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BRAKES
14
24
Set ScrewW/Cyl. Assy
25
Dust Cover
26
Piston
27
Cup Seal
28
Seal Retainer
29
Spring
30
Wheel Cylinder Body
31
Bleed Screw
32
Dust Cap
33
Gasket
34
Adaptor
35
Grommet
36
Grommet Hand Brake Lever
REAR DRUM BRAKES
CONSTRUCTION AND WORKING
This brake is designed for use on rear wheels and
is equally efficient in both forward and reverse
direction of movement. A mechanical lever
mechanism is incorporated for normal hand brake
operation. The feature of this brake is that the
brake shoe adjustment takes place automatically
when the service brake is applied.
The leading and trailing shoes are connected at
one end by a two-piston wheel cylinder and an
adjuster assembly. The adjuster assembly
consists of a male and female pushrod with an
adjuster nut operated by a pawl.
Coupled on the trailing shoe is a hand brake lever
which pivots on a pin at the wheel cylinder end of
the shoe.
A spring dowel fitted at the leading shoe provides
a pivot for the pawl lever, which is retained in
position by a spring hooked on to the web. The
hand brake cable passes through a hole in the
back plate, and the slotted cable end fits in the
end of the hand brake lever. When the handbrake
is applied, the cable pulls the lever and this
movement is transferred via the adjuster
assembly to the shoes, which moves outwards
onto the drum. When the foot brake is operated,
both the shoes are pushed on to the drum by the
wheel cylinder pistons. As the shoe linings wear,
the outward movement of the shoes exceeds a
predetermined amount and the pawl pivots on the
spring dowel to rotate the adjuster nut. This action
lengthens the adjuster assembly sufficiently to
reduce the clearance between the brake shoes
and drum to the desired minimum. The
adjustment is repeated, whenever necessary,
according to the rate of lining wear.
THERMO CLIP :
The rear brake is provided with 'THERMO CLIP'.
Thermo clip is a Bimetallic spring that opens to
expand the adjuster length during exposure to
higher temperature and prevents over adjustment
due to thermal expansion of brake drum.
Thermoclip comes into action above 150 degree
Celsius. approx. Increase in brake & drum
temperature will cause opening of thermo clip.
Above 150 deg. C temperature and at 'BRAKE
ON' condition, opening of thermo clip prevents the
adjuster lever movement. Hence over adjustment,
contributed due to drums thermal expansion, does
not take place.