Directory of automotive words, all automotive words with few diagrams

1. DICTIONARY OF AUTOMOTIVE TERMS
(A - E)
A:
Abbreviation or symbol for absolute temperature, absorption coefficient,
acceleration, adenine, ampere, amplitude, angular acceleration, area,
attenuation coefficient, fine-structure constant, helium nucleus, Helmhotz
free energy, magnetic vector potential, relative atomic mass, a
stereoisomer of a sugar, substitution on a carbon atom next to one common
to two condensed aromatic nuclei, substitution on the carbon atom next to
the hetero-atom in ahetero-cyclic compound, and substitution on the
carbon atom of a chain next to the functional group.
A-2 tire:
A term used for tire sizes 16.00 and larger in nominal cross section. Also
called earthmover or off-the-road tire.
AA:
Abbreviation for "Automobile Association" a term used in Great Britain.
aa:
A term of Hawaiian origin for lava flows with a rough, jagged surface.
AAA:
Acronym for "American Automobile Association" or "Alberta Automobile
Association."
AABM:
Acronym for "Association of American Battery Manufacturers, Inc."
AAE:
Acronym for "Association of Automotive Employers" (Poland).

2. AAIA:
Acronym for "Automotive Aftermarket Industry Association".
AALA:
Acronym for "American Automobile Labelling Act."
aalenian:
The oldest stage of the Middle-Jurassic.
AAM:
Acronym for "Alliance of Automobile Manufacturers".
AAP:
Acronym for "auxiliary acceleration pump".
A arm:
See A-arm
A-arm:
A 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."
Also see
double wishbone
A-arm suspension:
See double wishbone
AAS:

3. Acronym for "air aspirator system".
abacus:
[1] The uppermost part of a column capital or
pilaster, on which the architrave rests.
[2] A bead frame. Used as an arithmetic
calculating aid.
abampere:
A unit of electric current in the CGS electromagnetic system of units. One
abampere equals 10A.
abamurus:
A supporting wall or buttress, built to add strength to another wall.
abandonment:
A voluntary surrender of legal rights or title to a mining claim.
abatjour:
An opening to admit light and generally to deflect it downwards; a
skylight.
abaxial:
Rays of light which do not coincide with the optical axis of a lens system.
ABC:
[1] Acronym for "aerial bunched conductors"
[2] Acronym for "automatic beam control".
ABDC:
Acronym for after bottom dead center. A term used in timing the relation
of the spark and the crankshaft.
Abel flashpoint apparatus:

4. A petroleum-testing apparatus for determining the flash-point.
Abelian group:
A group in which the group operation is commutative. It is important in
the study of rings and vector spaces.
aberration:
[1] An apparent change of position of a heavenly body, due to the speed of
light having a finite ratio to the relative velocity of the source and the
observer.
[2] In an image-forming system, e.g., an optical or electronic lens, failure
to produce a true image, e.g., a point object as a point image. Geometrical
aberrations include spherical aberration, coma, astigmatism, curvature of
the field, and distortion.
See chromatic aberration
abhesive:
A substance which prevents two materials sticking together, e.g., Teflon®
on frying pans.
ability:
See
climbing ability
cold cranking ability
ABL:
Acronym for "atmospheric boundary layer" panel.
ablation:
[1] Any one of the processes by which snow and ice are lost from a glacier,
mainly by melting and evaporation (sublimation).
[2] Removal of surface layers of a meteorite and tektites during flight.
ablative polymer:
A material which degrades controllably in an aggressive environment,
especially on re-entry space-craft. Extreme temperatures are reached on
heat shield, so it is protected with ablation shield made of e.g., silicone
polymer. The same principle is used in intumescent paints for fire

5. resistance.
Abney law:
A rule stating that if a spectral color is desaturated by the addition of white
light, and if its wave length is less than 570 nm, its hue then moves
towards the red end of the spectrum, while if the wavelength is more than
570 nm its hue moves towards the blue.
Abney level:
Hand-held instrument in which angles of steep sights are measured while
simultaneously viewing a spirit-level bubble.
Abney mounting:
A form of mounting for a concave diffraction grating, in which the eye-
piece (or photographic plate holder) is fixed at the center of curvature of
the grating and the slit can move around the circumference of the Rowland
circle, to bring different orders of spectrum into view.
abnormal glow discharge:
A discharge carrying current in excess of that which is required to cover
the cathode completely with visible radiation.
abnormal reflection:
Reflection from the ionosphere of a radio wave whose frequency is greater
than the critical frequency.
aboard:
See lighter aboard ship
aboard ship:
See lighter aboard ship
A-bomb:
See atomic bomb
A bone:

6. Nickname for a Ford Model "A".
abort:
To terminate a vehicle's flight either by failure or deliberate action to
prevent dangerous consequences; if manned, a predetermined sequence of
events is followed to ensure the safety of the crew.
ABPV:
Acronym for "air bypass valve".
abradant:
A substance, usually in powdered form, used for grinding.
Also see
abrasive
abrade:
To scratch or tear away two surfaces in contact by relative motion.
Abram's law:
A rule that the ratio of water to cement for chemical action to impart
strength to concrete is 0.85:1.
abrasion:
[1] Wearing or rubbing away some surface because of friction.
[2] Mechanical wearing away of rocks by rubbing during movement.
abrasion hardness:
Resistance to abrasive wear, under specified conditions, of metal or
mineral.
abrasive:
A hard grit used for sanding or grinding. It is usually in powdered form,
used for the removal of material by scratching and grinding, e.g., silicon
carbide powder (carborundum).
Also see
bonded abrasive

7. coated abrasive
non-woven abrasive
abrasive blast cleaning:
A method for preparing steel for painting whereby abrasive particles, e.g.,
copper slag, are projected under pressure through a nozzle. Very effective
in removing rust and mill scale, leaving an anchor pattern (a pattern of
minute projections) on the substrate affording good paint adhesion.
abrasive cleaner:
A cleanser with some hard grit used to remove the grime and oils from a
surface.
abrasive disc:
A circular plate (often made of plastic with hard grit
embedded into it) used for grinding or sanding.
abrasive paper:
Sandpaper (a paper upon which sand or hard grit has been glued) used for
sanding or grinding.
abrasive wear:
A mechanism of wear due to the presence in one or both surfaces of hard
particles (e.g., carbide in steels), or to hard particles trapped between them.
A/B roll editing:
Video editing using two source players (A and B) enabling dubbing from
both. Necessary if scenes are to be superimposed.
A/B roll printing:
A method of film printing with alternate scenes assembled in two rolls,
each having black spacing equivalent in length to the omitted scene;
double printing from the two allows the inclusion of fade and dissolve
effects and avoids visible splice marks between scenes in 16 mm printing.

8. ABS:
[1] Acronym for "anti-lock brakes. The acronym ABS comes from the
German anti blockier system.
[2] Acronym for "acylonitrile-butadiene-styrene."
Also see
copolymer
abscissa:
For rectilineal axes of coordinates, the distance of a point from the axis of
ordinates measured in a direction parallel to the axis of abscissae, which is
usually horizontal. The sign convention is that measurements to the right
from the axis of ordinates are positive, measurements to the left negative.
absolute:
A conic (a quadric in three dimensions) formed by the assemblage of the
points at infinity on a line (in general two points). Its form determines the
metrical properties of the geometrical system being operated. Thus in
Euclidean geometry, the absolute is the degenerate conic comprising the
line at infinity taken twice, while in non-Euclidean geometry, the absolute
is either a real conic (hyperbolic geometry) or an imaginary conic (elliptic
geometry).
Also see
manifold absolute pressure sensor
POA suction throttling valve
absolute address:
A computer code designation of a specific memory location as determined
by the hardware.
absolute age:
The geological age of a fossil, mineral, rock or event, generally given in
years.
absolute ampere:
The standard MKS unit of electric current; replaced the international
ampere in 1948.

9. absolute ceiling:
The height at which the rate of climb of an aircraft, in standard
atmosphere, would be zero; the maximum height attainable under standard
conditions.
absolute electrometer:
A high-grade attracted-disk electrometer in which an absolute
measurement of potential can be made by weighing the attraction between
two charged disks against gravity.
absolute filter:
A filter which removes most particulate matter from gases.
absolute humidity:
The mass (actual amount) of water vapor present in a unit of volume of
moist air.
absolute instrument:
An instrument which measures a quantity directly in absolute units,
without the necessity for previous calibration.
absolute permeability:
See permeability
absolute pressure:
Pressure measured from a starting point of zero in perfect vacuum. When
measured by the absolute pressure scale, atmospheric pressure is 14.7 psi
or 29.92 inches of mercury (in-Hg).
Also see
manifold absolute pressure sensor
absolute pressure sensor:
See manifold absolute pressure sensor
barometric absolute pressure sensor
absolute reaction rate:
The reaction rate determined from statistical thermodynamics; uses the
assumption of the theory of absolute reaction rates that the rate of a

10. chemical reaction is governed by the rate of crossing an energy barrier or
of forming an activated complex.
absolute temperature:
Temperature measured with respect to absolute zero, i.e., the zero of the
kelvin thermodynamic scale of temperature, a scale which cannot take
negative values.
absolute temperature scale:
Also called the absolute scale temperature as measured on a scale in
which the hypothetical lowest limit of physical temperature is assigned the
value zero. The Kelvin scale is an example of the absolute temperature
scale.
absolute units:
Units derived directly from the fundamental units of a system and not
based on arbitrary numerical definitions. The differences between absolute
and international units were small; both are now superseded by the
definitions of SI units.
absolute wavemeter:
A wavemeter in which the frequency of the injected radio-frequency signal
is by calculation of physical properties (circuit elements or dimensions) of
a resonant circuit line or cavity.
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, minus 459.67°F
(-273.15°C).
absorbance:
[1] The logarithm of the ratio of the intensity of light incident on a sample
to that transmitted by it. It is usually directly proportional to the
concentration of the absorbing substance in a solution.

