Glossary Automotive Terms - A

Glossary of Automotive Terms – A

Letter A – Dictionary of Automotive Terms


  1. Abbreviation or symbol for
  2. Designation for A roads in Britain
A-2 tire
Tire sizes 16.00 and larger in nominal cross section.

  • Also called earthmover, off-road, or off-the-road tire.
Abbreviation for Automatic Overdrive Electronic Wide Ratio Transmission
Abbreviation for Automobile Association a term used in Britain.
Abbreviation for American Automobile Association
Abbreviation for Association of American Battery Manufacturers, Inc.
Abbreviation for Auxiliary Air Control Valve
Abbreviation for Annual Average Daily Traffic — a measure of traffic flow.
Abbreviation for Association of Automotive Employers (Poland).
Abbreviation for Automotive Aftermarket Industry Association.
Abbreviation for American Automobile Labeling Act
Abbreviation for Alliance of Automobile Manufacturers.
Abbreviation for auxiliary acceleration pump
A arm


suspension linkage 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.
A-arm suspension
Abbreviation for air aspirator system.
Abbreviation for American Association of State Highway and Transportation Officials
Abbreviation for Anti-Afterburning Valve (Mazda)
Abbreviation for Annual Average Weekday Flows — a measure of traffic flow.
Abbreviation for Annual Average Weekday Traffic — a measure of traffic flow.
Toward the back of a ship
  1. The act of a transporting company (bus, courier, railway, ship, etc.) in which it will no longer service a previously serviced route. In some cases abandonment must be approved by the ICC
  2. The act of a shipper or consignee who refuses to accept delivery
  3. The act of relinquishing title to damaged or lost property by claiming a total loss.
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A model of car produced by Fiat
A screw used in sheet metal but rarely in stainless steel.

  • The AB designation is made because it has a pointed end similar to a type-A screw and thread dimensions similar to a type-B screw.
  1. Abbreviation for Aerial Bunched Conductors
  2. Abbreviation for Automatic Beam Control.
ABC Classification
An inventory classification system

  • A system for classifying inventory or parts within a warehouse where fast moving products are designated as ‘A’ items, while ‘B’ and ‘C’ items are not as fast moving.
  • In some warehouses, however, ‘A’ items are those with the best profit margins.
The cgs electromagnetic unit of charge, equal to ten coulombs.
Abbreviation for Air Bleed Control Valve (Ford)
Abbreviation for After Bottom Dead Center.

  • A term used in timing the relation of the spark and the crankshaft
  • measured in degrees of rotation.
Abel flashpoint apparatus
A device for testing the flash point of gasoline.
Abel tester
A closed-cup flash tester for kerosene and other oils
A deviation from normal standards

To refuse to stick together.

A substance which does not allow two materials to stick together

  • e.g., Teflon® on frying pans does not allow eggs to stick to its surface.
  • Opposite of adhesive
A light-weight: (5.5 kg) folding bicycle invented by Sir Clive Sinclair in the United Kingdom
Aboard ship
A bone
Nickname for a Ford Model ‘A’
Abbreviation for Air Bypass Valve.
A grinding powder


To grind or roughen up a surface by rubbing
The action of removing some of the surface through rubbing friction.
Abrasion hardness
The ability of something (e.g., metal, ceramic) to resist abrasion.
  1. A hard grit used for sanding or grinding.
    • Usually a powder e.g., silicon carbide powder.
  2. Materials such as sand or chipped rock that are spread on paved roads to increase vehicle traction.
    • Also called aggregates
abrasive blast cleaning
A process of cleaning with gusts of fine particles

  • In order to clean steel or remove rust from iron or scale from metal, sand or some other powder substance is forced by air pressure through a nozzle.
  • In this way the small particles of abrasive can penetrate the metal where sanding with sandpaper cannot.
  • Also, very small craters are formed on the surface of the metal from the blasting action.
  • When thoroughly cleaned the metal is ready for painting.
  • Paint adheres better to these craters and imperfections than to a perfectly smooth surface.
abrasive cleaner
A cleaning paste with some hard grit.

  • It is used to remove the grime and oils from a surface or from your hands.
abrasive disc
Abrasive disc
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.
Side by side
Abbreviation for Anti-lock Brake System.

  • The Abbreviation ABS comes from the German Anti Blockier System.
  • A computer, sensors, and solenoid valves work together to sense wheel speed in order to modulate braking force if wheels lockup during braking.
  • ABS can help the driver retain control of the vehicle during heavy braking on slippery roads.
  • It works on the principle of braking a wheel until it just begins to skid (this is the point where braking efficiency would drop off dramatically) and then releasing the brake pressure and re-applying the brakes.
  • Wheel speed sensors identify the skid point and trigger a release in brake pressure.
  • The cycle is repeated many times a second.
  • The driver will feel a rapid pulsing at the brake pedal and hear a chattering noise as ABS is applied.
Absolute ampere
The metric standard unit of electric current which replaced the international unit in 1948
Absolute humidity
The ratio of the mass of water vapor in a sample of moist air to the volume of the sample.
Absolute Liability
The shipping carrier assumes responsibility for all damages and for late shipment, etc. and is not protected by normal exemptions found in a bill of lading or common law liability.
Absolute pressure
  1. 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).
  2. Total pressure equal to gauge pressure plus 14.7 lbs./sq. in. at sea level.
Absolute pressure sensor
Absolute temperature
The temperature above absolute zero

  • The temperature plus 273°C.
Absolute Valve
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, -273.15°C.
A substance with the property of assimilating another substance (e.g., sponge and water).

Something which converts the dynamic energy of motion into potential energy (e.g., of a spring) such as in a shock absorber.

Absorber Surface
Absorber tower
Absorbing bumper
Absorbing steering
Absorbing steering column
  1. The use of a chemical or filter to remove unwanted particles or characteristics from something.
  2. When light strikes a surface, some of it penetrates into the material and is trapped. This trapped energy is called absorption. Transformation into other forms suffered by radiant energy passing through a material substance.
Absorption capacitor
capacitor connected across a spark gap to reduce 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.
Absorption dynamometer
A measuring device which absorbs and dissipates power, e.g., the ordinary rope brake and the Froude hydraulic brake.
Absorption hygrometer
An instrument that measures the amount of moisture in the atmosphere
Absorption refrigerator
A refrigerator which creates low temperatures by using the cooling effect formed when a refrigerant is absorbed by chemical substance
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 anti-lock braking system.
Abbreviation for Air Bypass Solenoid Valve (Mazda)
ABS warning light
Indicator lamp mounted in the instrument cluster. It illuminates when there is a problem in the anti-lock brake system. It will also illuminate momentarily when starting the vehicle to indicate that the lamp is functioning.
The action of two gear teeth making contact.
  1. A part which stops the motion of another part from proceeding any farther.
  2. The contact made between opposing teeth of two gears.
  3. The structure that supports the end of a bridge.
Abutting edge
The edge or side of a panel which joins the edge or side of another panel.
Abbreviation for air bypass valve.
the cgs unit of potential difference in the electromagnetic system; the potential difference between two points when work of 1 erg must be done to transfer 1 abcoulomb of charge from one point to the other: equivalent to 10-8 volt (i.e., one hundred-millionth of a volt).
An abbreviation for across corners

  1. An abbreviation for across corners
    • Indicates the distance on a nut or bolt head from one corner to the opposite corner rather than the distance from one flat surface (A/F) to the opposite.
    • The A/F measurement determines the size of wrench needed to install or remove the nut or bolt.
    • The A/C measurement determines the size of hole needed to insert a recessed nut or bolt head.
  2. Abbreviation for alternating current.
  3. Abbreviation for air conditioning or air conditioner.
    • Sometimes spelled ‘A/C’ or ‘A.C.’
  4. Symbol for actinium
  5. The transformation temperature on heating of the phase changes of iron or steel, subscripts indicating the designated change, e.g., Ac1 is the eutectoid (723°C) and Ac3 the ferrite/austenite phase boundary.
  6. Abbreviation for Asphaltic concrete.
    • A mixture of asphalt cement, graded aggregate, mineral filler, and additives.
A vehicle brand built by the AC Cars Group, Limited of which the 1925-48 models are classic cars.
1956 AC Ace
1956 AC Ace Click image for books on AC
AC Ace
A vehicle brand built by the AC Cars Group, Limited of which the 1954-61 Ace models are milestone cars.
Ac aceca
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AC Aceca
A vehicle brand built by the AC Cars Group, Limited

Abbreviation for Associação do comércio automovóvel de Portugal
AC balancer
An arrangement of transformers used to equalize the voltages between the wires of a multiple-wire system.
AC Buckland
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AC Buckland
A vehicle brand of which the 1949 Buckland Open Tourer is a milestone car.
Abbreviation for accessories.
  1. Abbreviation 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.
  3. Abbreviation for Air Conditioning Clutch
  4. Abbreviation for Automatic Climate Control
Abbreviation for air conditioner clutch compressor signal
  1. To increase the speed of a vehicle. Opposite of decelerate.
  2. To increase the speed of a chemical reaction
    • To speed up the chemical reaction or curing process of an adhesive.
    • For example, you can speed up the drying time of an adhesive or sealer by increasing the temperature or by adding a chemical curing agent, or accelerator, to a base compound.
Accelerating machine
Accelerating-well ports
These ports or passageways in the carburetor 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.
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 (or metres) per second per second or feet (or metres) per second squared).
  • It is a vector quantity and has both magnitude and direction.
  • It may be positive or negative depending upon whether the object is speeding up or slowing down.
  • According to Newton’s second law of motion, acceleration is equal to the force, divided by mass (A=F/M).
  • The latter is often called deceleration.
Acceleration enrichment
(AE) The action of increasing the fuel/air mixture during acceleration in order to improve the vehicle’s speed and its smooth response.
Acceleration pump
A small pump in a carburetor that squirts fuel into the carburetor throat as the throttle is opened. When you accelerate, the accelerator pump delivers extra fuel through the accelerator pump circuit to allow the engine to deliver more power. Also called accelerator pump.’

Acceleration Sensor
Acceleration slip regulation
(ASR) The Bosch term for traction control.
Acceleration stress
The influence of acceleration (or deceleration) on certain physiological parameters of the human body.

  • The degree of tolerance depends on the magnitude and duration of the acceleration as well as the direction of the force against his body.
Acceleration Switch
Acceleration tolerance
The maximum acceleration force that a person can withstand before blacking out or otherwise losing control.
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  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.
    • Also called throttle linkage.
  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.
    • A material added to an adhesive to speed up its cure or to chemically convert the whole mass to a solid.
    • Accelerators differ from catalysts in that they are a part of the chemical reaction and lose their chemical identity as a result.
  3. Any substance increasing the speed of the vulcanization process of rubber.
Accelerator interlock
A connection between the gas pedal and the automatic transmission.
Accelerator pedal
The acceleratorgas pedal, or throttle pedal.
Accelerator pump
An auxiliary carburetor pump

  • A small cylinder and piston 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 fully depressing the throttle pedal.
An instrument which measures the amount of acceleration in a specific direction.
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.
  1. The act of receiving and signing for a shipment by the consignee which terminates the carrier’s contract and obligation.
  2. A consignee’s promise to pay the shipping costs by signing and dating the bill for the goods and acknowledging any indebtedness to the company who shipped the goods.
Acceptance test
An examination of a part or its assembly to determine if it meets a prescribed standard.
A way of reaching something that is usually hidden or covered.

Access Cab
A pickup truck (by Toyota) which has a second row of seating

Access hole
An opening through which you can reach something

  • It is usually covered with a removable panel for aesthetic or safety reasons to hide wiring, hoses, etc.
Accessible hermetic
Assembly of motor and compressor inside a single bolted housing unit.
An extra activity or material beyond normal handling and storage for which the client will be billed.
Accessorial Charge
The amount the client must pay for providing extra service or materials.
Items and packages of equipment which are beyond the standard equipment supplied in a new vehicle.
Accessory gearbox
A transmission, driven remotely from the main engine, to which other items (e.g., generator, pumps) are mounted.
Accessory package
A set of features or appointments which may be ordered at extra cost on a new vehicle.
Accessory system
Part of the electrical system consisting of lights, horn, electric starter, turn signals, warning systems, etc.
Access panel
  1. The cover which conceals the engine on a mid-engine vehicle.
  2. A decorative plate which covers an access hole


Access road
A temporary or permanent road over which timber is transported from a loading site to a public road.

Access slots
Openings in the brake backing plates or brake drums that allow you to reach the star-wheel adjusters
Accident damage
The destruction caused to a vehicle’s bodywork when it is involved in an accident.
AC circuit
A circuit which passes only alternating current as opposed to direct current, e.g., it may have a capacitor in series, which blocks direct current.
Accommodation Ladder
A portable set of steps attached to the side of a ship to permit people to board from small boats or from a pier.
AC commutator motor
An AC motor which has a commutator as an essential part of its construction.
Honda Accord?
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A model of automobile manufactured by Honda.
Accordion bus
A colloquial term for an articulated bus
Abbreviation for A/C Cycling Clutch Switch
  1. A storage battery for an electric car.
  2. A part of a hydraulic system filled with nitrogen gas and used to store high pressure fluid to provide pressure assistance for system operation.
  3. A pressurized container for an automatic leveling suspension system.
  4. 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.
  5. A device in the fuel line between the pump and filter that keep up the fuel pressure when the fuel pump is off thus preventing vapor lock and excessive fuel pump noise in having to build up pressure when needed
  6. A vessel that stores hydraulic fluid under pressure.
  7. A storage tank which receives liquid refrigerant from the evaporator and prevents it from flowing into the suction line before vaporizing.
  8. A refrigerant storage device used on General Motors and Ford systems that receives vapor and liquid refrigerant from the evaporator.
    • The accumulator, which contains desiccant, performs a function similar to that of a receiver-drier it separates liquid from the vapor, retains the liquid and releases the vapor to the compressor.
    • Always located on the low side of the system.
Accumulator battery
A storage battery (i.e., the main battery in your vehicle).
Accumulator box
A vessel usually made of plastic which contains the plates and electrolyte of an accumulator.
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).
Accumulator grid
The lead grid which forms one of the plates of a lead-acid accumulator having pasted plates.
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 traction
Accumulator valve
A device which operates the hydraulic accumulator piston in an automatic transmission.
Accumulator vehicle
AC Current
AC current sine wave
Wave form of single frequency alternating current; wave whose displacement is sine of angle proportional to time or distance.
Abbreviation for Air Conditioning Demand Switch
An American trucker’s colloquial term for someone with a class A license.


Abbreviation for Association des Constructeurs européens d’Automobiles (i.e., European Automobile Manufacturers’ Association).


A fast drying solvent used in some rapid drying adhesives, such as nitrile rubber, or vinyl resin-based types
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.
Acetylene bottle
Acetylene cutting
Acetylene cylinder
Acetylene cylinder
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
AC generator
AC generator
AC generator
  1. An electromagnetic generator for producing alternating EMF and delivering AC to an outside circuit.
  2. 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 rack
Oldmobile Achieva books
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A model of automobile built by Oldsmobile from 1992-98. Built on the N-chassis.
Acid deposition
After acid compounds are sent into the atmosphere (e.g., through a smokestack), it returns to the surface mixed with the rain.


Acid Fuel Cell
The presence of acid-type constituents whose concentration is usually defined in terms of neutralization number.

  • The constituents vary in nature and may or may not markedly influence the behavior of the oil.
Acid mine drainage
Water pollution that results when sulfur-bearing minerals associated with coal are exposed to air and water and form sulfuric acid and ferrous sulfate.

  • The ferrous sulfate can further react to form ferric hydroxide, or yellowboy, a yellow-orange iron precipitate found in streams and rivers polluted by acid mine drainage.
Acid precipitation


Acid process
A way of making steel where the iron has a low level of phosphorous and the furnace is lined with silicon.

Acid rain
  1. 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.
  2. A form of wet deposition in which acid molecules or particles in the atmosphere are returned to the surface having been washed out by rain or snow as it falls.
    • The unnatural acidity (pH 3-5.5) is caused mainly by the oxides of sulfur and nitrogen from the burning of coal and oil.
  3. Precipitation containing harmful amounts of nitric and sulfuric acids formed primarily by sulfur dioxide and nitrogen oxides released into the atmosphere when fossil fuels are burned.
    • It can be wet precipitation (rain, snow, or fog) or dry precipitation (absorbed gaseous and particulate matter, aerosol particles or dust).
    • Acid rain has a pH below 5.6.
    • Normal rain has a pH of about 5.6, which is slightly acidic.
    • The term pH is a measure of acidity or alkalinity and ranges from 0 to 14.
    • A pH measurement of 7 is regarded as neutral.
    • Measurements below 7 indicate increased acidity, while those above indicate increased alkalinity.
    • Also called acid precipitation or acid deposition
Acid Rechargable Battery
Acid Tester
AC Ignition System
Ackerman steering
Ackerman steering
Ackermann steering
  1. 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.
    • Notice 20 degrees on left wheel and 30 degrees on right wheel
  2. Arrangement whereby a line extended from the track-arms, when the wheels are set straight ahead, should meet on the chassis centerline at 2/3 of the wheelbase from the front, allowing the inner stub-axle to move through a greater angle than the outer.
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 non-rotating axle that is steerable and has two pivot points (one on each end of the axle) with vertical kingpins.
Abbreviation for air cleaner bi-metal sensor.
Abbreviation for air cleaner duct and valve vacuum motor.
AC motor
An electric motor which operates from a single or polyphase alternating current supply.

Abbreviation for Air Conditioning On Signal
Acorn Die
A form of threading die for use in screw machines.

  • The cutting portion resembles an acorn.
Acorn Nut
A blind tapped hex nut with an acorn shaped top.

  • Provides sealing for projecting threaded parts.
Acoustic amplifier
A device or system that increases mechanical vibrations
  1. The science of sound waves including production and propagation properties.
  2. The characteristics of the interior of a car which determine the quality of sound transmission inside.
Abbreviation for Air Conditioning Pressure Signal
Abbreviation for Air Conditioning Pressure Switch
Acquisition fee
A charge for processing a vehicle 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.
Abbreviation for Air Conditioning Relay
Abbreviation for Air Conditioning Refrigerant, Recovery, Recycling, Recharging
Across Corners
Across Corners
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
Across Flats
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.

Abbreviation for Air Cushion Restraint System
ACR tubing
Abbreviation for Air conditioning and refrigeration tubing.

  • The ends are sealed to keep tubing clean and dry.
A polymer used to strengthen rubber (e.g., ethyl acrylate).
A term relating to a type of paint made by polymerizing acrylonitrile.
Acrylic fibers
Continuous long filaments or fibers from linear polymers.
Acrylic finish
A final coating of paint which uses acrylic paint, often where the pigment and an acrylic paint are mixed together.

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.
  1. Abbreviation for active control system
  2. Abbreviation for air conditioning system
  3. Abbreviation for attitude control system
AC Shelby Cobra
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AC Shelby Cobra
A vehicle brand of which the 1962-67 Shelby Cobra models are milestone cars.
  1. Abbreviation for air charge temperature.
  2. Abbreviation for active control technology
Action brakes
Action locking
Action locking pliers
To change an adhesive film from a dry or inactive state to a useful, sticky state.
Activated alumina
Chemical which is a form of aluminum oxide.

Activated carbon
A very porous carbon that is used to strain liquid leaving behind impurities on the carbon and the pure substance going through it
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
Charcoal treated with acid to increase its adsorptive power

Activated charcoal trap
Activating agent
A substance which is used to speed up the process of curing a tire.

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

  • Also called activating agent.
Activation polarization
Activation polarization is present when the rate of electrochemical reaction at an electrode surface is controlled by sluggish electrode kinetics.

  • This is similar to chemical reactions where the reacting species must overcome an activation barrier.
  • For fuel cells, this region is characterized by a drop from the theoretical EMF or ideal voltage prior to electron or ion flow.
Active Area cell
The surface area of an individual fuel cell that is available for chemical reaction.

  • The active area is typically less than the total area of a cell to accommodate cooling, distribution, and sealing mechanisms.
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 control system
(ACS) A flight control system designed to improve the performance and behavior of an airplane.
Active Gases
Active material
In a storage battery, the brown peroxide of lead of the positive plates and the gray metallic lead of the negative plates upon which the sulfuric acid acts.
Active noise control system
Active power
The component of electric power that performs work, typically measured in kilowatts (kW) or megawatts (MW).

Active safety
The opposite of passive safety.

  • Passive safety involves seat beltsairbagsbumpers, 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 solar
Energy from the sun collected and stored using mechanical pumps or fans to circulate heat-laden fluids or air between solar collectors and a building or vehicle.
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.
Activity factor
AC transformer
An electromagnetic device which alters the voltage and current of an alternating current supply in inverse ratio to one another.

  • It has no moving parts and is very efficient.
Abbreviation for air charge temperature sensor.
Actual cash value
(ACV) The amount of money a dealer has invested in the purchase of a used vehicle plus any additional costs to repair the unit in order to get it ready for resale.
The action of bringing something into operation.
Actuating lever
A triggering device used to bring something into operation.
Actuating switch
A triggering device used to bring something into operation.
Actuating system
The parts of a brake system that transmit the braking force applied at the brake pedal to the wheel friction assemblies and increase it to a usable level.
Actuation Distance
Actuation Time
  1. A device which controls or operates another device.
  2. A regulating valve which converts a form of energy into mechanical motion to open or close the valve seats
  3. A device which responds to an output signal from a computer.
  4. The portion of a regulating valve which converts mechanical fluid, thermal energy, or electrical energy into mechanical motion to open or close the valve seats
  5. An electrical mechanism for moving or controlling something indirectly instead of by hand, such as a door lock. The output device that the PCM controls such as solenoids, relays, fuel injectors and stepper motors.
Actuator arm
A linkage connecting the diaphragm to the contact breaker platform in an advance mechanism of a distributor.

  • Also called diaphragm link.
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An upscale series of vehicles from the Honda manufacturers. It includes the following:

  • CL (1997-2003)
  • Integra (1988-2001)
  • Legend (1988-95)
  • MDX (2001-07)
  • NSX (1991-2005)
  • RDX (2007-2009)
  • RL (1996-2008)
  • RSX (2002-06)
  • SLX (1996-99)
  • TL (1995-2008)
  • TSX (2004-08)
  • Vigor (1992-94)
  1. Abbreviation for actual cash value
  2. Abbreviation for air control valve
  3. Abbreviation for air cushion vehicle (i.e., hovercraft).
An abbreviation for a classified advertisement
Abbreviation for Analog to Digital Converter
Adapter (Also spelled adaptor)
  1. A device used to connect two different types or sizes of electrical terminals
  2. A connector which links two items usually of dissimilar structure or size.
  3. A bracket on disc brakes on which the caliper mounts, or slides or floats.
Adapter 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 Controller Module
Adapter plate
A flat piece of material which is placed between two different parts in order to join them.

