through in this manner, it is again drawn though the pump and forced again through the same path.
Force feed lubrication system	In this system, oil is forced by pressure fromthe oil pan bya pump to the crank shaft bearings, then through drilled holes in the crank pins.
Forward stroke	See stroke, of piston.
Foundation	A mass of concrete, stone, brick or other material on which the engine is mounted.
Four-cycle	See cycle.
Four-stroke cycle	See cycle.
Four-port motor	A two-cycle motor using crankcase compression, provided with both a suction valve and a piston controlled crankcase port.
Frame	That part of the engine attached to the foundation and carrying the crankshaft bearings, etc.  Sub frame - In engines of large size the frame is made in two parts, the frame proper, carrying the crankshaft bearings, and the sub frame being underneath the frame proper between it and the foundation.
Fuel consumption	The amount of fuel required per horsepower hour to operate an engine. Usually measured in pounds for liquid fuel and cubic feet for gaseous fuels.
Full floating axle	The weight is taken from the axle, and supported on the housing through which the axle passes.  In this type of axle all the bending stress due to the static force and skidding force is carried by the housing.  The driving shafts run freely within the housing and bear on the torque, or stress, of turning the wheels.  The shafts are said to float within the housing
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Galvanometer	An instrument for measuring the presence, extent, and direction of an electric current.
Gap, Spark	In jump-spark ignition, the distance between the points of the spark plug or between any two separate parts of the high tension circuit.  A device usually mounted exterior to the engine containing an opening in the high tension circuit.  Also safety device on a magneto to prevent the armature windings being strained or short circuited owing to a faulty spark plug or wiring circuit.
Garage	Derivation, French. The word has been taken bodily, pronunciation and spelling, from the French language, in which it is a variation of the word gare, a station or terminal for either railway trains or boats.  Garage, as a noun, means, in both French and English, a place in which motor cars are kept and is sometimes applied to shops wherein motor cars are repaired. The verb, to garage, means the act of putting a car in the garage building.
Gas	Aeriform elastic fluid. For example, air, oxygen, hydrogen, etc., are all gases.  Air gas - Term generally used for air charged with gasoline vapor.  Artificial gas - Any manufactured gas, usually confined to gas manufactured by the distillation of coal for domestic use.  Blast furnace gas - Gas made in the blast furnace during the reduction of iron ore.  Coal gas - Gas made by the distillation of coal.  Illuminating gas - Gas manufactured for illuminating purposes.  Oil gas - Gas made from oil.  Producer gas - Gas manufactured by the incomplete combustion of either a solid or a liquid fuel, principally carbon monoxide.  Water gas - Gas usually manufactured from coal by the partial combustion of the fuel combined with the disassociation of water.
Gas engine	An internal combustion engine, strictly, one using gas as fuel.  See also engine, air-cooled.
Gas engine indicator	See indicator.
Gas producer	A device for the manufacture of producer gas.
Gas tractor	A farm or road locomotive powered with an internal combustion engine.
Gasoline locomotive	See locomotive, gasoline.
Gasoline or gasolene	>A light grade of petroleum.
Gasoline	Usually a fuel with a distillation range of 100 degrees to 400 degrees F.
Gasoline-electric 1ocomotive	See locomotive, gasoline.
Gear set	The transmission.
Gear ratio	The number of revolutions of the engine made for one revolution of the road wheels - this depending on which “speed" or gear is in use. Thus the high speed gear ra­tio may be 4 to 1, that is, four revolutions of the engine to one of the road wheels.
Governor	Any device for regulating the speed of an engine so as to maintain it between certain limits.  Centrifugal governor - A governor depending upon the change in centrifugal force due to change of speed. Electric governor - A governor regulating by the change in voltage of a generator. Hit-or-miss governor - A method of governing by omitting, entirely, one or more explosions.  Throttling governor - A method of governing by choking the inlet passages.  Governor valve - A valve for controlling the amount of mixture passing through the inlet passages.
Governor, inertia	See inertia governor.
Governor valve	See governor.
Grease cup	See cup, grease.
Ground	Connection of electric wiring to frame of car or metal part of engine. The term was originally derived from the fact that with telegraph and telephone systems one wire was used, which was insulated from the ground. The other, or return wire to complete the circuit the ground was used.  A piece of wire was attached to an iron pipe and driven deep into the ground at each end of the circuit. This same principle is used in automobiles. One wire is insulated from the frame or metal part of car.  The frame is used as the return wire.
Gudgeon pin	The wrist pin also referred to as the piston pin, the latter being correct term.
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Half speed shaft	The small shaft, revolved at one-half the speed of the crankshaft by means of any suitable gearing - the camshaft.
Hammer-break igniter	See make-and-break igniter
Hand brake	Also called emergency brake. See emergency brake.
Head, cylinder	See cylinder head. Head end - The end of an engine opposite that carrying the crankshaft. Piston head - The piston proper in a double-acting engine. Valve in head engine - An engine having the valve in the cylinder head.
Heat analysis	A test to determine the distribution of heat in the operation of a heat engine. Heat balance - The result obtained by heat analysis. Heat of combustion - The heat given off when burning a unit quantity of fuel. The unit generally being one pound. Heat engine - Any prime mover deriving its power from the expenditure of heat. Heat unit - A measure of heat. English unit, the amount of heat required to raise a pound of water 16 degrees Fahrenheit; known as the British Thermal Unit or BTU. Metric unit, the amount of heat required to raise a gram of water 1degree centigrade, known as a calorie. Heat value, high - The heat of combustion of a fuel including the latent heat of steam for the hydrogen content. Heat value, low - The heat of combustion less the latent heat of steam for the hydrogen content.
