PIN 5016911 - Caterpillar

Illustration 1 g06228121
Parking brake activation
(1) Parking Brake Switch
Illustration 2 g06228125
Top view of the parking brake assembly
(2) Parking brake actuator
(3) Actuator rod
(4) Brake lever
(5) Caliper assembly
(6) Brake pads
(7) DiscThe parking brake assembly is bolted to the front of the center axle. The parking brake is spring engaged and hydraulically released. Heavy springs on the outside of the brake pads (6) force the pads inward, clamping the pads against disc (7) to keep the parking brake engaged. The rotor is mechanically connected to the drive shaft. When engaged, the parking brake holds the truck stationary by preventing rotation of the drive shaft.When parking brake switch (1) in the cab is pressed to release the parking brake, the parking brake solenoid is energized by the transmission ECM. The solenoid valve then directs oil into parking brake actuator (3), pressurizing the chamber behind the actuator piston and moving the actuator outward. As the piston moves outward, the piston compresses an internal bias spring and moves actuator rod (3) outward, rotating brake lever (4) counterclockwise. As brake lever (4) rotates, the lever moves the brake pads away from the parking brake rotor to release the brake.When the parking brake switch is pressed to engage the brake, the parking brake solenoid is de-energized, which drains the oil behind the actuator piston. As the piston chamber is de-pressurized, the actuator bias spring pulls actuator rod (3) inward and brake pads (6) clamp against disc (7) to engage the brake.