Adaptive control
  1. A control device which learns from repeated input so that under particular circumstances the control gives the learned response.
  2. The ability of a control unit to adapt its closed-loop operation to changing operating conditions, such as engine wear, fuel quality or altitude, to maintain proper air-fuel mixture control, ignition timing or idle rpm. Also referred to as self-learning


Adcock antenna
A directional antenna with pairs of vertical wires used for direction finding.
A/D converter
Circuitry to convert analog information into numeric form for use in a digital computer
Addition agent
A substance added to the electrolyte in an electrodeposition process to improve the formed deposit
A substance (liquid or powder) which is added to gasoline or oil and is intended to improve the characteristics of the original product.

An accessory.
Abbreviation for Asociacion de Fabricas de Automotores (Argentina).
Abbreviation for Automatic direction finding.
To stick or be glued to something.

  1. Each surface that is to stick to another
  2. A material which is stuck together by an adhesive.
  1. The force which causes two surfaces to stick together
  2. The sticking together of surfaces in contact with each other
  3. The bonding of materials with adhesives (glues, cements, binders, etc), in which the intermolecular forces between adhesive and adherend provide the bonds.
  4. The sticking together of two metals as a result of compressing them together
  5. The sticking together of two dissimilar metals because of electrical transference of electrons.
  6. The ability of paint, Primer, or glue to stick to the surface to which it is applied.
  7. The ability of a tire to grip the surface of the road.
  8. Mutual forces between two magnetic bodies linked by magnetic flux, or between two charged non-conducting bodies which keeps them in contact
  9. Intermolecular forces which hold matter together, particularly closely contiguous surfaces of neighboring media, e.g., liquid in contact with a solid.
Adhesion failure
  1. A substance (like glue) that is used to join two substances.
    • An adhesive must bond both mating surfaces through specific adhesion (molecular attraction), through mechanical anchoring (by flowing into holes in porous surfaces), or through fusion (partial solution of both surfaces in the adhesive or its solvent vehicle).
    • Various descriptive adjectives are used with the term adhesive to indicate types, such as
      a. physical form
      Liquid adhesive, film adhesive, etc.
      b. composition
      Resin adhesive, rubber adhesive, silicone based, mastic, etc.
      c. end use
      Metal-to-metal adhesive, plastic adhesive, rubber adhesive
      d. application
      Sprayable adhesive, hot melt adhesive, etc.
  2. Agent for joining materials by adhesion, usually polymeric material.
    • May be based on thermoplastic resin (e.g., polystyrene cement) or thermoset (e.g., epoxy resin).
    • Viscosity is important for gap filling (high, as in epoxies) or surface penetration (low, as in cyano-acrylates).
    • Also called binder, cement, or glue
Adhesive bonding
The union of two materials with some chemical adhesive between them
Adhesive film
A thin layer of dried adhesive.

  • Also describes a class of adhesives provided in dry film form with or without reinforcing fabric and which are cured by means of heat and pressure
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) to distinguish it from the sticky side.
Adhesive weight
Lead wheel weights which have a sticky backing.

  • It comes in strips and is applied to a wheel rim to balance the wheel.
  • Also called tape weight.
A property of being able to maintain heat evenly.

  • It does not gain any heat or lose it
Adiabatic change
Without changing the temperature of an enclosure or its surroundings, there is a change in the volume and pressure of the contents of the enclosure.
Adiabatic compression
Compressing refrigerant gas without removing or adding heat.
Adiabatic efficiency
The ratio of that work required to compress a gas adiabatically to the work actually done by the compressor piston or impeller.
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.
Adiabatic processes
A change of state or process on a gas in which the gas neither receives nor rejects heat while it expands or is compresed.


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.)


A characteristic of something that can be changed, removed, or given different properties.

Adjustable bottom bracket
A component of a bicycle through which the crank is mounted.

  • It has two bearing cups on either side.
  • One cup is fixed in place while the other is removable or adjustable.
  • This is the older type of bottom bracket before sealed cartridge bottom brackets became prevalent.
  • The adjustable bottom bracket requires fixed and adjustable cup tools to properly tension the bearings.
  • The bearings are not sealed, but they are easily accessible for cleaning and lubrication.
Adjustable cup
The left-hand cup in a bottom bracket of a bicycle, used in adjusting the bottom bracket bearings and removed during bottom bracket overhaul. The other cup is the fixed cup.
Adjustable off-idle air bleed
An air adjustment screw

  • 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 requirements.
Adjustable part throttle
(APT) a supplementary circuit on some carburetors

  • The APT 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-pitch propeller


Adjustable-port proportioning valve
Air and fuel valves for oil or gas burners, motor operated in unison by automatic temperature-control equipment.
Adjustable rocker arm
A type of rocker arm with an adjusting nut that can be tightened or loosened to adjust valve lash.
Adjustable shock
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
adjustable shock absorberClick to supersize
Adjustable shock absorber

A type of shock absorber which can compensate for varying needs of stiffness or softness.

  • Manual types (especially on motorcycles) require that you physically make the adjustment from one level to another by rotating securing rings.
  • Automatic types are controlled by a computer as it senses particular changes in road condition.
Adjustable spanner
British term for Adjustable wrench.
Adjustable speed drives
Drives that save energy by ensuring the electric motor’s speed is properly matched to the load placed on the motor. Terms used to describe this category include

Adjustable steering
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

Crescent WrenchAdjustable Wrench

Crescent® wrench or pipe wrench.

  • A tool which has a fixed jaw and a movable jaw which is controlled by a spiral gear or slide.
  • 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 electricity
A measurement of electricity that includes the approximate amount of energy used to generate electricity. To approximate the adjusted amount of electricity, the site-value of the electricity is multiplied by a factor of 3. This conversion factor of 3 is a rough approximation of the Btu value of raw fuels used to generate electricity in a steam-generation power plant.
A device for moving something into the correct position or into a different position — usually a better position.

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.
Adjuster mechanism
A mechanism used with drum brakes that maintains the proper lining clearance as wear takes place.
Adjusting cams
The eccentric bolts that adjust the shoe-to-drum clearance. Located in the backing plate of drum brakes, the cam positions the shoe(s) closer to the drum. Some adjust automatically and some manually.
Adjusting gage
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.

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 threaded 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
Adjusting tool
Adjusting wrench
  1. Changing or modifying the position or alignment of two components.
  2. The distance of travel that a component has.
Adjustment Factor
Adjustment screw
The brand name of a vehicle. With required application the 1928-1934 Standard 8 models are classic cars.
Admiralty brass
The point in the working cycles of a steam or internal-combustion engine at which the intake valve allows entry of the working fluid into the cylinder.
This converter dolly has an ‘A’ shaped drawbar that joins at a single connection point to the trailer ahead of it. These dollies can have one or more axles and are the most common in use.


Adopt-A-Highway program
A volunteer program organized to keep roads and highways litter-free.

  • Groups, organizations, or individuals volunteer to clean a defined stretch periodically.




A paint dryer which has the heating elements below the paint drying line.
  1. Abbreviation for Association of Diesel Specialists.
  2. Abbreviation for Air data system
Substance with the property to hold molecules of fluids without causing a chemical or physical change.
The bonding that takes place when a gas or vapor comes into contact with a solid. The opposite is desorption.
Adsorption canister
Abbreviation for Average Daily Traffic — The total traffic volume during a given period (from 1 to 364 days) divided by the number of days in that period.
Abbreviation for Analog-Digital Unit
Ad Valorem
Latin for ‘according to value’ indicating that the freight rate is determined as a fixed percentage of the value of articles being shipped.
  1. The act of changing the ignition timing so that the spark occurs earlier in the cycle.
  2. It may refer to the device which makes this adjustment.
  3. The length of railway track beyond a signal which is covered by that signal
Advance capsule
Advance Control
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.
  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 Charge
  1. Pre-paid shipping costs paid by the shipper
  2. Freight costs advanced by one transportation company to another.
Advanced rim taper
A rim where both bead seats are tapered 5°.
Advanced Stop Lines
Stop line for cyclists ahead of other vehicle stop line at traffic signals.
Advance mechanism
Advance spring

Advance springAdvance spring

Located in the distributor, one of two small springs which pulls the advance weight back as the engine slows down.

Advance System
Advance unit
Advance weight

Advance weightAdvance weight

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

A colloquial term for a police car with its emergency lights flashing.
Advice Of Shipment
Information sent ahead of the shipment indicating its impending arrival.

  • Sometimes supplied with a copy of the invoice and/or the bill of lading.
Advisory Cycle Lane
Cycle lane, marked by a broken line, into which it is not an offence for other vehicles to enter.
Abbreviation for Acceleration Enrichment which is the enriched mixture provided when the throttle position sensor signal changes at various rates.
  1. Abbreviation for Automotive Electric Association
  2. Automotive Electronic Association.
Abbreviation for Automotive Engine Rebuilders Association.
  1. Act of combining substance with air
  2. 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.
Aeration test burner
(ATB) A burner for measuring the features of the combustion of commercial gases
British term for Antenna.

Aerial bunched conductors
(ABC) Method of power transmission where the three conductors are twisted into a thicker insulated cable.

  • More expensive but better at surviving blizzard conditions than normal separate conductors.
Abbreviation for Air Education and Recreation Organization in the UK.
Prefix from Greek αερ (aer) indicating air


An extension to bicycle handlebars which project forward to give the rider an alternate riding position and a lower, more aerodynamic position.

  • His elbows rest in the pads while he grabs the upright ends of the bars.
  • Aerobars were popularized by triathletes and Greg LeMond.
Sometimes referred to as Tri bars.

  • Aerobars popularized by triathletes and Greg LeMond, are attached to handlebars in order to provide a rider with a lower, more aerodynamic position.
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.

The efficient flow of air around an object.
Aerodynamic balance
A balance, usually but not necessarily in a wind tunnel, designed for measuring aerodynamic forces or moments.
Aerodynamic center
The point about which the pitching moment coefficient is constant for a range of airfoil incidence.
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, mufflersbumpers)
    • the amount of turbulence at the rear of the vehicle
    • the nature of the vehicle’s skin surface
    • 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).
  • Force proportional to frontal area, drag coefficient and speed squared, measured in pounds or kilograms as determined in a wind-tunnel.
Aerodynamic heating
The heating of a vehicle passing through the atmosphere, caused by friction and compression of air (or other gas).
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.
The power unit of a small aircraft.

British spelling for airfoil a body or body panel shaped like a wing so as to produce an aerodynamic reaction (lift) normal to its direction of motion, for a small resistance (drag), in that plane; e.g., a wing, plane, aileron, tailplane, rudder, or elevator.


Aero lever
One of a pair of road bike brake levers employing hidden cables that travel out the back of the level body and under the handlebar tape.
British spelling for airplane.
Aero system
A roof rack designed for cars without external rain gutters. The rack is held on by clips that extend down into the door.


Abbreviation for Automatic expansion valve.

A/C boltAcross Flats

  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.
  2. Abbreviation for air/fuel
  3. Abbreviation for Automatic focusing
  4. Abbreviation for Audio-frequency.
Abbreviation for Aluminum four-barrel, as in Carter AFB carburetor.
  1. Abbreviation for Air Flow Control
  2. Abbreviation for Air flow controlled fuel injection
  3. Abbreviation for Automatic frequency control
Abbreviation for Automatic flight control system
Abbreviation for Alternative Fuels Data Center
  1. Abbreviation for Audio-frequency modulation.
  2. Abbreviation for Air Flow Meter
Abbreviation for Air Fuel Ratio which is the mass ratio to fuel in the combustion chamber.

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-frame barricade

A-frame barricadeA-frame barricade

A traffic marker indicating that the road is not usable.

A/F ratio
Abbreviation for Air Flow Sensor
The back of a vessel.

Aft adjustment
Nearer stern (i.e., back of the ship).
After bottom dead center
(ABDC) The position of the piston as it starts its way up.
A device for burning excess carbon wastes produced by the engine so that Air pollution is reduced.
In an internal-combustion engine, persistence of the combustion process beyond the period proper to the working cycle, i.e., into the expansion period.
Delayed further collapse of underground workings after a rockburst.
  1. A device in a diesel engine which removes the relatively warm air which enters the engine.
  2. Chamber in which heat generated during compression of air is removed, allowing cool air to be piped underground.
Cooling the engine intake air after the turbocharger and prior to introduction into the cylinder. Aftercooling increases engine power and lowers NOx emissions. Also called Intercooling
  1. The period during which the glow plugs of a diesel engine continue to operate after the engine is started.
  2. The glow of a gaseous medium immediately after the cessation of electric current or downstream of an electric discharge.
All products and services used in the repair and maintenance of vehicles after the vehicle has been sold.
Aftermarket converted vehicle
A standard conventionally fueled, factory-produced vehicle to which equipment has been added that enables the vehicle to operate on alternative fuel.
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.
Aftermarket vehicle converter
An organization or individual that modifies OEM vehicles after first use or sale to operate on a different fuel (or fuels).
Nearest the back of the ship
After Peak
The compartment in the narrow part of the stern, aft of the last water-tight bulkhead.
After Perpendicular
A vertical straight line at, or near the after edge of rudder post.
After-start enrichment
(ASE) 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.
Aftertreatment Devices
Devices which remove pollutants from exhaust gases after the gas leaves combustion chamber (e.g., Catalytic converters or Diesel particulate filters). The term exhaust gas aftertreatment is considered derogatory by some in the emission control industry, but there is no consensus on the use of such alternatives as post-combustion treatment or exhaust emission control
Abbreviation for Alternative Fuels Utilization Program
Abbreviation for Alternative-Fuel Vehicle — a vehicle powered by a fuel other than gasoline or diesel.
Abbreviation for Air-guard.
Abbreviation for American Gas Association
Abbreviation for Automatic gain control.
Age harden
To use modified heat treatments at various temperatures over a period of time to harden and strengthen metal.
Age Hardening
A process of aging that increases hardness and strength, and ordinarily decreases ductility. Age hardening usually follows rapid cooling or cold working.


  1. An intermediary with legal authority to operate on behalf of the manufacturer.
  2. A chemical substance with a designated purpose
Agent fee
Although you can register your vehicle and obtain your license 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.
  1. Rock of specified quality and gradation.
  2. Materials such as sand or chipped rock that are spread on paved roads to increase vehicle traction. Also called abrasives
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 driving
A driving style in which the driver exceeds the speed limit, tailgates, weaves through traffic, fails to signal lane changes, fails to obey traffic signs and signals. May lead to or cause road rage.
  1. The cracking, checking, or general deterioration produced by exposure of an adhesive, coating or sealer to the weather or some other given set of conditions for a length of time
  2. The deterioration of rubber properties by oxidation over a period of time.
  3. A change in the properties of some metals after heat treatment or cold working (i.e., hammering or bending when metal is cold).
  4. The final stage of precipitation hardening, producing an increase in strength and hardness in metal alloys, due to precipitation of second phase particles from supersaturated solid solution over a period of days at room temperature, or several hours at an elevated temperature (called Artificial aging)
  5. Loss of strength in the cladding or the pressure vessel in a nuclear reactor due to irradiation. Artificial aging would be the simulation of such processes by increasing the rate of irradiation to obtain information more rapidly
  6. Change in the properties of a substance with time. A change in the magnetic properties of iron, e.g., increase of hysteresis loss of sheet-steel laminations; also the process whereby the subpermanent magnetism can be removed in the manufacture of permanent magnets
Agitation cup
A type of spray gun paint container which has an agitator.
  1. A device used to cause motion in confined fluid
  2. A device for mixing paint by shaking the container.
  3. A tank, usually cylindrical, which has a mixing device such as a propeller or airlift pump near the bottom. Finely ground mineral slurries (the aqueous component perhaps being a leaching solution) are exposed to appropriate chemicals for purpose of extraction of gold, uranium, or other valuable constituents. Types include pachuca tank or Brown agitator.
Abbreviation for Automotive gas oil.
Abbreviation for Advanced gas-cooled reactor.
Abbreviation for Aircraft general standard.
Abbreviation for Automated Guided Vehicle System.
Abbreviation for ampere-hour.
Abbreviation for Association of the Hungarian Automotive Industry.
Abbreviation for As High As Possible.
Abbreviation for As High As Reasonably Achievable.
Ahead Set
A type of Headset made by Dia-Compe that fits on a Fork that has a nonthreaded steerer
Abbreviation for Ampere-hour meter.
The sound of a particular kind of horn found on early model vehicles
Abbreviation 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.
Abbreviation for Air Injection
Abbreviation for American Institute of Aeronautics and Astronautics.
Abbreviation for American International Automobile Dealers Association.
Abbreviation for Association of International Automobile Manufacturers.
Abbreviation for Automotive Industry Association (Czech Republic).
Abbreviation for Automotive Industry Association (Slovakia).
Abbreviation for Automatic Idling Control Valve
Abbreviation for Associação dos Industriais de Montagem de Automóveis (Portugal).

aimerHeadlight Aimer

A tool for aiming a vehicle’s headlights.

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.
  1. Abbreviation for air conditioner.
  2. A bicycling or motorcycling term describing the space or gap between the tires and the ground when the bike takes a jump. Both tires must be off the ground before it can be called ‘air’ as in the expression, ‘I really caught air on that last jump.’
  3. A gas containing approximately 80% nitrogen, 20% oxygen, and a small portion of other gases and water vapor. One of the essential factors in a combustion engine (fuel, air, proper proportion of mixture, compressiontiming, and spark).
  4. A gas for combustion, heating, cooling, ventilation, breathing, and other uses.
An Abbreviation for Air Injection Reactor system of reducing objectionable exhaust emissions. A belt-driven pump sends air through a pipe to the exhaust manifold and/or catalytic converter to help control emissions. Replacement for the term EAC

Air Act
Air Act Amendments of 1990
Air and fuel
Air Anti-backfire Valve
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 aspirator valve
A device that uses a diaphragm to draw air into the exhaust system to reduce emission. If a large volume of air is needed, an air pump is used instead
Air-assisted hydraulic brake system
A hydraulic-type brake system actuated by an air hydraulic power unit.
Abbreviation for Air Bypass Solenoid
Air bag
  1. A device which is part of the passive safety system. In the event of a collision, sensors will cause the air bag to be deployed so that your head will be pillowed by the bag instead of hitting the instrument panel or windshield.
  2. A durable, inflatable bag used to force and secure freight to the inside walls of a trailer.
A device which is part of the passive safety system. In the event of a collision, Sensors will cause the airbag to be deployed so that your head will be pillowed by the bag instead of hitting the dash or windshield.

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 instrument panel or doors or even in the shoulder strap. Also called passive restraint system.
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.

Air bleed
Air bleed screw
Air box
A plastic, fiberglass, or metal container which may hold the air filter. Some are mounted between the carburetor and the air filter. This box provides a volume of still, filtered air for induction into the engine.
Air brake
  1. 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.
  2. An extendable device, most commonly a hinged flap on wing or fuselage, controlled by the pilot, to increase the drag of an aircraft. Originally a means of slowing bombers to enable them to dive more steeply, it is an essential flight control on clean jet aircraft and sailplanes
  3. A mechanical brake operated by air-pressure acting on a piston
  4. An absorption dynamometer in which the power is dissipated through the rotation of a fan or propeller.
Air break
An inverted opening placed in the chimney of a gas furnace to prevent back pressure from outside wind from reaching the furnace flame or pilot
  1. A paint spray gun used for precise detailing work and custom painting.
  2. The act of using an airbrush.
Air Bypass Solenoid
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 anti-backfire valve, diverter valve, or gulp valve.

Air Can Trailer
Colloquial term for a pneumatic tank trailer for transporting solids in bulk cargo

Air cap
Air capacitor
A capacitor in which the dielectric is nearly all air, for tuning electrical circuits with minimum dielectric loss.
Air capacity
Air cell
  1. A small auxiliary combustion chamber used in certain types of compression-ignition engines, for promoting turbulence and improving combustion.
  2. A space provided in the piston or cylinder to trap air during the compression stroke. It later flows out into the combustion chamber
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

air filterAir filter

  1. A device which filters the air entering the engine to remove airborne impurities, dust, dirt, and bumblebees. Without it, impurities could cause internal wear and damage. Also called air cleaner.
  2. A device using filters or electrostatic precipitators to remove indoor-air pollutants such as tobacco smoke, dust, and pollen. Most portable units are 40 watts when operated on low speed and 100 watts on high speed.
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

air filter elementAir filter 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.

Air cleaner intake
The neck, called a snorkel, into which air flows en route to the throttle body
Air coil
Coil on some types of heat pumps used either as an evaporator or a condenser.
Air collector
A medium-temperature collector used predominantly in space heating, using pumped air as the heat-transfer medium.
Air compressor
A device which compresses air and stores the air into a tank so that the compressed air can be used in a shop to fill tires, run tools, spray paint, etc. In a vehicle, it can be used in brake systems, leveling systems, automatic tire inflation systems, and air supply systems.
The state of exchanging warm air for cold so that a vehicle or home is cooler than the outside temperature.
Air conditioner
(A/C) or (Air)

  1. A device used to control temperature, humidity, cleanliness, and movement and sometimes the air purity, in an enclosed space
  2. A system of devices which causes a reduction or control of the temperature and humidity within the cab of a vehicle. It was first offered on the 1941 Packard. Two types are used in vehicles: receiver-dryer type and accumulator type.
Air conditioner clutch compressor signal
(ACCC signal) the input to the computer regarding the status of the air conditioner clutch (engaged or disengaged).
A system or process for controlling the temperature, humidity, air movement, and sometimes the purity of the air in an enclosed space by use of a refrigeration unit powered by electricity or natural gas. Note Fans, blowers, and evaporative cooling systems (swamp coolers) that are not connected to a refrigeration unit are excluded..

Air conditioning compressor
  1. Pump of a refrigerating mechanism which draws a low pressure on cooling side of refrigerant cycle and squeezes or compresses the gas into the high-pressure or condensing side of the cycle.
  2. An air conditioning component which pumps, circulates, and increases the pressure of refrigerant vapor
Air conditioning sensor
A detection device which provides information that the air conditioning compressor is operating for idle speed control.
Air control
Air Control Solenoid Vacuum Valve Assembly
Air control valve
(ACV) a vacuum-controlled diverter valve (or a combination bypass/diverter valve) in an air injection system that diverts air pump air to either the upstream (exhaust manifold) or downstream (oxidation catalyst) air injection points as necessary.

Any device whose produced heat is reduced by the flow of air around it
Air-cooled apparatus
An electric apparatus in the heat caused by the losses is removed solely by natural or fan-assisted air flow.
Air-cooled condenser
A heat exchanger which transfers the heat of compression from condensing coils to surrounding air. This may be done either by convection or by a fan or blower.
Air cooled engine

Air cooled engineAir cooled engine

An engine which generally has large fins or ribs and is often exposed to the outside air. The heat of the engine is dissipated through the fins of the engine. In contrast, the heat in a liquid-cooled engine is reduced by channels throughout the inside of the engine through which liquid (antifreeze) passes. Most older Volkswagens and some motorcycles use air cooled engines.