Head end	See head, cylinder.
Heat balance	See heat analysis.
Heat of combustion	See heat analysis.
Heat engine	See heat analysis.
Heat unit	See heat analysis.
Heat value, high	See heat analysis.
Heat value, low	See heat analysis.
Heater jacket	See jacket.
High frequency ignition	See ignition.
High gear	Combination of gears ordinarily used in running. The highest ratio of gearing - on some cars 2 ½ to 1, others 3 to 4 ½ to 1.
High-tension ignition	See ignition.
Hit-or-miss governor	See governor.
Honeycomb radiator	Originally applied to a cell type of radiator due to its likeness to a honey-comb, but now that tubular type of radiator can be constructed so as to have the appearance of a cell radiator, the term could also be applied to the tubular type.
Hopper	A form of water jacket enlarged or extended at the top to form a reservoir.
Horizontal engine	One in which the axis of the cylinder is normally parallel to the earth's surface.
Horsepower	The expenditure of 3,300 foot pounds in one minute. Brake horsepower - The power derived by a brake test. Delivered horsepower - The power delivered to the belt or other means of transmission. Drawbar horsepower - The power based on the pull at the drawbar of a locomotive or tractor. Electric horsepower - 745.941 watts. Indicated horsepower - The horsepower based on the mean effective pressure as shown on the indicator diagram. Metric horsepower - 4,500 kilogram-meters per minute. Nominal horsepower - Also called rated horesepower. The rated or catalog horsepower of an engine. Rated Horsepower - (Bore2 x no. cylinders/2.5. This was the standard calculation for Rated Horsepower, but this did not come from Dyke’s Dictionary.) See nominal horsepower. Horsepower of water - Indian government standard, 15 cubic feet falling 1 ft. in one second.
Hot bulb engine	An engine in which the charge is ignited with a hot bulb. See also engine, air-cooled.
Hot bulb ignition	See ignition. See also bulb, hot.
Hot plate ignition	See ignition.
Hot tube ignition	See ignition.
Hotchkiss suspension	A type of leaf spring rear suspension where the leaf springs also act to absorb the torque of the wheel and axle housing.
Housing	A term of varying significance frequently employed to denote the frame or crankcase of an engine.
Hydraulic brakes	Brakes which use a fluid hydraulic system to press the brake shoes against the brake drum as pressure is applied to the pedal.
Hydrocarbon engine	A gasoline engine.
Hydrocarbon	A substance formed chiefly of hydrogen and carbon in chemical combination.
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"Int."	When found stamped on a coil or ter­minal, means interrupter connection.
Idling	Refers to engine when running slow, and car is standing still.
Ignite	To set fire to.
Igniter	This has various meanings. On "make and break" ignition the part that makes the spark. On high tension it sometimes means the spark plug and others call the "commutator" or "timer" the igniter. The correct meaning should be the part that ignites the gas.
Ignition	The act of igniting. Battery ignition - Electrical ignition having as its primary source of electrical pressure, an electric battery. Catalytic ignition or Contact ignition - Said of ignition produced by the rise of temperature caused by the gas-or mixture coming in contact with some material like spongy platinum. Flame ignition - See flame ignition. High frequency ignition - Electric ignition by means of a high frequency alternating current. Usually that form of current produced by a condenser discharge. High tension ignition - Ignition caused by a current of sufficiently high voltage to make the spark leap an open gap. Hot bulb ignition - Ignition by means of an unwater-cooled pocket in the engine cylinder. Hot plate ignition - Ignition by means of an unwater-cooled plate attached either to the inside of the cylinder head or to the end of the piston and heated by the combustion of the cylinder. Hot tube ignition - Ignition by means of a tube heated by a flame exterior to the tube. Jump spark ignition - See high tension ignition. Magneto ignition - Electrical ignition having as its primary source of electrical pressure, a magneto. Premature ignition - Ignition taking place before the proper time in the cycle. Ignition system - The method and apparatus used in any form of ignition.
Ignition, duplex	See duplex ignition.
Ignition, dual	See dual ignition.
Ignition, electric	See electric ignition.
Ignition, flame	See flame ignition.
Ignition, tube	See tube ignition.
Ignition cable	See cable, ignition.
Ignition cam	The small cam on the half-speed shaft which either causes a make and break of the current, or is notched to receive the nose of the trembler in timers of the mechanical vibrator type.
Ignition system	See ignition.
Illuminating Gas	See gas, illuminating.
Increments	Gradual increase or increasing a specified amount.
Indicated horsepower (IHP)	The power delivered to the piston inside of cylinder and can be measured by taking an indicator diagram which shows the pressure of the explosion in pounds per square inch. From this the mean effective pressure during the stroke can be calculated. See also horsepower.
Indicator	An instrument for registering the pressures at different points in the cycle. Indicator card - A sheet of paper on which the indicator diagram is recorded. Indicator diagram - The trace of the indicator pencil or stylus on the indicator card. Gas engine indicator - A special form of indicator, usually with a 1/4 inch area piston for indicating a gas engine.
Independent parallelogram suspension	A coil spring front suspension system with two control arms of nearly equal length.
Indicator card	See indicator.
Indicator diagram	See diagram, indicator.
Induced current	The momentary current set up in a circuit, by the proximity of wires conveying the primary current, but not connected with those wires.
Induction	An influence exerted by an electrical charged body, or by a magnetic field or neighboring bodies without apparent communication or connection.
Induction coil	A step-up transformer. An apparatus through which the primary current is made to pass close to the secondary wires, thus setting up the induced, or high tension current.
