DICTIONARY OF AUTOMOTIVE TERMS - "At"

ATA:

1. Acronym for "American Trucking Association."
2. Acronym for Air Transport Association

ATB:

1. Acronym for all-terrain bike. Sometimes called MTB (mountain bike), but ATB is the preferred acronym.
2. Acronym for aeration test burner

ATC:

1. Acronym for "automatic temperature control."
2. Acronym for air-traffic control
3. Acronym 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 acronym sometimes loosely translated from the German as anti-spin regulation.

ATDC:

See:
after top dead center

ATE:

Acronym for "automatic test equipment."

ATF:

See:
automatic Transmission Fluid
transmission fluid

A thread:

See:
class A thread

Athwartship:

Across the ship, at right angles to the fore-and-aft centerline.

ATIS:

Acronym for "Advance Traveler Information Systems"

ATM:

Acronym for standard atmosphere.
Also see:
atmospheric pressure

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:

The force due to atmosphere per unit area. Atmospheric pressure at sea level is 14.7 psi absolute; it decreases as altitude increases.

Atmospheric-suspended power chamber:

A booster power chamber with atmospheric pressure on both sides of its diaphragm when the brakes are not applied.

ATMS:

Acronym for "Advance Traffic Management Systems"

Atomize:

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.

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.

Atomizer:

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.

ATR:

Acronym for attenuated total reflection

Atramentizing:

A corrosion protection process in which steel is coated with phosphate using a zinc phosphate solution at 90° C (194° F).

ATR tube:

Abbreviation for anti-transmit-receive tube

Attachment:

A fitting or accessory to be used in conjunction with a tool, such as a grinding disc for use with an electric drill.
Also see:
bearing attachment
inner attachment face

Attachment face:

See:
inner attachment face

Attack:

1. Chemical corrosion of metal.
2. To damage something by corrosion.

Also see:
angle of attack
base metal attack
pickling attack

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.

Attenuation:

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.
Also see:
pre-emphasis

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.
Also see:
decibel
neper
propagation constant

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.

Attenuator:

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.

Attitude:

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.
Also see:
heading indicator

Attracted-disk electrometer:

Fundamental instrument in which potential is measured by the attraction between two oppositely charged disks.

Attrition:

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.

Attwood's formula:

A formula for determining the moment of static stability at large angles of heel of a ship. Taking angle of heel θ, and the weight of the ship W, the moment where v is the volume of emerged wedge, hh₁ is the distance between the cg's of emerged and immersed wedges, V is the volume of displacement, B is the center of transverse buoyancy, and G is the center of gravity.

ATV:

Acronym for "All Terrain Vehicle" -- a vehicle designated for all types of terrain

At your back door:

Trucker slang for "behind your truck" as in "You got a Smokey at your back door!."

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