11. [2] The capacity of materials such as textile fibers and paper to absorb
liquids.
absorbed dose:
Quantity of energy imparted by ionizing radiation to a unit mass of
biological tissue. Unit is the gray.
absorbent:
Substance with the ability to take up or absorb another substance.
absorber:
Any material which converts energy of radiation or particles into another
form, generally heat. Energy transmitted is not absorbed. Scattered energy
is often classed with absorbed energy.
Also see
air shock absorber
arc absorber
adjustable shock
absorbers
damper
direct-acting shock
absorber
double-tube shock
absorber
friction shock
absorber
gas shock absorber
impact absorber
lever-type shock
absorber
monotube shock
absorber
self-levelling shock
absorber
shock absorber
single-tube shock
absorber.
telescopic shock
absorber
UV absorber
absorber rod:
See control rod
absorber tower:
See shock absorber tower
absorbing:
See energy absorbing steering column
energy absorbing bumper
absorbing bumper:
See energy absorbing bumper
absorbing material:
Any medium used for absorbing energy from radiation of any type.

12. absorbing steering:
See energy absorbing steering column
absorbing steering column:
See energy absorbing steering column
absorptance:
A measure of the ability of a body to absorb radiation; the ratio of the
radiant flux absorbed by the body to that incident on the body.
absorption:
The use of reagents to remove unwanted antibodies or antigens from a
mixture.
Also see
acoustic absorption
air absorption
atmospheric absorption
sound absorption
absorption band:
A dark gap in the continuous spectrum of white light transmitted by a
substance which exhibits selective absorption.
absorption capacitor:
A capacitor connected across a spark gap to damp 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.
[3] The reduction of amplitude, for a beam of radiation or other wave
system incident on a discontinuity in the medium through which it is
propagated, or in the path along which it is transmitted.
[4] In a medium, the natural logarithm of the ratio of incident and
emergent energy or amplitude for a beam of radiation passing through unit
thickness of a medium.
Also see
acoustic absorption coefficient

13. absorption discontinuity:
See absorption edge
absorption dynamometer:
A dynamometer which absorbs and dissipates the power which it
measures, e.g., the ordinary rope brake and the Froude hydraulic brake.
absorption edge:
The wavelength at which there is an abrupt discontinuity in the intensity of
an absorption spectrum for electromagnetic waves, giving the appearance
of a sharp edge in its photograph. The transition is due to one particular
energy-dissipating process.
absorption factor:
See acoustic absorption factor
absorption hygrometer:
An instrument by which the quantity of water vapor in air may be
measured.
absorption inductor:
See interphase transformer
absorption lines:
Dark lines in a continuous spectrum caused by absorption by a gaseous
element. The positions (i.e., wavelengths) of the dark absorption lines are
identical to those of the bright lines given by the same element in
emission.
absorption nebula:
See dark nebula
absorption plant:
Plant where oils are removed from natural gas by absorption in suitable
oil.
absorption refrigerator:

14. [1] A plant in which ammonia is continuously evaporated from an aqueous
solution under pressure, condensed, allowed to evaporate, and then
reabsorbed.
[2] A refrigerator which creates low temperatures by using the cooling
effect formed when a refrigerant is absorbed by chemical substance.
absorption spectrum:
The system of absorption bands or lines seen when a selectively absorbing
substance is placed between a source of white light and a spectroscope.
absorption wavemeter:
A wavemeter which depends on a resonance absorption in a tuned circuit,
constructed with very stable inductance and capacitance.
absorptive power:
See absorptance
absorptivity:
See absorptance
ABS override button:
A button or switch which disengages the automatic anti-lock braking
system so that the driver can operate the brakes himself.
ABS relay valve:
An electrically controlled valve which modulates the air pressure in the
ABS.
abundance:
See relative abundance
frequency
abundance ratio:
For a naturally occurring element, the proportion or percentage of one
isotope to the total.
abundant number:

15. A natural number for which the sum of the proper factors is greater than
the number itself, e.g., 18 is abundant since 1+2+3+6+9>18. Compare
deficient number and perfect number.
abut:
The action of two gear teeth making contact.
abutment:
[1] A part which stops the motion of another part from proceeding any
farther.
[2] A cement raised shoulder secured to the side of the road to prevent a
vehicle from going over the edge.
[3] The contact made between opposing teeth of two gears.
abutment load:
In stopping or other deep-level excavation, weight transferred to the
adjacent solid rock by unsupported roof.
abutting edge:
The side or edge of a panel which joins another panel.
abutting joint:
a timber joint whose plane is at right angles to the fibers, the fibers of both
joining pieces being in the same straight line.
ABV:
Acronym for "air bypass valve".
abyssal:
term describing the ocean floor environment between ca4000 and 6000 m.
abyssal deposits:
Pelagic marine sediments, accumulating in depths of more than 2000 m
including, with increasing depth, calcareous oozes, siliceous oozes and red
clay (500 m).

16. abyssal plain:
a flat region of the deep ocean floor with a slope of less than 1:1000.
abyssopelagic:
relating to the open waters of the abyssal zone.
A/C:
[1] An abbreviation for air conditioning or air conditioner.
[2] An abbreviation for "across corners" which indicates the distance on a
nut (for instance) from one corner to the opposite corner rather than the
distance from one flat surface (A/F) to the opposite (which would be the
size of wrench needed to install or remove the nut). The purpose of the
A/C dimension is to know how large a hole might be needed to insert a
recessed nut.
AC:
[1] A vehicle brand of which the 1925-48 models are classic cars.
[2] Acronym for "alternating current."
[3] Acronym for "air conditioning" or "air conditioner."
[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.
AC-3:
Trade name for the digital audio coding used in 35 mm motion picture film
to provide six-channel surround sound. It uses data blocks recorded
optically between the perforations, leaving room for a conventional
soundtrack. It is also suitable for multi-channel TV audio, as well as video
software and home cinema.
AC Ace:
A vehicle brand of which the 1954-61 Ace models are
milestone cars.

17. AC Aceca:
(pronounced ah-SEEK-uh) A vehicle
brand of which the 1955-61 Aceca
models are milestone cars.
acanthite:
An ore of silver, Ag2S, crystallizing in the monoclinic system.
ACAP:
Acronym for "Associação do comércio automovóvel de Portugal".
ac balancer:
An arrangement of transformers or reactors used to equalize the voltages
between the wires of a multiple-wire system. Also called static balancer.
ac bias:
A high-frequency signal applied to a magnetic tape recording head along
with the signal to be recorded. This stabilizes magnetic saturation and
improves frequency response, at the same time reducing noise and
distortion. The bias signal frequency has to be many times the highest
recording frequency.
AC Buckland:
A vehicle brand of which the 1949
Buckland Open Tourer is a milestone
car.
ac-boundary layer:
See stokes layer
acc:

18. Abbreviation for "accessories."
ACC:
[1] Acronym 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.
ACCC:
Acronym for "air conditioner clutch compressor" signal.
accelerate:
[1] To increase the speed of a vehicle. Opposite of decelerate.
[2] To accelerate an adhesive is to speed up a chemical reaction or a curing
process. For example, you can speed up the drying time of an adhesive or
sealer by increasing the temperature. Also, by adding a chemical curing
agent, or accelerator, to a base compound.
accelerated aging test:
A stability test for cables using twice normal working voltage. It is
claimed this give quick results that correlate with service records.
accelerated fatigue test:
Test which applies a cyclic loading schedule, which can be of varying
frequency and/or amplitude, to a machine or component simulating its
loading in service, but at a higher rate, to determine its safe fatigue life
before it is reached in service.
accelerate-stop distance:
The total distance, under specified conditions, in which an aircraft can be
brought to rest after accelerating to critical speed for an engine failure at
take-off.
accelerating chain:
The section of an electron beam tube or system, e.g., cathode-ray tube or
electron microscope, in which electrons are accelerated by voltages on
accelerating electrodes. Also used in particle accelerators.

