of 1852 /1852
DICTIONARY OF AUTOMOTIVE TERMS "A" [Home][A] [B][C] [D][E] [F][G] [H][I] [J][K] [L][M] [N][O] [P][Q] [R][S] [T][U] [V][W] [X][Y] [Z] [A] [Ab] [Ac] [Ad] [Ae] [Af] [Ag] [Ah] [Ai] [Al] [Am] [An] [Ap] [Aq] [Ar] [As] [At] [Au] [Av] [Aw] [Ax] A: Abbreviation or symbol for absolute temperature , absorption coefficient , acceleration , adenine , ampere , amplitude , angular acceleration , area , attenuation coefficient , fine-structure constant , helium nucleus, Helmhotz free energy , magnetic vector potential , relative atomic mass , a stereoisomer of a sugar, substitution on a carbon atom next to one common to two condensed aromatic nuclei, substitution on the carbon atom next to the hetero-atom in ahetero-cyclic compound, and substitution on the carbon atom of a chain next to the functional group A-2 tire: A term used for tire sizes 16.00 and larger in nominal cross section. Also called "earthmover" or "off-the-road" tires AA: Abbreviation for "Automobile Association" a term used in Great Britain aa: A term of Hawaiian origin for lava flows with a rough, jagged surface AAA: Acronym for "American Automobile Association" or "Alberta Automobile Association." AABM: Acronym for "Association of American Battery Manufacturers, Inc." AAE: Acronym for "Association of Automotive Employers" (Poland). AAIA: Acronym for "Automotive Aftermarket Industry Association" AALA: Acronym for "American Automobile Labelling Act ." Aalenian: The oldest stage of the Middle-Jurassic AAM: Acronym for "Alliance of Automobile Manufacturers" AAP: Acronym for "auxiliary acceleration pump "

Dictionary of Automotive Terms

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DICTIONARY OF AUTOMOTIVE TERMS "A" [Home][A] [B][C] [D][E] [F][G] [H][I] [J][K] [L][M] [N][O] [P][Q] [R][S] [T][U] [V][W] [X][Y] [Z] [A] [Ab] [Ac] [Ad] [Ae] [Af] [Ag] [Ah] [Ai] [Al] [Am] [An] [Ap] [Aq] [Ar] [As] [At] [Au] [Av] [Aw] [Ax]

A: Abbreviation or symbol for absolute temperature, absorption coefficient, acceleration, adenine, ampere, amplitude, angular acceleration, area, attenuation coefficient, fine-structure constant, helium nucleus, Helmhotz free energy, magnetic vector potential, relative atomic mass, a stereoisomer of a sugar, substitution on a carbon atom next to one common to two condensed aromatic nuclei, substitution on the carbon atom next to the hetero-atom in ahetero-cyclic compound, and substitution on the carbon atom of a chain next to the functional group

A-2 tire: A term used for tire sizes 16.00 and larger in nominal cross section. Also called "earthmover" or "off-the-road" tires AA: Abbreviation for "Automobile Association" a term used in Great Britain aa: A term of Hawaiian origin for lava flows with a rough, jagged surface AAA: Acronym for "American Automobile Association" or "Alberta Automobile Association." AABM: Acronym for "Association of American Battery Manufacturers, Inc." AAE: Acronym for "Association of Automotive Employers" (Poland). AAIA: Acronym for "Automotive Aftermarket Industry Association" AALA: Acronym for "American Automobile Labelling Act." Aalenian: The oldest stage of the Middle-Jurassic AAM: Acronym for "Alliance of Automobile Manufacturers" AAP: Acronym for "auxiliary acceleration pump"

A arm: See A-arm. A-arm: A suspensionlinkage formed in the shape of an "A" or "V" found commonly on the front suspension. The sides of the two legs of the A-arm are connected to the chassis by rubber bushings and the peak of the A-arm is attached to the wheel assembly. In this way, the wheel can freely move up and down. Sometimes there is an upper A-arm, a lower A-arm, or both upper and lower A-arms. The British call it a "wishbone." Also see twin A-arm suspension A-arm suspension: See twin A-arm suspension AAS: Acronym for "air aspirator system" abacus: [1] The uppermost part of a colurnn capital or pilaster, on which the architrave rests. [2] A bead frame. Used as an arithmetic calculating aid. abampere: A unit of electric current in the CGS electromagnetic system of units. One abampere equals 10A. abamurus: A supporting wall or buttress, built to add strength to another wall. abandonment: A voluntary surrender of legal rights or title to a mining claim. abatjour: An opening to admit light and generally to deflect it downwards; a skylight abaxial: Rays of light which do not coincide with the optical axis of a lens system. Abbe refractometer: An instrument for measuring directly the refractive index of liquids, minerals and gemstones. ABC: [1] Acronym for "aerial bunched conductors." [2] Acronym for "automatic beam control" ABDC: A term used in timing the relation of the spark and the crankshaft. It stands for after bottom dead center. Abegg's rule: Empirical rule that the solubility of salts of alkali metals with strong acids decreases from lithium to caesium, i.e., with increase of relative atomic mass, and those with weak acids follow the opposite order. Sodium Chloride is an exception to this rule, being less soluble than potassium chloride. Abegg's rule of eight: A rule that the sum of the maximum positive and negative valencies

of an element is eight, e.g., sulphur in SF6 and H2S. Abel flashpoint apparatus: A petroleum-testing apparatus for determining the flash-point Abelian group: A group in which the group operation is commutative. It is important in the study of rings and vector spaces. abelite: An explosive, composed mainly of ammonium nitrate and trinitrotoluene. aberration: [1] An apparent change of position of a heavenly body, due to the speed of light having a finite ratio to the relative velocity of the source and the observer. [2] In an image-forming system, e.g., an optical or electronic lens, failure to produce a true image, e.g., a point object as a point image. Geometrical aberrations include spherical aberration, coma, astigmatism, curvature of the field and distortion. See chromatic aberration abhesive: A substance which prevents two materials sticking together, e.g., teflon on frying pans.

ability: See climbing ability cold cranking ability ABL: Acronym for "atmospheric boundary layer" panel ablation: [1] Any one of the processes by which snow and ice are lost from a glacier, mainly by melting and evaporation (sublimation). [2] Removal of surface layers of a meteorite and tektites during flight. ablative polymer: A material which degrades controlably in an aggressive environment, especially on re-entry space-craft. Extreme temperatures are reached on heat shield, so it is protected with ablation shield made of e.g., silicone polymer. The same principle is used in intumescent paints for fire resistance Abney law: A rule stating that if a spectral color is desaturated by the addition of white light, and if its wave length is less than 570 nm, its hue then moves towards the red end of the spectrum, while if the wavelength is more than 570 nm its hue moves towards the blue. Abney level: Hand-held instrument in which angles of steep sights are measured while simultaneously viewing a spirit-level bubble. Abney mounting: A form of mounting for a concave diffraction grating, in which the eyepiece (or photographic plate holder) is fixed at the center of curvature of the grating and the

slit can move around the circumference of the Rowland circle, to bring different orders of spectrum into view. abnormal glow discharge: A discharge carrying current in excess of that which is required to cover the cathode completely with visible radiation. Abnormal reflection: Reflection from the ionosphere of a radio wave whose frequency is greater than the critical frequency. aboard: See lighter aboard ship aboard ship: See lighter aboard ship A-bomb: See atomic bomb A bone: Model "A" Ford. abort: To terminate a vehicle's flight either by failure or deliberate action to prevent dangerous consequences; if manned, a predetermined sequence of events is followed to ensure the safety of the crew. ABPV: Acronym for "air bypass valve" abradant: A substance, usually in powdered form, used for grinding. See abrasive abrade: To scratch or tear away two surfaces in contact by relative motion. Abram's law: A rule that the ratio of water to cement for chemical action to impart strength to concrete is 0.85:1. abrasion: [1] Wearing or rubbing away some surface because of friction. [2] Mechanical wearing away of rocks by rubbing during movement. abrasion hardness: Resistance to abrasive wear, under specified conditions, of metal or mineraL abrasive: A hard grit used for sanding or grinding. It is usually in powdered form, used for the removal of material by scratching and grinding, e.g., silicon carbide powder (carborundum). Also see bonded abrasive coated abrasive non-woven abrasive abrasive blast cleaning: A method for preparing steel for painting whereby abrasive particles, e.g., copper slag, are projected under pressure through a nozzle. Very effective in

removing rust and mill scale, leaving an anchor pattern (a pattern of minute projections) on the substrate affording good paint adhesion. abrasive cleaner: A cleanser with some hard grit used to remove the grime and oils from a surface. abrasive disc: A circular plate (often made of plastic with hard grit embedded into it) used for grinding or sanding. abrasive paper: Sandpaper (a paper upon which sand or hard grit has been glued) used for sanding or grinding. abrasive wear: A mechanism of wear due to the presence in one or both surfaces of hard particles (e.g., carbide in steels), or to hard particles trapped between them. A/B roll editing: Video editing using two source players (A and B) enabling dubbing from both. Necessary if scenes are to be superimposed. A/B roll printing: A method of film printing with alternate scenes assembled in two rolls, each having black spacing equivalent in length to the omitted scene; double printing from the two allows the inclusion of fade and dissolve effects and avoids visible splice marks between scenes in 16 mm printing. ABS: [1] Acronym for "anti-lock brakes. [2] Acronym for "acylonitrile-butadiene-styrene." Also see copolymer abscissa: For rectilineal axes of coordinates, the distance of a point from the axis of ordinates measured in a direction parallel to the axis of abscissae, which is usually horizontal. The sign convention is that measurements to the right from the axis of ordinates are positive, measurements to the left negative. absolute: [1] A conic (a quadric in three dimensions) formed by the assemblage of the points at infinity on a line (in general two points). Its form determines the metrical properties of the geometrical system being operated. Thus in Euclidean geometry, the absolute is the degenerate conic comprising the line at infinity taken twice, while in nonEuclidean geometry, the absolute is either a real conic (hyperbolic geometry) or an imaginary conic (elliptic geometry). Also see manifold absolute pressure sensor pilot operated absolute absolute address: A computer code designation of a specific memory location as determined by the hardware.

