Automotive Technical Terms |
|
|
|
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. |
|
Common name for ball-and-socket
joints used on steering arm ends and suspension components
where two-directional movement is required between
joined components.
|
|
Used widely before the advent
of independent front suspension, beam axles became
more prevalent as part of the rear suspension set-up
of front-wheel-drive cars through the 1970’s
and 1980’s.
They are a one-piece solid transverse members usually
suspended on coil springs, but in the case of heavy
commercial vehicles they are used as a front suspension
component in conjunction with leaf springs.
|
|
Berlina:
European term used to describe
sedan or saloon body styles, before becoming used by
GMH in Australia to define their mid-luxury Commodore
variant. Other European terms describing sedan style
include Berline and Berlinetta.
|
|
A tire construction technique
developed in the US that consists of a mixture of cross-ply
and radial-ply construction. It is aimed at producing
a superior ride comfort level than that found with
a radial ply tire without sacrificing any road-holding
capabilities. The bias-belted tire fell from favor
during the late 1970’s.
|
|
Blueprinting:
Hand preparation and assembly
of an engine or other mechanical components to ensure
correct tolerances are achieved and thus optimum performance
obtained. Can include x-ray type techniques used to
determine minor imperfections not detectable to the
human eye. Commonly includes;
Block - Align hone main saddles, parallel boring and
honing with deck plates, equal-distance decking;
Pistons - Checked for size and dome height and then
pin fitted; pistons are notched where necessary for
valve clearances,
Crankshaft - Magnafluxed, indexed, machined; oil holes
radiused, journals micropolished. The compression ratio
is calculated for maximum performance;
Balancing - The entire rotary assembly is precision
electronically balanced.
|
|
Big End:
The connecting point of the
connecting rod to the crankshaft.
|
|
Colloquial term to describe
a super-charger or turbo-charger.
|
|
Originally a French term,
but now used widely by all manufacturers to describe
soft-top or convertible style automobiles.
|
|
Driven off the crankshaft,
the camshaft consists of a series of machined eccentric
lobes that open and close the valves, thus controlling
gas flow in and out of the cylinder head.
|
|
A calculated ratio
that relates the uncompressed volume of the cylinder
with the piston at bottom dead-centre to the compressed
volume of the cylinder with the piston at top dead-centre.
Hence a 9:1 compression ratio means that the air-fuel
mixture is compressed to one-ninth of its original
volume before being ignited. The compression ratio
bears little relationship to the actual effective pressure
created in the cylinder.
|
|
Short for “connecting-rod”,
it joins the piston assembly to the crankshaft and
is an essential component in power transmission.
|
|
Refers to French auto designer
de Dion and his independent rear suspension that utilizes
a connecting tube.
|
|
Detonation:
Also called “pinging”,
refers to the mechanically dangerous situation where
combustion is uncontrolled and not a function of ignition.
Generally a result of an incorrect air-fuel mixture
or too high a compression ratio for the octane level
of the fuel.
|
|
Differential:
Gear assembly that transmits
power from the drive shaft to the wheels. The
name is derived from the provision that allows one
wheel to turn at a different rate to the other wheel.
|
|
Displacement:
Swept volume of a cylinder
or a group of cylinders comprising an engine. Formerly
expressed in cubic inches (cu. in), it is now measured
in cubic centimeters (cc) or liters (L).
|
|
Distributor:
Shaft-driven mechanical
device that controls a low-tension ignition circuit
by making and breaking contact.
|
|
DOHC:
Double overhead camshafts. Originally
only found in high performance engines, they have become
common-place on all modern engine designs.
|
|
Drive Line:
Transmission shaft that takes
power from the gearbox to the differential. Usually
incorporates two universal joints to allow for suspension
movement.
|
|