19. accelerating electrode:
An electrode in a thermionic valve or cathode-ray tube maintained at a
high positive potential with respect to the electron source. It accelerates
electrons in their flight to the anode but does not collect a high proportion
of them.
accelerating machine:
See accelerator
accelerating potential:
The potential applied to an electrode to accelerate electrons from a
cathode.
accelerating-well ports:
These ports prevent momentary leanness during the period that occurs
between the opening of the air valve and the actual discharge of fuel from
the secondary nozzles.
acceleration:
The rate of change of velocity or speed. Velocity is steady and is measured
in distance per time (e.g., feet per second, miles per hour, kilometers per
hour). Acceleration keeps increasing and is measured in velocity per time
(e.g., feet (or meters) per second per second or feet (or meters) per second
squared). It is a vector quantity and has both magnitude and direction.
Also see
angular acceleration
lateral acceleration
sluggish acceleration
yaw acceleration
acceleration due to gravity:
(g) Acceleration with which a body would fall freely under the action of
gravity in a vacuum. This varies according to the distance from the Earth's
center, but the internationally adopted value is 9.80665ms-2
.
Also see
Helmert's formula
acceleration enrichment:

20. The action of increasing the fuel/air mixture during acceleration in order to
improve the vehicle's speed and its smooth response.
acceleration error:
The error in an airborne magnetic compass due to maneuvering; caused by
the vertical component of the Earth's magnetic field when the center of
gravity of the magnetic element is displaced from normal.
acceleration pump:
See auxiliary acceleration pump
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. Man can withstand transverse accelerations
better than longitudinal ones, which have a profound effect on the
cardiovascular system. The degree of tolerance also depends on the
magnitude and duration of the acceleration.
acceleration tolerance:
The maximum acceleration force that a person can withstand before
"blacking out" or otherwise losing control.
accelerator:
[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.
[2] A device, similar to a
catapult, but generally

21. mounted below deck level, for
assisting the acceleration of
aircraft flying off aircraft
carriers. Land versions have
been tried experimentally.
[3] 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.
[4] A substance which
increases the efficient action
of an enzyme
[5] Any substance increasing
the speed of the vulcanization
process of rubber. The
principal types are aldehyde
derivatives of Schiff's bases:
butyraladehyde-butylidene-
aniline, di-orthotolyl-
guanidine, diphenyl-
guanidine, benzthiazyl
disulphide, tetramethyl-
thiuran disulphide and zinc
dimethyl-dithiocarbamate.
[6] A special circuit board
which is placed within a
computer to speed up some
aspect of its operation.
[7] Machine used to
accelerate charged particles to
very high energies such as
betatron, cyclotron, linear

22. accelerator, synchrocyclotron,
and synchrotron.
[8] A chemical used to
increase the rate of
development, e.g., sodium
carbonate or borax
[9] Any muscle or nerve
which increases rate of action.
Also see
depress the accelerator
ease up on the accelerator
step on the accelerator
take foot off the accelerator
accelerator board:
A circuit board plugged into a computer motherboard to increase the
operating speed of a computer.
accelerator interlock:
A connection between the gas pedal and the automatic transmission.
accelerator pedal:
The accelerator, gas pedal, or throttle pedal.
accelerator 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 depressing the pedal.
accelerometer:
[1] A transducer used to provide a signal proportional to the rate of
acceleration of a vibrating or other body, usually employing the
piezoelectric principle.
[2] An instrument which measures the amount of acceleration in a specific
direction.
Also see
impact accelerometer
vertical-gust recorder

23. 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.
acceptance angle:
The solid angle within which all incident light reaches the photocathode of
a phototube.
acceptance test:
An examination of a part or its assembly to determine if it meets a
prescribed standard.
acceptor:
[1] The reactant in an induced reaction whose rate of reaction with a third
substance is increased by the presence of the inductor.
[2] The atom which accepts electrons in a co-ordinate bond.
[3] Impurity atoms introduced in small quantities into a crystaline
semiconductor and having a lower valency than the semiconductor, from
which they attract electrons. In this way holes are produced, which
effectively become positive charge carriers; the phenomenon is known as
p-type conductivity.
Also see
donor
impurity
acceptor level:
See energy levels
access:
A way of reaching something that is usually hidden or covered.
Also see
access panel
Access Cab:
A type of pickup truck (by Toyota) which as a second row of seating; but
unlike a crew cab (which has four full size doors) it has a "half-door" that
can be opened only after the main door is opened. The seating is usually a

24. little more cramped than in a crew cab. Also called club Cab, extended
Cab, king Cab, xtracab, supercab, or cab Plus
access charge:
A financial charge for access to a computer or telecommunications
network.
access eye:
A screwed plug provided in soil, waste and drain pipes at bends and
junctions, to clear a stoppage.
access hole:
An opening through which you can reach something. It is usually covered
with a panel.
accessible hermetic:
Assembly of motor and compressor inside a single bolted housing unit.
accessories:
Items and packages of equipment which are beyond the standard
equipment supplied in a new vehicle.
accessory:
See accessories
accessory gearbox:
A gearbox, driven remotely from an aero-engine, on which aircraft
accessories, e.g., hydraulic pump and electrical generator, are mounted.
accessory minerals:
Minerals which occur in small, often minute, amounts in igneous rocks;
their presence or absence makes no difference to classification and
nomenclature.
accessory package:

25. A set of features or appointments which may be ordered at extra cost on a
new vehicle.
accessory plates:
Quartz-wedge, gypsum plate and mica plate. Used with petrological
microscope to help determine the optical character of a mineral as an aid in
its examination.
accessory shoe:
A mounting bracket on the body of a camera to which separate units such
as a flash or range-finder may be fitted.
access panel:
The cover which conceals the engine on a mid-engine vehicle. Also called
engine cover.
Also see
hood
access time:
The time interval between the instant at which data are called from
memory and the instant at which the data can be used. It can vary from
microseconds with fast store to minutes with magnetic tape.
access to store:
Entry or extraction of data from a memory location. The method and speed
of access depends on the type of memory.
Also see
backing store
fast store
random access memory
serial access memory
accident:
See car accident
accident damage:
The destruction caused to a vehicle's bodywork when it is involved in an
accident.

26. ac circuit:
A circuit which passes alternating current as opposed to direct current,
e.g., it may have a capacitor in series, which blocks direct current.
ac commutator motor:
An ac motor which embodies a commutator as an essential part of its
construction.
Also see
ac series motor
compensated induction motor
repulsion motor
Schrage motor
Accord:
A model of automobile manufactured by
Honda
.
Click for books on Honda
Accord
accordion:
The method of folding a leaflet or insert so that it opens out and closes in a
zig-zag fashion. The British term is concertina fold.
accretion:
[1] The process in which a celestial body, particularly an evolved star in a
binary system, is enlarged by the accumulation of extraneous matter
falling in under gravity
[2] The process of enlargement of a continent by the tectonic coalescences
of exotic crustal fragments.
accretion disc:
The disc of material at the edge of a black hole, which has been attracted
from a neighboring star and which emits X-rays as its inner edge
disappears into the gravitational field of the hole.

27. accumulation point:
A mathematical term which says that of a set of points, one such that every
neighborhood of it includes at least one point of the set.
accumulator:
[1] A storage battery for an electric car.
[2] A pressurized container for an automatic leveling suspension system.
[3] 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.
[4] A vessel that stores hydraulic fluid under pressure.
[5] A storage tank which receives liquid refrigerant from evaporator and
prevents it from flowing into the suction line before vaporizing.
[6] 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.
[7] A special storage register associated with the arithmetic logic unit, used
for holding the results of a computation or data transfer
Also see
accumulator piston
fuel accumulator
hydraulic accumulator
pressure accumulator
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

28. evaporator outlet. It stores the excess refrigerant and removes the moisture
from the refrigerant (thus the name "drier").
Also see
receiver 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:
See battery traction
accumulator valve:
A device which operates the hydraulic accumulator piston in an automatic
transmission.
accumulator vehicle:
See battery traction
AC current sine wave:
Wave form of single frequency alternating current; wave whose
displacement is sine of angle proportional to time or distance.
Ace:
An American trucker's colloquial term for someone with a class "A"
licence.
Also see
AC Ace

29. ACEA:
Acronym for "Association des Constructeurs européens dAutomobiles"
(i.e., European Automakers Association).
Aceca:
See AC Aceca
acet-:
Prefix from the Latin acetum meaning vinegar.
acetate film:
Film with its photographic emulsion coated on a base of cellulose
triacetate, of low flammability.
aceto-:
Prefix from the Latin acetum meaning vinegar.
acetylene:
[1] Ethyne HC≡CH. A colorless, poisonous gas, owing its disagreeable
odor to impurities; soluble in ethanol, in acetone (25 times its volume at
standard temperature and pressure) and in water. Boiling point -84°C,
relative density 0.91. Prepared by the action of water on calcium carbide
and catalytically from naphtha.
[2] 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.
[3] Also used for illuminating, acetic acid synthesis and for manufacturing
derivatives
Also see
oxygen acetylene cutting
acetylene bottle:
See acetylene cylinder
acetylene cutting:
See oxygen acetylene cutting

30. 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:
acetylene cylinder.
acetyl group:
Ethanoyl group CH3CO-. The radical of acetic acid.
aceval:
Abbreviation for air combat evaluation.