absolute age: The geological age of a fossil, mineral, rock or event, generally given in years. absolute alcohol: Water-free ethanol; rel.d. 0.793 (15.5C); bp 78.4C; obtained from rectified spirit by adding benzene and refractionating. Very hygroscopic. absolute ampere: the standard MKS unit of electric current; replaced the international ampere in 1948

absolute ceiling: The height at which the rate of climb of an aircraft, in standard atmosphere, would be zero; the maximum height attainable under standard conditions

absolute configuration: the arrangement of groups about an asymmetric atom, especially a tetrahedrally bonded atom with four different substituents

absolute electrometer: A high-grade attracted-disk electrometer in which an absolute measurement of potential can be made by weighing the attraction between two charged disks against gravity

absolute filter: A filter which removes most particulate matter from gases

absolute humidity: the mass (actual amount) of water vapor present in a unit of volume of moist air

absolute instrument: An instrument which measures a quantity directly in absolute units, without the necessity for previous calibration

absolute permeability: See permeability

absolute potential: The theoretical true potential difference between an electrode and a solution of its ions, measured against a hypothetical reference electrode, having an absolute potential of zero, with reference to the same solution

absolute pressure: pressure measured from a starting point of zero in perfect vacuum. When measured by the absolute pressure scale, atmospheric pressure is 14.7 psi or 29.92 inches of mercury (in-Hg). Also see manifold absolute pressure sensor absolute pressure sensor: See manifold absolute pressure sensor

absolute reaction rate: The reaction rate determined from statistical thermodynamics; uses the assumption of the theory of absolute reaction rates that the rate of a chemical reaction is governed by the rate of crossing an energy barrier or of forming an activated complex

absolute temperature: Temperature measured with respect to absolute zero, i.e., the zero of the kelvin thermodynamic scale of temperature, a scale which cannot take negative values

absolute temperature scale: also called the "absolute scale temperature" as measured on a scale in which the hypothetical lowest limit of physical temperature is assigned the value zero. The Kelvin scale is an example of the absolute temperature scale

absolute units: Units derived directly from the fundamental units of a system and not based on arbitrary numerical definitions. The differences between absolute and international units were small; both are now superseded by the definitions of SI units

absolute wavemeter: A wavemeter in which the frequency of the injected radio-frequency signal is by calculation of physical properties (circuit elements or dimensions) of a resonant circuit line or cavity

absolute weight:

The weight (or mass) of a body in a vacuum

absolute zero: The point at which there is a total absence of heat, minus 459.67F (-273.15C)

absorbance: [1] The logarithm of the ratio of the intensity of light incident on a sample to that transmitted by it. It is usually directly proportional to the concentration of the absorbing substance in a solution. [2] The capacity of materials such as textile fibers and paper to absorb liquids

absorbed dose: Quantity of energy imparted by ionizing radiation to a unit mass of biological tissue. Unit is the gray

absorber: Any material which converts energy of radiation or particles into another form, generally heat. Energy transmitted is not absorbed. Scattered energy is often classed with absorbed energy. Also see air shock absorber damper direct-actingshock absorber double-tube shock absorber friction shock absorber gas shock absorber impact absorber lever-type shock absorber monotube shock absorber self-levelling shock absorber shock absorber single-tube shock absorber telescopic shock absorber UV absorber absorber rod: See control rod

absorber tower:

See shock absorber tower

absorbing: See energy absorbing steering column energy absorbing bumper absorbing bumper: See energy absorbing bumper

absorbing material: any medium used for absorbing energy from radiation of any type

absorbing steering: See energy absorbing steering column

absorbing steering column: See energy absorbing steering column

absorptance: A measure of the ability of a body to absorb radiation; the ratio of the radiant flux absorbed by the body to that incident on the body

absorptiometer: An apparatus for determining the solubilities of gases in liquids or the absorption of light

absorption: The use of reagents to remove unwanted antibodies or antigens from a mixture. Also see sound absorption absorption band: A dark gap in the continuous spectrum of white light transmitted by a substance which exhibits selective absorption

absorption capacitor:

A capacitor connected across a spark gap to damp the discharge

absorption coefficient: [1] The volume of gas, measured at stp, dissolved by unit volume of a liquid under normal pressure (i.e., one atmosphere). [2] The fraction of the energy which is absorbed. [3] The reduction of amplitude, for a beam of radiation or other wave system incident on a discontinuity in the medium through which it is propagated, or in the path along which it is transmitted. [4] In a medium, the natural logarithm of the ratio of incident and emergent energy or amplitude for a beam of radiation passing through unit thickness of a medium.

absorption discontinuity: See absorption edge

absorption dynamometer: A dynamometer which absorbs and dissipates the power which it measures, e.g., the ordinary rope brake and the Froude hydraulic brake

absorption edge: The wavelength at which there is an abrupt discontinuity in the intensity of an absorption spectrum for electromagnetic waves, giving the appearance of a sharp edge in its photograph. The transition is due to one particular energy-dissipating process.

ABS override button: A button or switch which disengages the automatic anti-lock braking system so that the driver can operate the brakes himself.

ABS relay valve: An electrically controlled valve which modulates the air pressure in the ABS.

abut: The action of two gear teeth making contact.

abutment: [1] A part which stops the motion of another part from proceeding any farther. [2] A cement raised shoulder secured to the side of the road to prevent a vehicle from going over the edge.

[3] The contact made between opposing teeth of two gears.

abutting edge: The side or edge of a panel which joins another panel.

ABV: Acronym for "air bypass valve"

A/C: [1] An abbreviation for air conditioning or air conditioner. [2] An abbreviation for "across corners" which indicates the distance on a nut (for instance) from one corner to the opposite corner rather than the distance from one flat surface (A/F) to the opposite (which would be the size of wrench needed to install or remove the nut). The purpose of the A/C dimension is to know how large a hole might be needed to insert a recessed nut.

AC: [1] A vehicle brand of which the 1925-48 models are classic cars. [2] Acronym for "alternating current." [3] Acronym for "air conditioning" or "air conditioner."

AC Ace: A vehicle brand of which the 1954-61 Ace models are milestone cars.

AC Aceca: A vehicle brand of which the 1955-61 Aceca models are milestone cars.

ACAP: Acronym for "Associao do comrcio automovvel de Portugal"

AC Buckland: A vehicle brand of which the 1949 Buckland Open Tourer is a milestone car.

acc: Abbreviation for "accessories."


[1] Acronym for "Automatic Cruise Control." [2] A term found on a cruise control switch which indicates the direction the switch needs to be moved to increase the speed (accelerate) of the vehicle.

ACCC: Acronym for "air conditioner clutch compressor" signal

accelerate: To increase the speed of a vehicle. Opposite of decelerate.

accelerating-well ports: these ports prevent momentary leanness during the period that occurs between the opening of the air valve and the actual discharge of fuel from the secondary nozzles

acceleration: The rate of change of velocity or speed. Velocity is steady and is measured in distance per time (e.g., feet per second, miles per hour, kilometres per hour). Acceleration keeps increasing and is measured in velocity per time (e.g., feet per second per second or feet per second squared). Also see lateral acceleration sluggish acceleration yaw acceleration acceleration enrichment: The action of increasing the fuel/air mixture during acceleration in order to improve the vehicle's speed and its smooth response.

accelerator: [1] In automobiles, this is the "gas pedal" which is attached by linkage to the throttle in the carburetor or to the fuel injection system. It regulates the amount of fuel which is sent to the engine. In motorcycles, the accelerator is located on the right-hand twist grip or an actuating lever. [2] A chemical which is added to something to make a process happen more quickly. For example, a chemical may be added to paint to cause it to dry faster. The opposite is "retarder." Also see depress the accelerator

ease up on theaccelerator step on the accelerator take foot off the accelerator accelerator interlock: A connection between the gas pedal and the automatic transmission.

accelerator pedal: The accelerator, gas pedal, or throttle pedal.

accelerator pump: A small pump usually located inside the carburetor that sprays an extra amount of fuel into the engine during acceleration. It improves acceleration by giving more boost and reducing a momentary lag in power. It is actuated by depressing the pedal.

accelerometer: An instrument which measures the amount of acceleration.

acceptable quality level: (AQL) A manufactured good that may not be perfect but does reach a level of shape, size, and performance, etc. that will make it work and last as long as the manufacturer expects.

acceptance test: An examination of a part or its assembly to determine if it meets a prescribed standard.

access: A way of reaching something that is usually hidden or covered. Also see access panel access hole: An opening through which you can reach something. It is usually covered with a panel.