Inertia governor	A governor utilizing the properties of inertia for the regulation of an engine. Usually employed in a hit-or-miss governor only.
Inflammation, period of	The time elapsing between the instant of ignition and the instant at which the entire charge has been ignited.
Inlet manifold	That part of the engine containing the passages from the carburetor to the cylinder. Inlet port - The opening in the cylinder wall through which the charge is drawn in. Inlet stroke - The first stroke in a four-stroke cycle during which the charge is drawn into the cylinder. Inlet valve - The valve controlling the opening from the inlet manifold to the cylinder.
Inlet port	See inlet manifold.
Inlet stroke	See inlet manifold.
Inlet valve	See inlet manifold.
Inlet valve cage	A housing used over an inlet valve.
Inspiration	Means the same as “suction” or “intake” as, suction stroke, intake stroke, or inspiration stroke.
Insulation	The protection of wires, or leads, by some suitable material which is a non-conductor of electricity.
Insulator	A material through which electricity cannot flow. for instance, porcelain, mica, india rubber, fibre, vulcanite, glass, celluloid, paraffin-wax, silk, shellac, steatite, slate, etc.
Intake	Synonymous with inlet.
Integral	The whole made up of parts.
Intensify	To increase, to render more intense. To intensify the voltage (pressure) means to increase the voltage.
Intermediate gear	Combination of gears intermediate in power and speed, between the low gear and the high gear.
Intermittent	Applied to a cam on the engine, meaning that the motion is not steady but at intervals.
Internal combustion engine	See engine, air-cooled.
Internal expanding band brake	Acts on the inside of the drum and may be a metal shoe or metal faced with asbestos, or a band faced with asbestos friction composition.
Inward stroke	The stroke during which the piston is approaching the cylinder head. See also stroke, of piston.
Isopiestic	Without change of pressure.
Isothermal	Without change of temperature.
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Jack shaft	The jack shaft, used in double chain drive, passes across the car, running in bearings in the gear case and on the frame. It is held so rigidly that while it is free to revolve, its bevel gear is always in correct relation to the bevel gear on the square shaft of the transmission.
Jacket	In a gas engine, a hollow space surrounding some portion of the engine, such as the water jacket around the cylinder. Water jacket - A jacket containing water, as the water jacket around the cylinder. Heater jacket - A jacket surrounding the inlet passages for the reception of either hot water or hot exhaust gas, or a jacket connected with the inlet passages and surrounding the exhaust pipe. Manifold jacket - A jacket surrounding either the intake or the exhaust manifold.
Journal	See bearing.
Jump spark	A spark which jumps from one terminal of the secondary coil to the other.
Jump spark coil	Another name for induction coil, spark coil or high tension coil.
Jump-spark ignition	See ignition.
Junk ring	A ring, usually forming a part of the piston, separating the piston rings, derived from the ring used to clamp the hemp or similar packing (junk) used in the early steam engines.
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K
Kerosene	A product of the fractional distillation of petroleum having a gravity of 40 to 46 Baume and with other characteristics usually fixed by State or National Law. Lamp oil.
Kilometer	1000 meters or 5/8 of a mile.
Kilowatt	1000 watts or 1 1/3 horsepower.
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Lag of valve	The distance measured in the direction of the piston travel or in degrees on the crank circle that a valve remains open after the piston has passed the dead center.
Lag of spark	The time elapsing between the operation of the timing device and the production of the spark.
Lag of magnet	The time required for an electro-magnet to reach its full strength after closing the circuit, magnetic inertia.
Laminate	Built up of thin plates of metal, as shims or a "laminated core in magneto armature.''
Landaulet	A body similar in appearance to the brougham, except that the enclosed section is shorter from back to front, and the roof is fully collapsible up to the partition at the back of the driver’s seat. The body has one fixed cross-seat in the rear section for two or three passengers, two doors made with either flappers or hinged upper parts, and glass windows in the doors only. The rear quarters, back and top are covered with leather or fabric. There are outside joints to support the top.
Lapping	A term applied to the operation of grinding in or fitting rings, pistons, etc.
Latent heat, of steam	The amount of heat required to transform water from a liquid form into steam at boiling temperature; of melting ice, the heat required to transform ice into water at the melting temperature.
Lay shaft (obsolete)	See camshaft.
Lead, of valves	The time measured along the travel of the piston or in degrees on the crank circle that the valve opens in advance of the dead center.
Lean mixture	A mixture of fuel and air in which there is much more air than required for complete combustion.
Lift of valves	The amount, measured in the direction of travel, that a valve is raised from its seat.
Live axle	This axle has a shaft supported directly in the bearings at center and at ends, carrying a differential and road wheels.
Limousine	Derivation, French. A motor car body with a permanent top projecting over the driver and having a protecting front. The name was originally applied to a cloak worn by the inhabitants of Limousine. Partially enclosed body, with a non-collapsible roof that extends the full length of the body and is attached at the front to the windshield standards. Only the rear portion of the body up to the partition at the rear of the driving seat is fully enclosed. Forward of this partition, the sides are enclosed only from approximately the belt downward. There are two low doors and one fixed cross-seat for two in the forward section. In the rear section there is one fixed cross-seat for two or three. Folding seats for two additional passengers are sometimes used. There are two doors in this section, and two movable glass windows on each side.
Limousine-Landaulet	A body that bears the same relation to the limousine as the sedan-landaulet bears to the sedan.
Liners	Metal plates, usually very thin, placed between two halves of a bearing so that by taking out a liner the bearing can be tightened.
Lines of force	Imaginary lines, in the direction of which it is assumed that the lines of magnetic attraction and repulsion pass or act.