31. 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:
See head ache rack
ache rack:
See head ache rack
achromatic lens:
A lens designed to minimize chromatic aberration. The simplest form
consists of two component lenses, one convergent, the other divergent,
made of glasses having different dispersive powers, the ratio of their focal
lengths being equal to the ratio of the dispersive powers.
achromatic prism:
An optical prism with a minimum of dispersion but a maximum of
deviation.
achromatic sensation:
A visual perception of grey. Represented by the equal energy point on a
chromaticity diagram.
achromatic stimulus:
Stimulus which produces an achromatic sensation.
acid:
Also see
battery acid
chromic acid

32. oxalic acid
acid brittleness:
The brittleness developed in steel in pickling bath, through evolution of
hydrogen.
acid condition in system:
Condition in which refrigerant or oil in system is mixed with fluids that
are acid in nature.
acid cure:
In extraction of uranium from its ores, lowering of gangue carbonates by
puddling with sulphuric acid before leach treatment.
acid deposition:
Acid compounds emitted into the atmosphere which then return to the
surface either in the form in which they were discharged or as new
compounds formed by reaction in the atmosphere. Includes dry deposition,
usually of sulphur and nitrogen oxides near the source, and wet deposition
which follows when acids are washed from the atmosphere by
precipitation (i.e., acid rain and occult deposition.
acid drift:
The process by which ores, pulps, and products become acidic through
pick-up of atmospheric oxygen through standing.
acid dyes:
Dyes which have their color associated with the negative ion or radical.
acid egg:
A pump for sulphuric acid, of simple and durable construction, with few
moving parts. The acid is run into a pressure vessel, usually egg-shaped,
from which it can be forcibly expelled by compressed air.
acid fixer:
Fixing solution (hypo) with the addition of an acid (sodium bisulphite or
potassium metabisulphite) to prevent staining.

33. acidizing:
Improving the flow of oil from a limestone formation by pumping acid
into it.
acid mine water:
Water containing sulphuric acid as a result of the breakdown of the
sulphide minerals in rocks. Acid mine water causes corrosion of mining
equipment, and may contaminate water supplies into which it drains.
acid process:
[1] A steel-making process in which the furnace is lined with a siliceous
refractory, and for which iron low in phosphorous is required, as this
element is not removed.
[2] Any pulp digestion process utilizing an acid regent, e.g., a bisulphite
liquor with some free sulphur dioxide.
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 sulphur and nitrogen from the burning of coal and oil.
acid refractory:
See silica
acid resist foils:
Blocking foils for use in etching metal. The foil is stamped on to paper and
the excess foil blocked on to the metal rule or other object which is then
exposed to an acidic etching fluid such as ferric chloride.
acid rock:

34. An igneous rock with more than 63% quartz.
acid slag:
Furnace slag in which silica and alumina exceed lime and magnesia.
acid smut:
See acid soot
acid soot:
A pollutant, consisting of particles of carbon bound together by water
containing sulphuric acid, formed as a by-product of the incomplete
combustion of carbon-based fuel. Also called acid smut.
acid steel:
Steel made by an acid process.
acid stop:
Weak acid photography processing solution used immediately after the
developer to halt its chemical activity and neutralize it before fixing.
AC Ignition System:
See continuous AC Ignition System
Ackermann:
See Ackermann steering

35. 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.
acknowledgement signal:
A signal transmitted along a circuit from B to A when triggered by a signal
from A to B.
A-class insulation:
Insulating material which will withstand temperatures up to 105°C.
ACL BI-MET:
Acronym for "air cleaner bi-metal sensor".
ACL DV:
Acronym for "air cleaner duct and valve vacuum" motor.

36. ACM:
Abbreviation for Association for Computing Machinery, a US professional
association.
ac magnet:
Electromagnet excited by alternating current having normally a laminated
magnetic circuit.
Also see
shaded pole
acme screw-thread:
A thread having a profile angle of 29° and a flat crest and root, used for
example for lathe lead screw for easy engagement by a split nut.
acmite:
A variety of aegirine; also used for the NaFe+3
Si2 O6 end-member.
ac motor:
An electric motor which operates from a single or polyphase alternating
current supply.
Also see
capacitor motor
induction motor
synchronous motor
acnode:
See double point
acoustic absorption:
Transfer of energy into thermal energy when sound is incident at an
interface.
acoustic absorption coefficient:
The ratio of the acoustic energy absorbed by a surface to that which is
incident on the surface. For an open window this can be 1.00, for painted
plaster 0.02. The value varies with the frequency of the incident sounds,
e.g., for 2 cm glass fiber it is 0.04 at 125 Hz, 0.80 at 4000 Hz. Also called
acoustic absorption factor.

37. acoustic absorption factor:
The ratio of the acoustic energy absorbed by a surface to that which is
incident on the surface. For an open window this can be 1.00, for painted
plaster 0.02. The value varies with the frequency of the incident sounds,
e.g., for 2 cm glass fiber it is 0.04 at 125 Hz, 0.80 at 4000 Hz. Also called
acoustic absorption coefficient.
acoustical inertia:
The quantity M, where ωM is the part of the acoustical reactance which
corresponds to the inductance of an electrical reactance: ω is the pulstance,
given by 2πf is the frequency in hertz. Also called acoustical mass.
acoustical mass:
The quantity M, where ωM is the part of the acoustical reactance which
corresponds to the inductance of an electrical reactance: ω is the pulstance,
given by 2πf is the frequency in hertz. Also called acoustical inertia.
acoustical stiffness:
For an enclosure of volume V, the quantity given by S-pc³/V, where c is
velocity of propagation of sound and p is density. It is assumed that the
dimensions of the enclosure are small compared with the sound
wavelength and that the walls around the volume do not deflect.
acoustic amplifier:
An amplifier of mechanical vibrations.
acoustic branch:
A branch of the dispersion curve (frequency ω against wavenumber q) for
crystal lattice vibrations for which ω is proportional to q for small q. For a
crystal containing n atoms per unit cell, the dispersion curve has 3n
branches of which three are acoustic branches. The branches are
characterized by different patterns of movement of the atoms.
Also see
optic branch
acoustic center:

38. The effective source point of the spherically divergent wave system
observed at distinct points in the radiation field of an acoustic transducer.
acoustic compliance:
The reciprocal of the acoustic stiffness.
acoustic construction:
Building construction which aims at the control of transmission of sound,
or of mechanical vibration giving rise to sound, particularly unwanted
noises. The parts of the structure are separated by air-spaces or acoustic
absorbing material and can be decoupled by the interposing of springs.
acoustic coupler:
A device which enables a digital signal to be transmitted over the
telephone network using an ordinary telephone handset.
acoustic delay line:
A device, magnetostrictive or piezoelectric, e.g., a quartz bar or plate of
suitable geometry, which reflects an injected sound pulse many times
within the body.
acoustic distortion:
Distortion in sound-reproducing systems.
acoustic emission:
Non-destructive testing method of investigating deformation and failure
processes in materials by the signals generated when the elastic waves
released by them are detected at the materials' surfaces.
acoustic feedback:
Instability or oscillation in a second reproduction system caused by the
microphone or pick-up receiving vibrations from the loudspeaker.
acoustic filter:
Filter which uses tubes and resonating boxes in shunt and series as
reactance elements, providing frequency cut-offs in acoustic wave

39. transmission, as in an electric wave filter.
acoustic grating:
A diffraction grating for production of directive sound. Spacings are much
larger than in optical gratings due to the longer wavelength of sound
waves. Both transmission and reflection grating are used.
acoustic impedance:
the complex ratio of sound pressure on surface to sound flux through
surface, having imaginary (reactance) and real (resistance) components,
respectively. Unit is the acoustic ohm.
acoustic interferometer:
Instrument in which measurements are made by study of interference
pattern set up by two sound or ultrasonic waves generated at the same
source.
acoustic lens:
A system of slats or disks to spread or converge sound waves.
acoustic microscope:
Microscope based on acoustic waves (longitudinal compressions and
rarefactions of density) at microwave frequencies the interaction of an
acoustic wave with a material is sensitive to its elastic properties. Images
can be created by modulating a display with the intensity received by a
detector/specimen system scanned synchronously (ultrasonic imaging).
Coupling between electrical signals and acoustic vibrations exploits the
piezoelectric effect.
acoustic model:
A scale model of a room (e.g., concert hall) or structure which is used to
measure qualities important for architectural acoustics and noise control
(e.g., sound distribution). The scale is typically between 1:10 and 1:20. In
order to adjust the wavelength, the frequency has to be increased by a
factor of 10-20.
acoustic ohm:

40. Unit of acoustic resistance, reactance, and impedance, equal to 105
Pasm-3
.
acoustic perspective:
The quality of depth and localization inherent in a pair of ears, which is
destroyed in a single channel for sound reproduction. It is transferable with
two microphones and two telephone ear-receivers with matched channels,
and more adequately realized with three microphones and three radiating
receivers with three matched channels.
acoustic plaster:
Rough or flocculent plaster which has good acoustic absorbing properties
and which can be used for covering walls. Added to the mix is fine
aluminum, which evolves gas on contact with water and so aerates the
mass. These tiny holes lower the acoustic impedance and so reduce the
reflection of incidence sound waves.
acoustic pressure:
See sound pressure
acoustic radiator:
Device to generate and radiate sound. The more common radiators are (1)
vibrating elastic systems (membrane, string, vocal cord) which cause a
fluctuating pressure in the surrounding medium; (2) electrically driven
membranes and plates (loudspeaker, sonar transducer); (3) vortices in
turbulent fluid flow.
acoustic ratio:
The ratio between the directly radiated sound intensity from a source, at
the ear of a listener (or a microphone), and the intensity of the reverberant
sound in the enclosure. The ratio depends on the distance from the source,
the polar distribution of the radiated sound power, and the period of
reverberation of the enclosure.
acoustic reactance:
See acoustic impedance
acoustic resistance:
See acoustic impedance