Items and packages of equipment which are beyond the standard equipment supplied in a new vehicle.

accessory: See accessories.

accessory package: A set of features or appointments which may be ordered at extra cost on a new vehicle.

access panel: The cover which conceals the engine on a mid-engine vehicle. Also called "engine cover." Also see hood accident: See car accident

accident damage: The destruction caused to a vehicle's bodywork when it is involved in an accident.

Accord: A model of automobile manufactured by Honda Click for books on Honda Accord accumulator: [1] A storage battery for an electric car. [2] A pressurized container for an automatic levelling suspension system. [3] A part of the hydraulic system which is charged by the fluid pump, absorbs fluctuating fluid delivery, stores fluid at pressure, and can provide a rapid flow of fluid under pressure. Also see accumulator piston fuel accumulator hydraulic accumulator pressure accumulator accumulator battery:

A storage battery (i.e., the main battery in your vehicle).

accumulator drier: A device which is part of the air conditioning system. It is made up of a tank, filter, drying agent, and a vapor return tube. It is usually found on the evaporator outlet. It stores the excess refrigerant and removes the moisture from the refrigerant (thus the name "drier"). Also see receiver drier accumulator piston: A unit found in the automatic transmission to assist the servo to apply the brake band quickly and smoothly.

accumulator system: In an automatic transmission, it includes a hydraulic accumulator piston which is controlled by a valve.

accumulator valve: A device which operates the hydraulic accumulator piston in an automatic transmission.

Ace: An American trucker's colloquial term for someone with a class "A" licence. Also see AC Ace ACEA: Acronym for "Association des Constructeurs europens dAutomobiles" (i.e., European Automakers Association)

Aceca: See AC Aceca.

acetylene: A gas composed of two parts of carbon and two parts of hydrogen. When burned in an atmosphere of oxygen, it produces one of the highest flame temperatures obtainable for welding.

Also see oxygen acetylene cutting acetylene bottle: See acetylene cylinder

acetylene cutting: See oxygen acetylene cutting

acetylene cylinder: A specially built container manufactured according to I.C.C. Standards. Used to store and ship acetylene. Also called "acetylene tank" or "acetylene bottle"

acetylene hose: A flexible medium used to carry gases from regulators to the torch. It is made of fabric and rubber.

acetylene regulator: An automatic valve used to reduce acetylene cylinder pressures to torch pressures and to keep the pressures constant.

acetylene tank: acetylene cylinder

AC generator: A generator produces direct current (DC) while an alternator produces alternating current (AC). Because alternators were introduced to automobile electrical systems after generators had been in use for some time, some people referred to the new alternator as "AC generator."

ache: See head ache rack

ache rack: See head ache rack


Also see battery acid chromic acid oxalic acid acid rain: When the smoke created by factories and vehicle exhausts is taken by the wind and joined with rain clouds, the mixture is often acidic. As a result the rain that falls to the ground (and even on your car) may damage whatever it strikes.

AC Ignition System: See continuous AC Ignition System

Ackermann: See Ackermann steering.

Ackermann steering: A double-pivoting steering system where the outer ends of the steering arms are bent slightly inward so that when the vehicle is making a turn, the inside wheel will turn more sharply than the outer wheel. This is done to compensate for the greater distance the outside wheel must travel. Ackermann angle: The toe-out or toe-in of a vehicle with Ackermann steering when the wheels are positioned straight ahead.

Ackermann axle: In a vehicle with Ackermann steering (at the front of the vehicle), it is a nonrotating axle that is steerable and has two pivot points (one on each end of the axle) with vertical kingpins.

ACL BI-MET: Acronym for "air cleaner bi-metal sensor"

ACL DV: Acronym for "air cleaner duct and valve vacuum" motor

acquisition fee:

A charge for processing a lease and is probably not negotiable. On a shorter term lease, the acquisition fee can have a large impact on the cost of the lease.

across corners: (A/C) The distance on a nut (for instance) from one corner to the opposite corner rather than the distance from one flat surface (A/F) to the opposite (which would be the size of wrench needed to install or remove the nut). The purpose of the A/C dimension is to know how large a hole might be needed to insert a recessed nut.

across flats: (A/F) The distance on a nut (for instance) from one flat surface to the opposite flat surface, i.e., this is the size of the wrench needed to install or remove the nut. Also see across corners. acrylate: A polymer used to strengthen rubber (e.g., ethyl acrylate).

acrylic: A term relating to a type of paint made by polymerizing acrylonitrile.

acrylic finish: A final coating of paint which uses acrylic paint, often where the pigment and an acrylic paint are mixed together. Also see two-pack paint. acrylic paint: A type of paint made by polymerizing acrylonitrile.

acrylic resin: A thermoplastic synthetic polymer made by polymerizing an acrylic derivative such as acrylonitrile, acrylic acid, ethyl acrylate, and methacrylate. It is used for adhesives, protective coatings, and paint finishes.

AC Shelby Cobra: A vehicle brand of which the 1962-67 Shelby Cobra models are milestone cars.

ACT: Acronym for "air charge temperature."

Act: See motor Vehicle Safety Act

acting: Also see double-acting dual-acting single-acting action: Also see capillary action caster action mist action oscillating action parallel action locking pliers reciprocating action action brakes: See servo action brakes

action locking: See parallel action locking pliers

action locking pliers: See parallel action locking pliers

activated: See cable activated

activated carbon: A highly porous carbon which is able to absorb gases and fluids. It is usually found in small pellets so that the surface area is greater than a large chunk of it. Also it has a number of pores on each pellet to increase the surface area more. Thus the greater surface area means greater ability to absorb. Also called "activated charcoal."

activated carbon canister: An automotive filter in which activated carbon has been placed so that gas tank fuel vapors, which have accumulated when the vehicle is not running, are trapped in the filter. When the engine is running, hot air is forced into the filter and push out the vapors into the engine. In this way, pollution is reduced and conservation of the fuel is maintained. Also called "activated charcoal trap" or "charcoal canister."

activated charcoal: Also see activated carbon charcoal activated charcoal trap: See activated carbon canister.

activator: A substance which is used to speed up the process of curing a tire.

active braking time: The length of time (excluding the driver's reaction time) a vehicle takes to come to a complete stop after the brakes are applied.

active material: in a storage battery, peroxide of lead (brown) in positive plates and metallic lead (gray) in negative plates upon which sulphuric acid acts

active noise control system: See anti-noise system.

active safety: The opposite of passive safety. Passive safety involves seat belts, airbags, bumpers, etc. so that in the event of an accident the passengers are protected. Active safety involves factors which will assist the driver in avoiding an accident. They include brakes, steering, handling response, acceleration, etc.

active suspension:

While conventional suspension uses springs and shock absorbers to isolate the vehicle from the bouncing movement of the wheels when it contacts rough roads, active suspension uses power actuators which are controlled by a computer. These actuators place the wheels of the vehicle in the best position to accommodate rough roads as well as compensate for different load levels.

Activities: See Kaizen Activities

activity: See catalytic activity low temperature activity specific activity ACTS: Acronym for "air charge temperature sensor"

actual cash value: (ACV) The amount of money a dealer has invested in the purchase of a used vehicle and any additional costs to repair the unit in order to get it ready for resale.

actual throat: A welding term which describes the distance from the face of a weld to the root of the weld

actuate: The action of bringing a part or assembly into operation.

actuating lever: A triggering device used to bring a part or assembly into operation.

actuating switch: A triggering device used to bring a part or assembly into operation.


See variable valve actuation

actuator: A device which controls or operates another device. Also see hydraulic actuators actuator arm: An arm connecting the diaphragm to the contact breaker platform in an advance mechanism. Also called "diaphragm link."

Acura: A vehicle brand from the Honda manufacturers ACV: [1] Acronym for "actual cash value." [2] Acronym for "air control valve" Click for books on Acura

ad: See classified ad

adapter: (Also spelled "adaptor") A connector which links two items usually of dissimilar structure or size. Also see bit adapter carburetor adapter engine adapter increasing adapter ratchet adapter reducing adapter transmission adapter wheel adapter. adaptor carburetor: a device attached to a gasoline carburetor which permits an internal combustion engine to run either on gas or liquefied petroleum gas (LP gas)

adapter plate:

(Also spelled "adaptor plate") A plate which is placed between two different parts in order to link them. Also see transfer plate additive: A substance (liquid or powder) which is added to gasoline or oil and is intended to improve the characteristics of the original product. Also see anti-knock additive fuel additive oil additive ADEFA: Acronym for "Asociacion de Fabricas de Automotores" (Argentina)

adhere: To stick or be glued to something.

adhesion: [1] The ability of paint, primer, or glue to stick to the surface to which it is applied. [2] The ability of a tire to grip the surface of the road. Also see intercoat adhesion failure limits of adhesion adhesion failure: See intercoat adhesion failure

adhesive: A substance (like glue) that is used to join two substances. Also see automotive adhesive impact adhesive separate-application adhesive adhesive tape: A tape with a sticky substance on one side. It usually comes in a roll of various widths. Sometimes used to insulate electrical wires (e.g., electrical tape) or to wrap a larger object (e.g., duct tape). Often the non-sticky side is shiny (but not always).

adhesive weight: Lead wheel weights which have a sticky backing. It comes in strips and is applied to a wheel rim. Also called "tape weight."