Air-cooled engine
Air-cooled machine
A machine in which the heat caused by the losses is removed solely by natural or fan-assisted air flow.
Air cooler
  1. Mechanism designed to lower temperature of air passing through it
  2. The cold accumulator used in the Lindé process of air liquefaction for the preliminary cooling of the air.
Air cooling
The cooling of hot bodies by a stream of cold air, instead of liquid (water) cooling.

Air core
Coil of wire not having a metal core.
Air core solenoid
Solenoid which has a hollow core instead of a solid core.
Air correction jet
A small orifice which permits air to enter the emulsion tube of a carburetor.
Any mechanically driven heavier-than-air flying machine with wings of fixed or variable sweep angle. Subdivision landplane, seaplane (float seaplane and flying boat), amphibian.
Aircraft quality
Fasteners made with a particularly high level of attention in manufacture and inspection.
Air cushion


Abbreviation for AIR Diverter Solenoid
Air dam
  • An attachment called a spoiler which is usually located below the front bumper. Its design, shape, and placement helps to reduce the flow of air under the vehicle. It may help to increase the flow of air to the radiator and engine compartment, affect aerodynamic drag, or affect positive and negative lift.
  • A barrier beneath the front bumper used to divert the flow of air beneath the car. Usually intended to reduce lift and drag.
Air deflector
A panel which is positioned at an angle on the roof of a truck or on the front of the hood to cause the air to flow over the vehicle. The hood air deflector (often made of transparent plastic) is designed to prevent bugs from hitting the windshield. British term is ‘air shield.’
Air diffuser
Air distribution outlet or grille designed to direct airflow into desired patterns.
Air Diverter Solenoid
Air drag
Resistance to the motion of a body passing through the Earth’s atmosphere, most serious in the lower regions, producing changes in the geometry of the orbit, even causing the body to re-enter. More generally the term atmospheric drag is used in reference to other planets.
Air dry
Allowing paint to dry at ambient (surrounding) temperatures, without the aid of an external heat source.
Allowing paint to dry at ambient (surrounding) temperatures, without the aid of an external heat source.
Air drying adhesives
Adhesives that can be dried at room temperature without the use of heat. This type of adhesive consists of solid particles dissolved or dispersed in a liquid. When the liquid evaporates, it leaves the dry adhesive film. Most elastomer based adhesives are of this type.
Air duct
A tube or channel which permits heated and ventilated air to enter the passenger compartment, building, or machinery to provide heating, cooling, or ventilation.
Aired up
Said of an oil plunger pump which no longer sucks because gas or air has filled the suction chamber.
Air ejector
A type of air pump used for maintaining a partial vacuum in a vessel through the agency of a high-velocity steam jet which entrains the air and exhausts it against atmospheric pressure.
Air engine
  1. An engine in which air is used as the working substance. Rapid heating from an external source expands the air in the cylinder with consequent motion being imparted to a piston. After transfer to a compression cylinder, for rapid cooling, the air is returned to the working cylinder for the next cycle. Also called hot-air engine.
  2. A small reciprocating engine driven by compressed air.
Air-entraining agent
Resin added to cement or concrete to trap small air bubbles
Air exhauster
  1. A suction fan.
  2. A vacuum pump.
Air filter
A device for removing impurities from the air which enters the combustion chamber.

Air filter element

Air Filter ElementAir Filter Element

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

Air filtration
Air filtration system
A system that cleans smog, pollen, exhaust smoke, and odors out of the air. Cleans both interior circulated air and that coming from the outside.
The passage of air which moves around an object (esp. a vehicle) or through an air duct (e.g., ventilation system or exhaust system).

Air flow controlled fuel injection
(AFC) a Bosch term for its early pulse fuel injection systems; usually refers particularly to the system which uses an L-Jetronic air mass sensor.
Air flow meter
  1. A sensor which measures the rate at which air enters the engine. In Bosch systems, any device that measures the amount of air being used by the engine. The control unit uses this information to determine the load on the engine. The two most common examples of airflow meters are the air-flow sensor used in the Bosch L-Jetronic and the air mass sensor used in the Bosch LH-Jetronic systems.
  2. An instrument, mainly experimental, for measuring the airflow in ducts
Airflow meter
Air flow sensor
  1. A device in an electronically controlled fuel injection system which detects the amount of air entering the combustion chambers. Continuous injection systems use an airflow sensor plate to measure airflow volume; electronic systems use a vane or flap-type airflow sensor.
  2. A detection device that provides information on the volume flow or mass flow rate of the intake air to the engine.
Air foil

air foilAir foil

An aerodynamic device used to improve traction by increasing the downward force on either end of the car. It can be compared to an airplane wing with this primary difference A wing is designed to provide lift so it can fly; the air foil pushes the vehicle closer to the ground. Although they may be called ‘wings,’ they are properly air foils. They increase the cornering ability, improve Stability, but add aerodynamic drag.

Airfoil section
The cross-sectional shape or profile of an airfoil.
Air Freight Container
A smaller and lighter cargo container often made out of fiberglass designed to hold cargos that are shipped in airplanes.
Air fuel
Air-fuel mixture
Finely atomized mist of air and fuel necessary for combustion.

Air fuel ratio
Air-fuel ratio
(A/F ratio) The mass of air supplied to the engine divided by the mass of fuel supplied in the same period of time (i.e., ratio of air weight to fuel weight). The Stoichiometric, or chemically correct, air-fuel ratio is the exact ratio necessary to burn all the carbon and Hydrogen in the fuel to carbon dioxide and water with no Oxygen remaining. The Fuel-air ratio is the reciprocal of the air-fuel ratio. The amount of air is much greater than the amount of fuel, usually between 14.7:1 and 15:1, depending on the type of fuel system.

Air Furnace
Air gap
  1. The space between the magnetic poles or between rotating and stationary assemblies in a motor or generator
  2. In a Regulator it is the distance between the contact Armature and the iron core that when magnetized, draws the armature down.
  3. The distance or space between the Reluctor tooth and Pick up coil
  4. The distance between the two electrodes of a spark plug.
  5. Gap with points or knobs, adjusted to breakdown at a specified voltage and hence limit voltages to this value.
  6. Section of air, usually short, in a magnetic circuit, esp. in a motor or generator, a relay, or a choke. The main flux passes through the gap, with leakage outside depending on dimensions and permeability.
Air gap voltage
Voltage across a gap or equivalent filler of nonmagnetic material across the core of a choke, transformer, or other magnetic device.
(AG) An American Motors air injection system that uses an air pump to supply air into the exhaust manifold to reduce HC and CO emissions.
Air gulp system
A system in vehicles with secondary air injection or induction, which prevents an very rich mixture of air-fuel from entering the inlet manifold during deceleration. If it did enter, unburned fuel would be forced over the hot exhaust system causing backfiring (i.e., uncontrolled detonation). The air gulp system prevents this condition by allowing a quantity of air to combine with the rich mixture in the inlet manifold.
Air gulp valve
A diverter valve which adds an amount of air to the rich air-fuel mixture entering the intake manifold during deceleration.
Air gun
Air hammer

Air hammerAir Hammer

A hammer-tool that is powered by compressed air and used for riveting, or chipping. Sometimes called an air gun or gun.

Air handler
Fan-blower, heat transfer coil, filter, and housing parts of a system.
A term for older, air-cooled BMW Boxer Twin motorcycles.
Air hold fitting
A tool which uses air pressure to keep the valves closed when working on an OHV engine. The device is screwed into the spark plug holes and air pressure keeps the valves from dropping down. In this way the valve seal or valve spring can be replaced without removing the cylinder head.
Air horn

Air HornCarburetor Air Horn

  1. The upper part of a carburetor into which the air is drawn. The choke butterfly is located in this air horn.
  2. It is also a term used for a warning horn which is operated by forcing compressed air through a reed.
Air horn baffle
Used on some Rochester Quadrajet carburetors to prevent incoming air from forcing fuel into the secondary wells through the bleed tubes. Prevents secondary-nozzle lag during heavy acceleration.
Air hydraulic brake power-assist unit
A unit consisting of an air cylinder or chamber, hydraulic cylinder(s) and control valve in which driver effort is combined with force from the cylinder piston or chamber diaphragm to displace fluid under pressure for actuation of the brake(s).
Air-hydraulic system
An air brake system that uses a single air chamber to power a hydraulic master cylinder that applies the wheel friction assemblies through conventional brake calipers and wheel cylinders.
Air induction
Air infiltration
Leakage of air into rooms through cracks, windows, doors, and other openings.
Air injection
A system that injects fresh air into the exhaust ports or a Thermal reactor, for additional conversion of Carbon monoxide to carbon dioxide and combustion of unburned Hydrocarbons (unburned fuel vapors) found in the exhaust gases as it comes in contact with the high heat in the exhaust manifold. Also called air induction.
Air injection manifold
The duct inside the cylinder head or the tube outside the cylinder head feeding secondary air into the exhaust ports.
Air injection reaction
Air injection reaction system
(AIR system) The AIR system helps to reduce Hydrocarbons and Carbon monoxide levels in the exhaust by injecting air into the exhaust ports of each cylinder during cold engine operation, or directly into the Catalytic converter during normal operation. It also helps the Catalytic converter to reach proper operating temperature quickly during warm-up. If a GM car has an Air pump, the system is an AIR otherwise it is a PULSAIR system.
Air injection system
(AIS) any system that injects air into the exhaust stream to promote more complete oxidation of unburned exhaust gases.
air inlet
Air Inlet System
Air inlet valve
An adjustable door, often vacuum operated, in the plenum blower assembly that permits election of outside or inside air for automotive heating and cooling systems.
Air intake
  1. Any opening introducing air into an aircraft; the opening for the main engine air is usually implied if unqualified.
  2. The opening through which air enters a component such as the carburetor, fuel injection system, radiator, heating system, or ventilation system.
  3. Vent in a carburetor through which air is sucked to mix with the gasoline vapor from the jet.
Air-intake guide vanes
Radial, toroidal or volute vanes which guide the air into the compressor of a gas turbine, or the supercharger of a reciprocating engine.
Air jet
A small jet in the air passage of a carburetor. It meters the amount of air fed to the diffuser in an air bleed carburetor.

Airless spraying
A paint spraying process where the coating material (i.e., paint) is not atomized by a stream of air. Instead, it is subjected to high pressure and forced through a narrow jet or nozzle which causes it to be atomized.
Airless spray gun

Airless spray gunAirless spray gun

A paint spraying tool used in Airless spraying.

Air Lift Axle
An air-powered axle which, when lowered, will both convert a vehicle into a multi-axle unit and provide greater load carrying capacity
Air line
  1. A pipe, hose, or duct in a vehicle which permits the flow of air or vacuum.
  2. The supply line coming from an air compression tank to drive air tools or inflate tires.
  3. Straight line drawn on the magnetization curve of a motor, or other electrical apparatus, expressing the magnetizing force necessary to maintain the magnetic flux across an air-gap in the magnetic circuit.
Air liquefier
A type of gas refrigerating machine based on the Sterling or hot-air engine cycle.
Air lock
  1. A bubble of air trapped in a fluid circuit which interferes with normal circulation of the fluid.
  2. Device by which access is obtained to the working chamber (filled with compressed air to prevent entry of water) at the base of a hollow caisson. The worker at surface enters and is shut in an air-tight chamber filled with air at atmospheric pressure. Pressure within this air-lock is gradually raised to that used in the working chamber, so that the worker can pass out through another door and communicate with the working chamber.
Air management system
(AMS) used to control the injected air to the exhaust manifold and catalytic converter. This improves the pollutant conversion efficiency in the converter.
Air management unit
(AMU) — An assembly of pressure switches, and other valves located in a chassis cross-member, designed to control the pneumatic accessory functions of a vehicle using the multiplex electrical system.
Air mass flow
In a gas turbine power plant, the quantity of air which is ingested by the compressor, normally expressed in pounds or kilograms per second.
Air mass meter
An instrument which measures both engine intake air mass and factors which affect air density, such as temperature, humidity, and pressure.
Air mass sensor
An airflow detection device that uses the changing resistance of a heated wire in the intake airstream to measure the mass of the air being drawn into the engine. Also referred to as a hot-wire sensor.
Air meter
An apparatus used to measure the rate of flow of air or gas.
Air micrometer
A control in a paint spray gun which adjusts the amount of air.
Air mixture
Air outlet
The vent or opening where the passage of air exits — especially in systems for air conditioning, ventilation, and defrosting as air enters the passenger compartment or flows out of the compartment.
Air outlet valve
A vacuum operated door which directs air flow into the heater core or ducts, usually located in or near the plenum blower assembly. A vacuum operated door which directs air flow into the heater core or ducts, usually located in or near the plenum blower assembly.
Air Over
(AO) An electric motor intended for Fan and Blower service and cooled by the air stream from the fan or blower
Air passage
Air pipe
Air pollution
Contamination of the earth’s atmosphere by various natural and man-made pollutants such as smoke, gases, dust, etc.
Air Port
A circular opening or window through the side of a ship or deck house to provide light or ventilation.
Air pressure
  1. The atmospheric pressure.
  2. Tire pressure.
  3. The force of air coming from a compressor used to power air tools or apply air brakes.
Air Principle
Air Pulse Valve
Air pump

Air pumpAir pump (Air Injection system)

  1. The device that supplies the fresh air needed by the Air injection system.
  2. Air pumpAir pump

    A reciprocating or centrifugal pump used to remove air, and sometimes the condensate, from the condenser of a steam plant.

  3. Any device used for transferring air from one place to another. A compressor increases the pressure, a Vacuum pump reduces the pressure and a blower causes a rapidly moving air blast
  4. A device used in the emissions system to provide fresh air into a vehicle’s exhaust to help complete the combustion process and reduce emissions. To get accurate lambda measurements with the LM-1, air pumps should be temporarily disabled.
Air quality
The extent to which air is free from contaminants, conventionally taken to be the respiratory irritants nitrogen dioxide and sulfur dioxide.
Air Quality Management District
(AQMD) A term used principally in California to describe administrative districts organized to control air pollution. Nationwide, AQMDs are parallel to the areas designated for classification against the National Ambient Air Quality Standards (NAAQS). Generally, AQMDs and their national parallel encompass multiple jurisdictions and closely follow the definition of Consolidated Metropolitan Statistical Areas and Metropolitan Statistical Areas.
Air Quality Standards
Air ratchet

Air ratchetAir ratchet

Ratchet tool powered by air pressure from an air compressor

Air ratio
The ratio of actual intake air volume to the air volume theoretically needed for complete combustion of a particular amount of the fuel. This ratio is represented by the Greek letter lambda λ (which looks like the letter y upside-down).

Air receiver
An air tank which holds the compressed air created by a compressor.
Air-recirculation system
Air Regulator
Air resistance
The resistance of the air to forward movement, sometimes called aerodynamic drag. This is a factor of the shape of the vehicle, the objects which stick out (i.e., mirrors, mufflersbumpers), 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).
Air Resources Board
Air Ride Suspension
(ARS) A suspension system in which the load is supported on air-filled rubber bags rather than steel springs. The engine’s air compressor fills the reservoir tanks which supplies air for the suspension and the air brake system.
Air scoop

Air scoopAir Scoop

A forward facing aerodynamic device or opening used to Duct cool outside air to some part of the vehicle such as the carburetor Intake, the brakes, the radiator, or an Oil cooler.



Air screw
Any type of screw designed to rotate in air; defined in 1951. Term now obsolete and replaced by Propeller, a device for propelling aircraft, and Fan, a rotating bladed device for moving air in ducts or wind tunnels.

Air select valve
A valve in a two-stage catalytic converter with secondary air injection. It is operated by a solenoid and is triggered by the electronic control module. It directs air to the exhaust valve ports or to the midbed catalytic converter, depending on operating conditions.
Air-sensing thermostat
The unit in which sensing element is located in refrigerated space.
Air sensor
  1. A detection device which checks for the presence of air pollutants entering the passenger compartment. If the pollutant concentration is too high, it operates flaps to cut off the external air to the air conditioning system.
  2. An air cone with a floating plate which measures air flow and determines plunger position on K-Jetronic type systems
Air shield
British term for Air deflector.
Air shock absorber
A shock absorber or damper which has a rubber bladder filled with compressed air. As the air pressure increases the vehicle is raised. The system is used in automatic leveling suspensions.
air shutter
An adjustable device for varying the size of the Air inlet(s) regulating primary or secondary air.
Air silencer
A device which is placed in the air cleaner assembly to reduce the sucking noise that air makes as it enters.
Air solenoid
Air-spaced coil
Inductance coil in which the adjacent turns are spaced (instead of being wound close together) to reduce self-capacitance and dielectric loss.
Air spring
A high pressure air-filled spring used in the suspension fork of some bicycles or the suspension of some cars.

Air springing
Air standard cycle
A standard cycle of reference by which the performance of different internal-combustion engines may be compared, and their relative efficiencies calculated.
Air standard efficiency
The thermal efficiency of an internal-combustion engine working on the appropriate air standard cycle.
Air stop
A registered trademark for Michelin tubes.
Air Strut
Air-suspended power booster
A type of power booster that contains atmospheric pressure in both chambers of the booster when the brake pedal is at res. When the pedal is applied, the front chamber is opened to manifold vacuum, causing the diaphragm of the booster to move toward the master cylinder which assist the driver in the application of the brakes.
Air suspension

Air suspensionAir suspension

Suspension system using air rather than metal springs to support the vehicle and control ride motions. Air springing results in a smoother ride, because the natural frequency of vibration of an air spring does not vary with loading as it does with metal springs. Air springs can be made very soft for the lightly loaded condition and the pressure automatically increased to match any increase in load, thus maintaining a constant sprint vibration period any load.

Air suspension power booster
A type of power booster that contains atmospheric pressure in both chambers of the booster when the brake pedal is at rest. When the pedal is applied, the front chamber is opened to manifold vacuum causing the diaphragm of the booster to move toward the master cylinder which assists the driver in the application of the brakes.
Air switching
Air switching valve
(ASV) a valve in an air injection system that senses intake manifold vacuum and during heavy loads, dumps part of the air pump output to the air cleaner to reduce air injections system pressure.

AIR system
Air system
Air tank
An air container which holds the compressed air created by a compressor.
Air temperature
Air temperature sensor
(ATS) A detection device which monitors the fluctuation of temperature in the air conditioning system so that the temperature in the cab of a vehicle can be maintained.

Air-to-air intercooler
A heat exchanger used on a turbocharged engine, which uses liquid coolant from the rad to cool the air coming from the turbo into the intake manifold.
Air tool
A tool such as an impact driver or drill which is powered not by electricity, but by air pressure coming from an air compressor.
Air Toxics
Toxic air pollutants defined under Title II of the CAA, including benzene, formaldehyde, acetaldehyde, 1-3 butadiene and polycyclic organic matter (POM). Benzene is a constituent of motor vehicle exhaust, evaporative and refueling emissions. The other compounds are exhaust pollutants.
Air transformer
A device which is placed between the compressor and a paint spray gun to provide clean spraying air and to regulate the oil pressure.
Air valve
A valve in a spray gun which controls the flow of air by the operation of the trigger.

Air valve carburetor
Air-valve carburetor
A type in which a spring-closed or weight-closed air valve opens in response to engine demand. This valve, through suitable linkage, varies the fuel-orifice opening to secure the desired mixture ratio throughout the range of operation. SU and Stromberg CD carburetors operate on this principle, referred to also as Constant-vacuumConstant-depression, or variable-Venturi.
Air vent
A valve, either manual or automatic, used to remove air from the highest point of a coil or piping assembly
Air volume
The amount of air.

Air Volume Controller
Air volume spraying
A method of spray application which involves higher volume and lower pressure of air than high-pressure air spraying.
Air washer
A device used to clean air while increasing or lowering its humidity
A passageway that allows air to enter.
  1. Abbreviation for Air injection system.
  2. Abbreviation for Automatic Idle Speed motor
Abbreviation for Air Inlet Temperature sensor–Used to measures inlet air temperature for fueling
  1. Abbreviation for atmospheric/automatic inlet valve, a system used on early motorcycle engines in which the intake valve is held shut by a weak spring and opens by atmospheric pressure when the falling piston creates a vacuum in the cylinder.
  2. Abbreviation for air injection valve
Abbreviation for Anti-knock Index — the average of the RON and MON. This is the number posted on the retail gasoline pumps normally indicating 87, 89, or 92 octane. Racing gasoline have AKI’s from 100 to 118.
Abbreviation for As Low As Possible.
Abbreviation for As Low As Reasonably Achievable. Used of radiation levels or decontamination.
A warning sound made by a security or safety device to warn off thieves, alert the driver to take some preventative measures (e.g., secure the seat belts), or warn those around the vehicle (e.g., backup warning alarm). Alarms may sound as a buzzer, a chime, or a human voice.

Alarm system
A theft protection system which may do one or more of the following Sound the horn or an auxiliary siren, flash the lights, lock the hood and trunk, make the ignition inoperative, put the engine in a Limp-home mode, notify the police, and alert the vehicle owner.
The condition of a vehicle which is protected by an alarm system.
Alberta Motor Association
(AMA) An Automobile Association in the Canadian province of Alberta affiliated with the American Automobile Association
Abbreviation for Automatic Level Control
Abbreviation for Assembly Line Communications Link (GM)
  1. A general term for compounds formed from hydroxyl groups attached to carbon atoms in place of hydrogen atoms. The series of molecules vary in chain length and are composed of a hydrocarbon plus a hydroxyl group; CH(3)-(CH(2))n-OH (e.g., methanolethanol, and tertiary butyl alcohol). It may be used as a fuel.
  2. A beverage which impairs a driver’s skill in operating a vehicle safely. Although the law has set down limits of the amount of alcohol allowable in the bloodstream before a person is considered drunk, the effects of the slightest amount of alcohol can impair one’s driving skill.
Alcohol brine
Water and alcohol solution which remains a liquid below 0°C
Alcohol content
Alcohol-ethyl Hexanol
Alcohol fuel
Volatile liquid fuel consisting wholly or partly of alcohol, able to withstand high-compression ratios without detonation.

Alcohol level
A class of organic compounds derived by removing the hydrogen atoms from an alcohol. Aldehydes can be produced from the oxidation of an alcohol.
  1. Abbreviation for Assembly Line Data Link connector a diagnostic connector.
  2. Abbreviation for assembly line data link.
Oldsmobile Alero BooksClick image for books on
Oldsmobile Alero

A model of automobile built by Oldsmobile from 1999-2004

Alert system
AlfaClick logo for books on

A vehicle brand of which all 1925-48 models are classic cars. The following models are milestone cars:

  • All 1956-64 Giuletta Spider models
  • All 1959-61 Giuletta/Giulia Sprint Speciale models
  • All 1949 6C 2500 Super Sport models

Other models include:

Alfa Romeo
AlfasudClick image for books on

A model of automobile from Alfa-Romeo

AlfettaClick image for books on

A model of automobile from Alfa-Romeo

Al fresco driving
Driving in a convertible with the top down.
Low form of plant life, found floating free in water and can accumulate in vehicle vents
Basic private pilot’s license in the UK.

