Parking Brake System: Description and Operation

DESCRIPTION






The parking brake lever mounts to the floor pan tunnel beneath the center console. It has a short output cable and equalizer bracket attached to it. Two parking brake cables attach to the equalizer bracket. These cables lead to each parking brake lever at the rear brakes.






The rear wheel disc brake calipers used on this vehicle not only operate the rear standard service brakes, they it also act as the vehicle's parking brakes. The rear disc brake caliper assembly has a park brake operating arm which connects to the park brake cable. This operating arm connects internally in the caliper assembly to a mechanism which applies the rear brake shoe assemblies when the park brake lever is engaged.

OPERATION
When parking brakes are applied (lever is pulled), the parking brake cables pull the parking brake operating levers forward. This rotates the discs and worm shaft causing the piston to extend and apply the brakes. Since normal brake shoe operating clearance is quite small, only a modest amount of piston movement is needed for brake application. A stop bolt is used to limit the total amount of piston extension.
The parking brake mechanism is self-adjusting to compensate for lining wear. As wear occurs, drive-to-driven disc clearance increases. This causes the drive disc ball bearings to move farther up the cam ramps in the driven disc increasing the amount of rotation. The extra rotation produced is enough to extend the piston for adjustment.