adiabatic: A property of being able to maintain heat evenly. It does not gain any heat or lose it. Also see thermal efficiency adiabatic engine: An engine which is very efficient in transferring combustion heat to those parts of the engine which are being cooled by the flow of anti-freeze coolant -- thus maintaining an even temperature of the engine. In this way the engine is warm enough for efficient running and it does not overheat.

adjust: The action of putting something into its proper alignment or position. It may involve one component (e.g., He adjusted the gasket to fit properly.) or a series of components (e.g., He adjusted the poor idle -- might mean he set the ignition timing, adjusted the carburetor screws, changed the choke setting, cleaned or replaced the spark plugs, etc.) Also see tweak adjustable: A characteristic of something that can be changed, removed, or give different properties. Also see height adjustable steering column adjustable cup: The left-hand cup in a bottom bracket of a bicycle, used in adjusting the bottom bracket bearings and removed during bottom bracketoverhaul. The other cup is the fixed cup.

adjustable off-idle air bleed: some emissions-era Rochester carburetors have a separate air passage to bleed air past an adjustment screw into the idle system. this screw is preset by the factory to produce precise off-idle air/fuel mixture ratios to meet emission-control


adjustable part throttle: (APT) a supplementary circuit on some carburetors that can be adjusted to control part-throttle mixtures more accurately than a fixed orifice. The APT detours around the main jet, going directly from the float bowl to the discharge nozzle feed well.

adjustable rocker arm: a type of rocker arm with an adjusting nut that can be tightened or loosened to adjust valve lash

adjustable shock: See adjustable shocks.

adjustable shock absorbers: shocks with adjustable jounce and rebound characteristics can be stiffened to compensate for wear or to fine tune a suspension for a particular application such as rough roads, heavy loads, or racing

adjustable shocks: Shock absorbers which can compensate for varying needs of stiffness or softness. Manual types require that you physically make the adjustment from one level to another. Automatic types are controlled by a computer as it senses particular changes in road condition.

adjustable spanner: British term for adjustable wrench.

adjustable steering: See height adjustable steering column

adjustable steering column: See height adjustable steering column

adjustable variable exhaust port: A device used on two-stroke engines which automatically alters or varies the exhaust port size.

adjustable wrench: A crescent wrench or pipe wrench. A tool which has a fixed jaw and a movable jaw which is controlled by a spiral gear. It is used to install or remove bolts and nuts of various sizes. The wrench itself comes in a variety of lengths and jaw sizes. A crescent wrench has smooth jaws while a pipe wrench has serrated jaws. British term is "adjustable spanner."

adjusted: See factory adjusted

adjuster: A device for moving something into the correct position or into a different position such as a seat adjuster. Also see automatic wear adjuster brake adjuster horizontal adjuster jet adjuster ride-height adjuster adjuster cam: A device for moving the shoes on drum brakes closer to the drum itself so that there is less travel when the brakes are applied.

adjusting: Also See electrode adjusting tool headlight adjusting screw self-adjusting adjusting gage: See adjusting gauge.

adjusting gauge: A tool used to determine the small distance between two parts so that they can be brought within specifications.

adjusting screw:

A small screw usually found on carburetors, brakes, or headlights which change the way something operates, such as increasing or decreasing the amount of fuel entering the engine; or changing the idle speed; or tightening up the brakes; or changing the setting on rocker arms; or the level of the headlights. Also see headlight adjusting screw tappet adjusting screw valve adjusting screw adjusting shim: A thin washer or plate which reduces or increases the clearance between two components (depending upon where they are placed). While some valves are adjusted by screws on the rocker arm, others are set by inserting a shim to make the same adjustment.

adjusting sleeve: A small cylinder on the end of the tie rod which shortens or lengthens the rod to make changes in the toe-in and toe-out.

adjusting spanner: See brake adjusting spanner

adjusting tool: See brake adjusting tool electrode adjusting tool adjusting wrench: See brake adjusting wrench

adjustment: [1] changing or modifying the position or alignment of two components. [2] the distance of travel that a component has. Also see fore and aft adjustment idle mixture adjustment screw idle speed adjustment adjustment screw:

See idle mixture adjustment screw

Adler: The brand name of a vehicle. With required application the 1925-48 models are classic cars.

a-dos: See dos-a-dos

A-drier: See a-dryer.

A-dryer: A paint dryer which has the heating elements below the paint drying line.

ADS: Acronym for "Association of Diesel Specialists"

adsorption: The bonding that takes place when a gas or vapor comes into contact with a solid. The opposite is desorption.

adsorption canister: See activated carbon canister.

advance: [1] The act of changing the ignition timing so that the spark occurs earlier in the cycle. The opposite is retard. [2] It may refer to the device which makes this adjustment. Also see automatic advance centrifugal advance electronic spark advance ignition advance mechanical advance ported vacuum advance spark advance

speed control vacuum advance vacuum advance advance capsule: See vacuum advance.

advance curve: As the speed of the engine increases the ignition advance also increases. On paper, a pattern is drawn as a curve to represent this relationship.

advanced: [1] A condition in which something occurs early. [2] A product which is on the cutting edge of technology and shows the latest in new ideas and concepts.

advanced rim taper: A rim where both bead seats are tapered 5.

advance mechanism: See vacuum advance mechanism

advance unit: See vacuum advance unit

advance weight: One of two small weights located in a centrifugal advance assembly.

advertising: A colloquial term for a police car with its emergency lights flashing.

AEA: Acronym for "Automotive Electric Association" or "Automotive Electronic Association"


Acronym for "Automotive Engine Rebuilders Association."

aeration: A foaming of a liquid because air has been introduced into the fluid. When it occurs in certain liquids, it decreases the efficiency of the liquid.

aerial: British term for antenna. Also see retractable aerial whip aerial aerobic sealer: a substance (such as room temperature vulcanizing (RTV), a common silicone rubber sealing compound) that requires the presence of oxygen to hold parts together. See anaerobic sealer

aerodynamic: The efficient flow of air around an object.

aerodynamic drag: The resistance of the air to forward movement, sometimes called "air resistance." This is a factor of the shape of the vehicle (drag coefficient and frontal area), the objects which stick out (i.e., mirrors, mufflers, bumpers), the amount of turbulence at the rear of the vehicle, the nature of the vehicle's skin surface, and the amount of air going through the vehicle for cooling and ventilation. The faster you go, the greater the air friction (air friction = velocity x velocity). The faster you go, the greater the amount of power needed to overcome this drag (power = velocity x velocity x velocity).

aerodynamics: The study of the flow of air as it passes over and around a moving object as well as the forces which the air makes on the object. An airplane, for instance, needs positive lift to get it airborne and negative lift to help it land. Thus the shape of a land vehicle (car, bicycle, etc.) either promotes positive or negative lift. Race cars may use spoilers and wings (air foils) to control lift. In vehicle design, the airflow is monitored in a wind tunnel. As well, aerodynamics also studies the most efficient shapes for increased speed and fuel economy.

aerodynamic stance:

In order to create less drag, the vehicle is lowered closer to the ground. This improves the flow of air over the vehicle. A better aerodynamic stance helps the vehicle to go faster when it is going in a straight line as well as give better fuel economy. Also, when a vehicle sits lower to the ground, it has a low center of gravity which makes it more stable when going through turns and enables the driver to maintain a higher speed.

aerofoil: A body shaped like a wing so as to produce lift. See air foil.

A/F: [1] Abbreviation for "across flats" which is the distance on a nut (for instance) from one flat surface to the opposite flat surface, i.e., this is the size of the wrench needed to install or remove the nut. Also see across corners. [2] Abbreviation for "air/fuel." See air-fuel ratio.

AFB: Acronym for "Aluminum four-barrel," as in Carter AFB carburetor.

AFC: Acronym for "air flow controlled"

affected zone: See heat-affected zone

A-Frame: A chassis frame which is shaped like the letter "A" where the crossbar is often the axle. It is usually found as the frame of a trailer.

A/F ratio: See air-fuel ratio.

aft: The back of a vessel. Also see fore and aft adjustment aft adjustment:

See fore and aft adjustment

after bottom dead center: (ABDC) The position of the piston as it starts its way up.

afterburner: A device for burning excess carbon wastes produced by the engine so that air pollution is reduced.

aftercooler: A device in a diesel engine which removes the relatively warm air which enters the engine.

afterglow: the period during which the glow plugs of a diesel engine continue to operate after the engine is started

aftermarket: All products and services used in the repair and maintenance of vehicles after the vehicle has been sold.

aftermarket equipment: Accessories and replacement parts added to a vehicle after it has been sold.

aftermarket overdrive: An overdrive device which is not original equipment, but has been added after it has been sold.

aftermarket part: Goods not for use as original equipment in the production of light-duty vehicles or heavy-duty vehicles, i.e., products and services used in the repair and maintenance of these vehicles.

aftermarket rustproofing: Although most vehicles come from the manufacturer with some rustproofing, there is no guarantee that every part of the exposed chassis and frame will be protected from the elements and the possibility of rust. Therefore rustproofing is applied by the owner of the vehicle to reduce the possibility of rust. If this rustproofing is not

done when the vehicle is new, it might seal in the rust and create a greater problem.

afterpeak bulkhead: First main transverse bulkhead forward of the sternpost

after perpendiculars: A vertical line at the intersection of the summer load line and the after side of the rudder post or sternpost, or the centerline of the rudder stock if there is no rudder post or sternpost

after-start enrichment: When an engine is first started, it needs a little richer fuel-air mixture (i.e., more fuel, less air). In a carbureted engine, this is accomplished by the choke (which restricts the amount of air). In a fuel injected engine, the after-start enrichment device increases the amount of fuel. As the engine warms up, the device gradually reduces the amount of enrichment. Some devices just reduce the amount gradually over time without sensing the temperature of the engine.

after top dead center: (ATDC) A term used in timing the relation of the spark and the crankshaft. The position of the piston as it starts its way down.