41. acoustic resonance:
Enhancement of response to an acoustic pressure of a frequency equal or
close to the eigenfrequency of the responding system. When a system is at
resonance, the imaginary part of its impedance is zero. Prominent in
Helmholtz resonators, organ, and other pipes and vibrating strings.
acoustics:
[1] The science of sound waves including production and propagation
properties.
[2] The characteristics of a room which determine the quality of sound
transmission inside.
Also see
architectural acoustics
atmospheric acoustics
acoustic saturation:
The aural effectiveness of a source of sound amid other sounds; it is low
for a violin, but high for a triangle. The relative saturation of instruments
indicates the number required in an auditorium of given acoustic
properties.
acoustic scattering:
Irregular and multi-directional reflection and diffraction of sound waves
produced by multiple reflecting surfaces the dimensions of which are
small compared to the wavelength; or by certain discontinuities in the
medium through which the wave is propagated.
acoustic spectrometer:
An instrument designed to analyze a complex sound signal into its
wavelength components and measure their frequencies and relative
intensities.
Also see
real-time analyzer
acoustic spectrum:
Graph showing frequency distribution of sound energy emitted by source.
acoustic streaming:

42. Generation of constant flows by a strong sound wave. Acoustic streaming
is a non-linear effect. It is responsible for the motion of the light particles
(lycopodium spores) in a Kundt's tube.
Also see
quartz wind
acoustic survey:
Determination of the porosity of a rock by measuring the time required for
a sonic impulse to travel through a given distance.
acoustic suspension:
Sealed-cabinet system of loudspeakers in which the main restoring force
of the diaphragm is provided by the acoustic stiffness of the enclosed air.
acoustic telescope:
An array of microphones. The signals of the microphones are added with
certain phase-delays so as to generate desired directions.
Also see
directional microphone
acoustic tile:
A tile made of soft, sound-absorbing substance.
acousto-optic modulator:
A telecommunication device in which acoustic waves in an optical
medium from a grating used to diffract an optical signal and thus
effectively turn it on or off.
acquisition fee:
A charge for processing a lease and is probably not negotiable. On a
shorter term lease, the acquisition fee can have a large impact on the cost
of the lease.
ACR:
Abbreviation for approach control radar.
acro-:

43. Prefix from Greek akros (ακρος), topmost, farthest, terminal.
Acrobat:
Trade name for a computer application which converts text, line drawings,
and half-tones into a stream of alphanumeric text while retaining the
format of the original. Such a page description file (PDF) is an extension
of the Adobe PostScript language and can be read by any type of
computer.
acronical rising:
The rising of a star at nightfall.
acronical setting:
The setting of a star at nightfall.
acronychal:
British term for "acronical".
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:
(A/F) The distance on a nut (for instance) from one flat surface to the
opposite flat surface, i.e., this is the size of the wrench needed to install or
remove the nut.
Also see
across corners.
acroterium:
A base or mounting on the apex and/or extremities of a pediment, for the
support of an ornamental figure or statuary.

44. ACR tubing:
Tubing used in air conditioners and refrigerators. The ends are sealed to
keep tubing clean and dry.
acrux:
A bright white supergiant star in the constellation Crux. A visual binary
consisting of two spectroscopic binary components. Distance 80 pc. Also
called Alpha Crucis.
acrylate:
A polymer used to strengthen rubber (e.g., ethyl acrylate).
acrylic:
A term relating to a type of paint made by polymerizing acrylonitrile.
acrylic fibers:
Continuous filaments or, more fibers from linear polymers which are
synthesized from several monomers containing at least 85% by weight of
acrylonitrile.
acrylic finish:
A final coating of paint which uses acrylic paint, often where the pigment
and an acrylic paint are mixed together.
Also see
two-pack paint.
acrylic paint:
A type of paint made by polymerizing acrylonitrile.
acrylic resin:
A thermoplastic synthetic polymer made by polymerizing an acrylic
derivative such as acrylonitrile, acrylic acid, ethyl acrylate, and
methacrylate. It is used for adhesives, protective coatings, and paint
finishes.
ACS:

45. [1] Abbreviation for active control system
[2] Abbreviation for attitude control system
[3] Abbreviation for air conditioning system .
ac series motor:
A series motor which operates from an ac supply with laminated field
construction and usually a compensating winding.
AC Shelby Cobra:
A vehicle brand of which the 1962-67 Shelby Cobra models
are milestone cars.
ACT:
[1] Acronym for "air charge temperature."
[2] Acronym for active control technology.
Also see
active control system
act:
See Motor Vehicle Safety Act
acting:
See double-acting
dual-acting
single-acting
actinic radiation:
Ultraviolet waves, which have enhanced biological effect by inducing
chemical change; basis of the science of photochemistry.
actinic rays:
Electromagnetic waves of wavelength that can cause a latent image,
potentially able to be developed, in a photographic emulsion. They include
an extension at each end of the visible spectrum and X-rays.
actino-:

46. Prefix from Greek aktis (ακτις).
actinolite:
A monoclinic calcium magnesium iron member of the amphibole group,
green in color and usually showing an elongated or needle-like habit;
occurs in metamorphic and altered basic igneous rocks.
action:
[1] The performance of a scene to be recorded on camera
[2] The film record of this performance as picture only, separate from the
sound record
[3] The time integral of kinetic energy (E) of a conservative dynamic
system undergoing a change, given by this formula:
Also see
capillary action
caster action
mist action
oscillating action
parallel action locking pliers
reciprocating action
action brakes:
See servo action brakes
action locking:
See parallel action locking pliers
action locking pliers:
See parallel action locking pliers
activate:
To change an adhesive film from a dry or inactive state to a useful, sticky
state.
activated:
See cable activated
activated alumina:

47. Chemical which is a form of aluminum oxide. it is used as a drier or
desiccant.
activated carbon:
[1] A highly porous carbon which is able to absorb gases and fluids. It is
usually found in small pellets so that the surface area is greater than a large
chunk of it. Also it has a number of pores on each pellet to increase the
surface area more. Thus the greater surface area means greater ability to
absorb. Used to clean air. Also called activated charcoal.
[2] Carbon obtained from vegetable matter by carbonization in the absence
of air, preferably in a vacuum. Activated carbon has the property of
absorbing large quantities of gasses. Important for gas masks, adsorption
of solvent vapors, clarifying of liquids, and in medicine.
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 cathode:
Emitter in thermionic devices comprising a filament of basic tungsten
metal, alloyed with thorium, which is brought to the surface by process of
activation, such as heating without electric field.
activated charcoal:
Charcoal treated with acid to increase its adsorptive power
Also see
activated carbon
charcoal
activated charcoal trap:
See activated carbon canister
activated sintering:
Sintering of a compact in the presence of a gaseous reactant. Also called
reaction sintering.

48. activating agent:
See activator
activation:
[1] Alteration of the surface of a metal to a chemically active state.
Compare passivation
[2] Induction of radioactivity in otherwise non-radioactive atoms, e.g., in a
cyclotron or reactor.
activation cross-section:
The effective cross-sectional area of a target nucleus undergoing
bombardment by e.g., neutrons for radioactivation analysis. Measured in
barns.
Also see
cross-section
activator:
[1] A substance which is used to speed up the process of curing a tire.
[2] Surface-active chemical used in a flotation process to increase the
attraction to a specific mineral in an aqueous pulp of collector ions from
the ambient liquid and increase in aerophilic quality. Also called activating
agent.
active array:
An antenna array in which the individual elements are separately excited
by integrated circuit or transistor amplifiers.
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 component:
The component of the vector representing an alternating quantity which is
in phase with some reference vector; e.g., the active component of the
current, commonly called the active current.
Also see

49. active current
active voltage
active volt-amperes
active control:
Modern technique of noise or vibration control using one or more sources
that generate signals with the aim of making the resulting total signal
smaller. Used for example for the control of low-frequency airborne noise
and vibration of machinery.
Also see
antisound
active control system:
(ACS) An advanced automatic flight control system designed to provide
several special features, for example activation of flight control surfaces to
minimize gust loads and bending stresses in the wing by detection and
response to normal accelerations, provision of stability to a naturally
unstable aircraft and implementation of pilot maneuver demands. All these
characteristics improve aircraft behavior and performance, but the active
control system demands extensive integration between aerodynamics,
structure, and electronic system design to achieve these advantages with
reliability and safety.
active current:
The component of a vector representing the ac in a circuit which is in
phase with the voltage of the circuit. The product of this and the voltage
gives power.
active device:
A component capable of controlling voltages or currents, to produce gain
or switching action in a circuit, valves, diodes, and transistors, and
integrated circuits are all classed as active devices or components.
active electrode:
The electrode of an electrical precipitator which is kept at a high potential.
Also called discharge electrode..
active filter:

