ROD 0887212 - Caterpillar

Illustration 1 g06020664
Rear of Machine
(1) Brake assemblyThe machine has two brake assemblies (1), one assembly is located on each rear axle. These components are accessed from under the machine.Each brake assembly is spring applied and released by hydraulic charge pressure. The assemblies are housed between each propel motor and the final gear drive of each rear axle.
Illustration 2 g06020680
Brake Assembly
(2) Brake housing
(3) Friction pack
(4) Brake shaft
(5) Piston
(6) SpringsCharge pressure is used to release the parking brakes. When the brakes are engaged, the passage for charge pressure in brake housing (2) is open to the hydraulic tank.The parking brakes are spring applied and hydraulically released. These wet brakes are engaged through the compression of brake friction pack (3). The friction pack consists of a series of disks and plates. The disks are splined to brake shaft (4). The plates are splined to brake housing (2). The hydraulic charge system directs oil through the brake housing in order to operate, cool, and clean the internal components.Springs (6) move piston (5) against friction pack (3). This action compresses the disks and plates of the friction pack, so brake shaft (4) cannot rotate.When the brakes are released, charge pressure is directed into the piston cavity. Charge pressure acts against piston (5), in opposition to springs (6). The charge pressure overcomes the spring force, and the piston moves. This movement releases the compressive force on the disks and plates of friction pack (3).The interlock solenoid on the propel pump and the brake dump valve control the oil flow to the brake assemblies. The brakes are engaged when the interlock solenoid and the brake dump valve are not energized. Both solenoids must be energized to release the brakes.The brake pedal sensor provides a value of zero percent at fully depressed to 100 percent at fully released position.The rate and percentage of brake pedal sensor output change is factored against other operator settings to reduce the propel command appropriately.The deceleration rate of the machine is changed as the brake pedal is depressed. A parking brake command signal is also determined from the brake pedal position.A second output, based on the position of the brake pedal, parking brake switch, and propel lever position controls the stop lights output.The brake pedal must be calibrated to use the full range of the pedal. The calibration process captures the duty cycle at each extreme position of the brake pedal.