AG: Acronym for "air-guard"

aged catalyst: A catalyst which has already been in service. Opposite to a fresh catalyst.

age-hardening: Aluminum and some metal alloys will become hard and even brittle with age which is an unwanted characteristic. On the other hand when paint or cement harden over time, this process may be a desirable characteristic.

ageing: See aging.


See driver and Vehicle Licensing Agency energy Protection Agency agent: An intermediary with legal authority to operate on behalf of the manufacturer. Also see aggressive agent anti-knock additive anti-knock agent bonding agent degreasing agent oxidizing agent reducing agent release agent rustproofing agent softening agent agent fee: Although you can register your vehicle and obtain your licence from a government office, some states and provinces permit an agent to perform that same service and allow the agent to collect an extra fee for the service. In this way the lineup at the government office is reduced.

aggressive: A French expression to indicate the reinforced front, rear, and side safety structures of a vehicle. If the strengthened structure causes more than normal damage to another vehicle, a pedestrian, or the occupants of the vehicle, then that structure is aggressive.

aggressive agent: A corrosive material or chemical which attacks metal to pit them. Also called "aggressive medium."

aggressive medium: A corrosive material or chemical which attacks metal to pit them.

aggressivity: See aggressive.

aging: [1] The deterioration of rubber properties by oxidation over a period of time. [2] A change in the properties of some metals after heat treatment or cold working (i.e., hammering or bending when metal is cold). See tire aging

agitation cup: A type of spray gun paint container which has an agitator.

agitator: A device for mixing paint by shaking the container.

Agreement: See Free Trade Agreement of the Americas General Agreement on Tariffs and Trade North American Free Trade Agreement Agreement of the Americas: See Free Trade Agreement of the Americas

Agreement on Tariffs: See General Agreement on Tariffs and Trade

Agreement on Tariffs and Trade: See General Agreement on Tariffs and Trade

aground: See hard aground

AGVS: Acronym for "Automated Guided Vehicle System."

a.h.: Abbreviation for ampere-hour.


Acronym for "Association of the Hungarian Automotive Industry"

AHAP: Acronym for "As High As Possible."

AHARA: Acronym for "As High As Reasonably Achievable"

ahoogah: The sound of a particular kind of horn.

AHRA: Acronym for "American Hot Rod Association."

AH Rim: A wheel rim which is able to run even when the tire is flat and provides safety in case of a puncture.

AIADA: Acronym for "American International Automobile Dealers Association"

AIAM: Acronym for "Association of International Automobile Manufacturers"

AIA-SAP: Acronym for "Automotive Industry Association" (Czech Republic)

AIA-ZAP: Acronym for "Automotive Industry Association" (Slovakia).

aided: See computer-aided


See suspension aids

AIMA: Acronym for "Associao dos Industriais de Montagem de Automveis" (Portugal).

aimer: A tool for aiming headlights.

aiming: Adjusting the direction of the headlight beams to shine without blinding oncoming traffic and yet providing the maximum illumination whether in low beam or high beam.

air: [1] Abbreviation for "air conditioner." [2] A gas containing approximately 80% nitrogen, 20% oxygen, and a small portion of other gases. One of the essential factors in a combustion engine (fuel, air, proper proportion of mixture, compression, timing, and spark). Also see ambient air bath air charge air cold air driver air bag electric air control valve electric air switching valve AIR: An acronym for "Air Injection Reactor" system of reducing objectionable exhaust emissions. Also see air injection air and fuel: See proper proportion of air and fuel external mix air cap fuel air mixture fuel air ratio heater air pipe idle air bleed screw idle air jet internal mix air cap L-jetronic air flow meter lateral air passage low-profile air cleaner modular air strut oil bath air cleaner paper air cleaner passenger-side air bag

proper proportion of air and fuel pulse air principle pulse air system ram air secondary air

air aspirator system:

(AAS) A passive air injection system that uses a one-way valve instead of an air pump to introduce extra air into the exhaust stream

air bag: A device which is part of the passive safety system. In the event of an accident, sensors will cause the airbag to be deployed so that your head will be pillowed by the bag instead of hitting the dash. Also see driver air bag passenger-side air bag side impact air bag airbag: A device which is part of the passive safety system. In the event of an accident, sensors will cause the airbag to be deployed so that your head will be pillowed by the bag instead of hitting the dash. Also see driver air bag passenger-side air bag side impact air bag airbag module: All the components that make up the airbag system: Airbag, inflator, cover, and sensor. Also called "airbag unit."

airbag restraint system: A system which uses an airbag to restrain occupants in the event of a collision. They may be placed on the dash or doors or even in the shoulder strap. Also called "passive restraint system."

air-bag system: See supplemental restraint inflatable air-bag system

airbag unit: All the components that make up the airbag system: Airbag, inflator, cover, and sensor. Also called "airbag module."

air bellows: A rubber bladder or sleeve filled with compressed gas or air. Found on some suspension systems to provide cushioning. See air suspension.

air bleed: See compensating jet idle air bleed screw air bleed screw: See idle air bleed screw.

airbox: The container which holds the air filter.

air brake: A system of braking which is usually found on large truck in which compressed air pushes against a brake piston or diaphragm in order to apply the brakes to stop or slow the vehicle.

airbrush: [1] A paint spray gun used for precise detailing work and custom painting. [2] The act of using an airbrush.

air bypass valve: (ABPV or ABV) a backfire-suppressor valve used in air injection systems. During high engine vacuum conditions such as deceleration, it vents pressurized air from the air pump to the atmosphere in order to prevent backfiring. At other times, it sends air to the exhaust manifold. On vehicles with a three-way catalyst, it sends air to the oxidation catalyst only when the engine warms up. Also called an antibackfire valve, diverter valve, or gulp valve

air cap: See external mix air cap internal mix air cap air capacity: See breathing capacity.

air charge temperature:

(ACT) The temperature of the air being forced into the carburetor or fuel injection system. An ACT sensor measures this temperature

air charge temperature sensor: (ACTS) a thermistor sensor that inputs the temperature of the incoming air stream in the air filter or intake manifold to the computer. It can be located in the intake manifold (EFI systems) or the air cleaner. On carbureted vehicles, if the air is cold, it signals the choke to let off slowly. It then alters engine speed after the choke is off and below a certain temperature, dumps air from the air injection system to the atmosphere for catalyst protection

air cleaner: A device which filters the air entering the engine to remove dust, dirt, and bumblebees. Also called "air filter." Also see bath air cleaner low-profile air cleaner oil bath air cleaner paper air cleaner thermostatic air cleaner air cleaner bi-metal sensor: (ACL BI-MET) a component of a thermostatic air cleaner system. It senses the temperature of incoming fresh air and bleeds off vacuum when the air is warm. When the air is cold, the sensor directs vacuum to the air cleaner vacuum motor.

air cleaner duct and valve vacuum motor: (ACL DV) a component of thermostatic air cleaner systems. It opens and closes the air duct valve to provide heated or unheated air to the engine in accordance with the temperature of the incoming air

air cleaner element: The replaceable filter which prevents impurities from the air which enters the combustion chamber. Also called "air filter element."

air cleaner horn: Many air cleaner canisters have a spout or horn extending from the edge of the canister into which the air is taken in. See heated intake.

[Ba] [Bb] [Bc] [Bd] [Be] [Bh] [Bi] [Bl] [Bm] [Bo] [Bp] [Br] [Bs] [Bt] [Bu] [Bw] [By]

BA: An abbreviation for "British Association" which is a term used to describe a series of fine, small diameter threads for electrical and precision equipment

babbitt: An alloy of tin, copper, and antimony having good antifriction properties. Used as a facing for bearings.

babbitt metal: See babbitt

baby seat: A specially designed seating device (which is not generally standard equipment) to hold safely very young children (usually under the weight of 10 kilograms).