50. A filter which combines amplification with conventional passive filter
components (capacitance, inductance, resistance) to enhance fixed or
tunable passband or rejection characteristics.
active galaxy:
A galaxy which emits unusually large amounts of radiation from a
compact central source, such as Seyfert galaxy, N galaxy, quasar, or BL
Lac object.
active homing:
A guidance system where the missile contains the transmitter for
illuminating the target and the receiver for the reflected energy.
active lattice:
The regular pattern of arrangement of fissionable and non-fissionable
materials in the core of a lattice reactor.
active lines:
Lines which are effective in establishing a picture.
active material:
In a storage battery, peroxide of lead (brown) in positive plates and
metallic lead (gray) in negative plates upon which sulphuric acid acts.
active materials:
[1] General term for essential materials required for the functioning of a
device, e.g., iron or copper in a relay or machine, electrode materials in a
primary or secondary cell, emitting surface material in a valve, or
photocell, phosphorescent and fluorescent material forming a
phosphorescent and fluorescent material forming a phosphor in a cathode-
ray tube, or that on the signal plate of a TV camera.
[2] Term applied to all types of radioactive isotopes.
active noise control system:
See anti-noise system
active power:

51. The time average over one cycle of the instantaneous input powers at the
points of entry of a polyphase circuit.
Also see
active volt-amperes
active safety:
The opposite of passive safety. Passive safety involves seat belts, airbags,
bumpers, etc. so that in the event of an accident the passengers are
protected. Active safety involves factors which will assist the driver in
avoiding an accident. They include brakes, steering, handling response,
acceleration, etc.
active satellite:
A satellite equipped for sending out probing signals and receiving returned
information. A passive satellite receives information only on the state of
the target.
active sun:
The Sun during periods of intense sunspot activity.
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.
active transducer:
Any transducer in which the applied power controls or modulates locally
supplied power, which becomes the transmitted signal, as in a modulator, a
radio transmitter or a carbon microphone.
active voltage:
The component of a vector representing the voltage which is in phase with
the current in a circuit.

52. active volt-amperes:
The product of the active voltage and the amperes in a circuit, or of the
active current (amperes) and the voltage of the circuit; equal to the power
in watts. Also called active power.
activities:
See Kaizen Activities
activity:
[1] The magnitude of the oscillations of a piezoelectric crystal relative to
the exciting voltage
[2] The rate at which transformations occur in a radionuclide. Unit is the
becquerel
Also see
catalytic activity
low temperature activity
specific activity
activity factor:
See blade activity factor
ac transformer:
an electromagnetic device which alters the voltage and current of an ac
supply in inverse ratio to one another. It has no moving parts and is very
efficient.
ACTS:
Acronym for "air charge temperature sensor".
actual cash value:
(ACV) The amount of money a dealer has invested in the purchase of a
used vehicle and any additional costs to repair the unit in order to get it
ready for resale.
actual throat:
A welding term which describes the distance from the face of a weld to the
root of the weld.

53. actuate:
The action of bringing a part or assembly into operation.
actuating lever:
A triggering device used to bring a part or assembly into operation.
actuating switch:
A triggering device used to bring a part or assembly into operation.
actuation:
See variable valve actuation
actuator:
[1] A Device which controls or operates another device.
[2] 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
Also see
hydraulic actuators
actuator arm:
An arm connecting the diaphragm to the contact breaker platform in an
advance mechanism. Also called diaphragm link..
Acura:
A vehicle brand from the Honda manufacturers
.
Click for books on Acura
acutance:
Objective formulation of the sharpness of a photographic image, expressed
as where .
"N" is the number of increments between "A" and "B", DB-DA is the
average gradient of density curve, and ΔD/Δx is the maximum gradient
curve.

54. ACV:
[1] Acronym for "actual cash value."
[2] Acronym for "air control valve"
[3] Acronym for air cushion vehicle (i.e., hovercraft).
ad:
See classified ad
A-D:
Analogue-to-digital, referring to the conversion of signals.
adamantine:
See lustre
adaptation layer:
See ATM adaptation layer
adapter:
[1] A device used to connect two different types or sizes of electrical
terminals
[2] An arrangement for using types of photographic material in a camera
different from that for which it was designed; e.g., filmpack in a plate
camera, or a smaller plate than normal
[3] A device for the interchange of lenses between different types of
camera
[4] A connector which links two items usually of dissimilar structure or
size. (Also spelled "adaptor")
Also see
bit adapter
bit adapter
caliper mounting bracket
carburetor adapter
engine adapter
increasing adapter
ratchet adapter
reducing adapter
transmission adapter
wheel adapter.

55. adaptive array:
A radar antenna (either a phased array or an active array) whose gain,
directivity and side lobes can be adjusted automatically to optimize the
radar's performance under specific operating conditions.
adaptive control:
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.
adaptive differential pulse code modulation:
A form of differential pulse code modulation in which the basic step size is
varied continually to suit the rate of change of the signal. A further
refinement is to transmit only differences from a continually adjusted
prediction of the signal. These measures greatly reduce the required
bandwidth.
adaptive radiation:
Evolutionary diversification of species from a common ancestral stock,
filling available ecological niches. Also called divergent adaptation.
adaptor carburetor:
A device attached to a gasoline carburetor which permits an internal
combustion engine to run either on gas or liquefied petroleum gas (LP
gas).
adapter plate:
A plate which is placed between two different parts in order to link them.
(Also spelled "adaptor plate")
Also see
transfer plate
Adcock antenna:
A directional antenna consisting of pairs of vertical wires, spaced by one
half wavelength or less, and fed in phase opposition; a figure-of-eight
radiation pattern results, and arrays of Adcock antennas can be used for
direction-finding.

56. ADD:
Acronym for "airstream direction detector" which is used for aircraft stall
protection.
add-drop multiplexer:
Equipment used to add data originating from a particular source or group
of sources to a synchronous digital hierarchy data stream, or conversely to
extract data destined for a particular source or group of sources.
addendum:
[1] The radial distance between the major and pitch cylinders of an
external thread.
[2] The radial distance between the minor and pitch cylinders of an
internal thread the height from the pitch circle to the tip of the tooth on a
gearwheel.
addition agent:
A substance added to the electrolyte in an electro deposition process in
order to improve the character of the deposit formed. The agent does not
take part in the main electrochemical reaction.
additive:
A substance (liquid or powder) which is added to gasoline or oil and is
intended to improve the characteristics of the original product.
Also see
anti-knock additive
fuel additive
oil additive
additive constant:
A survey term used in the computation of distance by tacheometric
methods. It is that length (usually constant and small) which must be
added to the product of staff intercept and multiplying constant to give the
true distance of the object.
Also see
anallatic lens

57. additive printer:
Photographic or motion picture printer or enlarger in which the intensity
and color of the exposing light is controlled by the separate variation of its
red, green, and blue components.
additive process:
Color reproduction in which the picture is presented by the combination
(addition) of red, green, and blue light representing these three
components in the original subject; it is effectively obsolete for general
photography and cinematography but is the basis for color TV display.
ADEFA:
Acronym for "Asociacion de Fabricas de Automotores" (Argentina).
adenine:
(A) One of the five bases in nucleic acids. It pairs with thymine in DNA
and uracil in RNA.
ADF:
Abbreviation for automatic direction finding.
adhara:
Avery bright blue-white giant star in the constellation Canis Major, which
is a visual binary. Distance 200 pc. Also called Epsilon Canis Majoris.
adhere:
To stick or be glued to something.
adherend:
[1] Each surface that is to adhere to another
[2] A material which is bonded by an adhesive.
adhesion:
[1] The force which causes two surfaces to adhere, the sticking together of
surfaces in contact with each other

58. [2] The bonding of materials with adhesives (glues, cements, binders, etc),
in which the intermolecular forces between adhesive and adherend provide
the bonds.
[3] The intimate sticking together of metallic surfaces under compressive
stresses by bonds which form as a function of stress, time, and
temperature. The speed of formation is related to dislocation, and may
occur virtually instantaneously under high shear stresses.
Also see
cold welding
[4] The ability of paint, primer, or glue to stick to the surface to which it is
applied.
[5] The ability of a tire to grip the surface of the road.
[6] Mutual forces between two magnetic bodies linked by magnetic flux,
or between two charged non-conducting bodies which keeps them in
contact
[7] Intermolecular forces which hold matter together, particularly closely
contiguous surfaces of neighboring media, e.g., liquid in contact with a
solid.
Also see
intercoat adhesion failure
limits of adhesion
adhesion failure:
See intercoat adhesion failure
adhesive:
[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.

