Parking Brake System: Description and Operation

Park Brake System Description and Operation

System Component Description

The park brake system consists of the following:

Park Brake Lever Assembly

Receives, multiplies, and transfers park brake system apply input force from driver to park brake cable system.

Releases applied park brake system when lever release button is depressed and lever is returned to the at-rest position.

Park Brake Cables

Transfers input force received from park brake lever, through park brake cable equalizer, to park brake apply levers.

Park Brake Cable Equalizer

Evenly distributes input force to both the left and right park brake units.

Threaded front park brake cable adjuster is also used to remove slack in park brake cables.

Park Brake Apply Lever

Multiplies and transfers input force to park brake actuator/adjuster.

Disc Brake Caliper Actuator

Uses multiplied input force from park brake apply lever to apply disc brake caliper piston which compresses the brake pads against friction surface of brake rotor.

Drum Brake Actuator/Adjuster

Uses multiplied input force from park brake apply lever to expand drum brake shoes toward the friction surface of the brake drum.

Threaded drum brake actuators/adjusters are also used to control clearance between the drum brake shoes and the friction surface of the brake drum.

System Operation - Disc Brakes

Park brake apply input force is received by the park brake lever assembly being applied. The input force is multiplied by the lever assembly, transferred and evenly distributed, through the park brake cables and the park brake cable equalizer, to the left and right park brake apply levers. The park brake apply levers multiply and transfer the apply input force to in turn apply the disc brake caliper pistons which compress the brake pads against the friction surface of the brake rotors in order to prevent the rotation of the rear tire and wheel assemblies. The park brake lever assembly releases an applied park brake system when it is released and returned to the at-rest position.

System Operation - Drum Brakes

Park brake apply input force is received by the park brake lever assembly being applied. The input force is multiplied by the lever assembly, transferred and evenly distributed, through the park brake cables and the park brake cable equalizer, to the left and right park brake apply levers. The park brake apply levers multiply and transfer the apply input force to the drum brake actuators/adjusters which expand the drum brake shoes toward the friction surface of the brake drum in order to prevent the rotation of the rear tire and wheel assemblies. The park brake lever assembly releases an applied park brake system when it is released and returned to the at-rest position.