  1. Process of bringing two or more items into mating conjunction so that all the bolt holes and locating pins fit properly.
  2. Process of adjusting the wheels and other devices so that they are in a straight line.
Align bore
A machining operation which corrects an engine’s out-of-round and/or warped main bearing housings. It may be done with either stationary or portable equipment.

Align hone
A machining operation which corrects an engine’s out-of-round and warped main bearing housings with a special honing mandrel. It must be done with stationary equipment.
Aligning cups
Devices used in mounting floating drums on the arbor of a brake drum lathe.
Aligning punch

Aligning PunchAligning Punch

A tool shaped like a thin rod used to make sure holes line up when assembling two or more components. Especially used on items which may move to one side before the other side can be aligned or another component installed or when the gasket is likely to slip out of place.

Aligning set
Aligning tool
  1. When referring to wheel alignment, it is the proper adjustment of a vehicle’s front or rear suspension for cambertoe-intoe-outkingpin inclination or steering axis inclination, and turning radius or toe-out on turnscaster, and ride height. Four-wheel alignment is necessary for front-wheel drive vehicles.
  2. The adjustment of two objects to bring them into the proper relation to each other.
  3. The setting in line (usually straight) of successive lengths of a railway which is to be constructed
  4. The plan of a road or earthwork
  5. The setting in a true line of a number of points, e.g., the centers of the bearings supporting an engine crankshaft
  6. Process of orientation of e.g., electric or magnetic dipoles when acted on by an external field. During magnetization, the alignment of domains is changed by the magnetizing field
  7. Adjustment of preset tuned circuits to give optimum performance
  8. The horizontal route or direction of an access road.
Alignment gap
The distance between two adjacent auto body panels. When an alignment gap varies too much, it is a sign of poor assembly quality.
Alignment gauge
Alignment pin
A pin or stud used to align one part with another, such as the pins used to align a cylinder head on an engine block.
Alignment stud
A pin or stud used to align one part with another, such as the pins used to align a cylinder head on an engine block.
Align ream
Machining or hand process which enlarges the inside diameter of bushings to the correct size.
A class of saturated or unsaturated carbon compounds, in which the carbon atoms are joined in open chains.
Alive Memory
Alkaline battery
A storage battery which uses an alkaline electrolyte (dilute potassium hydroxide).
Alkaline degreasing
A process of removing an oily or greasy substance with the use of an alkaline solution. Often used in preparing a surface for painting.
Alkaline fuel cell
(AFC) A type of hydrogen/oxygen fuel cell in which the electrolyte is concentrated KOH (varies between 35 to 85 percent by weight depending on the intended operating temperature) and hydroxide ions (OH-) are transported from the cathode to the anode. Temperature of operation can vary from below 120°C to approximately 250°C depending upon electrolyte concentration.
The product of an alkylation reaction. It usually refers to the high-octane product from alkylation units. This alkylate is used in blending high octane gasoline.
A refining process for chemically combining isobutane with olefin hydrocarbons (e.g., propylenebutylene) through the control of temperature and pressure in the presence of an acid catalyst, usually sulfuric acid or hydrofluoric acid. The product, alkylate, an isoparaffin, has high octane value and is blended with motor and aviation gasoline to improve the antiknock value of the fuel.
All-alloy engine
An engine which uses a light alloy for the block, crankcase, sump, and cylinder head.
All-aluminum body
A body shell which is mostly made of aluminum.
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Cadillac Allanté

A model of automobile manufactured by the Cadillac division of General Motors from 1987-93

Allan valve
Once popular slide-valve design with an internal passage designed to reduce valve travel and wear.
A vehicle brand of which the 1946-56 Series J2, K2, K3 models are milestone cars.
All-Commodity Rate
The fixed charge to transport a number of items in a single vehicle at one time from the consignor (i.e., shipper) to the consignee (i.e., receiver). This rate is based on the actual cost of transportation not the value of service.
All electronic ignition
All-electronic ignition
Allen key
Allen screw
A fastening device (either a wood screw type or bolt threads) with a recessed hexagon hole in the head. Also called a hex hole screw.
All-enveloping body
A modern passenger car body style in which the fenders, headlamps, and radiator grille are one smooth body line. It contrasts with the style before World War II where the fenders and headlights were separate from the main body.
Allen wrench
An rod with six sides and often L-shaped. Used to remove certain bolts or screws and fastenings, especially set screws. Sometimes called hex wrenches or Allen key.
  1. A privately maintained thoroughfare, tract, or easement, usually narrower than a street, which provides access to the rear boundary of one or more lots and is not intended for general traffic circulation.
  2. A public road, usually single lane, which separates rows of houses and is used for access for garbage pickup, etc.
  3. A groove in a block of metal along which ball bearings or a rod slides.
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An automobile manufactured by AMC

Alliance of Automobile Manufacturers
(AAM) See website Alliance of Automobile Manufacturers.
A colloquial term for a large piece of a tire on the road.
Alligator clip

alligator clipsAlligator clips

A small spring clip which is X-shaped. As you squeeze the two legs of the clip, the other two jaws (usually serrated) open. Used to make temporary electrical connections. Larger ones are used at the ends of jumper cables. The British call it a crocodile clip.

Alligator hood
The engine bay hood that opens from the front and its hinge is near the firewall. Although it is the most common, older cars opened from the side. Some sports cars and large trucks open with the hinge at the front of the vehicle.
All-insulated switch
All-mountain bike
mountain bicycle designed to balance climbing and descending abilities with slightly more emphasis on descending prowess; features dual suspension with 4 to 6 inches of travel
Allocated Inventory
A warehouse term for product which has been ordered for a specific customer or promotional event and is not to be used for other requests. A good WMS will tag the items so that they are not available apart from the designated purpose.
All-out braking
A situation where the driver uses the maximum braking effort possible. Although this seems to be the best way to stop a vehicle, in fact it may not because there may be the tendency to swerve or the brakes may overheat and lose effectiveness. It is better to pump the brakes (if ABS is not available) to control steering and get maximum braking.
Allowable working pressure
The maximum gauge pressure at which a part or system may be operated in accordance with the provisions of this standard. It is the pressure used in determining the setting of pressure limiting or relieving devices installed to protect the part or system from accidental overpressuring.
A reduction of the shipping costs if the carrier does not provide the necessary equipment (e.g., pallet jack, crane) and that equipment is supplied instead by the shipper.

Fuel reserves, usually specified as time factors under certain conditions, as distance plus descent, or as a percentage (by weight or volume) of the cruising fuel for a given stage.
A mixture of two or more elements, especially where one is aluminum.

Alloy cast-iron
Cast-iron containing alloying elements in addition to carbon and the normal low levels of manganese and silicon, usually some combination of nickel, chromium, copper, and molybdenum. These elements may be added to increase the strength of ordinary irons, to facilitate heat treatment, or to obtain martensitic, austenitic, or ferritic irons.
Alloy engine
  1. The process of making an alloy
  2. The addition of one or more elements to a pure metal to alter the pure metal’s properties such as strength, elongation, weight reduction, etc.
Alloy Layer
Alloy piston
A piston made primarily of aluminum.
Colloquial term for Alloy wheels.
Alloy steel
  1. A steel to which elements not present in carbon steel have been added, or in which the content of manganese or silicon is increased above that in carbon steel.
  2. Molybdenum alloy steel used in bicycle frames.
Alloy wheel

alloy wheelAlloy Wheel

A generic term used to describe any non-steel road wheel usually cast as one piece. The usual alloys are either aluminum or magnesium; the latter material led to the common usage of the term mag wheel, often referring to any non-steel wheel or even a one-piece plastic wheel. Also called Cast Aluminum Wheel

All-season tire

all-season tireAll-season Tire

A tire that usually has a more aggressive tread pattern than a summer tire, but not nearly as aggressive as a mud and snow tire. Most new automobiles are sold with all-season tires.

All short
A situation in which none of the freight is received with the movement document.
All-steel body
A vehicle body shell which is made entirely of steel rather than one with a wooden frame with steel panels or steel frame with aluminum panels.
All terrain
For use on any kind of ground surface (not on lakes or ocean, though).
All terrain bike

ATBAll-terrain Bicycle

(ATB) A bicycle with straight handlebars, sturdy fat tires, and wide-range gearing designed for off-road use. Also called mountain bike.

All-terrain bike
(ATB) A bicycle with straight handlebars, sturdy fat tires, and wide-range gearing designed for off-road use. Also called mountain bike.
All terrain tire
A tire which has a number of lugs or knobs used to propel the vehicle over rough surfaces.
All terrain vehicle
A vehicle used in rough surface conditions. Also called off-road vehicle.
A model of automobile from the Buick division of General Motors from 2005-current. The same model in the United States is called the LaCrosse (an offensive term in Quebec). It has a 3.8 litre V-6 engine and a 4-speed automatic transmission; wheelbase is 2807mm; overall length is 5031mm.
Allure libre
A self-paced long-distance bicycle ride as promoted by the Audax Club Parisien, the Randonneurs Mondiaux, and the Randonneurs USA. You can ride at your own pace so long as you finish within the time limit. This is not a race where riders are recognized for finishing ahead of other riders. The important thing is to finish the ride.
All Weather
An early car term referring to the first convertibles. Commonly used in the twenties and thirties to denote a four door convertible sedan.
All-weather tire
A tire that can be used on roads that are bare or covered with rain, snow, or ice.
All wheel drive
All-wheel drive
(AWD) A variation of four-wheel drive (4WD) designed to improve on-road traction in unfavorable road conditions or for ultra high performance driving. All-Wheel Drive (AWD) reduces wheel slippage and provides greater driver control over the vehicle. AWD usually does not require the driver to actively engage the system and does not have a low range. AWD automatically splits engine torque between the front and rear wheels as needed. All-Wheel Drive is generally an on-road system and is not designed for off-road use.
All-wheel steering
Alnico® magnet
A high-energy permanent magnet which is an alloy of aluminum, nickel, cobalt, iron, and copper.
  1. Point of delivery beside a vessel
  2. Statement designating where the title to goods passes from one party to another.
Alpha brass
An alloy of copper and zinc in which there is up to 38% zinc.
Alpine gearing
gearing system in which a shift between chainwheels on a bicycle is equivalent to one-and-a-half shifts on the freewheel.
Abbreviation for Alternator. Sometimes abbreviated as GEN
Alternate Routing
A change in the normal direction of a shipment that may be less desirable, but results in identical terms.
Alteration effect
Alternating current
  • (AC) An electric current that first flows one way in the circuit and then the other at regularly recurring intervals. This is the type used in homes. It contrasts with direct current. It is also the type of current produced by a vehicle’s alternator. Since the rest of the vehicle uses direct current, the current coming from the alternator must be changed by the rectifier.
  • Current in which the charge-flow periodically reverses, as opposed to direct current, and whose average value is zero. Alternating current usually implies a sinusoidal variation of current and voltage.
Alternative Fuel
  1. As defined pursuant to the EPACTmethanoldenatured ethanol and other alcohols, separately or in mixtures of 85% by volume or more with gasoline or other fuels, CNGLNGLPG, hydrogen, coal derived liquid fuels, fuels ‘other than alcohols’ derived from biological materials, electricity, neat biodiesel, or any other fuel determined to be substantially not petroleum and yielding ‘substantial energy security benefits and substantial environmental benefits.’
  2. Low-polluting fuels which are used to propel a vehicle instead of high-sulfur diesel or gasoline. Examples include methanol, ethanol, propane or compressed natural gas, liquid natural gas, low-sulfur or ‘clean’ diesel and electricity.
Alternative Fueled Vehicle
(AFV) Abbreviation for Alternative Fueled Vehicle — a vehicle powered by a fuel other than gasoline or diesel.

Alternative-Fuel Provider
A fuel provider (or any affiliate or business unit under its control) is an alternative-fuel provider if its principal business is producing, storing, refining, processing, transporting, distributing, importing, or selling (at wholesale or retail) any alternative fuel (other than electricity); or generating, transmitting, importing, or selling (at wholesale and retail) electricity; or if that fuel provider produces, imports, or produces and imports (in combination), an average of 50,000 barrels per day of petroleum and 30% (a substantial portion) or more of its gross annual revenues are derived from producing alternative fuels.
Alternative Fuels Data Center
(AFDC) A program sponsored by DOE to collect emissions, operational and maintenance data on all types of AFVs across the country.
Alternative Fuels Utilization Program
(AFUP) A program managed by DOE with the goals of improving national energy security by displacing imported oil, improving air quality by development and widespread use of alternative fuels for transportation and increasing the production of AFVs.
Alternative-Fuel Vehicle

  1. As defined by the Energy Policy Act, any dedicated, flexible-fueled, or dual-fueled vehicle designed to operate on at least one alternative fuel.
  2. A vehicle designed to operate on an alternative fuel (e.g., compressed natural gas, methane blend, electricity). The vehicle could be either a dedicated vehicle designed to operate exclusively on alternative fuel or a nondedicated vehicle designed to operate on alternative fuel and/or a traditional fuel.
Alternative fuel vehicle converter
An organization (including companies, government agencies and utilities), or individual that performs conversions involving alternative fuel vehicles. An AFV converter can convert (1) conventionally fueled vehicles to AFVs, (2) AFVs to conventionally fueled vehicles, or (3) AFVs to use another alternative fuel.
Alternative Motor Fuels Act of 1988
(AMFA) Public Law 100-494. Encourages the development, production and demonstration of alternative motor fuels and AFVs.
alternative power plant
Hybrids, fuel cells, and other innovations designed to replace the internal combustion engine.


(ALT) A device which produces AC by converting the engine’s turning (mechanical) energy into alternating electrical current at all engine speeds. The AC must be rectified (converted from AC to DC) by using diodes before reaching the vehicle’s electrical system. The alternator is driven by a belt at the front of the engine. Alternators replaced the direct-current (DCgenerators used up to the 1960’s because they were less efficient especially at idle. The electrically demanding options like air conditioning forced the use of alternators over generators.

Alternator regulator
Alternator Starter
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Nissan Altima

A model of automobile manufactured by Nissan in Japan

  1. An instrument to reveal the height (or barometric pressure) above sea level.
  2. An aneroid barometer used for measuring altitude by the decrease in atmospheric pressure with height. The dial of the instrument is graduated to read the altitude directly in feet or metres, the zero being set to ground or aerodrome level.
  1. The height in feet or metres above sea level. For precision in determining the performance of an aircraft, this must be corrected for the deviation of the meteorological conditions from that of the International Standard Atmosphere.
  2. The angular distance of a heavenly body measured on that great circle which passes, perpendicular to the plane of the horizon, through the body and through the zenith. It is measured positively from the horizon to the zenith, from 0° to 90°.
  3. The line through the vertex of a geometrical figure or solid perpendicular to its base.
  4. The length of the line of definition #3.
Altitude compensation system
A barometric switch and solenoid used to provide better drivability over 4000 feet (1200 metres) above sea level.
Altitude compensator
Altitude correction capsule
A barometric pressure sensor that detects the change in altitude and sends a signal to the ECU to alter the amount of fuel required for optimum combustion.
Altitude valve
A manually or automatically operated valve fitted to the carburetor of an aero-engine for correcting the mixture strength as air density falls with altitude.

Alumina beads
Tiny beads of alumina used in some catalytic converters.
British spelling for aluminum. Pronounced al-yoo-MIN-ee-um not ah-LOO-min-um
Something that is coated with aluminum or aluminum paint.
(Al or Alum) A silver-white metal which is used in cars because of its lightness. In pure form, it does not have the strength of the same size of iron. Thus vehicle manufacturers use aluminum in an alloy form to produce body panels, wheels, engine blockstransmission housingsdifferential housings, and even frames. British spelling adds an extra i near the end of the word aluminium and pronounces it al-you-MIN-ee-um instead of ah-LOO-min-um.

Aluminum alloy
A metal which is formed from aluminum and another metal.
Aluminum body
Aluminum oxide
A metallic abrasive used to manufacture sandpaper and sanding discs.
Aluminum Arch Culvert
A large arch installed under the road surface to let a stream flow under the road. An aluminum arch culvert is usually larger than a regular culvert
Aluminum wheel

Aluminum wheelAluminum wheel



A vehicle brand of which the Speed 20, 3.5 litre, 25, and 4.3 litre models are classic cars.

  • Abbreviation for Amplitude modulation.
  • Abbreviation for ‘air mass’ or ‘atmospheric mass’ which is the measure of the absorption and scattering of light by the Earth’s atmosphere. AM 0 indicates no atmosphere in the path of the light. This is the condition in space where the power density of light is about 1.36 kilowatt/square metre. AM 1 is the condition at the surface of the Earth where the light passes through one atmosphere. Power density is about 1.0 kilowatt/square metre.
Abbreviation for Air Management 1, AIR Bypass
Abbreviation for Air Management 2, AIR Diverter
Abbreviation for Alberta Motor Association — An Automobile Association in the Canadian province of Alberta affiliated with the American Automobile Association
Abbreviation for Ambient
Surrounding on all sides.
Ambient air
Air outside and surrounding a vehicle or equipment.
Ambient Air Quality Standards
Ambient air temperature
The temperature of the surrounding air.
Ambient noise
  1. Random uncontrolled and irreducible noise at a location, or in a valve or circuit.
  2. The noise existing in the passenger compartment or any other environment.
Ambient sensor
A detection device which samples and monitors changes in the temperature of the air outside the vehicle.
Ambient switch
An outside air temperature sensing switch which prevents operation of the compressor and the recirculating air mode below an outside temperature of 5°C.
Ambient temperature
  1. The surrounding air temperature. The temperature of fluid (usually air) which surrounds an object on all sides.
  2. Temperature of the atmosphere, outside of any fuel containers or tanks.
  3. The temperature of the surrounding medium, usually used to refer to the temperature of the air in which a structure is situated or a device operates.
Ambient temperature switch
A control device in an air conditioning system which delays the compressor action when the outside temperature is low.
Technique of sound reproduction which creates an illusion to the listener of being in a very large room.


A vehicle designed for carrying sick or injured people.

AMCClick logo for books on

Abbreviation for American Motors Corp an organization which merged with Chrysler Corporation. Includes the following models:

AMC Eagle
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AMC Eagle

An automobile manufactured by AMC until 1988

Amendments of 1990
American Automobile Association
(AAA) A U.S. Automobile association
American Automobile Labeling Act
(AALA) regulations requiring vehicle manufacturers to include content information on vehicle labels for cars and trucks for sale in the U.S. after October 1, 1994.
American Battery Manufacturers
American Free Trade
American Free Trade Agreement
American Industrial Classification
American Industrial Classification System
American Motors
AMCClick logo for books on

A vehicle brand of which the 1968-70 AMX models are milestone cars.

American Petroleum Institute
(API) Was established on March 20, 1919 to work with the federal government to promote the use and trade of petroleum products, oil, and natural gas.
American produced
American Society for Testing and Materials
(ASTM) Society for developing and publishing agreed standards. A non-profit organization that provides a management system to develop published technical information. ASTM standards, test methods, specifications and procedures are recognized as definitive guidelines for motor fuel quality as well as a broad range of other products and procedures.
American standard pipe thread
Type of screw thread commonly used on pipe and fittings to assure a tight seal.
American Standards
Dimensional standards for fasteners, etc., developed by the American Society of Mechanical Engineers. (ASME)
American Standard Wire Gauge
Abbreviation for Alternative Motor Fuels Act of 1988
A radio capable of receiving amplitude modulation (AM) and frequency modulation (FM) signals.
Abbreviation for advanced metering infrastructure
Abbreviation for Asocicion Mexicana de la Industria Automotriz.
The middle portion of a ship or vehicle.
A vehicle brand of which the Supercharged Sports models with required application are classic cars.
An electric instrument used to measure the rate of electrical current flow scaled in amperes.

Chemical combination of nitrogen and hydrogen (NH3). Ammonia refrigerant is identified as R-117.
Ammonium Bases
Amorphous silicon
An alloy of silica and hydrogen, with a disordered, noncrystalline internal atomic arrangement, that can be deposited in thin-film layers (a few micrometers in thickness) by a number of deposition methods to produce thin-film photovoltaic cells on glass, metal, or plastic substrates.
Uncommon abbreviation for ampere. It is preferred to use A
The strength of an electric current in amperes. Electron or current flow of one coulomb per second past a given point in circuit.
Amperage rating
The strength of an electric current in amperes.
  1. (A) A unit of measurement used in expressing the rate of electrical current flow in a circuit. It is determined by dividing the voltage by the resistance.
  2. A unit of electric current equivalent to flow of one coulomb per second, where a coulomb is the quantity of electricity which must pass through a circuit to deposit 0.0011180 grams of silver from a solution of silver-nitrate.
  3. The unit of measurement of electrical current produced in a circuit by 1 volt acting through a resistance of 1 Ohm.
  4. That current which, if maintained in two parallel conductors of infinite length, of negligible cross-section, and placed one metre apart in vacuum, would produce between the conductors a force equal to 2×10-7Nm-1.
  1. Measurement of the ability of a battery to deliver a stated amount of current for a stated period of time. The higher the amp/hr. rating, the more powerful the battery.
  2. Unit of charge equal to 3600 coulombs or 1 ampere flowing for one hour.
Ampere hour capacity
A measurement of storage battery’s ability to deliver a specified current over a specified length of time.
Ampere-hour efficiency
In an accumulator, the ratio of the ampere-hour output during discharge to the ampere-hour input during charge.
Ampere-hour meter
(Ahm) An instrument designed to monitor and record the product of electrical current and time (ampere-hours) for a given circuit or passing at a given point. If the voltage is constant, the meter can be calibrated as an energy (kilowatt-hour) meter.
Ampère’s law
The relation between the magnetizing field H around a conductor, length l, carrying a current i, given by the formula
Ampere turn
  1. The magnetomotive force produced by a current of one ampere in a coil of one turn
  2. A term used to measure magnetic force. Represents product of amperes times number of turns in coil of electromagnet
Ampère’s rule

Amperes RuleAmpère’s rule

Rule giving the direction of the magnetic field associated with a current. If the conductor is grasped with the right hand, the thumb pointing in the direction of the current, the fingers will curl around the conductor in the direction of the field. Also called right-hand rule.

Ampère’s theory of magnetization
A theory based on the assumption that the magnetic property of a magnet is due to currents circulating in the molecules of the magnet.
(At) SI unit of magneto-motive force, which drives flux through magnetic circuits, arising from one ampere flowing around one turn of a conductor.
Ampere-turn amplification, gain
Ratio of the load ampere-turns to the control ampere-turns in a magnetic amplifier.
Ampere turns
Term used to measure magnetic force. Represents product of amperes times number of turns in coil of electromagnet.
Ampere-turns per meter
SI unit of magnetizing force, magnetic field intensity.
Amp/hr. rating
Measurement of the ability of a battery to deliver a stated amount of current for a stated period of time. The higher the amp/hr. rating, the more powerful the battery.
Amplification Gain
A device used to increase the electron flow in an electric or vacuum circuit. It produces a greater electrical signal such as the radio signal. Most automobile radios have a built-in amplifier; but a few have a separate amplifier which is sometimes located in the trunk.