BAC: Acronym for "Blood Alcohol Content"

back: See blow back die-back die back kamm back popping back spine-back back axle: The rear axle

back axle ratio: See final drive ratio


See backbone frame.

backbone chassis: See backbone frame

backbone frame: A frame, having the cross-section of a rectangular box, that runs along the center of the vehicle and occupies the space between the seats. This box generally divides at the front, running along each side of the gearbox and engine up to a crossmember to which the front suspension pieces are attached. At the rear a similar triangular frame encloses the final-drive housing and provides attaching points for the rear suspension. Lightness combined with high torsional rigidity are features of this frame design, made famous by Colin Chapman with the Lotus Elan. Also see tubular backbone frame backfire: [1] Passage of unburned fuel mixture into the exhaust system where it is ignited and causes an explosion (backfire) prematurely. [2] Sometimes ignition takes place in the intake manifold by a flame from a cylinder because the intake valve leaks. Burning of the fuel mixture in the intake manifold may be caused by faulty timing, crossed plug wires, leaky intake valve, etc. [3] A welding term referring to a short "pop" of the torch flame followed by extinguishing of the flame or continued burning of the gasses

backfiring: Repeated backfires in the exhaust or the cylinders

backflow scavenging: See loop scavenging

backflushing: See flushing the cooling system.

backhand welding: Welding in the direction opposite to the direction that the gas flame is pointing. Also called "backward welding."

backing: Some material placed on the root side of a weld to aid control of penetration. Also see steel backing backing pad: A rubber disc which is secured to a spindle which in turn is attached to a drill or other tool which rotates the spindle. An abrasive disc or polishing disc is secured to the backing pad.

backing plate: See brake backing plate.

backlash: The amount of "play" or clearance between two parts. In the case of gears, it refers to how much one gear can be moved back and forth without moving the gear into which it is meshed.

backlight: The rear window of a vehicle.

backlight heater: Heated rear window

backlight defogging system: Heated rear window

back panel: The panel of the body shell set underneath the trunk lid. It is sometimes referred to as the rear valance if the area below the trunk lid consists of only a single panel that extends down to the bottom of the body; in many designs, however, the rear valance is a separate horizontal panel that extends from the rear bumper area downward. The British term is "rear panel"


British term for brake backing plate

back pressure: The resistance to the flow of exhaust gases through the exhaust system. By rerouting the exhaust gases for noise suppression, a muffler causes back pressure, but a straight pipe alone causes only minimal back pressure. Some engines require back pressure, so that removing the exhaust system will cause internal damage. Also see exhaust back pressure negative back pressure valve negative back pressure modulated valve back pressure modulated: See negative back pressure modulated valve

back pressure modulated valve: See negative back pressure modulated valve

back pressure valve: See negative back pressure valve

backpressure variable transducer: (BVT) a system combining a ported EGR valve and a backpressure variable transducer to control emissions of NOx

backrest: The back (upright) part of the seat against which your back reclines

back-seat: An air conditioning term which means to rotate a service valve counterclockwise all the way down until the valve is back-seated. When referring to a stem type service valve, the term has a more specific meaning-in the back-seated position, the valve outlet to the system is open and the service port in the valve is closed (its normal operating position)

back-step welding: Welding small sections of a joint in a direction opposite the direction that the weld as a whole is progressing.

back up: To go in reverse

back up alarm: An annoying loud beeping which is repeatedly sounded when a vehicle (usually a large truck) is placed in reverse. It is designed to warn pedestrians behind the vehicle. The British term is "reversing warning signal"

back up light: A light which is located at the rear of the vehicle and is illuminated when the transmission is placed in reverse. The British term is "reversing light"

back-voltage: Voltage which opposes the current when the current in an inductive circuit changes and the magnetic field cuts the conductors. Also see self-induction back-voltage backward welding: See backhand welding

BAC level: Blood Alcohol level

badge: An emblem with a manufacturer's name and/or logo on a plate to identify a model or component. Also see hood badge badge engineering: When a manufacturer sells two identical vehicles but the model names are different, he is badge engineering. For example, General Motors may sell a vehicle as a Chevrolet or a Pontiac where the only difference is the model name, logo, and more or less chrome or other minor alterations.


The tendency of a manufacturer to engage in badge engineering

baffle: An obstruction used to slow down or divert the flow of gases, liquids, sound, etc. They are found in the fuel tank, crankcase, muffler, and radiator. baffle plate: A metal plate that acts as a baffle.

bag: See air bag courier bag cruiser bag driver air bag passenger-side air bag shot bag side impact air bag tank bag bake: A process of drying or curing paint by using heat

Bakelite: The trademark for a synthetic thermosetting plastic resin used in electrical parts because it is a good insulator. The name comes from its inventor, L. H. Baekeland, 1863-1944.

baking finish: Paint that requires baking in order to dry

baking temperature: The temperature at which a varnish or paint must be baked to develop desired final properties of strength and hardness

balance: [1] The state in which weight is evenly distributed. [2] The action of applying weights or drilling holes in something to establish even weight distribution so that vibration is reduced.

Also see balance shaft counter balance crankshaft counter-balance dynamic balance harmonic balancer heat balance kinetic balance off-car balance on-car balance spool balance valve static balance steering wheel balance tire balance wheel balancer balance control: A switching device on a stereo radio which adjusts the amount of sound coming from the left and right speakers or from the front and rear speakers

balanced crankshaft: A crankshaft with extended reinforcements to form counterbalancing or act as a vibration damper

balance disc: A disc-shaped device in a centrifugal pump which is attached to the pump shaft. The disc lifts when a force is applied to the underside of the disc allowing pressure to leak past until the axial forces are balanced

balanced engine: An engine in which all the reciprocating parts such as pistons and connecting rods are adjusted to exactly the same weight

balance patch: A factory installed patch used to bring a new tire within quality control balance tolerances before distribution and sale. It is placed inside the tire casing and looks much like a nail hole repair patch.

balance pipe:

A tube which joins two or more carburetors to even out the flow difference.

balancer: See harmonic balancer wheel balancer balance shaft: An engine will normally vibrate because of the up-and-down motion of the pistons which turn a crankshaft in one direction. A balance shaft rotates (often in the opposite direction) so that its vibration cancels some of the vibration of the engine. Sometimes an engine will have two balance shafts turning in opposite directions located on either side of the crankshaft.

balance valve: See spool balance valve

balance weight: A lead weight attached to the rim of a wheel. See wheel weight.

balancing: [1] Dismantling engine and reassembling it to exact specifications and tolerances. This process may help to improve engine performance, smoothness, and reliability. Sometimes called "blueprinting." See balanced engine. [2] Keeping wheels in balance. Also see wheel balancing off-the-car balancing on-the-car balancing balancing machine: See wheel balancing machine

balancing weight: See wheel weight

bald tire: A tire on which the tread is all worn away. A slick also has no tread, but this is done deliberately for racing purposes

balk ring: A friction-regulated pawl or plunger used to make the engagement of gears easier. British spelling is "baulk ring" ball: A sphere usually made of metal when used in automotive applications. Also see ball and spring ball bearing ball joint ball joint rocker arm check ball detent ball and spring hitch ball impact swivel ball universal joint recirculating ball and nut steering recirculating ball steering recirculating ball worm and nut recirculating ball towing ball ball and nut: See recirculating ball and nut steering

ball-and-nut steering: See recirculating ball steering

ball and socket: See ball joint

ball and socket joint: See ball joint

ball and spring: See detent ball and spring.


Any liquid or solid weight placed in a ship to change the trim, increase the draft, or to regulate the stability. Also see dry ballast lead ballast liquid ballast ballast ignition system: An ignition system which uses a ballast resistor connected in series with the coil primary winding and which is bypassed when the starter is engaged so that the spark is more efficient under cold weather starting

ballast tank: Tanks at the bottom or sides of a ship which are filled with seawater for ballasting purpose.

ballasting: The addition of liquid or dry weight inside the tire to act as a counterbalance, to increase traction, reduce wheel spin, and dampen out bounce.

ballast resistor: (BAL RES) A resistor constructed of a special type wire, the properties of which tend to increase or decrease the voltage in direct proportion to the heat of the wire.

ball bearing: An antifriction bearing consisting of an inner and outer hardened steel race (or cage) separated by a series of hardened steel balls.

ball bearing puller: A tool for removing a ball bearing from a shaft or from a housing

ball cage: A circular frame which holds the balls in place in a ball bearing

ball end hexagon screwdriver: A tool that looks like an Allen wrench except it has a small ball at the very end. This arrangement allows it to work at various angles.

ball joint: A flexible joint using a ball and socket type of construction, used in steering linkage setups, steering knuckle pivot supports, etc. Their flexibility helps to compensate for the changes in the wheel and steering when turning or hitting a bump on the road. There are usually upper and lower ball joints attached to the upper and lower A-arms. ball joint rocker arm: A rocker arm that instead of being mounted on a shaft, is mounted upon a ballshaped device on the end of a stud.

ball joint separator: A tool for forcing out ball or tapered joints. One style is shaped like a two-prong fork with a wedge-shaped jaw which is struck with a hammer to separate the joint. Another style uses direct pressure from a screw or screw-activated lever action to split the joint.

ball joint steering knuckle: A steering knuckle that pivots on ball joints instead of on a kingpin.

balloon tire: A type of low pressure tire which was first introduced in the 1920s. Its width and height were the same which gave it a rounded shape. This style was used on bicycles as well as automobiles.

Ballot: A vehicle brand of which the 1925-1948 model automobiles with required application are classic cars.

ball pien hammer: A hammer with two ends on the head. One is round and the other is flat. They are best used for hammering and shaping metal. Also spelled "ball peen"

ball peen hammer: A hammer with two ends on the head. One is round and the other is flat. They are best used for hammering and shaping metal. Also spelled "ball pien"

ball socket:

A recessed spherical well for receiving the ball in a ball joint

ball steering: See recirculating ball steering

ball universal: See impact swivel ball universal joint

ball universal joint: See impact swivel ball universal joint

ball valve: A check valve in which a ball in a tube is used to control the flow of liquid.

ball worm: See recirculating ball worm and nut

ball worm and nut: See recirculating ball worm and nut

BAL RES: Abbreviation for ballast resistor

band: Bands are like a metal belt which is in the shape of a circle where the two ends are close, but do not meet. They wrap around parts inside the transmission called "drums." The drums house the gears and clutches and freewheel until a certain gear needs to be applied. When first gear needs to be applied, the drum for first gear is locked up by the application of the band. By locking up the drum, the gears now drive the wheels rather than freewheel inside the drum. Also see brake band power band squish band band brake:

See brake band

band radio: See citizens band radio

bands: See band.

bandwidth: The range of audio frequencies that an audio component (radio) can handle

B & S: bore and stroke.