59. [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
Also see
automotive adhesive
air drying adhesives
impact adhesive
separate-application adhesive
adhesive binding:
Unsewn binding in which the back of the sections are trimmed and
roughened before adhesive is applied to bind the leaves and the cover.
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).
adhesive wear:
Mechanism of wear due to the welding together and subsequent shearing
off of the contact areas between two surfaces sliding over one another.
adhesive weight:
Lead wheel weights which have a sticky backing. It comes in strips and is
applied to a wheel rim. Also called tape weight..
adiabatic:
A property of being able to maintain heat evenly. It does not gain any heat
or lose it.
Also see

60. thermal efficiency
adiabatic change:
A change in the volume and pressure of the contents of an enclosure
without exchange of heat between the enclosure and its surroundings.
adiabatic compression:
Compressing refrigerant gas without removing or adding heat.
adiabatic curve:
The curve obtained by plotting pressure against volume in the adiabatic
equation.
adiabatic demagnetization:
A method of obtaining very low temperatures. A paramagnetic salt is
cooled to 1K by liquid helium. The salt is magnetized under isothermal
conditions and then magnetized under adiabatic conditions. As a result the
temperature falls. Temperatures below 10-2
K can be obtained this way.
adiabatic efficiency:
[1] Of a steam engine or turbine, the ratio of the work done per unit mass
of steam to the available energy represented by adiabatic heat drop.
[2] Of a compressor, 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 equation:
The equation PVγ = constant, expressing the law of variation of pressure
(P) with the volume (V) of a gas during an adiabatic change, γ being the
ratio of the specific heat of the gas at constant pressure to that at constant
volume. The value of γ is approximately 1.4 for air at standard temperature

61. and pressure.
adiabatic expansion:
An adiabatic change in which a substance expands.
adiabatic heating:
Self-heating effect which occurs in extruder or injection molding barrel
from action of rotating screw on polymer melt. Attributed to dissipation of
mechanical shear forces as heat. Important in injection molding of rubbers.
Also called shear heating.
Also see
damping
adiabatic lapse rate:
The rate of decrease of temperature which occurs when a parcel of air rises
adiabatically through the atmosphere.
adiabatic process:
A process which occurs without interchange of heat with surroundings.
adiactinic:
Said of a substance which does not transmit photochemically active
radiation, e.g., safelights for darkroom lamps.
adinole:
An argillaceous rock that has undergone albitization during contact-
metamorphism.
adipo-:
Prefix from Latin adeps "fat".
A-display:
Co-ordinate display on a cathode-ray tube in which a level time base
represents distance and vertical deflections of beam indicate echoes.
adit:

62. A horizontal passage or tunnel into a mine.
adjacent channel:
A channel whose frequency is immediately above or below that of the
required signal.
adjust:
The action of putting something into its proper alignment or position. It
may involve one component (e.g., He adjusted the gasket to fit properly.)
or a series of components (e.g., He adjusted the poor idle -- might mean he
set the ignition timing, adjusted the carburetor screws, changed the choke
setting, cleaned or replaced the spark plugs, etc.)
Also see
tweak
adjustable:
A characteristic of something that can be changed, removed, or give
different properties.
Also see
height adjustable steering column
adjustable bottom bracket:
[1] A component of a bicycle through which the crank fits. It has two
bearing cups on either side. One cup is fixed in place while the other is
removable or adjustable.
[2] 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're easily accessible for cleaning and lubrication.
Also see
bottom bracket
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:

63. 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 that can be adjusted to
control part-throttle mixtures more accurately than a fixed orifice. The
APT detours around the main jet, going directly from the float bowl to the
discharge nozzle feed well.
adjustable-pitch propeller:
See 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:
See adjustable shocks
adjustable shock absorbers:
Shocks with adjustable jounce and rebound characteristics can be stiffened
to compensate for wear or to fine tune a suspension for a particular
application such as rough roads, heavy loads, or racing.
adjustable shocks:
Shock absorbers which can compensate for varying needs of stiffness or
softness. Manual types (especially on motorcycles) require that you
physically make the adjustment from one level to another. Automatic types
are controlled by a computer as it senses particular changes in road

64. condition.
adjustable spanner:
British term for adjustable wrench.
adjustable steering:
See height adjustable steering column
adjustable steering column:
See height 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:
A crescent wrench or pipe wrench. A tool which has a fixed jaw and a
movable jaw which is controlled by a spiral gear. It is used to install or
remove bolts and nuts of various sizes. The wrench itself comes in a
variety of lengths and jaw sizes. A crescent wrench has smooth jaws while
a pipe wrench has serrated jaws. British term is "adjustable spanner."
adjusted:
See factory adjusted
adjuster:
A device for moving something into the correct position or into a different
position such as a seat adjuster.
Also see
automatic adjuster

65. automatic wear adjuster
brake adjuster
horizontal adjuster
jet adjuster
ride-height adjuster
adjuster cam:
A device for moving the shoes on drum brakes closer to the drum itself so
that there is less travel when the brakes are applied.
adjusting:
Also see
electrode adjusting tool
headlight adjusting screw
self-adjusting
adjusting gage:
See adjusting gauge
adjusting gauge:
A tool used to determine the small distance between two parts so that they
can be brought within 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.
Also see
headlight adjusting screw
tappet adjusting screw
valve adjusting screw
adjusting shim:
A thin washer or plate which reduces or increases the clearance between
two components (depending upon where they are placed). While some
valves are adjusted by screws on the rocker arm, others are set by inserting
a shim to make the same adjustment.

66. 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:
See brake adjusting spanner
adjusting tool:
Also see
brake adjusting tool
electrode adjusting tool
adjusting wrench:
See brake adjusting wrench
adjustment:
[1] Changing or modifying the position or alignment of two components.
[2] The distance of travel that a component has.
Also see
fore and aft adjustment
idle mixture adjustment screw
idle speed adjustment
adjustment screw:
See idle mixture adjustment screw
Adler:
The brand name of a vehicle. With required application the 1925-48
models are classic cars.
admiralty brass:
See Tobin bronze
admission:
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.
admittance:

67. Property which permits the flow of current under the action of a potential
difference. The reciprocal of impedance.
a-dos:
See dos-a-dos
Adrastea:
A tiny natural satellite of Jupiter, discovered in 1979 by the Voyager 2
mission. Distance from the planet 129,000 km; diameter 24 km.
A-drier:
See a-dryer
ADS:
Abbreviation for air data system.
A-dryer:
A paint dryer which has the heating elements below the paint drying line.
ADS:
Acronym for "Association of Diesel Specialists".
adsorbent:
Substance with the property to hold molecules of fluids without causing a
chemical or physical change.
adsorption:
The bonding that takes place when a gas or vapor comes into contact with
a solid. The opposite is desorption.
adsorption canister:
See activated carbon canister
adularescence:

68. A milky or bluish sheen shown by moonstone.
advance:
[1] The act of changing the ignition timing so that the spark occurs earlier
in the cycle. The opposite is retard.
[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
Also see
angle of advance
automatic advance
centrifugal advance
electronic spark advance
ignition advance
mechanical advance
ported vacuum advance
spark advance
speed control vacuum advance
vacuum advance
advance capsule:
See vacuum advance
advance curve:
As the speed of the engine increases the ignition advance also increases.
On paper, a pattern is drawn as a curve to represent this relationship.
advanced:
[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 gas-cooled reactor:
(AGR) Carbon-dioxide-cooled, graphite-moderated reactor using slightly
enriched uranium oxide fuel clad in stainless steel, in use in the UK.
advanced intelligent network:
A form of intelligent network, developed in the US from 1987 onward, in
which signalling, software, and accounting procedures are designed to
allow service providers to compete freely for network users' business.

69. advanced mobile phone system:
(AMPS) The American forerunner of the UK total access communications
system. Developed by Bell in 1978, AMPS like TACS, is an analog
cellular system using frequency modulation.
advanced rim taper:
A rim where both bead seats are tapered 5°.
advance mechanism:
See vacuum advance mechanism
advance metal:
Copper-base alloy with 45% nickel.
advance spring:
A small spring which pulls the advance weight back.
See picture in advance weight
advance unit:
See vacuum advance unit
advance weight:
One of two small weights located in a
centrifugal advance assembly.
advance workings:

70. In flat seams, mining in which the whole face is carried forward, no
support pillars being left.
advantage ratio:
Ratio between the radiation dosage received at any point in a nuclear
reactor and that of a reference position.
advection:
The transference of any quantity by horizontal motion of the air.
advection fog:
Fog produced by the advection of warm moist air across cold ground.
advection layer:
The region immediately adjacent to the event horizon where matter is
being continuously pulled into the black hole.
advertising:
A colloquial term for a police car with its emergency lights flashing.
Ae:
The transformation temperature at equilibrium of the phase changes in iron
and steel, subscripts indicating the designated change. Also called A.
AE:
Abbreviation for automatic exposure.
AEA:
Acronym for "Automotive Electric Association" or "Automotive
Electronic Association".
aeolian tone:
A musical note set up by vortex action on a stretched string when it is
placed in a stream of air.
Also see

71. Strouhal number
aeolotropic:
Having physical properties which vary with direction or position.
Also see
anisotropic
AERA:
Acronym for "Automotive Engine Rebuilders Association."
aeration:
A foaming of a liquid because air has been introduced into the fluid. When
it occurs in certain liquids, it decreases the efficiency of the liquid.
aeration test burner:
(ATB) Burner for measuring the combustion characteristics of commercial
gases.
aerial:
British term for antenna.
Also see
retractable aerial
whip aerial
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.
aerial fog:
Fog caused by exposure of portions of the film to air in the processing
machine.
aerial radiometric surveying:
Use of low-flying aircraft to measure gamma-ray intensity due to natural
radioactive emissions or radioactive contamination over large areas.
Scintillators are used with photomultipliers whose signals are fed to
multichannel analyzers to distinguish the energies of the gamma rays

72. received from a wide area; typically 90% of the gamma rays can be
recorded from an area with linear dimensions about five times the aircraft's
height above the ground. Also called airborne radiometric surveying.
aerial ropeway:
An apparatus for the overhead transport of materials in carriers running
along an overhead cable or cables supported on towers.
aerial surveying:
A process of surveying by photographs taken from the air, the photographs
being of two types:
1. those giving a vertical or plan view;
2. those giving an oblique or bird's-eye view.
Also see
vertical aerial photograph
oblique aerial photograph
AERO:
Abbreviation for "Air Education and Recreation Organization" in the UK.
aero-:
Prefix from Greek aer (αερ) indicating "air".
aero-acoustics:
Branch of acoustics that treats sound generation and transmission by fluid
flow.
aerobar:
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.