Amplitude modulation
(AM) A type of radio wave in which the amplitude changes rather than the frequency.

Abbreviation for advanced mobile phone system.
Amputee spinner

amputee spinnerAmputee spinner

A device which is attached to a steering wheel to allow a disabled person to steer a vehicle.

Abbreviation for automated meter reading
Abbreviation for Air management system.
Abbreviation for above mean sea level.
Abbreviation for Air Management Unit — An assembly of pressure switches, and other valves located in a chassis cross-member, designed to control the pneumatic accessory functions of a vehicle using the multiplex electrical system.
Abbreviation for Association of Motor Vehicle Importers Representatives (Greece).
AMXClick image for books on

An automobile manufactured by AMC. The 1968-70 models are milestone cars.

Amyl Ethyl Ether


Anaerobic sealer
A substance used to prevent bolts and screws from loosening up and backing out. Anaerobic sealers do not require oxygen for activation. The Loctite® brand is the most widely used anaerobic sealer.
Analog British spelling is analogue
  1. A display which uses a dial rather than a read-out of numbers (digital).
  2. A signal that varies proportionally with the data it measures. In a computer, an analog signal is a constantly fluctuating voltage that ranges from high to low.
Analog clock
The traditional clock with rotating hands. Contrast with digital clock.
Analog cluster
An instrument panel display using dials. Opposite to electronic cluster.
Analog display
Instrument display that uses gauges with moving needles.
Analog filter
Filter suitable for use with analog signals, i.e., those which are continuous with time. Contrast with Digital filter.
Analog speedometer

speedometerAnalog speedometer

A speedometer which shows the speed by a needle on the dial of a gauge. It contrasts with a digital speedometer

British spelling of Analog.
Analogue cluster
A device for evaluating something.

Anatomic saddle

anatomic saddleAnatomic saddle

A bicycle seat that is designed with cut out sections or bumps to accommodate your ischial tuberosities (i.e., sit-down bones).

Abbreviation for at no extra cost
  1. A mounting point on the vehicle frame or unibody for a non-structural but stressed component, such as a seat or seat belt.
  2. The stationary portion of a leading/trailing drum brake on which the heels of the brake shoes ride.
  3. A heavy hook-shaped device for holding a ship at rest in water. The anchor grips the ocean bottom and is fastened to the ship by a chain.
  4. An obsolete, heavy piece of equipment that has no use or function is considered euphemistically as nothing more than a boat anchor.
The point where something is attached — such as where the seat-belt is attached to the frame.

Anchor bolt
  1. A bolt used to secure frameworks, stanchion bases, etc. to piers or foundations, and having usually a large plate washer built into the latter as anchorage
  2. The bolt which goes through a bracket to secure something. British term is through bolt.
Anchor clamp
A fitting attached to the overhead contact wire of a tramway or railway to support the wire, and also to take the longitudinal tension and prevent movement of the wire in a direction parallel to the track.
Anchor Drum Brake
Anchor end
The end of a brake shoe that’s attached to or positioned against a fixed point on the backing plate.
Anchor eyes
The semi-circular notches at the ends of some shoe webs where they contact the shoe anchor on the backing plate.
Anchor gate
A heavy gate, such as a canal lock gate, which is supported at its upper bearing by an anchorage in the masonry such as an anchor bolt.
Anchor pin
  1. The stationary portion of a duo-servo drum brake on which the tops of the brake shoes rest. The secondary shoe bears against the anchor pin when the brakes are applied and the vehicle is moving forward. Conversely, when the vehicle is backing up and the brakes are applied, the primary shoe bears against it.
  2. The point in a drum brake system where the braking forces are transmitted to the axle and which prevents the brake shoes from revolving with the drum.
Anchor plate
  1. The stationary portion of a leading/trailing drum brake on which the heels of the brake shoes ride.
  2. A bracket, solidly attached to the vehicle suspension, on which a floating or sliding caliper mounts
Anchor ring
A male veteran bicycle rider who has completed a 1200 kilometre randonnée.
A female veteran bicycle rider who has completed a 1200 kilometre randonnée.
The various components attached to the main part of the engine and driven by the engine itself — such as the alternator, generator, power steering pump, supercharger, fuel pump, and water pump.
Instrument for measuring the rate of airflow or motion.
Aneroid altitude compensator
A bellows device, installed integrally with the APT system on some post-1975 Rochester Quadrajet carburetors, that automatically compensates for changes in altitude by raising or lowering the primary metering rods, thus richening or leaning out the air/fuel mixture in accordance with changes in air pressure.
Aneroid barometer
A device to determine atmospheric pressure with the use of a vacuum chamber or syphon bellows
Aneroid-type thermostat
An older style thermostat located in the engine coolant system. It has a metal expandable bulb partially filled with acetone, alcohol, or another volatile liquid. As the coolant reaches operating temperature, the liquid in the bulb will boil and expand the bulb, closing the valve to allow coolant to the radiator.
Abbreviation for Asociacion Espanola de Fabricantes de Automoviles y Camiones (Spain).
Abbreviation for Associação Nacional de Veículos Automotores (Brazil).
Abbreviation for Associazione Nazionale Fra Industrie Automobilistiche (Italy).
Radar echoes from an invisible and sometimes undefined origin. High-flying birds, insect swarms, and certain atmospheric conditions can be responsible.
Angle bar
An ‘L-shape’ length of iron.

Angle bearing
A shaft-bearing in which the joint between base and cap is not perpendicular to the direction of the load, but is set at an angle.
Angle block
  1. A cylinder block that doesn’t have a deck at 90 degrees to the cylinders
  2. A small wooden block used in woodwork to make joints, esp. right-angle joints, more rigid.
Angle bracket
  1. A bracket projecting from the corner of a building beneath the eaves, and not at right-angles to the face of the wall.
  2. A bracket consisting of two sides set at right angles, often stiffened by a gusset. Also called gallows bracket.
Angle Clip
A short piece of angle bar
Angle Collar
A ring made of angle bar
Angled deck
British term for Canted deck.
bulldozer with a blade able to be set in such a way to push material to the side of the road. Usually called a grader or motor grader.
Angle elevation
The vertical angle measured above the horizontal, from the surveyor’s instrument to the point observed.
Angle grinder

angle grinderAngle grinder

A power tool (driven by electricity or compressed air) which has abrasive discs. The tool helps to remove old paint or rough metal surface

Angle iron
Mild steel bar rolled to an L-shaped cross-section, used in structural work. Legs may be equal or unequal and leg lengths up to 800 mm are available. Also called angleangle barangle steel, and L-iron.
angle joint
Angle joint
Angle joint
A compression ring where the open ends meet with a matching 45° angle.
Angle-nose pliers

Angle-nose pliersAngle-nose pliers

A pair of pliers with long jaws that are bent at right angles to aid in gripping something which cannot be reached with regular pliers.

Angle of advance
  1. The angle in excess of 90° by which the eccentric throw of a steam-engine valve gear is in advance of the crank.
  2. The angle between the position of ignition and outer dead center in a spark-ignition engine, optimizes combustion of the fuel.
Angle of attack
The angle between the chord line of an airfoil and the relative airflow. Also called (in error) angle of incidence.
Angle of contact
The angle subtended at the center of a pulley by that part of the rim in contact with the driving belt.
Angle of Flex
The total angle of chain joint articulation as a chain enters or leaves a sprocket or wheel. The angle is equal to 360 degrees divided by the number of teeth in the sprocket.
Angle of Head
In countersunk heads, the included angles of the conical underportion or bearing surface, usually 82 or 100 degrees.
Angle of lock
The angle between the line through the center of the wheel seen from above when turning a corner and the same line when going straight.
Angle of thread
Angle parking

Angle parkingAngle parking

A system of parking on the side of the street where the car is about 45 degrees from parallel with the edge of the street. The British term is echelon parking

Angle screwdriver
A tool that is shaped like the letter L and has a blade at either end.
Angle Sensor
Angle steel
Angle stone


Angle valve
Type of globe valve design, having pipe openings at right angles to each other. Usually, one opening is on.
The Ångström is a measure of the wavelength of light. One Ångström = 10-10 metre. Yellow light from a sodium street-light is about 5500 Ångströms.
Angular motion


Angular thread
Angular velocity
The angular displacement per unit time, measured in degrees per time or radians per time
Angular vibration
Side to side movement or shimmy of a tire.

A compound that does not contain any water. Ethanol produced for fuel use is often referred to as anhydrous ethanol, as it has had almost all water removed.
Anhydrous calcium sulphate
Dry chemical made of calcium, sulphur, and oxygen (CaSO4)
An oily liquid poisonous (C6H5NH2) obtained especially by the reduction of nitrobenzene and used chiefly in organic synthesis (as of dyes)
Aniline Point
The aniline point of a petroleum product is the minimum equilibrium solution temperature with an equal volume of freshly distilled aniline.
The characteristic of something (like a crystal) that when light or magnetism passes through it from one angle, it gives a different reading or measurement than when measured from a different angle because the molecules are arranged in a regular lattice which allow or inhibit the light or magnetism.
To remove hardness from metal by heating, usually to a red color, then allowing it to cool slowly. Unlike steel, copper is annealed by heating, and then plunging it into cold water. It is the reverse of hardening.
Process of heat treating metal to get desired properties of softness and ductility (easily formed in to a new shape). For example heating and slow cooling of a piece of iron.

Anniversary Billing
A method of charging a client for the first month of storage and then if it remains in storage it will be charged a monthly rate due on the anniversary of its arrival.
Annual Inventory
A physical count of all product in the warehouse done on a yearly basis.
Something in the form of a ring.
Annular ball bearing
A ball bearing with a non-adjustable inner and outer race or races.
Annular combustion chamber
A gas turbine combustion chamber in which the perforated flame tube forms a continuous annulus within a cylindrical outer casing.
Annular electric brake
An electric brake design in which the electromagnet is shaped like a circle or ring (annulus) inside the brake shoes.
Annular gap
Something in a circular gap.
Annular gear
A round gear with teeth cut on the outside for engagement with a pinion. Usually shrunk fit on to a mating diameter, e.g., starter ring on automobile flywheel.
Annular Nail
A nail with circular ridges along the shank (like screw threads, but not in a spiral pattern) used in securing a pallet.
A hollow gear which is in the form of a ring with internal teeth.

  1. In an electrical circuit it is the positive pole. It is that part of an electrical circuit to which electrons are flowing.
  2. The electrode at which oxidation occurs. For fuel cells that create potential, it is also the electrode towards which negative ions flow.
  3. The positive terminal of an electrolytic cell
  4. Zinc, aluminum, or an alloy that is attached to the hull of a vessel. As electric current moves from the vessel to the water, the anode is destroyed (oxidized). Without this anode shell, the metal hull plating would be dissolved by electrolysis.
Anodic Coating
By electrolytic action, this is the process of coating or plating a metal (usually aluminum) with a thin protective film or material such as chrome. It is sometimes applied with colored dye.
An electroplating process commonly performed on aluminum parts, which forms a thin protective film on the surface of the metal. Anodizing is sometimes accompanied by the use of a colored dye, which gives a lustrous colored finish to the aluminum parts.
The process by which a hard, non-corroding oxide layer is deposited on aluminum.

Anodizing bath
A tub in which the anodizing process is performed.
Anodizing tank
A tub in which the anodizing process is performed.
Abbreviation for anti-noise system
Abbreviation for American National Standards Institute which is the organization which sets the standards by which mechanical things should be manufactured.
ANSI assembly identifier
The serial numbering scheme adopted by the ANSI to ensure uniqueness of an assembly serial number.


Antagonizing screws
A small auxiliary combustion-chamber, used in some compression-ignition engines, in which partial combustion of the fuel is used to force the burning mixture into the cylinder, so promoting more perfect combustion.
A device which pulls in radio reception. Also called aerial.
Automobiles employ three basic types of radio antennas.

  1. Wires embedded in the glass of the windshield
  2. Power operated staff which rises from the surface of the sheet metal when the radio is turned on, but is lowered almost flush when the radio is turned off. It is usually made up of several sections which telescope together. It is mounted on one of the four fenders. See Power antenna
  3. A one-piece flexible rod or shorter stiff rod which is mounted to the surface of the sheet metal. It is called a ‘fixed-mast antenna’ in contrast to a power antenna. It is usually mounted in one of three basic locations: on either side of the front fender ahead of the A-pillar; either side of the rear fender behind the backlight (i.e., rear window); on the front or back of the roof. Fixed-masts are relatively trouble-free, unlike power antennas which rely upon a motor that may fail. However, some fixed-masts are subject to breakage by vandals or car-washes.
Antenna changeover switch
Switch used for transferring an antenna from the transmitting to the receiving equipment, and vice versa, protecting the receiver.
Antenna downlead
Wire running from the elevated part or conductor of an antenna down to the transmitting or receiving equipment.
Antenna load
Made or generated by a human or caused by human activity. The term is used in the context of global climate change to refer to gaseous emissions that are the result of human activities, as well as other potentially climate-altering activities, such as deforestation.
Antibackfire valve
Anti-backfire valve
(Anti-BFV) Valve used in air injection reaction (exhaust emission control) system to prevent backfiring during the period immediately following sudden deceleration by diverting the air coming from the air pump away from the exhaust ports. Otherwise the exhaust gases which contain unburned gasoline could mix with fresh air and cause unwanted backfiring.

Abbreviation for Anti-backfire valve.
Anti-chip coating
A resilient coat of paint between the primer and the top coat to protect the body shell from chipping damage caused by gravel or stones.
An area of the earth’s crust where folding has made a dome like shape in the once flat rock layers. Anticlines often provide an environment where natural gas can become trapped beneath the earth’s surface, and extracted.

A substance used to protect against rust.

Anti-Corrosion Code
Anti-corrosion warranty
Manufacturers usually state that all body sheet metal components are warranted against rust-through corrosion for 6 years or 160,000 kilometres, whichever comes first.
That which prevents or limits corrosion.
Anti-dazzle mirror
A mirror that can be set to reduce the glare of the lights from a vehicle following your vehicle.

Anti-dieseling solenoid
A front suspension design that counteracts front-end lowering under braking.

Anti-dive system
dive is the action of the front of the vehicle to point downward during braking. The suspension in cars is designed to remove this tendency.
Anti-drum compound
A sticky material which is applied to the inside of panels to reduce the noise caused by vibration or drumming
Antifouling composition
A substance applied in paint form to ships’ bottoms and structures subject to the action of sea water, to discourage marine growths.
A chemical (usually ethylene glycol) added to the cooling system to prevent the coolant from freezing in cold weather. It also inhibits the formation of rust and other deposits which may clog the radiator and other cooling passageways. Its resistance to freezing is better with a mix of 50-50 with water than 100% antifreeze.
Anti-friction bearing
Antifriction bearing

Antifriction bearingAntifriction bearing

A bearing containing rollers, needles, or balls plus an inner and outer race. The bearing is designed to roll instead of slide thus minimizing friction between two moving parts. To avoid disintegration, the bearing must use lubrication (i.e., wet friction)

Anti-friction metal
Resistant to the effects of high acceleration, esp. of an astronaut’s equipment.
Anti-g suit
A close-fitting garment covering the legs and abdomen. When inflated, it equalizes the pressure especially around the head and heart during high-speed maneuvers. Colloquially, g-suit.
The process of applying chemicals such as salt brine, liquid calcium chloride, or calcium magnesium acetate on the ice-covered road surface
Anti-knock additive
Antiknock agent
Anti-knock agent
A substance like tetraethyl lead which is added to gasoline to raise the octane number and reduce the gasoline’s tendency to detonate, knock, or ping. In unleaded gasoline, tetraethyl lead is not used because of its environmental danger.
Anti-knock agents
Anti-knock index
(AKI) The measure of the anti-knock properties of a brand and type of gasoline. It is defined as half the sum of the research octane number (RON) and motor octane number (MON). This is the number posted on the retail gasoline pumps normally indicating 87, 89, or 92 octane. Racing gasoline have AKI’s from 100 to 118.
Antiknock substances
Substances like lead (IV) ethyl added to fuel to lessen its tendency to detonate or knock in an engine.
Antiknock value
The relative immunity of a volatile liquid fuel from detonation in a gasoline engine as compared with some standard fuel.



Lift is the action of the rear end of the vehicle to rise during braking. The suspension in cars is designed to remove this tendency.
Antilock brake

Anti-lock brake

Anti-lock brake controller
(CAB) Chrysler Corporation’s term for the electronic control unit.
Anti-lock brake system
(ABS) A device which senses that one or more of the wheels are locking up during braking.

  • It monitors the rotational speeds of the wheels and reduces hydraulic pressure to any wheel it senses locking up.
  • It is controlled by both mechanical and electronic components.
  • When you apply the brakes, the ABS will regulate the flow of brake fluid being delivered to the brake calipers.
  • It must be remembered that a wheel cannot be steered unless it is rolling; so if the wheel is locked up, there is no steering control.
  • By the use of electronic computers, the brakes rapidly alternate (at a rate of 30 times per second) from full pressure to full release.
  • This process will also alternate from the left-front wheel and the right-rear wheel and switch to the right-front wheel and left-rear wheel.
  • In this way both maximum braking and maximum steering control is allowed during braking.
  • Before the advent of ABS, drivers were advised to pump the brakes to maintain the same effect.
  • However, the human foot cannot pump the brakes faster than the computer control.
  • Also, steady application of the brakes without ABS may cause brake failure (i.e., brake fade) because of the excess heat.
  • Never pump the brakes if you have ABS.
  • When you firmly apply the brakes with ABS, you may feel a pulsing sensation and hear a banging noise.
  • The abbreviation ABS comes from the German anti blockier system.
  • Sometimes called anti-skid brakes.
Anti-lock braking system
(Sb) A pure element, metal, used in alloys
Antimony alloy
A combination of antimony and another substance like aluminum used in bearings and battery plates
Antimony black
When antimony is ground to fine powder, it has a black metallic color.
Anti-noise system
(ANS) A noise counteraction system. This is a sophisticated system which has a number of small microphones placed around the vehicle to detect driving noises. A computer microprocessor analyzes these noises and generates matching counter-frequencies which are sent to small speakers located in the passenger compartment. In this way the road noises are cancelled or erased.
Antipercolation valve
Anti-percolation valve
A device for venting vapors from the main discharge tube, or the well, of a carburetor. The vented vapors are not released into the atmosphere, but rerouted into an evaporative emission canister where they are stored until the next time the vehicle is started. Thus it provides a richer mixture needed for starting.

Antique Car
  1. A vehicle built prior to 1915 sometimes called the brass era because of the widespread use of fancy brass fittings and brass lanterns that were a natural addition to the new ‘horseless carriage.’ The Brass era lasted from around 1905 to 1914. This was the beginning of mass produced affordable vehicles for the common public rather than the domain of the elite.
  2. A vehicle built between 1880 and 1916 (inclusive)
  3. A vehicle (including hardtop or convertible) built before 1950 and in original form with no modern technology, equipment, or refinements except wheels.
Anti-rattle spring
  1. clutch antirattle spring clipclutch antirattle spring clip

    A specially shaped wire that prevents the clutch plate and spring from making noise when no pressure is applied to the plate.

  2. A device that attaches to disc brake pads to keep them from making a rattle noise when the brakes are not applied.
  3. A component in disc brakes shaped like the letter X and made of spring steel. It applies radial pressure to the brake pads to prevent rattling. Also called spreader spring.
Antiroll bar
Anti-roll bar

anti-roll barAnti-roll bar

  • Sometimes called the anti-sway bar, stabilizer bar, or even (incorrectly) roll-bar. It is usually a round bar which connects the left wheel suspension assembly with the right side. It may be found at the front and/or rear. Its main function is to keep both wheels rolling at the same rate when meeting bumps; but it also affects handling. A front anti-roll bar increases understeer and a rear bar increases oversteer.
  • An anti-roll bar yields low roll centers with the attendant advantage of minimum jacking effect due to lateral loading and minimum lateral wheel deflection on the bump — without the disadvantage of large roll angles and consequent camber change.
Antiroll device
Anti-roll device
Anti-rust treatment
Antisag bar
A vertical rod connecting the main tie of a roof truss to the ridge to support it against sagging under its own weight.
The ability of a precision insert bearing to resist scuffing or scratching the shaft journal in the event that the oil surface skin is destroyed.
Antiseize compound
A paste that is applied to metal parts to keep them from sticking to other metal parts, particularly threaded surfaces such as spark plug threads and wheel studs and bolts
Anti-siphon bleeds
Small holes drilled into the cluster to prevent main-system fuel from continuing to flow when the throttle is closed, stopping airflow through the carburetor.


(ASBS) A computer controlled automotive device which senses when one or more of the wheels are locking up during braking. It eases up on the amount of hydraulic pressure to that wheel. It must be remembered that a wheel cannot be steered unless it is rolling; so if the wheel is locked up, there is no steering control. By the use of electronic computers, the brakes rapidly alternate from full power to none so that both maximum braking and maximum steering control is allowed. If you jam on the brakes, you will feel a pulsing sensation. Sometimes called anti-lock brakes.
Antiskid brake system
A non-standard term for Wheel slip brake control system
Antismog device
A special part or system designed to reduce or eliminate emission of noxious gases from exhaust of engine.
Antisolar glass
Glass which absorbs heat from sunshine and reduces glare, but transmits most of the light.
Sound signal with same amplitude but opposite phase of some unwanted sound signal so that both signals cancel each other when superimposed.
Anti-spin regulation
(ASR) The control or prevention of wheelspin under power, normally by means of electronic sensing and in conjunction with anti-lock brakes.
Anti-spin regulation traction control system
(ASC) The system which prevents wheelspin.

Anti-spray flap


Rear suspension design that counteracts rear-end lowering under acceleration.

Anti-squat system
Squat is the action of the rear end of the vehicle to point downward during hard acceleration. The suspension in cars is designed to remove this tendency. Contrasts with anti-dive system.
Anti-squeal shim
A shim (metal plate) placed behind the brake piston or the brake pad to reduce noise when the brakes are applied.
Anti-stall dashpot
A diaphragm unit mounted on the carburetor that allows air to escape slowly from its vacuum chamber to prevent throttle plate(s) in the carburetor from closing too suddenly–and stalling the engine–during deceleration.
Antisurge valve
A valve for bleeding off surplus compressor air to suppress the unstable airflow due to surge in a gas turbine engine.
Anti-sway bar
Anti-theft system
Any device (mechanical or electrical) which tends to reduce the theft of a vehicle. It may involve an alarm system, ignition lockouts, steering locks, steering wheel locks, transmission locks, and/or wheel locks.
An arm, usually with a small wheel attached at the outer end, which is secured to the back of a wheelchair to prevent the chair from falling on its back and thereby injuring the patient.
Anti-vibration mounting
  1. Because the engine, transmission, differential, and other components tend to vibrate when in motion, noise increases and there is possible wear at the points of contact with the frame members. Rubber blocks are used to cushion the vibration at the mounting points.
  2. Rubber springs designed to absorb vibrations from engines, etc. Care needed in design and materials selection to match vibration frequency with main damping peak of elastomer.
Abbreviation for Air Over
Abbreviation for Automatic Overdrive
Abbreviation for Automatic Overdrive Electronic Transmission
Abbreviation for Automatic Overdrive Electronic Wide (ratio transmission)
Abbreviation for Automatic Overdrive Transmission
  1. Abbreviation for Actual Power
  2. Abbreviation for Accelerator Pedal
The side panel used to fill the gap between the rear edge of the front fender and the front edge of the doors.
Abbreviation for automatic performance control
Ape hangers
A term coined at the height of the custom-bike movement to describe tall handlebars that forced the rider to reach skyward to grasp the controls, making the rider adopt an ape-like posture.
A recess in which the propeller is located.