Load, brake	The load on the end of the arm of a prony brake. Occasionally used to denote brake horsepower.
Load, rated	See horsepower, nominal.
Locomotive, gasoline	A locomotive which is driven by a gasoline engine through gearing. Gasoline-electric 1ocomotive - A locomotive driven by a gasoline engine through an electrical transmission.
Low speed	The ratio of gearing in a transmission for running rear axle at the lowest speed.
Low-tension magneto	A magneto designed for low tension ignition delivering current at about eight volts.
Low-tension ignition	Ignition produced by breaking a circuit of low voltage. See also make-and-break ignition.
Lubricant	Anything which lubricates.
Lubricate	To reduce friction by means of an oil, grease or equal material. Otherwise to apply a lubricant.
Lubrication	The act of lubricating.
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Magnetic igniter	A low-tension igniter in which the circuit is broken by an electro-magnet.
Magneto	An electric generator having permanent magnets for the field. It is a device operated mechanically and driven direct from the engine and which generates electric current but "alternating” instead of "direct”. High tension, low tension, dual, duplex, independent magneto - See ignition.
Magneto ignition	See ignition.
Main bearing	See bearing, main.
Make-and-break ignition	Low tension system. No spark plug used.
Make-and-break igniter	A low-tension igniter in which the ignite points are brought together and separated mechanically in the combustion space. Hammer-break igniter - Sometimes used instead of make-and-break igniter. The term is, however, not sufficiently inclusive.
Maker, contact	In an ignition apparatus a device for closing the circuit mechanically at the moment of ignition.
Manganese bronze	Composed of copper, zinc and manganese. It makes very strong and tough castings. Forged front axles of this alloy are used on some American cars.
Manifold	See inlet manifold. See also exhaust, water.
Manifold, inlet	See inlet manifold.
Manifold, exhaust	See exhaust, water.
Manifold jacket	See jacket.
Manograph	A form of gas-engine indicator in which the diagram is produced by means of a ray of light reflected from a mirror attached to a diaphragm, the latter being acted upon by the pressure within the cylinder.
Marine engine	An engine designed to propel a boat or a ship.
Marine motor	See motor, automobile.
Marine-type connecting rod	A type of connecting-rod in which the bearings are held in place by a bolted cap.
Master vibrator	In a group of jump-spark coils, a vibrator which functions each of the coils in turn.
Mean effective pressure (MEP)	The average net pressure developed during a cycle, as shown by the indicator diagram.
Mechanical equivalent of heat	This is repre­sented by the number 778, which is the number of foot-pounds of work equivalent to one British Thermal Unit.
Mechanical efficiency (ME)	The ratio of the brake or delivered horsepower to the indicated horsepower.
Mechanical valve	Applied to either the exhaust or inlet valves when operated by a cam or mechanical means. The exhaust valve is always mechanically operated, whereas the intake is sometimes opened automatically by the suction of the piston.
Mechanician	A racing driver's helper.
Mesh	Usually applied to the meshing of the teeth of two gears; for instance, the teeth of the large half time gear.
Metric horsepower	See horsepower.
Mica plug	A spark plug in which the insulation is made of mica.
Misfire	Term applied to missing of one of the spark plugs.
Mixer	A term frequently employed to designate a simple form of carbureting device or mixing valve. See mixing valve.
Mixing valve	A check valve form of carbureting device in which the lift of the check valve opens the passage into the gasoline supply.
Mixture	The combination of fuel and air drawn into the cylinder during the suction stroke. Compare charge.
Mono-block cylinders	Another name for en-bloc or all in one casting.
Motor	The engine or motive power. Technically it refers to an electric motor and should never be used when referring to the engine. See also engine.
Motor car	An automobile.
Motor, automobile	An engine designed to drive an automobile. Airplane motor - An engine designed to drive an airplane. Diesel motor - See engine, Diesel. Marine motor - See marine engine. Semi-Diesel motor - A term employed for the hot bulb engine, but now gradually increasing in disfavor. Super-Diesel motor - A term employed by some manufacturers to designate a motor employing the Brons cycle.
Motor boat	A boat driven by an internal combustion engine.
Motor fire apparatus	A fire engine or other apparatus propelled by a gasoline engine.
Movable electrode	See electrode, of the spark plug.
Muffler	A device for quieting the sound of the exhaust.
Muffler Cut-out	See Cut-out, Muffler
Multi-cylinder (adjective)	Having two or more cylinders.
Mushroom valve	A poppet valve.
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Naphthalene	A solid hydrocarbon having the formula (C10H8).
Naphthol	An alcohol with the chemical formula (C10H7OH).
Naptha	A hydrocarbon of rather uncertain constitution. The term is frequently employed as a synonym to gasoline. Scientifically, a term applied to the lighter shale oils with a specific gravity of about .765.
Napthene	A group of hydrocarbons having the general formula (CnH2n).
Natural gas	Gas obtained from underground.
Needle valve	A sharply pointed valve in a carburetor whose function is to regulate the admission of fuel into the air stream.
Negative pole (minus sign)	The point to which the current returns after passing through the circuit. Designated thus: (-)
Nickel	Used in the form of an alloy with steel, vis., nickel-steel. For exhaust valve a high percentage (20 to 25%) nickel steel is the most suitable material, as it effectively resists the intense heat and oxidizing action of the exhaust gases. Nickel is now the standard material for spark plug electrodes.
Nominal horsepower	See horsepower.
Non-circulating lubrication system	A system such as drip or gravity, or a mechanical feed, so many drops per minute, depending on the speed and size of the engine, with no provision for circulating the oil again.
Nozzle	The end of the stand-pipe in a carburetor through which the liquid fuel is admitted to the air stream.
