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| Illustration 1 | g03883693 |
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Rear view of parking brake assembly (drive shaft removed for clarity) (1) Cylinders | |
The parking brake assembly is a multiple disc brake with a dry cavity. The parking brake is engaged by springs and disengaged by oil pressure.
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| Illustration 2 | g03873265 |
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Sectioned view of parking brake assembly (1) Cylinders (two) (2) Discs (four) (3) Plates (three) (4) Pressure plate (5) Pistons (two) (6) Rods (four) (7) Springs (nineteen) (8) Pins (four) (9) Port | |
Plates (3) react against pins (8). Discs (2) have splines on the inside diameter which align and mesh with the drive shaft. When the parking brake is engaged, plates (3) are pressed in contact with discs (2), which prevents the drive shaft from rotating.
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| Illustration 3 | g03880135 |
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View of the dash panel (10) Parking brake switch | |
Parking brake switch (10) is positioned on the left side of the dashboard. This switch activates the parking brake control valve to engage or disengage the parking brake.
When the parking brake switch is in the OFF position, oil flows from the accumulators to the chamber behind piston (5). Oil enters cylinders (1) of the parking brake through port (9). As the oil fills the chamber behind piston (5), the following items move to the right: piston (5), rod (6), and pressure plate (4). This action causes springs (7) to compress. As the springs compress, pressure against plates (3) and discs (2) is removed. The release of pressure against plates (3) and discs (2) disengages the parking brake. Disengaging the parking brake will allow the drive shaft to rotate and the machine to move.
When the parking brake switch is in the ON position, the flow of oil from the accumulator stops. The flow of oil to the parking brake also stops. This action allows the oil in cylinders (1) to return to the parking brake control valve and to the steering and brake system hydraulic tank. As the return oil flows out of port (9), springs (7) cause the following items to move to the left: pressure plate (4), rod (6), and piston (5). This action allows plates (3) and discs (2) to compress together. The compression of the discs and the plates engages the parking brake. Engaging the parking brake will stop the drive shaft and cause the machine to stop, or prevent the machine from moving if already stopped.
If the brake pump does not maintain the pressure of the oil in the brake hydraulic system at