Aperture panel
A large side panel of a vehicle making up the rear fender, door frame, and side window frame.

The top of a triangle. In racing, it is the point or area closest to the inner corner.
Apex seal

Apex sealApex seal

wedge shaped device found on the tips of the triangular rotor in rotary (Wankel) engines. Its purpose is to prevent the escape of compressed gas or combustion gases. It may also release engine heat.

Abbreviation for American Petroleum Institute, the organization that classifies oil.

Abbreviation for Association of Automotive Manufacturers and Importers (Romania).
API Gravity
Gravity (weight per unit volume) of oils as measured by the API scale. This standard was adopted by the API 5/4/22 as the standard for the American petroleum industries. The measuring scale is calibrated in terms of degrees API
API scale
Abbreviation for American Petroleum Institute scale. Scale of relative density, similar to Baumé scale. Degrees API=(141.5/s)-131s, where s is the relative density of the oil against water at 15°C.
A pillar




When you look at the side of a car, the pillar that is attached to the windshield and supports the roof is called the A-post or A-pillar. There are two to each car. Generally the middle post is the B-post and the back post is the C-post.

The name of a number of vehicles such as the following:

  • Gumpert Apollo — a German sports car
  • Buick Apollo — a compact car built from 1973 to 1975
  • Apollo — A car made in the U.S. (1906-07)
  • Apollo — A car made in Germany (1910-27)
  • Apollo — A car made in Britain (1971)
  • Apollo GT — A sports car
Apollo (Buick)
A compact car based on the GM front engine/rear drive ‘X’ car platform and built by Buick from 1973-75 that was essentially a re-badged Chevrolet Nova like the Oldsmobile Omega and Pontiac Ventura and later the Cadillac Seville.
Apollo GT
A vehicle brand of which the 1963-66 models are milestone cars.
A post




When you look at the side of a car, the post that is attached to the windshield and supports the roof is called the A-post or A-pillar. There are two to each car. Generally the middle post is the B-post and the back post is the C-post.

Apparent power
  1. The square root of the sum of the squares of the active and the reactive powers.
  2. The product of the voltage (in volts) and the current (in amperes). It comprises both active and reactive power. It is measured in volt-amperes and often expressed in kilovolt-amperes (k VA) or megavolt-amperes (MVA).
Structures extending beyond the main hull. They include items like shafting, rudder, bossing, struts, and bilge keels.
Apple paint
  1. A piece of equipment, commonly powered by electricity, used to perform a particular energy-driven function.
  2. A British term for a Fire engine.
Appliance flue
The passage(s) within an appliance through which combustion products pass from the combustion chamber of the appliance to the outlet of the appliance.
The act of applying adhesives and coatings. The principal methods of application are:

  • brushing
  • spraying
  • dipping
  • stenciling
  • flowing
  • stamp-padding
  • roll coating
  • knife coating
  • squeegeeing
  • troweling with spatula or notched trowel

For sealers:

  • spatula
  • caulking gun
  • flow gun
  • pressure extrusion units
  • spray gun
A tool for putting something on something else, e.g., a spreader or brush.
Applied Fender
A fender that is fastened onto or stamped into the surface of the body.
Applied stress
The stress induced in a member under load.
Applied Trim
Trim that is fastened onto or stamped into the surface of the body.
(appliqué) A sticker or decal which is applied to the body panel of a vehicle.
To put something on something else.
A secondary road leading up to a highway or to a bridge.

Approach angle
  1. The most sharply angled incline the vehicle can make without its front scraping the ground. Measured in degrees, it’s the angle formed on one side by the horizontal axis, and on the other by a straight line connecting the forward edge of the front tire and the most prominent front-end feature extending beyond that line — the bumper, fog lamps, tow hook, etc.
  2. In side-view, the angle between the ground and a line, ahead of the vehicle, joining the periphery of the front wheel and (typically) the front bumper or other low component. It represents the size or steepness of a slope or obstacle that can be approached or climbed without striking bodywork.
Approval certificate
Acceptable to the authority having jurisdiction.
A well-regarded Italian motorcycle manufacturer, known for 250 GP race bikes that are tiny and lightweight.
  1. The paved area directly below the racing surface that separates the track from the infield.
  2. The panel under the vehicle’s doors or the panel acting as an air dam at the front of a vehicle.
  3. kick panel.
  4. A firm surface of concrete or tarmac laid down adjacent to aerodrome buildings to facilitate the movement, loading and unloading of aircraft.
  5. The area outside the warehouse or loading dock door which is used by delivery vehicles to park or position for loading and unloading. The apron height matches the height of the floor of the trailer and makes it easy to load and unload merchandise.
  1. Abbreviation for Absolute Pressure Sensor (GM)
  2. Abbreviation for Atmospheric Pressure Sensor (Mazda)
Abbreviation for adjustable part throttle
Abbreviation for Advanced Public Transportation Systems
Abbreviation for Auxiliary power unit
Abbreviation for American Public Works Association
Abbreviation for Acceptable quality level.
Abbreviation for Air Quality Management District

hydroplaning tireAquaplaning tire

Also called hydroplaning. A dangerous tendency for a tire to ride on a thin film of water, thus creating a loss of driver control until tire contact with the road surface returns.

tread pattern of a tire designed to dissipate water lying on the road and provide good traction in the rain.
Abbreviation for Amsterdam-Rotterdam-Antwerp
Aramid fiber
A synthetic product used as a reinforcing agent in brake linings. Aramid fiber has impressive wear properties.
  1. Charge in addition to regular freight charge to compensate for unusual local conditions.
  2. Fixed amount accepted by a carrier when dividing joint rates.
  1. A rotating shaft in a lathe or drill.
  2. Cylindrical or conical shaft on which a cutting tool or part to be machined is mounted.
  3. The axis or shaft upon which a rotatable part is mounted the shaft upon which a gear or wheel is mounted.


  1. The discharge of electric current across a gap of two electrodes. The term given to the flow of electricity through a gaseous space or air gap.
  2. A welding term referring to the flow of electricity through the air which produces high temperatures.
  1. Abbreviation for Aeronautical Research Council in the UK.
  2. Abbreviation for Ames Research Center in the USA
  3. Abbreviation for Automatic Ride Control
Arc blow
A welding term referring to the tendency for an arc to wander or whip from its normal course during arc welding. It is caused by magnetic changes.
Arc crater
  1. Depression formed in electrodes between which an electric arc has been maintained.
  2. In arc welding, the depression which occurs in the weld metal.
Arc cutting
A welding term referring to making a kerf in a metal using the energy of an electric arc.
Arch culvert
Bridge feature that resembles the top half of a large tube. The arch shape makes it easier for fish to swim down the creek that passes under the arch.
Arch extension
Architectural acoustics
The study of how sound is transmitted and received in various parts of a building or even a vehicle, thus involves the placement of speakers.
Arch protector
  1. The action of electricity when it leaps the gap between two electrodes. Usually causes premature wear of breaker points.
  2. A faulty paint spraying technique where the spray gun is not moved along the panel surface at a uniform distance. Instead it is moved toward the panel when starting and moved away toward the end of the panel. The result of this technique is an uneven application of paint.
  3. A process where the brake shoes are ground to the proper curvature for the drums they are to be used with. Modern brake shoes are pre-arced.
Arc Lamp
Arc of approach
The arc on the pitch circle of a gearwheel over which two teeth are in contact while approaching the pitch point
Arc of contact
The arc on the pitch circle of a gearwheel over which two teeth are in contact.
Arc of recess
The arc on the pitch circle of a gearwheel over which two teeth are in contact while receding from the pitch point.
Arc process
Arc-suppression coil
Arc suppressor
A device for automatically grounding the neutral point of an insulated-neutral transmission or distribution line if an arc to ground occurs. Also called arcing-ground suppressor
Arc welding
Welding by using an electric current to melt both the metal to be welded and the welding rod or electrode that is being added.

Area Cell
A part attached to or projecting from something.

  1. In a relayregulatorhorn, etc., it is the movable part of the unit which indicates the presence of electric current as the agent of actuation.
  2. Piece of low-reluctance ferromagnetic material (keeper) for temporarily bridging the poles of a permanent magnet, to reduce the leakage field and preserve magnetization.
  3. In a starter or generator, it is the portion that revolves between the pole shoes, made up of wire windings of copper on an iron core or axle. When it revolves, an electric current is induced.
  4. Part of an electric motor, generator, or other device moved by magnetism
  5. The wooden, metal, or hard-foam supporting structure under a clay model.
Armature brake
A mechanical or electrical component in a starter used to stop the armature movement after the starter motor has been switched off.
Armature end plate
The end plate of a laminated armature core. It is of sufficient mechanical strength to enable the laminations to be clamped together tightly to prevent vibration. Also called armature head
Armature head
Armature reaction
The electrical current that flows in the armature winding of a DC motor tends to produce magnetic flux in addition to that produced by the field current. This effect, which reduces the torque capacity, is called armature reaction and can affect the commutation and the magnitude of the motor’s generated voltage
Armature relay
A relay operated electromagnetically, thus causing the armature to be magnetically attracted.
Armature shaft
The primary shaft on which the armature is mounted in a starter or generator.
Armature winding
The complete assembly of conductors carried on the armature and connected to the commutator or to the terminals of the machine.
Arm cover
Armor plate
Traditionally, specially heavy alloy steel plate hardened on the surface; used for the protection of fighting vehicles and ships. There is also a form of armor plate based on aluminum alloy particularly suitable for fast moving military vehicles.
Panels and glass that are extra thick to be bullet-proof.
British spelling of armor
A projection upon which the occupants can rest or support their arms. Usually located on the door panel and sometimes in the center of the front seats or the center of the rear seat.
Arm shaft
A colloquial term for manual steering. Without power assist, steering will need a strong arm, thus the name.
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A vehicle brand of which the 1924-1933 Model 30 and 1933-1939 Special with required application are classic cars.
Arm Stud
Arm suspension
Arnolt Bristol
A vehicle brand of which the 1952-62 models are milestone cars.
  1. Road designation used in Britain
    • They do not have controlled access like M roads
    • they range from one-lane roads to two-lane divided highways called ‘dual carraigeways
    • They are the main routes between towns
Aromatic Hydrocarbons
Hydrocarbons based on the ringed six-carbon benzene series or related organic groups. Benzene, toluene and xylene are the principal aromatics, commonly referred to as the BTX group. They represent one of the heaviest fractions in gasoline. They are called aromatics because many of their derivatives have sweet or aromatic odors.
A device which prevents a certain action. For example, a spark arrester is a special pipe mounted in the end of the exhaust pipe which prevents any burning gasses from coming out with the possible danger of igniting any combustibles in the area (i.e., setting the forest on fire).

Arrival Notice
A shipping report given to the consignee indicating the arrival of freight.
The finish line of a brevet or randonnée.
  1. Abbreviation for Air Ride Suspension — a suspension system in which the load is supported on air-filled rubber bags rather than steel springs. The engine’s air compressor fills the reservoir tanks which supplies air for the suspension and the air brake system.
  2. Abbreviation for Automatic Restraint System
Arterial highway
A major thoroughfare, used primarily for through traffic rather than for access to adjacent land, that is characterized by high vehicular capacity and continuity of movement.
Jointed. An articulated rod is made of two sections with a moveable joint which permits its shape to go from perfectly straight to right angle.

Articulated bus

Honda AccordArticulated bus

A large public passenger bus, usually more than 55 feet in length, with two connected passenger compartments with an accordion-like section between them which flexes or bends to allow the bus to turn sharply around curves or corners as it bends at that part of the bus. Also called an accordion bus, bendy bus, banana bus, caterpillar bus, double bus, slinky bus, stretch bus, tandem bus, or wiggle bus.

Articulated mounting
A term used where parts are connected by links and links are anchored to provide a double hinging action.
Articulated Pistons
Two-piece pistons incorporating an entirely separate piston crown or dome with a separate skirt, and linking the two together with the piston pin. Many 1994 and later engines incorporate steel crown/aluminum skirt articulated pistons.
Articulated truck
A large truck with two sections to allow it to turn sharply around corners.
  1. The space between the power unit and trailer that allows the combination to pivot and turn corners.
  2. The ability of one axle to move — left wheel up, right wheel down or vice versa — relative to the chassis or its corresponding axle. It is a measure of the ease with which off-road wheels can maintain traction and control in excessively rough terrain.
  3. The action of a chain joint flexing from the straight to an angle and back to straight, as the joint enters and leaves the sprocket or other path, causing it to flex.
Articulation angle, longitudinal
See Longitudinal articulation angle, where wheels run within rigid casings without joints to allow vertical hinging as with independent suspension. In an off-road vehicle rigid axles have the advantage of maintaining maximum under-axle ground clearance at all times and always keeping the tire tread flat on the ground.
Articulation coefficient
See Longitudinal articulation coefficient.
Artificial aging
The method of speeding up the process of hardening by subjecting the substance (e.g., aluminum alloy) to a change in temperature or pressure.
Artificial antenna
An electrical unit which simulates an antenna without actually transmitting or receiving a signal. It is used to check or test radios and transmitters.
Artificial rubber
Formerly, abbreviation for American Standards Association. Now known as American National Standards Institute.
Abbreviation for Air Suspension Automatic Ride Control
  1. A heat resistant and non-burning fibrous mineral (in combination with bonding materials like asphalts and resins) widely used for brake shoesclutch linings, etc. Asbestos is a health hazard and the dust created by brake systems should never be inhaled or ingested.
  2. A group of naturally occurring minerals that separate into long, thin fibers.
Something that has no asbestos — especially brake and clutch linings.
An incurable lung disease caused by the inhalation of asbestos fibers over an extended period of time.
Abbreviation for American Society of Civil Engineers
Ascending stroke


Sheet metal screws with sharp-pointed ends, fewer threads per inch than type AB screws, and deeper threads with better gripping power than type AB. The Industrial Fasteners Institute incorrectly labels type A an ‘obsolete’ thread though it is universally preferred in 18-8 stainless over type AB, especially by the marine industry.
  1. Abbreviation for Automatic slip-control differential.
  2. Abbreviation for Automatic Shutdown Relay
Abbreviation for Airbag System Diagnostic Module (Chrysler)
  1. Abbreviation for National Institute for Automotive Service Excellence
  2. Abbreviation for Automotive Service Excellence
  3. Abbreviation for After-start Enrichment
Abbreviation for Association of South East Asian Nations.
Inorganic residue remaining after ignition of combustible substances determined by definite prescribed methods.
Ash frame
A frame of a car made of wood from the ash tree and covered with aluminum panels.
A device (in a vehicle) for holding cigarette ashes.
Abbreviation for Automotive Service Industry Association
Abbreviation for Acceleration Simulation Mode
Abbreviation for American Society of Mechanical Engineers
Abbreviation for Advance Shipping Notice which is sent to the warehouse to indicate that a shipment is on its way.
Abbreviation for Air Sensor Potentiometer
Aspect ratio
  1. The ratio of length to width of rectangular air grille or duct.
  2. The relationship in a tire or wheel between the distance from the rim to the tread and the tire’s width (i.e., ratio of section height to section width). Thus, in a P185/80R13 tire, 80 is the aspect ratio, showing the height is 80% of the width. A lower aspect ratio describes a shorter, wider tire.
  3. In a wing, it is the relationship of its span (horizontal length) to its chord (height). Important for induced drag and range/speed characteristics. Defined as S²/A where S is the span and A is the area. Normal figure between 6 and 9, lesser values than 6 being low aspect ratio, greater than 9 high aspect ratios.
  4. Ratio of the length of a fiber or wire to its width or diameter.
  5. (AR) Ratio of the width to the height of the reproduced picture or computer screen, e.g., 4×3, often expressed with the height as unity. 1.331. Wide-screen systems have aspect ratios between 1.651 and 2.351.
  6. In a Tokamak type of fusion machine, the ratio of the major to minor radii of the torus.


Asphalt (pronounced ASS-falt or ASH-falt)
  1. A bituminous substance found naturally in oil-bearing strata from which the volatiles have evaporated
  2. A residue in petroleum distillation
  3. A mixture of asphaltic bitumen and granite chippings, sand, or powdered limestone. Asphalt is used extensively for paving, road-making, damp-proof courses, in the manufacture of roofing felt and paints and as the raw material for certain molded plastics.
  4. A dark brown-to-black cement-like material obtained by petroleum processing and containing bitumens as the predominant component; used primarily for road construction. It includes crude asphalt as well as the following finished products cements, fluxes, the asphalt content of emulsions (exclusive of water), and petroleum distillates blended with asphalt to make cutback asphalts. Note The conversion factor for asphalt is 5.5 barrels per short ton.
Insoluble, semi-solid, or solid particles which are combustible and are highly aromatic. Asphaltenes contain a high carbon to hydrogen ratio and entrap water, fuel ashes and other impurities.
Asphaltic concrete
(AC) A mixture of asphalt cement, graded aggregate, mineral filler, and additives.
Asphalt overlay
  1. A new layer of asphalt is placed on the road, making it look brand new. First a layer of liquid asphalt or tack coat is sprayed on the road. Next, fabric may be placed on any badly broken areas for added strength. Finally hot asphaltic concrete is applied, raked and rolled to a prescribed density. Work moves quickly and you can drive on the new asphalt as soon as the rolling is complete. The work must be done when the ground is dry and reasonably warm.
  2. Asphalt concrete placed on the roadway with a paver. Overlays can be anywhere from 25mm to 15cm thick. Thick overlays are typically placed in two to three layers. The work will take anywhere from a day or two, up to a week or two depending on the thickness and the distance to be covered.
  1. A device which is energized by ingesting air (usually oxygen).
  2. To draw into or from a cylinder by suction. The normally aspirated engine operates only on its ability to create a vacuum in the cylinder to bring in air, as compared to the turbocharged engine which pumps in air.
Aspirated engine
Aspirating psychrometer
Device which draws a sample of air through it to measure humidity
The process of sucking or inhaling the air-fuel mixture into a combustion engine.
The air intake of a sensor.
Aspirator system
Aspirator valve
A check valve in an air injection system.

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Ford Aspire

A model of automobile manufactured by Ford

  1. Abbreviation for Anti-spin regulation. A Bosch term for traction control
  2. Abbreviation for Acceleration Slip Regulation
The action of putting something together from a number of component parts.
  1. The finished union of a number of parts to make a component.
  2. Construction of product from several or many components. Methods used for attachment include welding, fastening, push-fit, snap-fit, lock-fit, adhesive bonding, ultrasonic welding, etc. Many products are now designed for robotic assembly.
Assembly Area
  1. A location in warehouse where products and loads are collected and combined.
  2. A location in a shop where a product is removed from its packing and bolted together
Assembly-fuel Vacuum
Assembly Identifier
Assembly line
The production line where a vehicle is put together from its component parts. Often one team will work on just the engine of each vehicle while another team works on another part, etc.
Assembly Line Data Link connector
(ALDL) a diagnostic connector used in General Motors vehicles
Assembly lube
A special lubricant used to coat parts that rub or rotate against each other during initial assembly.
Assessed reliability
The probability that a device will function without failure over a specified time period or amount of usage.
Assist power steering
Assist steering
Assisted brakes
Assisted steering
Associated-dissolved natural gas
Natural gas that occurs in crude oil reservoirs either as free gas (associated) or as gas in solution with crude oil (dissolved gas).
Association of American Battery Manufacturers, Inc.
Association of South East Asian Nations
(ASEAN) An organization of states (including Brunei, Myanmar (Burma), Indonesia, Laos, Malaysia, the Philippines, Singapore, Thailand, and Vietnam) founded in 1967 to present an united front that addresses the political, economic, and strategic dynamics of the region.
Abbreviation for Assembly.
A backward movement of a vessel.
Abbreviation for American Society for Testing Materials.
ASTM standards
Standards issued by the American Society of Testing Materials.
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A vehicle brand of which all 1927-39 models with appropriate application are classic cars.

Aston Martin
A vehicle brand of which the 1948-63 models are milestone cars. All the DB4, DB5, DB6 from 1964-67 are milestone cars.
Astray freight
A situation in which freight is separated from the freight bill.
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A model of mid-size van produced by the Chevrolet division of General Motors from 1985 to 2005

A pattern in which one side does not correspond to the other side.
A pattern in which one side does not correspond to the other side. Also called dissymmetrical or non-symmetrical.
Asymmetrical beam
A headlight system in which one beam is of greater intensity than the other.
Asymmetrical power distribution
A system in a four-wheel vehicle in which more power is transmitted to the front wheels than the rear wheels or more to the rear wheels than the front wheels.
Asymmetrical tread

asymmetrical treadAsymmetrical tread

The tread of a tire which has different shapes/patterns and sizes of grooves in the same tire. Often they are divided into three distinct patterns The outside shoulder, the center zone, and the inside shoulder. The outside shoulder tread will have larger shoulder elements with very few sipes to provide increased cornering stability. The center tread zone enhances steering control. The inside shoulder tread zone provides additional traction because the shape of the tread elements, sipes and larger shoulder slots help disperse water and slush. Obviously these tires must be mounted only one way so that the outside pattern is actually on the outside of the wheel.