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Ohm	A unit of electrical measurement of resistance. The resistance an electric current meets in flowing through a conductor, is measured in ohms.
Oil	A term usually applied to a large variety of liquids of a more or less unctuous nature and insoluble in water. As a fuel, it usually means any combustible liquid having a dry point above 400 degrees F. The term applies not only to petroleum products but to combustible liquids of other derivation.
Oil cup	See cup, grease.
Oil engine or motor	An internal combustion engine employing any of the fuel oils. See also engine, air-cooled.
Oil gas	See gas.
Oil groove	A groove in a bearing for the guidance of lubricating oil.
Oil ring	A ring resting on the top of a horizontal shaft in a bearing and dipping into the oil in an oil pocket. The rotation of the shaft rotates the ring by friction and helps it to drag the oil to the top of the shaft.
Oil, lubricating	Any oil used for lubrication.
Oiler	See lubricator.
Open Limousine	A touring car with permanent standing top and disappearing or removalbe glass sides.
Open Sedan	A sedan so constructed that the sides can be removed or stowed so as to leave the space entirely clear from the glass front to the back.
Oscillate	A pendulum like movement,
Otto cycle	A four stroke "cycle”. An expression often used in connection with gasoline engines. It means that the power is developed during a complete cycle or four strokes, the principle first adopted in tho Otto gas engine. Generally considered to have been originated by Beau de Rochas, but actually put into operation by Doctor N.A. Otto in 1876. The complete cycle comprises four distinct operations, one -occurring at each half revolution of every stroke of the piston: thus (1) suction stroke, (2) compression stroke, (3) impulse or firing stroke, and (4) exhausting stroke.
Outlet	See exhaust, water.
Outlet manifold	Also called exhaust manifold. See exhaust, water.
Outward stoke	See stroke, of piston.
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Packing ring	See ring, piston.
Parabolic	Pertaining to, or formed like a parabola. One of the conic sections.
Paraffin wax	One of the lower hydrocarbons, usually of the Methane group and solid at ordinary temperatures. It is usually white or bluish white, and devoid of either taste or smell. It contains various hydrocarbons, and it has about 15 percent of hydrogen and 85 percent carbon.
Paraffin oil	An English term for kerosene.
Passage, inlet	An opening leading from the carburetor to the inlet valve. Exhaust passage - The passage leading from the exhaust valve to the exhaust pipe and usually considered as the exhaust passage in the exhaust manifold.
Pendulum governor	A form of governor employed on a hit-or-miss engine, depending for its regulation upon the inertia of a pendulum.
Period of inflammation	See inflammation, period of.
Periphery	That part of a wheel or disk furthest from its center. The circumference.
Pet cock	It is also called a relief cock or compression cock. A small valve usually placed in head of cylinder or on carburetor. See also cylinder priming cock.
Petrol	Gasoline.
Petroleum	A natural, oily liquid obtained from underground, mineral oil.
Phaeton	An open-type body, with two fixed cross-seats for four or five passengers. Folding seats in the tonneau for two additional passengers are sometimes used. The conventional body has four doors and a folding phaeton-top with emergency side-curtains that are removable. The principal reason for recommending the use of the term “phaeton” instead of the term “touring” is that the latter has lost its significance as applying to any particular type of body, as all types are used for touring. The term “phaeton” is used extensively in Europe, and to a considerable extent in America, in connection with passenger-cars; it is the name of a horse-drawn prototype; it is inelegant and in a technical sense is not distinctive of any particular type of motor vehicle body.
Phosphor-bronze	An alloy mainly consisting of copper and small proportions of tin, lead and phosphorus, the proportion of the latter being very small. It is a very tough, hard-wearing alloy. Largely used for engine bearings.
Pin	See crank pin, piston pin.
Pinions	Gears that have the teeth cut right in the hub.
Pipe, exhaust	Pipe for carrying off the exhaust gases. ­Inlet pipe - Usually the inlet manifold or a pipe connected to the inlet manifold. Water pipe - A pipe for carrying water to or from the water jacket of an engine. See also exhaust, water.
Piston	A sliding cylindrical part fitting into the cylinder of an engine and through which power is transferred through the connecting rod to the crankshaft. Differential piston - See dif­ferential piston. Piston head - See head, piston. Piston valve - A valve in piston form regulating the intake or the exhaust or both by covering and uncovering ports in the walls of a cylindrical valve chamber. Piston pin - A cylindrical journal for connecting the piston to the end of the connecting rod. Trunk piston - A piston closed at one end only. Piston rod - A cylindrical rod for connecting the piston to the crosshead. Piston speed - Twice the stroke in feet multiplied by the r.p.m.
Piston head	See head, cylinder.
Piston pin	See piston.
Piston ring	See ring, piston.
Piston rod	See piston.
Piston speed	See piston.
Piston stroke	See Stroke, of piston.
Piston valve	See piston.
Pit, exhaust	A form of large muffler hollowed out of the ground.
Plate clutch	This is a multiple disk clutch with more than 3 disks where one plate (or disk) is clamped between two others.
Plate, deflecting	See deflecting plate.
Plate, handhole	A plate or cover for closing a handhole.
Platinum	This very expensive metal is used for the contacts of the magneto. It is practically infusible (a very high melting point) and non-corrodible, and thus effectively resists the burning and oxidizing action of the electric spark. It is also used for the “ leading in wires” of the electric bulbs used for car lighting, as its ratio of expansion (due to heat) is the same as glass.  Sparking plug electrodes are, in a few instances, also made of it.  Tungsten now extensively used instead.
Plug, spark	See spark plug.
