accelerator pump
The part of the carburetor that provides an extra squirt of fuel to enrich the fuel/air mixture, thus enabling the car to respond swiftly to increased acceleration when you suddenly depress the gas pedal.

accessory (or drive) belt
A V-shaped or serpentine belt that's driven by a crankshaft pulley and transmits this drive to various accessories, such as the alternator, air conditioning compressor, fan, power steering pump, and water pump.

Substances that may be added to gasoline, diesel fuel, coolant, or lubricating oil. Popular additives clean gasoline and diesel fuel injectors, add water pump lubricant and corrosion preventers to coolant, and add viscosity extenders to lubricating oil.

air cleaner
A container located on or in the air intake duct to the fuel injection system or carburetor that contains an air filter, which removes dust and dirt from the air before it enters the engine. Also acts as a flame arrester in case of backfire.

air filter
The element in the air cleaner that removes impurities from the air. Some air filters are disposable; others can be cleaned and reused.

air intake duct
The passage through which air travels to the air cleaner and the fuel injection system or carburetor.

air springs
Rubber boots filled with air that are computer controlled to cushion the bumps and vibrations of driving. See also suspension system.

An inflatable bladder that pops out of the dash, steering wheel, or side panels during a collision to protect the vehicle's occupants.

air-cooled engine
An engine that uses air instead of water in its cooling system.

The position of the car wheels relative to the car body. Proper wheel alignment improves handling and performance and reduces tire wear. The front wheels and on some cars. The rear wheels have adjustments to allow the alignment to be changed. See also camber, caster, toe-in, toe-out, steering-axis inclination, turning radius.

allen wrench
An L--shaped rod designed to remove certain screws and fastenings with hexagonal holes in their heads. These wrenches come in sets of assorted sizes and are sometimes called hex wrenches.

all-wheel drive
A vehicle on which the drive train delivers power to all the wheels, rather than just to the front or rear wheels. Full-time all-wheel drive operates constantly and improves handling even on dry pavement. Selectable all-wheel drive is engaged manually at the driver's discretion. See also four- wheel drive, traction control.

alternative fuel
A substance other than gasoline or diesel fuel, such as electricity, natural gas, hydrogen, and fuel cells.

alternative power plants
Hybrids, fuel cells, and other innovations designed to replace the internal combustion engine.

Generates electric current that's stored in the battery and used to start the car and run the electrical equipment. Alternators generate alternating current (AC), which is converted to DC before being fed to the battery. Alternators have replaced generators that produced direct current (DC) but otherwise performed the same functions on older cars.

anti-lock braking system (abs)
Anti- lock braking systems have become increasingly popular because they enhance traction in slippery conditions and allow you to keep steering control of a vehicle, even in a skid. There are two-wheel and four-wheel anti-lock systems.

automatic choke
A choke that automatically adjusts the amount of air entering the carburetor by sensing changes in engine temperature. See also thermostatic coil choke, thermostatic spring choke.

automatic transmission
A transmission that selects gears automatically by means of a hydraulic converter and a system of bands and clutches.

A solid metal shaft to which the wheels of a vehicle are attached.