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 and transfers park brake system apply input force from driver 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 lever.

Park Brake Cable Equalizer
^ Evenly distributes input force to both the left and right park brake units.
Threaded park brake cable equalizers are also used to remove slack in park brake cables.

Park Brake Apply Lever
^ Multiplies and transfers input force to park brake actuator.

Park Brake Actuator
^ Uses multiplied input force from apply lever to expand park brake shoe toward the friction surface of the drum-in-hat portion of the rear brake rotor.
Threaded park brake actuators are also used to control clearance between the park brake shoe and the friction surface of the drum-in-hat portion of the rear brake rotor.

Park Brake Shoe
^ Applies mechanical output force from park brake actuator to friction surface of the drum-in-hat portion of the rear brake rotor.

System Operation

Park brake apply input force is received by the park brake lever assembly being depressed, 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 which expand the park brake shoe toward the friction surface of the drum-in-hat portion of the rear brake rotor 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.