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:  The uppermost part of a
colurnn capital or pilaster, on which the architrave rests.  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:  Acronym for "aerial bunched conductors."  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:  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.  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:  Any one of the
processes by which snow and ice are lost from a glacier, mainly by
melting and evaporation (sublimation).  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:  Wearing or
rubbing away some surface because of friction.  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:  Acronym for
"anti-lock brakes.  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:  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
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
absolute filter: A filter which removes most particulate matter
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
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
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
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
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:  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.  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
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
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
A capacitor connected across a spark gap to damp the
absorption coefficient:  The volume of gas, measured at stp,
dissolved by unit volume of a liquid under normal pressure (i.e.,
one atmosphere).  The fraction of the energy which is absorbed.
 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. 
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
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:  A part which stops the motion of another part from
proceeding any farther.  A cement raised shoulder secured to the
side of the road to prevent a vehicle from going over the edge.
 The contact made between opposing teeth of two gears.
abutting edge: The side or edge of a panel which joins another
ABV: Acronym for "air bypass valve"
A/C:  An abbreviation for air conditioning or air
conditioner.  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:  A vehicle brand of which the 1925-48 models are classic
cars.  Acronym for "alternating current."  Acronym for "air
conditioning" or "air conditioner."
AC Ace: A vehicle brand of which the 1954-61 Ace models are
AC Aceca: A vehicle brand of which the 1955-61 Aceca models are
ACAP: Acronym for "Associao do comrcio automovvel de
AC Buckland: A vehicle brand of which the 1949 Buckland Open
Tourer is a milestone car.
acc: Abbreviation for "accessories."
 Acronym for "Automatic Cruise Control."  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
ACCC: Acronym for "air conditioner clutch compressor" signal
accelerate: To increase the speed of a vehicle. Opposite of
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
accelerator:  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.  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
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
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
accelerometer: An instrument which measures the amount of
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
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
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:  A storage battery for an
electric car.  A pressurized container for an automatic
levelling suspension system.  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
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
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 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
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
ACL BI-MET: Acronym for "air cleaner bi-metal sensor"
ACL DV: Acronym for "air cleaner duct and valve vacuum"
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
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
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.
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
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
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: 
Acronym for "actual cash value."  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)
(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"
adhere: To stick or be glued to something.
adhesion:  The ability of paint, primer, or glue to stick to
the surface to which it is applied.  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
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
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
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
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
adjustable variable exhaust port: A device used on two-stroke
engines which automatically alters or varies the exhaust port
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
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
adjusting spanner: See brake adjusting spanner
adjusting tool: See brake adjusting tool electrode adjusting
tool adjusting wrench: See brake adjusting wrench
adjustment:  changing or modifying the position or alignment
of two components.  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:  The act of changing the ignition timing so that the
spark occurs earlier in the cycle. The opposite is retard.  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
speed control vacuum advance vacuum advance advance capsule: See
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:  A condition in which something occurs early.  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
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
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.
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
A/F:  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.  Abbreviation for
"air/fuel." See air-fuel ratio.
AFB: Acronym for "Aluminum four-barrel," as in Carter AFB
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
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
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
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:  The deterioration of rubber properties by oxidation
over a period of time.  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: A device for mixing paint by shaking the
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
Agreement on Tariffs: See General Agreement on Tariffs and
Agreement on Tariffs and Trade: See General Agreement on Tariffs
aground: See hard aground
AGVS: Acronym for "Automated Guided Vehicle System."
a.h.: Abbreviation for ampere-hour.
Acronym for "Association of the Hungarian Automotive
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
AIAM: Acronym for "Association of International Automobile
AIA-SAP: Acronym for "Automotive Industry Association" (Czech
AIA-ZAP: Acronym for "Automotive Industry Association"
aided: See computer-aided
See suspension aids
AIMA: Acronym for "Associao dos Industriais de Montagem de
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:  Abbreviation for "air conditioner."  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
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
airbag unit: All the components that make up the airbag system:
Airbag, inflator, cover, and sensor. Also called "airbag
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
airbrush:  A paint spray gun used for precise detailing work
and custom painting.  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
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
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:  Passage of
unburned fuel mixture into the exhaust system where it is ignited
and causes an explosion (backfire) prematurely.  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.  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
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
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
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-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
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
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
balance:  The state in which weight is evenly distributed.
 The action of applying weights or drilling holes in something
to establish even weight distribution so that vibration is
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
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.
A tube which joins two or more carburetors to even out the flow
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:  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.  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
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
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 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
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"
A recessed spherical well for receiving the ball in a ball
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:  A colloquial term used to express the cylinders in
an engine. Often used with a number such as "six banger." Also see
four banger  A British colloquial term for beater (an older,
cheaper, well-worn car which is still usable).  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:  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.  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:  A unit of pressure. One bar equals 100 kilopascals or
14.5 psi.  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
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:  Acronym for barometric pressure sensor.  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
barrel:  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  Another name for the carburetor barrel
cylinder, cylinder barrel, four barrel, polishing barrel, and
single barrel.  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
bar roof: See t bar roof
bars: See ladder bars landau bars wear bars wheelie bars bar
suspension: See torsion bar suspension
base:  The lowest supporting part of an upright member. 
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
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
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
base metal:  Metal that is under a coating or that needs to
be coated.  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
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:  A number of things which are produced as a group.  A
mixture of natural and synthetic rubber with other material such as
fillers, chemicals, and vulcanizing agents in the production of
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
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
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
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
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
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
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
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
battery ignition system: See battery ignition
battery is flat:
The battery does not have enough electrical power to start the
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:  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.  A
rubber strap with metal hooks at each end and is used to secure a
battery in place, especially on motorcycles
battery terminal:  A battery post on the top of the battery
or a lug with a hole on the side of the battery.  The clamp at
the end of a battery cable
battery tester:  A voltage meter or hydrometer for checking
the state of charge of a battery.  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
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:  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.  A small ball-like
particle used in bead blasting or in some catalytic converters. 
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
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
beader: A power tool for forming beads on the edges of body
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
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
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
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
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:  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  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  The width of a ship. Also
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
beam headlight: See sealed beam headlight
beam indicator: See high beam indicator main beam indicator beam
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,
bearing:  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.  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
bearing attachment: See split bearing attachment
bearing block: The two halves of metal which encase a
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
bearing cone:  taper roller bearing.  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
bearing cup:  Retainers, held in place by bolts and nuts,
that hold the bearings in place. Also called bearing shell.  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