TIAGO BSVI MCE - SERVICE MANUAL

BRAKES 45 INTRODUCTION This brake is designed for use on rear wheels and is equally efficient in both directions of rotation. A mechanical lever mechanism is incorporated for normal hand brake operation. The feature of this brake is the automatic adjustment of the brake shoes takes place when the foot brake is applied. The leading and trailing shoes are connected at one end by a twin-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, which is restrained in position by a spring attached in the web. The hand brake cable passes through a hole in the back plate assembly (6), and the nipple 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 (4) to the shoes, which move outwards onto the drum. When the foot brake is operated, both the shoes are pushed on to the drum by the wheel cylinder plunger. 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 serrated 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.