Asymmetric rim
A wheel rim where the well is located outside the centerline of the wheel. Opposite of symmetric rim.
Abbreviation for Automatic Transmission
  1. Abbreviation for American Trucking Association — a national federation of independent and autonomous truck carrier conferences and state trucking associations. Includes Regular Common Carrier Conference, National Tank Truck Carriers Conference.
  2. Abbreviation for Air Transport Association

ATBAll-Terrain Bike

  1. Abbreviation for all-terrain bike. Sometimes called MTB (mountain bike), but ATB is the preferred Abbreviation.
  2. Abbreviation for aeration test burner
  1. Abbreviation for automatic temperature control.
  2. Abbreviation for air-traffic control
  3. Abbreviation for Automatic Traction Control — an optional feature based on ABS which prevents spinning of the drive wheels under power on slippery surfaces by braking individual wheels and/or reducing engine throttle. Also called ASR, an Abbreviation sometimes loosely translated from the German as anti-spin regulation.
Abbreviation for Automatic test equipment
Abbreviation for Automatic Transmission Fluid
A thread
Athwart ship
Across the ship, at right angles to the fore-and-aft centerline.
Abbreviation for Advance Traveler Information Systems
  1. Abbreviation for Standard atmosphere
  2. Abbreviation for Actuator Test Mode
Atmosphere Burner
Atmospheric acoustics
The study of how sound is transmitted in the air at different altitudes, weather, humidity, and atmospheric pressure.
Atmospheric air
Air under the prevailing atmospheric conditions.
Atmospheric corrosion
The gradual eating away of metal caused by the action of the gaseous elements in the atmosphere including oxygen’s rusting action on iron and the effects of acid rain
Atmospheric crude oil distillation
The refining process of separating crude oil components at atmospheric pressure by heating to temperatures of about 316°C to 400°C (depending on the nature of the crude oil and desired products) and subsequent condensing of the fractions by cooling.
Atmospheric distillation unit
The primary distillation unit that processes crude oil (including mixtures of other hydrocarbons) at approximately atmospheric conditions. It includes a pipe still for vaporizing the crude oil and a fractionation tower for separating the vaporized hydrocarbon components in the crude oil into fractions with different boiling ranges. This is done by continuously vaporizing and condensing the components to separate higher oiling point material. The selected boiling ranges are set by the processing scheme, the properties of the crude oil, and the product specifications.
Atmospheric dust spot efficiency
A measurement of a device’s ability to remove atmospheric air from test air
Atmospheric engine
Earliest form of practical steam engine, in which a partial vacuum created by stem condensation allowed atmospheric pressure to drive down the piston.
Atmospheric gas-burner system
A natural-draft burner injector, in which the momentum of the gas passing into the injector throat inspirates part of the air required for combustion.
Atmospheric pressure
  1. The force due to atmosphere per unit area. Atmospheric pressure at sea level is 14.7 psi absolute; it decreases as altitude increases.
  2. The pressure of the weight of air and water vapor on the surface of the earth at sea level, namely 760 mm mercury column or 101.3 kPa.
Atmospheric pressure sensor
A detection device that measures atmospheric pressure. This allows the computer to change engine output in relation to atmospheric pressure and engine vacuum.
Atmospheric-suspended power chamber
A booster power chamber with atmospheric pressure on both sides of its diaphragm when the brakes are not applied.
Abbreviation for Advance Traffic Management Systems
The basis of all matter. It consists of a nucleus made up of protons and neutrons, and one or more orbiting electrons.
Atomic Mass
Atomization characteristics
The ability of an oil to be broken up into a fine spray by some mechanical means.
The process of changing liquid to minute particles or a fine spray. The extent to which a spray gun breaks up paint into a fine mist, fog, or spray.
Tiny particles of a solid or liquid substance (fuel or paint) mixed with air, making a fine mist.
Atomized powder
A powder produced by the dispersion of molten metal or other material by spraying under conditions such that the material breaks down into powder.
A device for producing a fine spray such as used on a paint spray gun.
Atomizing pressure
The pressure needed to atomize a liquid like paint.
British term for strays
Abbreviation for Attenuated total reflection
Colloquial term for a truck tractor pulling more than one trailer connected by A-dollies
A corrosion protection process in which steel is coated with phosphate using a zinc phosphate solution at 90°C.
Abbreviation for Air temperature sensor
A fitting or accessory to be used in conjunction with a tool, such as a grinding disc for use with an electric drill.

Attachment face
  1. Chemical corrosion of metal.
  2. To damage something by corrosion.
Attack angle
The angle of the rear spoiler where it is most effective against lift.
Attendant parking
Parking which is left to a valet and supervised by an attendant.
Attenuated total reflection
Spectroscopic method of analyzing thin films on reflective substrates, esp. using infrared radiation.
  1. A reduction of noise or emission.
  2. General term for reduction in magnitude, amplitude, or intensity of a physical quantity, arising from absorption, scattering, or geometrical dispersion. The latter, arising from diminution by the inverse square law, is not generally considered as attenuation proper.
Attenuation coefficient
The coefficient which expresses energy losses of electromagnetic radiation due to both absorption and scattering in a medium. Relevant to narrow beam conditions. Also called total absorption coefficient
Attenuation compensation
The use of networks to correct for frequency-dependent attenuation, e.g., in transmission lines.
Attenuation constant
The real part of α in the relationship ρ=ρe– αx, where ρ is a physical quantity, such as the amplitude of a wave propagating along a transmission path, and x is the distance along the path. The imaginary part of α is known as the phase constant. More simply, but less commonly defined by μ = αλ where μ is the attenuation and λ is wavelength, i.e., α is the attenuation per wavelength distance of propagation.


Attenuation distortion
Distortion of a complex waveform resulting from the differing attenuation of each separate frequency component in the signal. This form of distortion is difficult to avoid, e.g., in transmission lines.
Attenuation of X-rays
Absorption and scattering of X-rays as they pass through an object.
An arrangement of fixed or variable resistive elements designed to reduce the strength of any signal (audio- or radio-frequency) without reducing appreciable distortion. Attenuators also incorporate impedance matching to the transmission lines or circuits to which they are connected, regardless of the attenuation they introduce. For lower frequency applications they may be simply variable or fixed resistances, for high frequencies they may be pieces of resistive material, introduced into transmission lines, stripline, or waveguide. Fixed attenuators are sometimes referred to as pad.
  1. The construction of a vehicle which gives the appearance of a particular characteristic which may be aggressive, intimidating, playful, cheerful, etc.
  2. The overall relationship of a vehicle to the ground
  3. Of an aircraft in flight, the angle made by its axes with the relative airflow; the aspect is the angle made by its axes with the ground when the aircraft is on the ground.
Attitude indicator
A gyro horizon which indicates the true attitude of the aircraft in pitch and roll throughout 360° about these axes.
Attracted-disk electrometer
Fundamental instrument in which potential is measured by the attraction between two oppositely charged disks.
A process of wearing out an object by friction.
Attrition test
A test for the determination of the wear-resisting properties of stone, particularly stone for road-making. Pieces of the stone are placed in a closed cylinder, which is then rotated for a given time, after which the loss of weight due to wear is found.
Abbreviation for All Terrain Vehicle — a vehicle designated for all types of ground surface.
Abbreviation for Automatic Transaxle
At your back door
Trucker slang for behind your truck as in ‘Smokey’s at your back door.’
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A vehicle brand of which all 8 and 12-cylinder models are classic cars.

A style of group bicycle touring found in Europe (esp. France) where a road captain sets a steady pace for a group of riders. All riders are to finish together, but (unlike regular randonneuring) a sag wagon is permitted.
Audax Club Parisien
A cycle-touring club in Paris, France which begun in 1904 to promote the Audax style of
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A German automobile manufacturer which began in 1899 has four interlocking rings as its emblem. These rings represent the 1932 union of four automakers (Audi, DKWHorch, and Wanderer). Later NSU joined in 1969. Audi was owned by Daimler-Benz from 1958 to 1965, and then by Volkswagen. It includes the following:

  • 80 (1988-92)
  • 90 (1988-95)
  • 100 (1989-94)
  • 200 (1989-1991)
  • 5000 (1988)
  • A3 (2006-2008)
  • A4 (1996-2008)
  • A6 (1995-08)
  • A8 (1997-2007)
  • Allroad (2001-05)
  • Cabriolet (1994-98)
  • Q7 (2007)
  • Quattro (1990-94)
  • RS4 (2007)
  • RS6 (2003)
  • S4 (1992-2008)
  • S6 (1995-2007)
  • S8 (2001-2007)
  • TT (2000-08)
Ability to be heard; said of faint sounds in the presence of noise. The extreme range of audibility is 20-20,000 Hz in frequency, depending on the applied intensity; and from 2 x 10-5Nm-2(ms) at 1000 Hz (the zero of the phon scale, selected as the average for good ears) to 120 dB.
Audible ringing tone
An audible tone fed back to a caller as an indication that ringing current has been remotely extended to the called subscriber’s telephone. On circuits in UK it is heard as a double beat recurring at 2 second intervals. Also called Audible signal
Audible signal
Audio codec
A codec for use in a multimedia system, designed to handle a range of sound signals in addition to speech
Audi Rings

Audi RingsAudi Rings

A logo of four interlocking rings from the German automobile manufacturer Audi. These rings represent the 1932 union of four automakers (Audi, DKWHorch, and Wanderer). Later NSU joined in 1969.

Au diode
Audio dub
Replacing the existing audio with new
Frequency which, in an acoustic wave, makes it audible. In general, any wave motion including frequencies in the range of 20 Hz to 20k Hz.
Audio-frequency amplifier
Amplifier for frequencies within the audible range.
Audio-frequency choke
Inductor with appreciable reactance at audio-frequencies.
Audio-frequency modulation
Method of facsimile transmission in which tone values from black to white are represented by a graded system of audio-frequencies
Audio-frequency transformer
Transformer for use in a communication channel or amplifier, designed with a specified, normally uniform, response for frequencies used in sound reproduction.
Standard graph or chart which indicates the hearing loss (in bels) of an individual ear in terms of frequency.
Instrument for measurement of acuity of hearing. Specifically to measure the minimum intensities of sounds perceivable by an ear for specified frequencies.
Audit Commission
Body overseeing public sector finances and service delivery.
A shaft with a broad spiral flange rotating inside a cylindrical casing to carry bulk material from one end of the shaft to the other. Augers are used to unload cargoes such as grain from grain trailers.
Auger effect
For an atom which has been ionized by the ejection of an inner electron, the loss of energy by the ejection of an outer electron. Energies of the Auger electrons emitted are characteristic of the atomic energy levels, provided a method of determining surface composition and character.
Auger yield
For a given excited state of an atom of a given element, the probability of de-excitation by Auger process instead of by X-ray emission.
  1. Means of increasing forces by afterburning in a gas turbine.
  2. Means of increasing forces by induced airflow in a rocket.
  3. Means of increasing forces in a wing of STOL aircraft by ducting compressed air flow from a gas turbine into circulation-increasing slots and flaps to create high lift coefficients, thereby giving slow landing speeds.
Aural masking
Luminous glow from the outer portion of electric arc which has a spectrum different from that of the highly-ionized core.
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Oldsmobile Aurora

A model of automobile built by Oldsmobile from 1995-2003

Auroral zone
Zone where radio transmission is affected by aurora
The higher density, high-temperature, face-centered cubic, γ form of iron and of solid solutions based on it. In pure iron it is stable between 1183°K and 1663°K.
A type of stainless alloy named for Sir Robert Williams Austen, an English metallurgist.
Austin Healey
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Austin Healey

A vehicle brand of which the 100-6 models from 1956-59 are milestone cars. The 3000 models from 1959-67 are milestone cars. The 100/100M model from 1953-56 are milestone cars.

A vehicle brand of which the all models built in the classic era 1925-1948 are designated classic cars by the CCCA.
Authentication center
A node within a personal communications network containing the database files needed to check that potential users have authority to use the system.
Authority Limit
Authority Limit Switch
Authorized Carrier
A person or company authorized by the ICC to transport goods as a common or contract carrier.
Authorized dealer
A company which sells and services a particular brand of vehicle and is appointed or recommended by a manufacturer.
  1. Abbreviation for automatic transmission.
  2. Abbreviation for Automobile.
Bonding together of identical surfaces, as with contact adhesives.
System of videotape editing in which selected scenes are transferred in their required sequence according to a pre-selected program of time-code information.
Auto bonnet
A British term for a Car cover.
Autocapacitance coupling
Coupling of two circuits by a capacitor included in series with a common branch
Auto Carrier

Auto carrierAuto carrier

A cargo body with two decks to carry automobiles. Also called auto transporter

A term for automatic choke.
A sealable high-pressure container used for polymerization and in tire production.
Auto coarse pitch
The setting of the blades of a propeller to the minimum drag position if there is a loss of engine power during take-off
  1. An instrument for accurately measuring small changes in the inclination of reflecting surfaces. Principally used for engineering metrology measurements.
  2. A convex mirror used to produce a parallel beam of light from a reflecting telescope. It is placed at the focus of the main mirror.
Technique for detecting weak signals against a strong background level. Signal is subjected to controlled delay, the original delay signals then being fed to the autocorrelation unit which responds strongly only if delay is an exact multiple of signal period.
A timed competition of low-to-medium speed driving, with one driver at a time navigating a small course defined by traffic cones. drivers compete against one another for the fastest timed lap (sometimes multiple laps) through the course.
A visual prompter which displays a script to persons in front of a TV camera. Normally mounted on the camera to give eye contact with the viewers.
An obsolete moped which is a form of a light motorcycle with a small engine (usually below 100cc) that uses pedals to start the engine and provide some extra help getting up hills.
Auto dealer
A retail outlet that carries one (or in some cases in the U.S., a number of) manufacturer’s product line and sells to general consumers and fleet operators. The outlet will also provide service and sell parts for the brand of vehicle that it carries. In some instances, a dealer may dual for another manufacturer’s product line.
Auto dealership
A retail outlet that carries one (or in some cases in the U.S., a number of) manufacturer’s product line and sells to general consumers and fleet operators. The outlet will also provide service and sell parts for the brand of vehicle that it carries. In some instances, a dealer may dual for another manufacturer’s product line.
Term describing an electrical circuit in which the same elements and valves are used both as oscillator and detector. Also called endodyne, or self-heterodyne.
Autodyne receiver
A receiver using the principle of beat reception and including an autodyne oscillator.
An automatic landing system which operates on the flare-out part of the landing, using an accurate radio-altimeter.
Autofocus assist
Device which improves autofocus performance in low light by projecting a high contrast light pattern onto the subject.

Auto graveyard
An auto wrecker where a large number of older or disabled cars and trucks are located.
  1. The rapid burning of the air-fuel mixture as a result of a flame or hot surface, not from a spark plug.
  2. The self-ignition or spontaneous combustion of a fuel when introduced into the heated air charge in the cylinder of a compression-ignition engine. Also called automatic ignition.
Auto-inductive coupling
Coupling of two circuits by an inductance included in series with a common branch.
A British term for a swap meet where parts for old cars are displayed for sale in various stalls.
A landing in which the descent, forward speed, flare-out, alignment with the runway, and touchdown are all automatically controlled.

Automated guided vehicle system
(AGVS) Vehicles equipped with automatic guidance equipment which follow a prescribed path, stopping at each machining or assembly station for manual loading and unloading of parts.
A manufacturing company that builds vehicles (cars, trucks, etc.).
  1. Colloquial term for automatic transmission.
  2. Anything that operates without the direct control of the driver.
Automatic adjuster
Brake adjusters that are actuated by the application of the park brake or by normal brake operation to compensate for lining wear. At one time, in order to activate the brake adjuster, it was necessary to operate the vehicle in reverse and hit the brakes.
Automatic adjusters
Brake adjusters that are actuated by the application of the parking brake or by normal brake operation, to compensate for lining wear.
Automatic advance
A mechanism which adjusts the ignition advance by means of centrifugal weights or by a diaphragm controlled by intake manifold vacuum.
Automatic air-conditioning
An air-conditioning system which automatically maintains a preset temperature.

Automatic air-recirculation system
A heating and ventilation system which automatically switches to the recirculation mode when the pollutant levels of the air inside the vehicle exceed certain levels; but after a certain period of recirculation, opens the intake air doors again to let some fresh air in, even if its quality is still questionable.
Automatic arc lamp
An arc lamp in which the feeding of the carbons into the arc and the striking of the arc are done automatically, by electromagnetic or other means.
Automatic arc welding
Arc welding carried out in a machine which automatically moves the arc along the joint to be welded, feeds the electrode into the arc, and controls the length of the arc.
Automatic beam control
(ABC) System in a TV camera which momentarily alters the beam current in the camera tube to reduce the tailing effects on moving highlights. Also called automatic beam optimizer
Automatic beam optimizer
Automatic brightness control
Circuit used in some television receivers to keep average brightness levels of screen constant
Automatic call distribution
An intelligent network service which takes account of factors such as time of day or caller location to route calls to the appropriate point within an organization.
Automatic camera
Camera in which the focus lens aperture and shutter speed are selected automatically, film advance by motor drive may also be included. Priority selection may be available, for example, exposure based on either general or spot areas and with aperture or shutter speed limitations.
Automatic car wash


Automatic choke
Automatic chokeClick to supersize
Automatic choke

A device attached to the carburetor that automatically reduces the amount of air entering the carburetor by sensing changes in engine temperature. It is usually controlled by a coil spring which changes length as the engine is warmed or cooled.

Automatic circuit-breaker
A circuit breaker which automatically opens the circuit as soon as certain predetermined conditions (e.g., an overload) occur.
Automatic closing system
A system which automatically closes the doors, windows, sunroof, trunk, and hood.
Automatic contrast control
Form of automatic gain control used in video signal channel of a television receiver.
Automatic control
  1. Valve action reached through self-operated or self-actuated means, not requiring manual adjustment.
  2. Switching system which operates control switches in correct sequence and at correct intervals automatically.
  3. Control system incorporating servomechanism or similar device, so that feedback signal from output of system is used to adjust the controls and maintain optimum operating conditions.
Automatic Cruise Control
(ACC) A term found on a cruise control witch which indicates the direction the switch needs to be moved to increase the speed (accelerate) of the vehicle
Automatic cut-out
A term frequently applied to a small automatic circuit breaker suitable for dealing with currents of a few amperes.
Automatic defrost
System of removing ice and frost from evaporators automatically.
Automatic direction finding
(ADF) Airborne navigational aid tuned to radio source of known position. Using rotatable loop aerial mounted above in aircraft to detect the direction of the radio source by rotating until the signal is zero.
Automatic expansion valve
(AEV) pressure-controlled valve which reduces high-pressure liquid refrigerant to low-pressure liquid refrigerant.

Automatic exposure
(AE) A control system using a photosensor in the camera to measure scene brightness and automatically set the lens aperture/shutter speed combination. Refinements include measuring particular areas of the scene and program exposure modes. A video camera uses the video signal to determine exposure.
Automatic flight control system
(AFCS) A category of automatic pilot for the control of an aircraft while en route. It can be monitored by speed and altitude data signals, signals from an instrument landing system and VOR, has automatic approach capability, and is disengaged before landing.

Automatic focusing
(AF) Control system for automatically setting the lens focus to the subject distance; in a simple form, this may be by means of coupled range-finder but advanced types employ completely automatic examination of the image. In an enlarger or rostrum camera, lens focus is mechanically set by the distance from the base.
Automatic four-wheel drive
(A4WD) A driving system that automatically engages 4WD as needed, usually by monitoring differences in individual wheel speeds and thus sensing when a tire is slipping.
Automatic frequency control
(AFC) FM stations tend to drift a little, so radios have incorporated the frequency control to maintain the desired frequency automatically.
Automatic frost control
Control which automatically cycles refrigerating system to remove frost formation on evaporator.
Automatic gain control
(AGC) System in amplifiers which compensates for a wide range of input signals to give a more uniform level of output and thus accommodate for a wide range of conditions including fading, masking of antenna, and ambient light.
Automatic gearbox
Automatic generating plant
A small generating station, e.g., a gasoline or diesel driven generator and battery which is automatically started when the battery voltage falls below a certain value and stopped when it is fully charged. The term is also applied to the plant in small unattended hydroelectric generating stations.
Automatic ice cube maker
Refrigerating mechanism designed to automatically produce ice cubes in quantity.
Automatic ignition
  1. Rapid, out of control combustion of the air-fuel mixture in a spark ignition engine, but not caused by an external ignition source such as a spark or flame; instead, it’s caused by a hot spot such as a carbon deposit in the roof of the combustion chamber. Also called auto-ignition.
  2. Ignition of fuel at the burner when the fuel controlling device is turned on, including reignition if the flames on the burner have been extinguished by means other than by the closing of the fuel controlling device.
Automatic ignition system
A system designed to ignite and re-ignite a main burner.
Automatic level control
A component of the suspension which raises or lowers either (or both) the front or rear of the vehicle when there is a change in the amount of load in the vehicle.
Automatic mixture control
A device for adjusting the fuel delivery to a reciprocating engine in proportion to air density.
Automatic muting
An automobile radio which cancels noise output when you turn the station dial.
Automatic observer
An apparatus for recording, photographically or electronically, the indications of a large number of measuring instruments on experimental research aircraft.
Automatic parachute
A parachute for personnel which is extracted from its pack by a static line attached to the aircraft.
Automatic phase control
In reproducing color TV images, the circuit which interprets the phase of the chrominance signal as a signal to be sent to a matrix.
Automatic pilot
A device for guiding and controlling an aircraft on a given path. It may be set by the pilot or externally by radio control. Also called autopilot. Colloquially called George
Automatic quiet gain control
Joint use of automatic gain control and muting
Automatic reel change
On rotary machines, equipment to attach a new reel to an old web, without stopping the machine and severing the butt end of the old web. Also called autopaster or flying paster.
Automatic ride control
Electronically operated soft or firm ride as required.
Automatic screw machine
Fully automatic single-spindle or multiple-spindle bar stock turret lathe.
Automatic seat belt
Automatic shutter
In a film projector, a shutter which cuts off the light when the mechanism stops, to protect the film from heat.
Automatic signaling
A system of railway signaling, usually with electric control, in which the signals behind a train are automatically put to danger as soon as the train has passed, and held in that position until the train has attained the next section of line.
Automatic slip-control differential
(ASD) An electronically controlled, automatic locking differential developed by Mercedes-Benz.
Automatic speed control
Automatic stabilizer
A form of automatic pilot, operating about one or more axes, adjusted to counteract dynamic instability. Also called autostabilizer.


Automatic starter
A starter for an electric motor which automatically performs the various starting operations (e.g., cutting out steps of starting resistance) in the correct sequence, after being given an initial impulse by means of a push-button or other similar device.
Automatic steering effect
Built in tendency of an automobile to resume travel in a straight line when released from a turn.
Automatic substation
A substation containing rotating machinery which, as occasion demands, is started and stopped automatically, e.g., by a voltage relay which operates when the voltage falls below or rises above a certain predetermined value.
Automatic synchronizer
A device which performs the process of synchronization in an AC circuit automatically
Automatic tap-changing equipment
A voltage-regulating device which automatically changes the tapping on the winding of a transformer to regulate the voltage in a desired manner.
Automatic temperature control
A system which regulates the heater and air conditioner so that the temperature inside the vehicle meets the preset temperature.
Automatic test equipment
(ATE) An electronic equipment for testing ignition, wiring, fuel injection systems, etc.
Automatic tracking
Servo control of radar system operated by a received signal, to keep antenna aligned on target.
Automatic Traffic Counter
An electric or mechanical device which determines (i.e., counts) how many vehicles pass a certain point on a designated road.
Automatic train stop
A catch, used in conjunction with an automatic signaling system, which engages a trip-cock on the train passes a signal at danger.
Automatic transmission

Automatic transmissionAutomatic transmission

A mechanism of the drivetrain which takes the power from the engine and transfers it to the driveshaft or wheels.

