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 operator to park brake cable system.

- Releases applied park brake system when lever is returned to at-rest, lowered, 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.

Park Brake Apply Lever

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

Park Brake Actuator/Adjuster

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

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

Drum Brake Shoes

- Applies mechanical output force from park brake actuator/adjuster to friction surface of the brake drum.

System Operation

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 park 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 returned to the at-rest, lowered, position.