B & S gage: Abbreviation for "Brown and Sharpe." A standard measure of wire diameter.

B & S gauge: Abbreviation for "Brown and Sharpe." A standard measure of wire diameter.

banger: [1] A colloquial term used to express the cylinders in an engine. Often used with a number such as "six banger." Also see four banger [2] A British colloquial term for beater (an older, cheaper, well-worn car which is still usable). [3] One who fakes an accident. See car banger

banger racing: A competition of speed on small racing tracks where older cars are driven as fast as they can go and where bumping other racing cars is permitted (encouraged??)

banging: See car banging

banjo: [1] Besides being a musical instrument, this is a fitting which is shaped like a banjo. It has round end that is doughnut shaped with a tube coming out from one side. It is usually used to transfer fluid from the center hole of the round end and out the lateral tube. [2] A drum-shaped central part of an axle casing containing the differential. Also see rear axle housing, banjo type axle housing banjo bank: See cylinder bank

banking: The slope of a track from the wall to the apron, generally measured in the corners.

bar: [1] A unit of pressure. One bar equals 100 kilopascals or 14.5 psi. [2] A rod. Also see anti-roll bar anti-sway bar antiroll bar boring bar bull bar bumper bar busbar compensating bar compensator extension bar freeway bar gunwale bar header bar hi-way bar highway bar hood bar ladder bars landau bar landau bars levering bar locking bar clamp main bar nerf bar

nudge bar port bar push bar roo bar side impact bar sissy bar spring bar stabilizer bar stringer bar strut bar sway bar t-bar targa bar test bar tommy bar torsion bar track bar traction bar tread bar wear bars wheelie bar wheelie bars wobble extension bar Barach: The author and compiler of this dictionary at Motorera.com

bar clamp: A tool with a stationary head and a sliding foot for clamping purposes. Also see locking bar clamp

bare shell: The shell of a car body in which all parts have been removed including doors, hood, and trunk lid

barge: A flat-bottomed boat for carrying cargo or bunker oil, usually pulled by tugs. Also see tank-barge barge carriers:

Ships designed to carry barges.

BARO: [1] Acronym for barometric pressure sensor. [2] Acronym for barometric absolute pressure sensor

barometric absolute pressure sensor: (BARO or BP) sends a variable voltage signal to the computer which varies in accord with atmospheric pressure, allowing adjustment of the spark advance, EGR flow, and air/fuel ratio as a function of altitude. Also called a barometric pressure sensor

barometric and manifold absolute pressure sensor: (BMAP) a housing containing both BP and MAP sensors

barometric pressure sensor: (BARO or BP) A sensor found in the engine management system which detects the ambient barometric pressure so that precise fuel mixture can be maintained at different altitudes

barrel: [1] The air horn in the carburetor. In particular, it is that part where the throttle valve is located. If a carburetor has four openings with a throttle valve in each, it is called a "four-barrel carburetor." Also see carburetor barrel four barrel carburetor four barrel [2] Another name for the carburetor barrel cylinder, cylinder barrel, four barrel, polishing barrel, and single barrel. [3] To travel fast as in "We barrelled down the highway well above the speed limit."

barrel carburetor: See four barrel carburetor single barrel carburetor twin barrel carburetor barrel tappet:

A hollow rocker arm shaped like a barrel

barrier: See crash barrier

barrier cream: A special cream which is applied to your hands before working on a greasy engine. When the job is over, you can wash your hands and easily remove the grease stains. Also called "invisible glove" or "silicon glove"

barrier effect: The effect produced by coating metal to shield it from corrosion

barrier paint: A primer which is used on bare metal to prevent corrosion.

bar roof: See t bar roof

bars: See ladder bars landau bars wear bars wheelie bars bar suspension: See torsion bar suspension

base: [1] The lowest supporting part of an upright member. [2] The bottom layer or coating in a series of paint coats. Also see bead base edison base flat base rim taper flat base rim lithium base grease

load base negative load base rim well base base and clear system: Paint finish which is made up of a colored base coat (usually a metallic finish) and clear lacquer coat

base circle: As applied to the camshaft the lowest spot on the cam, the area of the cam directly opposite the lobe or nose. No lift is produced by the base circle. Also called cam heel

base coat: The first coat in a paint system. It is either the undercoat or primer or a colored coat which is covered by clear lacquer

base gasket: The gasket directly below the cylinder and between the cylinder and crankcase. Also called "cylinder gasket."

base grease: See lithium base grease

base idle: The idle speed determined by the throttle lever setting on the carburetor or throttle body while the idle speed control (ISC) motor, or any other computer-controlled idle speed control device, is fully retracted and disconnected.

base interest rate: The interest paid on the usage of the vehicle during a lease. It is the "cost" of a lease before factoring in discounts, fees, and penalties and is not directly comparable to the APR for a loan. Lowering the base interest rate is one of the methods manufacturers use to subsidize leases. The phrase "money factor" measures the same cost and can be converted into a base interest rate. For example, to convert a money factor of 0.00276 into an approximate base interest rate would multiply the money factor by 24. The result would be 0.0662 or 6.6%.


A fore-and-aft reference line at the upper surface of the flat plate keel at the centerline for flush shell plated vessels. Vertical dimensions are measured from a horizontal plane through the baseline, often called the molded baseline.

base material: Any material (metal or plastic) which needs to be coated

base metal: [1] Metal that is under a coating or that needs to be coated. [2] Metal to be welded, cut, or brazed.

base model: The least expensive vehicle with the least amount of features as standard equipment. It has the smallest engine and often manual transmission as well as few power equipment. Base models constitute only a small percentage of the cars sold. Sometimes called a "stripper" or "stripped down" unit.

baseplate: A strong metal plate which is the main support for something. See distributor baseplate

base rim: See flat base rim flat base rim taper base rim taper: See flat base rim taper

basic ignition setting: The ignition setting on a non-running engine according to the specifications. After the engine is running, the timing can be set more accurately

basic ignition timing: The ignition timing on a non-running engine according to the specifications. After the engine is running, the timing can be set more accurately

basic price:

The price of a vehicle without including any optional accessories, taxes, delivery charges, etc.

basic timing: The ignition timing on a non-running engine according to the specifications. After the engine is running, the timing can be set more accurately

basin: See building basin

basket case: An old car which probably does not run. Often many engine and transmission parts have been removed and are either missing or stored in the trunk or a "basket"

bastard: A file (a tool) which has a coarse cut

bastard file: A file with a coarse cut

bat: A lump or collection of something. Also see fibreglass batch: [1] A number of things which are produced as a group. [2] A mixture of natural and synthetic rubber with other material such as fillers, chemicals, and vulcanizing agents in the production of tires

batch number: A number which may be added to a serial number to identify when the product was manufactured. In this way, when a problem occurs to some products of the same batch, action can be taken to correct or replace others from the same batch.

bath: A tub into which something is immersed.

Also see anodizing bath galvanizing bath oil bath air cleaner primer bath sealing bath zinc bath bath air: See oil bath air cleaner

bath air cleaner: See oil bath air cleaner

bathtub: Bodywork resembling an upside-down bathtub used on the rear of some Triumph motorcycles. It was introduced in 1957 and dropped in the early 1960s

battens: See cargo battens hatch battens battery: An electrochemical device for producing electricity by converting chemical energy. The typical automotive lead-acid battery supplies the source of power for cranking the engine and also provides the necessary electrical energy for the ignition system. In addition, it can (for a limited time) furnish current when the electrical demands of the vehicle exceed the alternator or generator output. Also called the "storage battery." Also see accumulator battery alkaline battery booster battery charged battery check the battery dead battery discharged battery disconnect the battery dry battery dry charged battery

flat battery gel cell battery high energy battery isolate the battery lead-acid battery low-maintenance battery low battery maintenance-free battery primary battery rechargeable battery secondary battery sodium-sulphur battery storage battery top up the battery battery acid: Electrolyte (usually sulphuric acid) in each of the battery cells

battery cap: Small caps which seal each battery cell

battery capacity: The amp-hour capacity

battery cell: Individual compartments in a battery which is filled with electrolyte. Six-volt batteries have three cells, 12-volt batteries have six cells

battery case: The box made of polypropylene holding several chambers (cells) which have lead plates and filled with electrolyte.

battery charge: The condition or state of the amount of electricity in a battery

battery charge indicator: An instrument which shows the state of charge in a battery

battery charger:

An electric device which is plugged into an electrical outlet (e.g., 110 volt AC) and connected to the two terminals of the battery to restore the state of charge in the battery. One of leads coming from the charger is red and the other is black. The red lead is clamped on the positive post of the battery while the other is clamped on the frame of the vehicle.

battery charging: The process of renewing the battery by passing an electric current through the battery in a reverse direction.