  • Without using a clutch, it uses a torque converter and fluid coupler to change the gear ratio.
  • It automatically effects gear changes to meet varying road and load conditions.
  • Gear changing is done through a series of oil operated clutches and bands.
Automatic transmission fluid
(ATF) A very thin viscosity liquid designed for use in automatic transmissions to transfer the movement of the torque converter to the driveshaft.

Automatic trolley reverser
An arrangement of the overhead contact line of a tramway, located at terminal points, which ensures that the trolley collector is reversed when the direction of motion of the car is reversed.
Automatic tuning
  1. System of tuning in which any of a number of predetermined transmissions may be selected by means of push-buttons or similar devices.
  2. Fine tuning of receiver circuits by electronic means, following rough tuning by hand.
Automatic voltage regulator
A voltage regulator which automatically holds the voltage of a distribution circuit or an alternator constant within certain limits, or causes it to vary in a predetermined manner.

Automatic volume compression
Reduction of signal voltage range from sounds which vary widely in volume, e.g., orchestral music. This is necessary before they can be recorded or broadcast but ideally requires corresponding expansion in the reproducing system to compensate.
Automatic volume control

  1. Alteration of the contrast (dynamics) of sound during reproduction by any means. By compression (compounder) a higher level of average signal is obtained for modulation of a carrier, the expansion (expander) performing the reverse function at the receiver. In high-fidelity reproduction, arbitrary expansion can be disturbing because of variation in background noise, if present.
  2. An automobile radio which automatically limits the maximum volume to a preset level.
Automatic volume expansion
Expansion of dynamic range, e.g., by keeping peak level constant and automatically reducing the lower levels. Used to counteract loss of dynamic range through studio or recording equipment, or during transmission.
Automatic wear adjuster
A device that automatically compensates for the wear of brakes or clutch.
Automatic welding
Welding in which the work, the torch, and/or the arc is mechanically moved and controls are used to control the speed and/or the direction of travel.
Automatic white balance
(AWB) A self-adjusting balancing system which monitors the lighting and corrects for changes in color temperature
Automatic wire stripper

wire stripperWire stripper

A tool which removes the outer insulation from a wire by automatically adjusting to the size of the wire thus avoiding damaging the wires.

Automixte system
A system of operation of gasoline-electric vehicles in which a battery, connected in parallel with the generator, supplies current during starting and heavy-load periods and is charged by the generator during light-load periods. Also called Pieper system
Four-wheeled passenger motor vehicle having a seating capacity for not more than 10 people. It includes police cars and racing cars but not ambulances, hearses, or trucks. In Britain, the word automobile is not in frequent use and has been replaced by motor car.
Automobile association
A motoring club which provides assistance to drivers including insurance, maps, travel arrangements, etc.

Automobile classification
  1. Vehicle classifications for automobiles and light duty trucks issued by the EPA mileage guide book. Almost every year there are small changes in the classifications, therefore the categories change accordingly. The EPA mileage guide can be found at any new car dealership.
  2. A designation of vehicles according to size, manufacturer, style, usage, price, age, modifications, etc. Includes the following:
Automobile Club
Automobile engineering
Automobile industry
The manufacturing industry for building automobiles. Also called motor industry.
Automobile insurance
A plan which a motorist can purchase for his vehicle which will offset the repair costs of a vehicle which has been involved in an accident. Some plans are offered by a government agency while others are run by independent agencies. All plans offer the basic coverage of property damage and public liability. Others offer extra benefits which cover glass damage, theft, vandalism, etc.
Automobile Labeling Act
Automobile manufacturer
An company which designs, builds, and distributes cars and trucks. Also called motor manufacturer.

Automobile mechanic
An individual who repairs and maintains cars and trucks. Also called (especially in Britain) motor mechanic.
Automobile polish
A wax or synthetic which is designed to give a glossy, protective finish to a painted surface. Also called car polish.
Automobile types


Relating to or occurring in automobiles.
Automotive adhesive
A glue used in the manufacturing of automobiles.
Automotive electrician
An individual who works with designing the electrical system for automobiles.
Automotive electronics
The use of electronic equipment in automobiles.
Automotive emissions
All the different types of fumes that are expelled into the atmosphere (exhaust gas, fuel fumes, crankcase fumes) as well as the noise it makes.
Automotive engineering
The design and construction of automobiles.
Automotive Engineers
Automotive gas oil
(AGO) US term for gas oil used mainly as diesel fuel; same as the UK term DERV
Automotive Repair and Service Council
Automotive Research
Automotive Technical Education Foundation
Automotive tool
Any of the tools used in the construction, maintenance, or repair of automobiles.
Study of self-regulating systems for process control, optimizing performance.
Autonomous vehicle
Generally unmanned aircraft operating without external assistance
Auto Pact base year
With respect to the Auto Pact, the 12 month period beginning on August 1, 1963, and ending on July 31, 1964.
Auto Pact Canadian value added
The aggregate of the costs of parts, material, labor costs, and transportation costs that are reasonably attributed to the production of vehicles or parts by manufacturers producing vehicles in Canada.
Trade name of Chrysler Corp for its automobile parts (i.e., AUTOmobilePARts). Chrysler also uses the name Mopar to indicate its motor parts (i.e., MOtorPARts).
Auto parts store
Jobber and retail auto parts stores which primarily sell automotive products and conduct business at the retail level.
A machine which can deliver a curved stereoplate for rotary printing; built to suit the requirements of each particular rotary machine.
Photographic record, usually of a biological specimen, produced by exposure to radiation from self-contained radioactive material which has been injected or absorbed.
Auto-reclose circuit breaker
A circuit breaker which, after tripping due to a fault, automatically recloses after a time interval which may be adjusted to have any value between a fraction of a second and 1 or 2 minutes
Auto reverse
A feature on a cassette player which will automatically play the next side of a cassette tape when one side is finished.
  1. The spin; continuous rotation of a symmetrical body in a uniform air-stream due entirely to aerodynamic moments.
  2. Unpowered rotorcraft flight, in a helicopter with engine stopped, in which the symmetrical airfoil rotates at high incidence parallel with the airflow.
Autoset level
A form of dumpy level for rapid operation, in which the essential features are a quick-leveling head, and an optical device which neutralizes errors of leveling so that the bubbles need not be central while an observation is being made.
A trademark name for a form of semi-automatic transmission.

  • It combines an automatic transmission with the gear-shifting feature of a manual transmission without the use of a foot-operated clutch.
  • In the normal automatic transmission drive mode, the transmission behaves like any other automatic.
  • The manual-shifting feature allows more control over the full range of rpms an engine offers.
  • Porsche and Audi offer a related transmission technology called Tiptronic.
  • The Lexus GS400 also has a similar transmission but instead of using a stick to change gears it employs buttons on the steering wheel.
  • Several other automakers offer similar technologies.
Autothermic piston
An aluminum piston in which steel or alloy inserts are cast to control expansion of the piston skirt.
A device for controlling the power of an aero-engine to keep the approach path angle and speed constant during an automatic blind landing.
Transductor in which the same winding is used for power transfer and control
Transformer in which both primary and secondary coils have turns in common. Step-up or step-down of voltage is accomplished by taps on common winding.
Autotransformer starter
A starter for squirrel-cage induction motors, in which the voltage, applied to the motor at starting is reduced by means of an autotransformer.
Auto transporter
Auto wrecker
A place where old and disabled cars and truck go. The parts are removed and sold. Also called an auto graveyard.
Abbreviation for auxiliary usually indicating those terminals on the fuse panel for non-standard equipment.
Additionally, supplementary. Equipment or component that is added to the main propulsion unit.
Auxiliary acceleration pump
(AAP) a pump that increases driveability during cold engine operation by providing an extra amount of fuel to the acceleration nozzle to supplement the main acceleration pump.
Auxiliary air bleeds
Used on some idle systems to add air to the idle system downstream from the regular idle air bleed; they act in parallel with idle air bleed.
Auxiliary Air Control Valve
(AAC) A device which allows air to bypass a closed throttle during engine start and warm-up, in order to maintain a higher idle speed. The auxiliary air valve provides extra air into the intake manifold during cold engine starting for a higher idle speed during warm-up.
Auxiliary air intake
  1. An air intake for accessories, cooling, cockpit air, etc.
  2. Additional intake for turbojet engines when running at full power on the ground, usually spring loaded so that it will open only at a predetermined suction value.
Auxiliary air regulator
A rotary gate valve which stabilizes idle speed during engine warmup
Auxiliary air valve
A device which allows air to bypass a closed throttle during engine start and warm-up, in order to maintain a higher idle speed. The auxiliary air valve provides extra air into the intake manifold during cold engine starting for a higher idle speed during warm-up.
Auxiliary brake light
Additional brake lights mounted at eye level in the rear window or on the rear fenders. They are designed to give a following vehicle more notice of your presence and intention of stopping.
Auxiliary contact
Auxiliary control valve
A unit which controls pressure in various portions of the brake system.
Auxiliary drive shaft
A secondary drive shaft which powers the fuel pump, water pump, or distributor.
Auxiliary driving lamp
A light which supplements the headlights such as a fog light or spot light.
Auxiliary driving light
A light which supplements the headlamps such as a fog light or spot light.
Auxiliary drum parking brake
Incorporates an extra parking brake drum inside a rear rotor on some four-wheel drive disc brake systems.
Auxiliary Foundations
Supports for small machinery, such as winches, condensers, heaters, etc.
Auxiliary gearbox
An extra gearbox used in conjunction with the main (manual) gearbox to provide an additional range of speeds.
Auxiliary gauge
The gauge which indicates compressor inlet pressure on older Chrysler Corporation vehicles with an Evaporator Pressure Regulator (EPR) valve; also used to measure evaporator pressure on some Ford vehicles with a Suction Throttling Valve (STV).
Auxiliary lane
The portion of the roadway adjoining the traveled way for parking, turning, or other purposes supplementary to through-traffic movement.
Auxiliary leaf
An extra leaf in a set of leaf springs. Also called helper leaf or helper spring.
Auxiliary lighting
Extra illumination device such as fog lights, spot light, and driving lights which are intended to improve visibility under adverse conditions.
Auxiliary plant
A term used in generating-station practice to cover the condenser pumps, mechanical stokers, feed-water pumps, and other equipment used with the main boiler, turbine, and generator plant.
Auxiliary pole


Auxiliary power
Power from an independent source that functions as required to augment/support various performance criteria established for the prime power source.
Auxiliary power unit
(APU) An independent airborne engine to provide power for ancillary equipment, electrical services, starting, etc. May be a small reciprocating or turbine.
Auxiliary rotor
A small rotor mounted at the tail of a helicopter, usually in a perpendicular plane, which counteracts the torque of the main rotor; used to give directional and rotary control to the aircraft.
Auxiliary shaft
In an overhead cam engine, a separate shaft that drives devices such as the fuel pump, the oil pump, and the distributor.
Auxiliary switch
A small switch operated mechanically from a main switch or circuit breaker; used for operating such auxiliary devices as alarm bells, indicators, etc. Also called auxiliary contact
Auxiliary tanks


Auxiliary transmission
Additional gear box increasing the gear ratio combinations when used with main transmission or multi-speed axles.
Auxiliary venturi
Auxiliary winding
A special winding on a machine or transformer, additional to the main winding.
An apparatus for measuring the magnifying power of an optical system
Available Inventory
The amount of product in the warehouse able to be shipped; does not include product designated as damaged, on hold, or pending shipment.
Available power efficiency
The ratio of electrical power available at the terminals of an electroacoustic transducer to the acoustical power output of the transducer. The latter should conform with the reciprocity principle so that the efficiency in sound reception is equal to that in transmission.
Available power gain
The ratio of the available power output of an amplifier to the input power; equal to power gain only when the output of the device or circuit is correctly matched to the load.
Toyota AvalonClick image for books on
Toyota Avalon

A model of automobile manufactured by Toyota

Abbreviation for automatic volume control.
Abbreviation for Advanced Vehicle Control Systems
Chevrolet Aveo BooksClick image for books on
Chevrolet Aveo

A model of automobile manufactured by the Chevrolet division of General Motors from 2004-08. Also includes the Aveo 5.

  1. A calculation in which the mean value or rate is determined. The average speed is determined by dividing the distance by the time (e.g., 273 kilometres divided by 3 hours = 91 kph). Average fuel consumption is determined as a ratio of fuel and distance. In the metric system, this is determined by multiplying the number of litres by 100 and dividing the result by the number of kilometres (e.g., 31.38 litres times 100 divided by 273 kilometres = 11.49 litres / 100 km). In the Imperial system divide the number of miles by the amount of fuel in gallons (e.g., 173 miles divided by 6.9 gallons = 25 mpg).
  2. Loss or damage of marine property, less than total compensation payment in proportion to amount insured.
Average current
The current obtained by adding together the products of currents flowing in a circuit and the times for which they flow and dividing by the total time considered. For direct current the average value is constant; for true alternating current, the average value is zero.
Average Daily Traffic
(ADT) The total traffic volume during a given period divided by the number of days in that period.
Average distance traveled
A ratio of the distance traveled over a period of time. For instance during the month of June I traveled 987 miles. My average for the month is (987 divided by 30) 32.9 miles per day.
Average fuel consumption
A ratio of the distance driven over a set period of time divided by the amount of fuel consumed. For example, during the year the car drove 12,000 miles and consumed 500 gallons yielding an average of (12,000/500) 24 miles per gallon. The same information according to the metric system would consider how many litres consumed for each 100 kilometre traveled. 12000 miles is equal to 19,312 kilometres and 500 U.S. gallons is equal to 1894 litres. Thus the metric fuel consumption is 1894 divided by 19312 divided by 100 which results in 9.8 l/100 km.
Average Fuel Economy
Average haul distance
The distance between the center of gravity of a cutting and that of the embankment formed from material excavated from the cutting.
Average power output
In an amplitude-modulated transmission, the radio-frequency power delivered by a transmitter, averaged over one cycle or other specified interval of the modulating signal.
Average weekly earnings
Gross taxable payrolls divided by the number of employees.
Abbreviation for aviation gasoline.

Abbreviation for Automatic Vehicle Identification — a system combining an on-board transponder with roadside receivers to automate identification of vehicles. Uses include electronic toll collection and stolen vehicle detection.


Aviation bi-phase shift keying
A digital modulation scheme in which a 1 is represented by a +90° phase transition and a 0 by a -90° transition of the carrier
Aviation fuel
A high octane fuel used primarily in aircraft but also used in racing vehicles to improve performance. Generally liquid hydrocarbons, because of high heat of combustion per unit of fuel mass (specific energy) and volume (energy density), ease of combustion, moderate volatility and viscosity, and good thermal stability and capacity. Liquid hydrogen and pentaborane (B5H9) have also been used experimentally.

Aviation gasoline

  1. Blends of liquid hydrocarbons, almost all petroleum products boiling between 32°C and 220°C, with anti-knock rating from 80 octane number to 145 performance number. Only small quantities are now used.
  2. A complex mixture of relatively volatile hydrocarbons with or without small quantities of additives, blended to form a fuel suitable for use in aviation reciprocating engines. Fuel specifications are provided in ASTM Specification D 910 and Military Specification MIL-G-5572. Note Data on blending components are not counted in data on finished aviation gasoline.
Aviation gasoline blending components
Naphthas that will be used for blending or compounding into finished aviation gasoline (e.g., straight run gasoline, alkylate, reformate, benzene, toluene, and xylene). Excludes oxygenates (alcohols, ethers), butane, and pentanes plus. Oxygenates are reported as other hydrocarbons, hydrogen, and oxygenates.
Aviation kerosine
For gas turbine engines, fuel which typically boils over the range 144°C – 252°C. Variants include Jet A-1 (AVTUR), the international jet fuel; Jet B (AVTAG), a blend of naphtha with kerosine now being phased out except for use in cold climates; AVCAT, a naval jet fuel with high flash-point for safety in enclosed spaces in ships; AVPIN, an aviation isopropyl nitrate; and AVGARD, trade name for an additive with anti-misting properties.

Aviation spirit
(avgas) A motor fuel with a low initial boiling point and complying with a certain specification, for use in aircraft. Ranges from 73 to 120/130 octane rating.

Female aviator
The collective word for a spacecraft or aircraft’s subsystem elements which involve electronic principles. A contraction of aviation electronics.


Abbreviation for Automated Vehicle Location — a class of technologies designed to locate vehicles for fleet management purposes and for stolen vehicle recovery. Infrastructure can be land-based radio towers or satellites.


Avoidance system
Abbreviation for Analog Volt / Ohm Meter
Abbreviation for aviation isopropyl nitrate
Abbreviation for aviation petrol, oil, and lubricant
Abbreviation for aviation wide-cut turbine fuel.
Abbreviation for aviation turbine fuel.

Abbreviation for airborne warning and control system
Abbreviation for automatic white balance
Abbreviation for all-wheel drive.
Abbreviation for American wire gauge system
A pointed or flat tool used to probe nail holes and injuries as well as for installing a repair plug.
A canvas roof which is stretched out from a parked trailer or camper to give protection from the sun and rain.
Awning deck
A superstructure deck, as the name implies. In its simplest form, it is the top deck of a two-deck ship, and places the ship in a certain category for scantling and freeboard.
Abbreviation for Automatic 4-Speed Transmission
Trade name for a range of digital switches manufactured by the Swedish company I. M. Ericsson Telefonaktiebolaget.
Plural of axis. When describing points on the body of a vehicle, they can be named from three parameters: its length (longitudinal), height (vertical), and width (cross-car). These three axes or dimensions are labeled X-Y-Z.

Axial compressor
  1. A compressor characterized by the unusual piston arrangement. The pistons are arranged horizontally around and parallel to the crankshaft axis or centerline.
  2. A multistage, high-efficiency compressor comprising alternate rows of moving and fixed blades attached to a rotor and its casing respectively.
Axial cooling fins
Brake drum cooling fins perpendicular to the centerline of the axle.
Axial engine
Turbine engine with an axial-flow compressor.
Axial-flow compressor
A compressor in which alternate rows of radially-mounted rotating and fixed airfoil blades pass the air through an annular passage of decreasing area in an axial direction.
Axial-flow turbine
Characteristic aero-engine turbine, usually of 1-3 rotating stages, in which the gas flow is substantially axial
Axial pitch
The distance from any point on one thread or helix to the corresponding point on the next thread or helix measured along the axis of the screw or helix.
Axial ratio
Ratio of major to minor axis of polarization ellipse for e.g., a wave propagated in waveguide, polarized light. Also called ellipticity
Axial response
The response of a microphone or loudspeaker, measured with the sound-measuring device on the axis of the appearance being tested.
Axial runout
Variation from the plane normal to its axis of a rotating part. Its wobble, rather than its eccentricity. Compare radial runout
Valve in which the electron stream to the anode is controlled by the magnetic field of the heating current
  1. The centerline, whether real or imaginary, around which a thing rotates.
  2. One of the three axes of an aircraft, which are the straight lines through the center of gravity about which change of attitude occurs longitudinal or drag axis in the plane of symmetry (roll); normal or lift axis vertically in the plane of symmetry (yaw); and the lateral or pitch axis transversely (pitch).
  3. Of a lens, the line of symmetry of the optical system; the line along which there is no refraction.
Axis inclination
Axis of a weld
An imaginary line along the center of gravity of the weld metal and perpendicular to a cross section of the weld metal.


An axle is a shaft on which the wheels revolve. A full-floating axle is used to drive the rear wheels. It does not hold them on nor support them. A semi-floating or one-quarter floating axle is used to drive the wheels, hold them on, and support them. A three-quarter floating axle is used to drive the rear wheels as well as hold them on, but it does not support them. A live axle holds the wheels and transmits power to the wheels. A dead axle or beam axle merely holds the wheels, but does not transmit power to the wheels.


Axle and steering
Axle articulation
The degree to which an axle can move up and down. Off-road vehicles need a great deal of axle articulation to allow for extremely uneven terrain, such as rocks or gullies.
Box-shaped housing containing the axle bearings and lubricant. Constrained laterally on guides and supports the weight of vehicle through springs.
Axle casing
A British term indicating a tubular housing which encloses the differential and half-shafts along with their bearings. The US term is axle housing.
Axle center differential
Axle connection
Axle crossmember
Axle designation
A numeric expression such as ‘4×2,’ ‘6×4,’ which describes the total number of wheels followed by the number of driven wheels. Thus ‘4×2’ is a vehicle with four wheels on two axles, but only two wheels (on the one axle) drive the vehicle. In contrast, a ‘4×4’ has four wheels on two axles and both sets of axles drive the vehicle.
Axle differential
Axle drive
The ring gear and pinion inside a differential housing.

Axle end gear
Axle end gears
The two gears, one per axle, that are splined to the inner ends of the drive axles. They mesh with and are driven by the spider gears.
Axle flange

Axle flangeAxle flange

A disc to which a road wheel is attached at the end of an axleshaft.

Axle housing
An American term indicating a tubular housing which encloses the differential and half-shafts along with their bearings. The British term is axle casing.

Axle Kingpin
A pin around which a steering axle’s wheels pivot
Axle load
Axle parallelism
Axles are determined to be parallel, thus minimizing tire wear, if a measurement between two or more axles is equal at both ends of the axle.
Axle ratio
Axle shaft
  1. The short shaft which connects the differential and the drive shaft on each side of an independent suspension configuration.
  2. The drive shaft or halfshaft of a rigid axle.
Axle stand

StandAxle stand

An adjustable height tripod used to support a vehicle when working underneath it. Although you can raise the car with the jack, use a pair of axle stands for safety. Also called Jack stand or Safety stand

Axle track
Distance between centerlines of tire tread measured across axle.
Axle tramp
A form of wheel hop which is usually found in live rear axle cars. It occurs when sudden torque loads on the suspension cause the driven wheels to shake violently by slightly rotating the wheels and then springing back.
Axle tube
The part of the axle housing which covers the half-shaft or a tubular rigid axle.
Axle weight
The part of the weight of the vehicle which rests on the wheels of the axle.

Axle weight rating
Axle wind up

Axle wind upAxle wind up

The phenomenon in which the torque transmitted to the wheels by the axle which causes the live axle to turn in its own centerline.

Abbreviation for Automatic Overdrive Transaxle
Abbreviation for Automatic Overdrive Transaxle – Electronically Controlled
Measurement of the axes of crystals
Having constant maximum and minimum boiling points.
Azeotropic mixture
Example of azeotropic mixture refrigerant R-502 is mixture consisting of 48.8% refrigerant R-22 and 51.2% R-115. The refrigerants do not combine chemically, yet azeotropic mixture provides refrigeration characteristics desired
  1. The angle between the vertical plane containing a line or celestial body and the plane of the meridian, conventionally measured from north through east in astronomical computations, and from south through west in triangulation and precise traverse work.
  2. The angle, normally 90°, between the direction of motion of the film or tape and the slit or gap in the optical or magnetic head.


Azimuthal power instability
Abnormal neutron behavior which results in uneven nuclear conditions in the reactor
Azimuth angle
Horizontal angle of observed line with reference to true north.
Pontiac AztekClick image for books on
Pontiac Aztek

A model of SUV manufactured by the Pontiac division of General Motors from 2001-07.