SAFARI

BRAKES

condition, opening of thermo clip prevents the adjuster

lever movement. Hence over adjustment, contributed

due to drums thermal expansion, does not take place.

Working Principle

The Thermoclip is assembled between the adjuster

nut and the adjuster pushrod.

In the brake 'OFF' condition, the shoe return spring

forces the shoe webs against the adjuster rods.

When brakes are applied the shoes move outward

and there will be no force on the adjuster rods. Also

the shoe movement makes the pawl to rotate the

adjuster nut ensuring adjustment.

Around 150 deg. C, the thermo clip opens and the

force exerted by the thermoclip will become higher

than the force exerted by adjuster pawl at the hinge

point. At this condition, the adjuster rods are moved

outward and also the rotation of the nut is prevented.

Thus the clearance which is caused due to thermal

expansion does not result in over adjustment.

REAR DRUM BRAKES

CONSTRUCTIONANDWORKING

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 push rod 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 backplate, and

the slotted cable end fits in the end of the hand

brake lever. When the hand brake 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'