Dictionary of Automotive Terms Abbreviations

DICTIONARY OF AUTOMOTIVE TERMS - "Af"

A/F

Across Flats

Abbreviation for "across flats" which is the distance on a nut (for instance) from one flat surface to the opposite flat surface, i.e., this is the size of the wrench needed to install or remove the nut.

Also see
across corners
Abbreviation for "air/fuel."

Also see
air-fuel ratio
Abbreviation for automatic focusing"
Abbreviation for audio-frequency."

AFC

AFM

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

A-frame barricade: A-frame barricade

A traffic marker indicating that the road is not usable.

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

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

Afterburning: In an internal-combustion engine, persistence of the combustion process beyond the period proper to the working cycle, i.e., into the expansion period.

Afterburst: Delayed further collapse of underground workings after a rockburst.

Aftercooler

A device in a diesel engine which removes the relatively warm air which enters the engine.
Chamber in which heat generated during compression of air is removed, allowing cool air to be piped underground.

Aftercooling: 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

Afterglow

The period during which the glow plugs of a diesel engine continue to operate after the engine is started.
The glow of a gaseous medium immediately after the cessation of electric current or downstream of an electric discharge.

Aftermarket: 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).

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

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

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."

AFV: Acronym for Alternative-Fuel Vehicle -- a vehicle powered by a fuel other than gasoline or diesel.