Plunger, pump	The pump piston.
Poppet valve	A disk or head attached to a cylindrical stem of comparatively small diameter for closing an opening by forcing it tight against a seat adapted to fit the disk-shaped head. The word poppet probably is a corruption of the name puppet applied to this type in England, on account of its resemblance to the popping up and down of the puppets in the old Punch and Judy shows.
Porcelain	The insulating material of the spark plug.
Port, exhaust	See exhaust, water.
Port, inlet	See inlet manifold.
Port	Opening in the cylinder for exhaust, inlet, water, or valves. Port area - The area of a cross section of a port. Exhaust port - See exhaust port. Inlet port - See inlet port.
Portable engine	See engine, air-cooled.
Positive pole	Usually indicated with a plus sign (+) means the positive terminal, or wire from which the current starts in an accumulator or dynamo. The carbon terminal of a primary or dry battery is positive.
Power	See horsepower.
Pre-Ignition	Ignition occurring earlier than intended. See also ignition.
Premature ignition	See pre-ignition. See also ignition.
Premature explosion	Explosion caused by premature ignition. See also explosion.
Pressure, compression	See compression.
Primary cells	See dry battery.
Primary Coil	An induction coil with a single winding, usually employed in primary or low tension ignition.
Primary battery	A series of either wet or dry cells depending upon chemicals for the generation of electricity, without charging from a dynamo or other battery.
Primary wires	The wires, or leads, conducting the primary, or low tension, current to the place, or places, where it is required for use.
Primer	A device for inserting a combustible, as gasoline, into a cylinder.
Priming cock or cup	See primer. See also cock, drain.
Projected area, of bearings	The length of the bearing multiplied by the diameter.
Propeller shaft	The drive shaft from transmission to rear axle.
Puppet valve	See poppet valve.
Push rod	In a valve mechanism, a block, usually of cylindrical form, intermediate between the cam and the valve or the valve operating mechanism.
Push rod, mushroom type	A push rod having an enlarged end bearing against the cam.
Push rod, roller type	A push rod containing a roller bearing against the cam.
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Quadrant	Usually applied to the quarter circle on which the spark lever and throttle lever is attached on the steering wheel.
R
Rack & Pinion	Used for smaller cars, this has a pinion gear at the end of the steering column assembly that connects with a ‘rack’. The ‘rack’ is a set of gear teeth on a rod assembly which goes between the tie rods at each end.
Radiator	As applied to an engine, a device of cellular or tubular structure for cooling the jacket water.
Radiator, cellular	See cellular radiator.
Radiator, honeycomb	See honeycomb radiator.
Radiator, tubular	See tubular radiator.
Range, spark	The angular distance from full retard to full advance in a timer.
Rated horsepower	See horsepower, nominal.
Rated load	See horsepower, nominal.
Reciprocating	A back and forth movement applied to the action of the pistons in the engine.
Reciprocating parts	Parts such as the piston, piston rod, crosshead and connecting rod, that move back and forth, usually in the direction of the axis of the cylinder.
Rectifier	An electrical device for changing alternating, into direct, current.
Recirculating ball and nut	A steering gear using balls which circulated between the worm and gear threads. These act as ball bearings to that the action is smoother than just one gear turning against another.
Relief cock	See pet cock. See also cock, drain.
Retard	A decrease in the speed. Usually applied to "retarding the spark," meaning to set the timer back so that the ignition will be later or slower.
Reverse gear	A device, usually applied to marine engines, by means of which the propeller shaft is caused to run in the direction opposite to that of the engine crankshaft.
Reversible engine	An engine which may be reversed in direction independently of a reverse gear.
Ring, piston	A ring of metal, usually cast iron, cut through in one or more places and so constructed that its periphery is forced into contact with the cylinder walls.
Roadster	A small open-type body, having one fixed cross-seat for two passengers and a space or compartment at the rear for carrying luggage. Folding seats fitting into the luggage compartment are sometimes used. The conventional type has two doors and a folding roadster top with emergency side-curtains that are removable.
Rod, connecting	See connecting rod.
Rod, piston	See piston rod.
Roller push rod	See push rod, roller type.
Rotary	Revolving motion; opposite of reciprocating motion.
RPM	Revolutions per minute.
Rubber	For tire construction rubber supplies come from various parts of the world. Amongst the finest grades is the well-known "Para" or Brazil rubber. South American rubber, generally is considered very good, but excellent supplies now come from Borneo, India, Ceylon, Federated Malay States, and, in fact, many other tropical lands. Pure rubber lacks certain important physical characteristics indispensable for tires, such as stability under change of temperature. Pure rubber becomes soft under the influence of heat, and hard and brittle when subjected to cold. The process of vulcanization renders the rubber proof against heat and cold, and also renders it tough and resilient, so as to possess "life" and vibration absorbing properties.
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Salon Touring Car	A touring car with folding top and disappering or revoable glass sides.
Scavenging	The act of clearing the cylinder of the residual burned gas or that gas remaining after the completion of the ordinary exhaust stroke. Scavenging is secured either by driving air through the combustion space or by mechanical means, such as a special piston.
Scored	Marred by ridges or grooves. Usually referred to in connection with cylinders.
Seats	That part of chamber upon which the valve rests, applied to the valve in engine.
Secondary battery	A storage battery.
Secondary coil	The winding in which the high tension current is generated, which is quite distinct from the primary current.
Sedan	An enclosed single-compartment body, with two fixed cross-seats for four or five passengers. Sometimes the front seat is divided by an aisle. Folding seats in the tonneau for two additional passengers are sometimes used. The conventional body has four doors, but some models have only two. There are three moveable glass windows on each side and the roof is non-collapsible.