battery charging station: With the advent of electric cars, there needs to be places where their batteries can be recharged periodically -- thus is born the battery charging station. Also called a "charging point."

battery clamp: A hold down device which secures the battery from moving around

battery compartment: A place in the vehicle where the battery is located. In cars and trucks it may be found under the hood (usually toward the front), under one of the seats, or in the trunk. In motorcycles it is found in the middle of the bike, under the seat

battery condition: See battery charge

battery connector: A plug on battery-powered vehicles to connect the batteries to the charging station

Battery Council International: A group which makes decisions related to battery composition and disposal.

battery cover: The top of the battery case. It has several holes (covered with caps) for access to the battery cells.

battery discharge controller:

A device on a vehicle which is driven by an electrical motor. It triggers a warning indicator when the battery power drops below a certain level.

battery discharge indicator: An instrument on a vehicle which is driven by an electrical motor which indicates the percentage of the maximum charge of the battery

battery earth: British term for battery strap or ground strap

battery filler: A device with a long hollow tube with a rubber bulb at one end. It is used for inserting into a container of battery acid and sucking up the acid, then inserting into the battery cell to fill it. However, motorcycle batteries arrive from the manufacturer with no electrolyte (battery acid). Battery acid comes in a large plastic container with a rubber hose to which a metering clamp is attached. The container is usually placed on a higher shelf so that it is fed into the battery by gravity and regulated by the metering clamp

battery fill line: A horizontal line on the side of a translucent battery case which indicates the level to which you fill it with electrolyte. Usually there are two lines indicating a minimum level and maximum level.

battery fluid: See battery acid

battery hold down clamp: See battery clamp

battery ignition: Any system where the battery supplies the initial voltage to power the starter motor and fire the spark plugs

battery ignition system: See battery ignition

battery is flat:

The battery does not have enough electrical power to start the car

battery is flat: The battery does not have enough electrical power to start the car

battery master switch: A control which disconnects the battery power from all the electrical components

battery post: The terminal on a battery to which the cable is attached. Older automobile batteries used a round post which stood up from the top of the battery. To avoid confusion, the positive post has a larger diameter than the negative. On newer batteries the post may or may not be abandoned in favor of a terminal on the side of the battery. On motorcycle batteries, the posts are usually flat with a hole for bolting the cables to them.

battery state indicator: See battery charge indicator

battery strap: [1] A wire cable or braided wire strap to transfer electricity. It can be found between the engine block and the chassis because the engine is isolated from the chassis by rubber mounts. Also called ground strap. See ground wire. [2] A rubber strap with metal hooks at each end and is used to secure a battery in place, especially on motorcycles

battery terminal: [1] A battery post on the top of the battery or a lug with a hole on the side of the battery. [2] The clamp at the end of a battery cable

battery tester: [1] A voltage meter or hydrometer for checking the state of charge of a battery. [2] An instrument for checking the condition of the battery cells

battery tray: A metal or plastic on which the battery sits.

baulk ring: British spelling for balk ring

bay: See engine bay

bayonet bulb: See bayonet cap

bayonet cap: A cylindrical base of an electric bulb, usually with two pins projecting on either side, which engage in J-shaped slots to lock the bulb securely in its socket.

bayonet fitting: See bayonet socket

bayonet socket: A socket for receiving a bayonet cap. It has two slots on either side (usually Jshaped) to accommodate the bulb's pins.

BBDC: Acronym for "before bottom dead center."

bbl: Abbreviation for "barrel," as in 4-bbl carburetor.

BCDD: Acronym for boost-controlled deceleration device

BCI: Acronym for "Battery Council International."

BCM: Acronym for body computer module


Acronym for "bottom dead center."

bead: [1] The portion of a tire which fits onto the rim of the wheel. On a tubeless tire, the contact of the bead with the rim seals the air into the tire. Bead heel, bead sole, and bead toe form a foot-like shape. Also see tire bead. [2] A small ball-like particle used in bead blasting or in some catalytic converters. [3] In welding, it is the appearance of the finished weld. It describes the neatness of the ripples formed by the metal while it was in a semi liquid state. Also see dual bead tire rim bead seat taper rim bead seat rolled bead single bead bead base: The part of the tire bead which is in contact with the rim bead seat

bead blaster: A cleaning device for removing paint and contaminants from an object. See bead blasting

bead blasting: A cleaning process which uses glass beads which are forced by air pressure against the object to be cleaned. This system removes paint and contaminants from objects which are awkwardly shaped.

bead breaker: A device used to remove a tire from its rim by releasing the tension the bead has upon the rim.

bead core: The ring of steel wires in the tire's bead. Also called bead wires

beaded edge: The edge of a body panel or upholstery panel wrapped around a wire or other stiffening item

beaded edge tire: An older form of high-pressure tire with projecting beads

beader: A power tool for forming beads on the edges of body panels

bead expander: A device used in the mounting of tubeless tires to prevent inflation air from escaping and bring the tire beads against the tapered bead seat area (rim).

bead heel: The portion of the tire bead in contact with the rim flange

beading: The action of forming a step in the middle of a panel (not at the edge) which creates a shallow indentation to reinforce the panel. Also see fender beading bead lock: See tire bead lock

bead movement: Movement of the bead on the rim caused by improper inflation, excessive loading, improper design, improper seating, or improper rim or tire size. Also called "bead rocking." See bead unseating

bead point: A feathered rubber extension of the bead toe used where a flap is not required; protects the tube from chafing between bead toes and rim base.

beads: See lubricate beads

bead seat: The portion of the wheel rim below the rim flange providing radial support to the bead of the tire.

See also rim bead seat taper rim bead seat safety bead seat bead seat mat: A seat cover made of a network of wood beads

bead seats: See contre pente on both bead seats

bead seat taper: See rim bead seat taper

bead seat diameter: The measurement of tire diameter, at the bead heel, where it seats on the rim. It is marked on the tire sidewall following section width.

bead separation: A situation where the bead comes off the wheel rim

bead tire: See dual bead tire

bead toe: The bottom portion of the tire bead in contact with the rim bead seat

bead unseating: Shifting of the tire bead from its seat on the wheel rim which often leads to the removal of the tire. See bead movement

bead wires: Steel wires wound around the circumference and placed in the beads. Their tension prevents the beads from lifting over the rim flanges. Also called bead core

beam: [1] A projection of light.

Also see dipped beam headlight beam setting high beam high beam indicator low beam main beam main beam indicator sealed beam [2] A supporting bar. Also see asymmetrical beam cant beam deck beam door beam hatch beam I-beam knee, beam molded beam pulling beam side impact intrusion beam transom beam [3] The width of a ship. Also called breadth.

beam axle: A rigid or dead axle which supports the non-driven wheels. See axle.

beam indicator: A light on the instrument panel which comes on when the high beams are activated. Also called high beam indicator

beam headlight: See sealed beam headlight

beam indicator: See high beam indicator main beam indicator beam knee:

Bracket between a deck beam and frame

beam setting: See headlight beam setting

beam unit: See sealed beam unit

bear: To turn as in the expression, When you get to the corner, bear right.

bearing: [1] The area of a unit in which the contacting surface of a revolving part rests in order to minimize wear and friction between two surfaces. [2] An antifriction reducing device that is usually found between two moving parts. The babbitt bearings found between the connecting rod and the crankshaft are lubricated and cushioned with oil, and the front wheel bearings must be repacked with grease at regular intervals. Bearings can be ball or roller type. Also see antifriction bearing ball bearing big-end bearing camshaft bearing carrier bearings clutch pilot bearing clutch release bearing clutch throwout bearing clutch thrust bearing connecting rod bearing con rod bearing friction bearing insert bearing jet bearing main bearing support main bearing needle bearing pilot bearing plain bearing precision insert bearing quill-type bearing quill bearing radial bearing

re-metalling the bearings release bearing rod bearing roller bearing rolling bearing sealed bearing shell bearing sleeve bearing small end bearing spigot bearing split bearing tapered roller bearing throw-out bearing throwout bearing thrust bearing timken bearing timken roller bearing wheel bearings bearing assembly: When more than one load needs to be supported, several bearings are used making up the bearing assembly. For instance, a crankshaft may have two bearings (one at each end) as well as a few more in the middle

bearing attachment: See split bearing attachment

bearing block: The two halves of metal which encase a bearing.

bearing cage: See ball cage

bearing cap: A rigid, semicircular part which encloses and holds the outer shell of a shell bearing

bearing clearance: The amount of space left between a shaft and the bearing surface, this space is for lubricating oil to enter.

bearing cone: [1] taper roller bearing. [2] The inner race in an adjustable axial or radial ball bearing

bearing crush: The additional height which is purposely manufactured into each bearing half to ensure complete contact of the bearing back with the housing bore when the engine is assembled

bearing cup: [1] Retainers, held in place by bolts and nuts, that hold the bearings in place. Also called bearing shell. [2] The bearing race that curves around the outside of a ring of ball bearings and works in conjunction with a cone.

bearing face: The bottom part of a nut or bolt head which clamps down on the surface of the part it is securing.

bearing housing: The cavity into which the bearing fits

bearing knock: The noise created by movement of a part in a loose or worn bearing

bearing material: The metal layer which forms the surface of the wear part of the bearing

bearing puller: A tool used to remove bearings from a shaft by pulling them off. It has two or more arms which circle around the back side of the bearing and a center post which butts up against the