The travel parking brake is built into the travel motor. When the oil delivery from the pump flows to the travel motor, the parking brake releases and the travel motor will start rotating. When no oil delivery flows to the travel motor, the rotation of the travel motor stops and the travel parking brake engages. For more information concerning the operation of the travel motor, refer to Systems Operation , "Travel Motor".
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| Illustration 1 | g06285412 |
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Parking brake (cross section) (1) Spool (2) Rear flange (3) Spring (4) Passage (5) Piston chamber (6) Brake piston (7) Passage (8) Separator plate (9) Friction plate (10) Barrel (11) Motor housing (12) Shaft | |
Separator plates (8) are splined to motor housing (11). Friction plates (9) are splined to barrel (10).
When no pump oil is supplied to the travel motor, brake piston (6) is forced to the right by the force of spring (3). The oil in piston chamber (5) flows through passage (7) and to the case drain port of the motor. When brake piston (6) moves to the right, separator plates (8) and friction plates (9) are forced against housing (11) by the force of spring (3). The rotation of barrel (10) and the rotation of shaft (12) stop and the parking brake is engaged.
Brake piston (6) restricts oil flow from piston chamber (5). The restriction of return oil flow delays the application of the parking brake. The parking brake is delayed to give the machine time to stop. Earlier wear and/or damage to the machine could result if the machine stayed in motion.
Prior to the operation of the travel motor, a portion of the pressure oil flows through passage (4) and flows into piston chamber (5). Brake piston (6) is moved to the left against the force of spring (3). Separator plate (8) and friction plate (9) release which allows barrel (10) and motor shaft (12) to turn.