73. aerobars:
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.
Also see
anaerobic sealer
aerodynamic:
The efficient flow of air around an object.
aerodynamic balance:
[1] A balance, usually but not necessarily in a wind tunnel, designed for
measuring aerodynamic forces or moments.
[2] Means for balancing air loads on flying control surfaces, so that the
pilot need not exert excessive force, particularly as speed increases. The
principle is to use aerodynamic forces, either directly on a portion of the
control surface ahead of the hinge line or indirectly through a small
auxiliary surface with a powerful moment arm, to counterbalance the main
airloads. An example of the first is the horn balance, and of the second the
balance tab.
aerodynamic braking:
Use of a planet's atmosphere to reduce the speed of space vehicles.
aerodynamic center:
The point about which the pitching moment coefficient is constant for a
range of airfoil incidence.
aerodynamic coefficient:
A non-dimensional measure of aerodynamic force, pressure, or moment
that expresses the characteristics of a particular shape at a given incidence
to the airflow. Typically the lift coefficient is given by CL=L/½ρV²S, where
L is the lift, ρ is the air density, V is the air speed, and S is a typical area of

74. the body (e.g., wing area). Similarly for drag coefficient.
aerodynamic damping:
The suppression of oscillations by the inherent stability of a aircraft or of
its control surfaces.
aerodynamic drag:
The resistance of the air to forward movement, sometimes called "air
resistance." This is a factor of the shape of the vehicle (drag coefficient
and frontal area), the objects which stick out (i.e., mirrors, mufflers,
bumpers), the amount of turbulence at the rear of the vehicle, the nature of
the vehicle's skin surface, and the amount of air going through the vehicle
for cooling and ventilation. The faster you go, the greater the air friction
(air friction = velocity x velocity). The faster you go, the greater the
amount of power needed to overcome this drag (power = velocity x
velocity x velocity).
aerodynamic heating:
The heating of a vehicle passing through the atmosphere, caused by
friction and compression of air (or other gas).
aerodynamics:
The study of the flow of air as it passes over and around a moving object
as well as the forces which the air makes on the object. An airplane, for
instance, needs positive lift to get it airborne and negative lift to help it
land. Thus the shape of a land vehicle (car, bicycle, etc.) either promotes
positive or negative lift. Race cars may use spoilers and wings (air foils) to
control lift. In vehicle design, the airflow is monitored in a wind tunnel. As
well, aerodynamics also studies the most efficient shapes for increased
speed and fuel economy.
aerodynamic sound:
See flow noise
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

75. 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.
aerodyne:
Any form of aircraft deriving lift in flight principally from aerodynamic
forces. Includes aircraft glider, kite, and helicopter. Commonly called
"heavier-than-air aircraft".
aero-elastic divergence:
Aero-elastic instability which occurs when aerodynamic forces, or
moments, increase more quickly than the elastic restoring forces or
couples in the structure. Generally applied to wing weakness where the
incidence at the tips increases under load, so tending to twist the wings off.
aero-elasticity:
The interaction of aerodynamic forces and the elastic reactions of the
structure of an aircraft. Phenomena are most prevalent when maneuvering
at very high speed.
aero-embolism:
Release of nitrogen bubbles into the blood stream resulting from too rapid
a reduction in ambient air pressure; the bends, encountered by undersea
divers.
Also see
caisson disease
aero-engine:
The power unit of an aircraft. Originally a lightweight reciprocating
internal-combustion engine, usually Otto cycle, as a general rule either air-
cooled radial, in-line, vee, or liquid-cooled vee; gas turbines gradually
superseded reciprocating engines from 1945 for large civil and military
aircraft but reciprocating engines are still widely used in small aircraft.
Also see
ducted fan
gas turbine
ramjet
turbojet
turboprop

76. turboramjet
turborocket
variable cycle engine
aerofoil:
British spelling for airfoil: a body 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.
Also see
air foil
aerogel:
A silicon-based solid with a porous structure with 99% of its volume as
open space, used as an insulator between sheets of things like glass.
aero-isoclinic wing:
A sweptback wing which has its torsional and flexural stiffness so adjusted
that the angle of attack remains constant as the wing bends under flight
loads, instead of decreasing with deflection toward the tip, which is the
normal geometric effect.
aerological diagram:
A thermodynamic diagram used for plotting the results of upper-air
soundings usually containing, as reference lines, isobars, isotherms, dry
adiabatics, saturated adiabatics, and lines of constant saturation humidity
mixing ratio.
aerology:
The study of the free atmosphere.
aeronautical engineering:
The branch of engineering concerned with the design, production, and
maintenance of aircraft structures, systems, and power units.
aeronautical fixed services:
(AFS) A telecommunication service between fixed stations for the
transmission of aeronautical information, particularly navigational safety

77. and flight planning messages.
aeronautics:
All activities concerned with aerial locomotion.
aerophone:
Group of musical instruments in which the air in a tube-shaped resonator
is excited to vibrate.
aeroplane:
British spelling for airplane.
Also see
aircraft
airplane
aerospaceplane:
Aircraft-like vehicle which can take off from and land on runways,
maneuver in the atmosphere, operate in space, and re-enter the
atmosphere.
aerostat:
Any form of aircraft deriving support in the air principally from its
buoyancy, e.g., a balloon or airship.
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.
aerothermochemistry:
The chemical reactions which occur with airflow heating, e.g., a candle
flame in air or the combustion of kerosine in a jet engine.
aerothermodynamics:
The branch of thermodynamics relating to the heating effects associated
with the dynamics of a gas; in particular the physical effects produced in
the air flowing over a vehicle during launch and re-entry.

78. aerothermo-elasticity:
Aero-elasticity complicated by heating effects.
aether:
See ether
AEV:
Acronym for automatic expansion valve.
A/F:
[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.
Also see
across corners
[2] Abbreviation for "air/fuel."
See air-fuel ratio
[3] Abbreviation for "automatic focusing"
[4] Abbreviation for "audio-frequency".
AFB:
Acronym for "Aluminum four-barrel," as in Carter AFB carburetor.
AFC:
[1] Acronym for "air flow controlled"
[2] Abbreviation for "automatic frequency control".
AFCS:
Abbreviation for automatic flight control system.
affected zone:
See heat-affected zone
affine:

79. Said of characteristic curves of apparatus when these curves differ only in
the scales of one or both coordinates.
AFM:
Abbreviation for audio-frequency modulation.
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.
Also see
shear-legs
A-frame barricade:
A traffic marker indicating that the
road is not usable.
A/F ratio:
See air-fuel ratio
AFS:
Abbreviation for aeronautical fixed services.
aft:
The back of a vessel.
Also see
fore and aft adjustment
aft adjustment:
See fore and aft adjustment
aft cg limit:
See cg limits

80. afterbody:
Rear portion of a flying-boat hull, aft of the main step.
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.
Also see
reheat
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:
[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.
afterdamp:
The non-flammable heavy gas, carbon dioxide, left after an explosion in a
coal mine. The chief gaseous product produced by the combustion of coal-
gas.
Also see
black damp
choke damp
fire damp
white damp
afterglow:

81. [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.
Also see
persistence
afterheat:
The heat which comes from fission products in a reactor after it has been
shut down.
after-image:
Formation of image on retina of eye after removal of visual stimulus, in
color complementary to this stimulus.
Also see
complementary after-image
aftermarket:
All products and services used in the repair and maintenance of vehicles
after the vehicle has been sold.
aftermarket equipment:
Accessories and replacement parts added to a vehicle after it has been
sold.
aftermarket overdrive:
An overdrive device which is not original equipment, but has been added
after it has been sold.
aftermarket part:
Goods not for use as original equipment in the production of light-duty
vehicles or heavy-duty vehicles, i.e., products and services used in the
repair and maintenance of these 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.

82. Therefore rustproofing is applied by the owner of the vehicle to reduce the
possibility of rust. If this rustproofing is not done when the vehicle is new,
it might seal in the rust and create a greater problem.
afterpeak:
Space abaft the aftermost bulkhead. Lower part frequently used as fresh-
water tank; upper part may be used as storeroom.
afterpeak bulkhead:
First main transverse bulkhead forward of the sternpost.
after perpendiculars:
A vertical line at the intersection of the summer load line and the after side
of the rudder post or sternpost, or the centerline of the rudder stock if there
is no rudder post or sternpost.
after-start enrichment:
When an engine is first started, it needs a little richer fuel-air mixture (i.e.,
more fuel, less air). In a carbureted engine, this is accomplished by the
choke (which restricts the amount of air). In a fuel injected engine, the
after-start enrichment device increases the amount of fuel. As the engine
warms up, the device gradually reduces the amount of enrichment. Some
devices just reduce the amount gradually over time without sensing the
temperature of the engine.
after top dead center:
(ATDC) A term used in timing the relation of the spark and the crankshaft.
The position of the piston as it starts its way down.
Ag:
Symbol for silver (argentum).
AG:
Acronym for "air-guard".
AGC: