SAFARI

21 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 pul ls 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'