Sedan-Landaulet	A body of the same general description as the sedan, except that the top back of the rear doors is collapsible. Forwards of this point the roof is non-collapsible, and the windows are the same in number as in the sedan. The rear quarters, the back above the belt, and the roof are covered with leather or fabric.
Self adjusting brake	This type of brake has a device which automatically compensates for the wear of the brake shoe and keeps the shoe close to the drum.
Semi-Diesel motor	See motor, automobile.
Semi-floating axle	Also called the fixed hub type. In this type of axle, the driving shafts turn freely within the housing. At their outer ends they are fixed in the hubs of the wheels and carry the bending stresses as well as the torque.
Service brake	See Foot brake.
Servo	Part of a hydraulic system, the piston contained in a cylinder of hydraulic fluid which moves in response to the pressure of the fluid. It thereby converts the fluid pressure to mechanical action.
Shaft, crank	See crankshaft.
Short circuiting	Providing a shorter path; placing a wire or other conductor, from positive to negative side.
Shunt	To turn aside or branch off.
Single acting engine	An engine in which the impulse is given at one end of the piston only.
Single plate clutch	A variation of the disk type, consisting of 3 broad disks or plates, usually with two driving plates and one driven plate.
Six cycle	See cycle.
Six-cycle engine	See cycle
Six-stroke cycle	See cycle.
Spark	The spark which passes between the points of the spark plug.
Spark coil	A coil through which electric current is passed and intensified.
Spark control lever	The lever on the steering column (usually the short one) attached to the timer.
Spark gap	See gap, spark.
Spark plug	A device for providing the spark gap in the cylinder for jump spark ignition.
Spark range	See range, spark
Speed piston	See piston.
Splash lubrication system	A true splash system alone is non-circulating. The crankcase is made oil tight and oil is placed in it to such a depth that the bottom end of the connecting rod dips into the oil and splatters it to all parts of the crankcase, bearings and the lower part of the piston. An oil groove is sometimes cut around the lower part of the piston and the oil splashing into this is carried upward and distributed on the cylinder walls and rings.
Starter, electric	See electric starter.
Starter	A device for setting the engine in motion so it will take up its cycle. See air, electric starter, etc.
Starting crank	A crank for starting the engine. See also crank case or chamber.
Starting plug	A small brass plug which fits into an opening on the dashboard and closes the circuit. When removed, the circuit is broken.
Static balance	See balance, running.
Stationary electrode	See electrode, of the spark plug.
Stationary engine	An engine for driving fixed machinery.
Stationary electrode	See electrode, of the spark plug.
Steering gear	Reduction gearing used to turn the front wheels, it converts the the motion of the steering wheel into the straight-line motion which turns the wheels. Although there are many names for steering systems, there are basically just two types. The first and oldest is a worm with a gear, and the second is modern rack and pinion. Worm & Sector - Consists of a worm which is attached to the lower end of the rod moved by the steering wheel. Meshing with the worm is a sector wheel, so that turning the steering wheel turns the worm and moves the sector wheel. Screw and Nut - Has a nut through which the worm passes. Insead of a sector the nut is used. The worm is fastened to the steering rod. Turning the steering wheel moves the nut up and down. Worm and Nut - Same as screw and nut. Irreversible - When an ordinary road wheel impact will be insufficient to turn the steering wheel. This is simply a question of reduction between the steering worm and the gear, the greater the reduction, the less reversible the system and likewise the slower the motion of steering the road wheels in relation to the movement of the steering gear. Therefore a heavy car will be normally less reversible than the steering gear on a lighter car. Rack & Pinion - Used for smaller cars, this has a pinion gear at the end of the steering column assembly that connects witha ‘rack’. The ‘rack’ is a set of gear teeth on a rod assembly which goes between the tie rods at each end.
Storage cell	See cell, electric.
Stroke	Usually referred to as the stroke of an engine, meaning the length of the up and down motion of a piston.
Stroke, compression	See compression.
Stroke, exhaust	See exhaust, water.
Stroke, inlet	See inlet manifold.
Stroke, inward	See inward stroke. See also stroke, of piston.
Stroke, of piston	The complete movement of the piston in the direction of the axis of the cylinder. Inward stroke - The movement of the piston toward the head of the cylinder, and away from the crankshaft. Outward stoke - The movement of the piston toward the crankshaft.
Stroke, outward	See stroke, of piston.
Stationary electrode	See electrode, of the spark plug.
Studs	Bolts, with threads cut on both ends screwed into engine cylinders to fasten them to base, also used to fasten down cylinder heads.
Sub frame	See frame.
Suction Valve	See automatic valve.
Suction gas	Producer gas secured by the suction of the engine drawing air through a bed of incandescent fuel.
Suction-gas engine	An engine operating on suction gas. Suction-gas valve. See automatic valve.
Super-Diesel motor	See motor, automobile.
Synchronization	To time two or more sparks to occur exactly at the same instant or at a similar period in a given cycle of operation.
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Tandem engine	An engine having two pistons on the same axis and connected by a piston rod.
Tappet	A push rod connected between the cam and valve. Also termed a plunger.
Thermal unit	See heat unit.
Thermal unit, British	See heat unit.
Thermal efficiency	See efficiency.
Thermo-syphon circulation	Circulation of the cooling water caused by the heat in the water jacket. Upon becoming heated, the water rises to the top, entering the pipe and passing into the radiator at the top, where it is brought into contact with a large cooling surface in the shape of the radiator. On being cooled, and thereby becoming heavier, the water sinks again to the bottom of the cooling system to enter the cylinder once more and repeat its circulation. The cooling action is further increased by a belt driven fan which draws air through the radiator spaces.
