Parking Brake System: Description and Operation

When the handbrake is applied, the effort required is transferred via cables to the lever of each brake unit (caliper) on the rear wheels. This lever is fixed to an eccentric shaft that presses on a stud when it is rotated. Via the adjusting mechanism, the stud presses on the brake piston and the inboard brake pad. Simultaneously, the entire hydraulic body slides sideways and also presses the outboard brake pad against the brake disc.

When the handbrake is released, the lever on the brake unit (caliper) is returned by the spring and the piston sealing ring in the brake cylinder retracts the brake pads to the rest (brake off) position.

The handbrake system is self-adjusting. As the brake pads wear, the clearance between pads and brake disc is adjusted automatically so that it is kept constant at all times. The adjusting mechanism consists of an adjusting screw and a threaded sleeve. When the clearance reaches a certain limit, the adjusting screw backs off slightly. Self-adjustment 'is therefore carried out in small steps.

When working on the brake system, adjustment should be carried out manually as described in "Adjustment".