Half shafts, otherwise known as
shafts, are fitted in rear-wheel-drive cars only. They give relatively little trouble during normal motoring, although they are highly stressed components.
The inner end of the shaft is supported and driven by the
, and the outer end is supported in
between shaft and
These bearings have either built-in or separate
. The bearings can be
(both with inner races), or
straight roller bearings
which use the axle shaft as the inner race.
When a half shaft fails, the rear wheels cannot be driven.
The main symptoms of a worn half shaft are a
or clunk when accelerating or decelerating. The cause is wear and excessive play between the shaft and differential
However, the same symptoms can be caused if the crown wheel and
in the differential are not meshing correctly, the drive-pinion
splines are worn, or the drive-flange bolts are loose.
If you are not sure of the noise source, consult a garage. Special tools are needed to check wear, called
between two parts such as the teeth of gears. data-term-id="1310">backlash
, in such components as the crown wheel and pinion.
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Reversing lights are not generally a legal requirement but they are useful.
They serve two purposes - to warn other road-users you are about to reverse,
and to provide light if you are reversing in the dark.