Three-port motor	A form of two-cycle motor in which the passage to the crankcase is through a piston-controlled port.
Three-quarter floating axle	Also called the flanged shaft type. The housing extends into the hubs of the wheels as in the full floating type, but the ends of the driving shafts are connected rigidly by flanges with the wheels so that the shafts take almost all the bending stresses and all the torque.
Throttle	A valve for choking the intake passage between the carburetor and the inlet valve.
Throttle, butterfly	See butterfly throttle.
Throttling governor	See governor.
Throw	Usually referred to as the crank, or the part where the big end of the connecting rod attaches to crank shaft.
Timer	A rotating switch for closing the ignition circuit at the proper time in the cycle.
Timing, exhaust	See exhaust, water.
Tonneau; plural, Tonneaux	Derivation, French word meaning a barrel;. a wooden vessel formed of staves and hoops and made to contain a tonneau (1,000 kilograms) of oil. Later, a horse drawn carriage, known in England as a governess car, having a rear entrance. A similar type of body was first applied to a motor car by M. Huillier, of Paris, and by reason of its resemblance to a barrel and to the horse drawn tonneau already existing, was known as a tonneau.
Torque	The word torque is a definite one and means the same whether referred to automobiles or any other piece of mechanism, and refers to the twisting or wrenching effect produced by the engine or motor.
Torque tube	This is the tube containing the drive shaft which runs fromt he transmission to the rear axle. As the rear wheels move, the wheel and axle housing reacts by trying to rotate in the opposite direction, which sould cause the torque tube to bend. This motion is what the torque tube was designed to resist.
Torsion bar suspension	Essentially a coil spring that has been pulled straight. It is fastened rigidly at one end to the frame and at the other end to a control arm. As the level of the wheel changes, the torsion bar is caused to twist or untwist, functioning like a spring.
Touche	The small plug used in the switch to complete the electrical circuit when required. (French.)
Tractor	See gas tractor.
Trans-axle	Combines the functions of the transmission and axle. Normally used in cars with a front engine and front wheel drive and in cars with a rear engine and rear wheel drive.
Transfer port	The passage from the base to cylinder of a two-cycle engine.
Transformer	Another name for a high tension coil. An electrical device for transforming the current from a low tension to a high tension. An induction or secondary or high tension, double wound, coil.
Transmission dynamometer	See dynamometer.
Tread	Distance between tires on the same axle.
Trembler	The small vibrating spring used for making and breaking the primary circuit of a coil.
Trunk piston	See piston.
Tube ignition	A small tube, usually of platinum, having its outer end closed, is screwed into the combustion chamber. This tube is so placed that the flame of a blow-lamp, generally supplied from. a separate and small tank of gasoline, acts upon it and causes it to become incandescent. Old method of ignition now out of date.
Tubular radiator	Consists of vertical tubes placed between the upper and lower radiator tank. The water passes downward through all of the tubes. If one tube becomes clogged, then all of the water must pass through the other tubes. Each tube is a separate path through the radiator.
Tuning an engine	Extreme care and special adjustment, as tuning up a car for a race, etc.
Twin engine	Same as duplex engine.
Two cycle	See cycle.
Two-cycle engine	An engine employing the two-stroke cycle. See also cycle.
Two-stroke cycle	See cycle.
Two-to-one gear	The gearing, usually consisting of two-gear wheels one having exactly double as many teeth as the other, also called "timing gears” and “halftime-gears”.
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Unsteadiness, coefficient of	See coefficient of unsteadiness.
V
Valve	A device for closing an opening in any part of the engine. See definitions under various heads, as automatic, exhaust, flat, inlet, etc.
Valve, automatic	See automatic valve.
Valve, compensating	See compensating air valve.
Valve, exhaust	See exhaust, water.
Valve, inlet	See inlet manifold.
Valve, mixing	See mixing valve.
Valve, poppet	See poppet valve.
Valve, suction	See automatic valve.
Valve in head engine	See head, cylinder.
Valve-lifter	An additional lever by means of which the exhaust valve may be raised and kept out of action, thereby reducing the compression and preventing the creation of a vacuum within the cylinder, so causing the inlet valve to remain closed. Used extensively on aero and stationary gasoline engines. This term also applies to a "valve spring lifter.”
Vaporizer	An early form of carburetor valve. The vaporizer is also a means of heating the fuel.
Venturi	Applies to the mixing chamber of a carburetor.
Vertical engine	One in which the axis of the cylinder is normally vertical.
Vibrator	The magnetic circuit breaker of a jump spark coil.
Viscosity	The adhesive or glutinous characteristic of oils used for lubrication.
Volumetric efficiency	See efficiency.
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Water carburetor	A simple carburetor for supplying water to the intake of a kerosene engine. Jacket, water - See jacket, water.
Water discharge	See discharge, water.
Water gas	See gas.
Water jacket	See jacket.
Watt	The unit of electrical power obtained by multiplying volts by amperes.
Wet-Cell	A battery using a liquid solution.
Wet plate clutch	A lubricated multiple disk clutch which runs in an oil bath. See also disk clutch.
White metal	Also called anti-friction metal. An easily fusible alloy of lead, antimony, and tin used for "lining" re-metalling bearings.
Wooden wheels	Made with a wood felloe, over which fits a steel rim that holds the tire. It is called an artillery type wheel.
Worm gear	A gear which resembles a screw with a giant thread that meshes with another gear.
Wrist pin	The piston pin, also called the gudgeon pin. The crank pin is sometimes, but erroneously, termed the wrist pin.
X
Y
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