Automotive Technical Terms |
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Throughout this site we use
many technical terms, and given the breadth of readership
our site enjoys, sometimes we are remiss and incorrectly
assume everyone knows what we are referring to. For those
that do not, here are some explanations of the technical
terms use. |
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A-Bracket:
Used in conjunction with some coil spring rear
axle set-ups. This type of location bracket stops the
axle moving back and forward in relation to the body
of the vehicle. The 'apex' of the "A" is fixed
to the differential while the 'legs' of the "A" are
fixed to the axle. |
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A-Frames:
Upper and lower front suspension brackets; more generally
termed wishbones. Used in conjunction with coil springs
as a front suspension arrangement. |
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A-Pillar:
Front-most pillar in vehicle body construction
that joins the roof to the lower portion of the body.
Successive pillars are called B, C and (with wagons)
D. |
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Accelerator Pump:
Attached to the carburetor body, it performs
the specific function of negating the lean-out effect
caused by sudden large throttle openings. It is activated
directly off the throttle cable (or linkage) via a diaphragm
arrangement and nozzle. Sudden throttle openings activate
the diaphragm which forces petrol through the nozzle
into the carburetor throat. On slow throttle openings,
there is a bleed-by arrangement that allows the fuel
to return to the pump bowl rahter than being forced through
the nozzle. |
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Additives:
There are two types, oil and fuel. Oil additives
make up about 15% of oil volume and are used to inhibit
oil oxidisation (the main reason for oil breakdown)
and to clean carbon deposits (detergent additives).
The main fuel additive is teteathyl lead which is used
for its anti-knock properties; its addition allows
octane levels to be dropped without fear of creating
mechanically dangerous pre-ignition or pinging. |
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Advance and Retard:
This refers to the change in ignition timing
that is made through both mechanical and vacuum
systems to allow for different combustion situations
for different rpm and smaller or larger throttle
openings. The mechanical system advances the ignition
as rpm increases to allow for the decreased time
for combustion. |
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The study
of physical forces at work when a body passes through
the air. In the automobile world, the term aerodynamic
drag is used to describe the resistance that the air
exerts on a car moving at speed. By changing the body
shape of a car to reduce dynamic drag, the energy output
of the engine can be better utilized either in the
form of reduced fuel consumption or improved performance.
The French auto manufacturer Citroën
pioneered the development of aerodynamic passenger
cars with the DS19 in 1955, and have remained leaders
in this field. |
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Also termed “wing” or “wings”,
these devices were first fitted to race cars to to
increase down-force and thus traction at high speed.
The greatest benefit, apart from keeping the car firmly
on the road, is to allow higher cornering speed.
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An aerodynamic aid placed across
the lower nose of the car to prevent the energy consuming
and dynamically un-stabilising effect of air being
forced under the car.
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A device fitted to the engine
to convert mechanical rotational energy into electrical
energy. This electrical energy is stored in the battery
and used to operate the various electrical functions
of the car.
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An instrument for measuring
electrical current and hence the electrical output
of the alternator
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A particular type
of suspension arrangement that minimizes nose dive
and tail-end lift during heavy braking. It produces
a more comfortable ride as well as providing higher
levels of traction.
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A suspension aid that
increases resistance to body roll without giving a
stiffer, less comfortable ride. The centre of the bar
is attached to the underside of the body, the ends
of the bar are bent through right angles and attached
to the suspension control arms.
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Refers to the height of
the tire expressed as a percentage of the cross-section
profile. Hence a 70% aspect ratio refers to a tire
that is 70% as high as it is wide.
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