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| Illustration 1 | g00468533 |
Final Drive (1) Final drive housing. (2) Inner planetary gears. (4) Ring gear. (5) Outer carrier. (6) Outer planetary gears. (7) Input shaft. (8) Inner sun gear. (9) Inner sun gear. (10) Brake plates. (11) Brake discs. (12) Stationary housing. (13) Coupling. (14) Brake piston. (15) Passage for charge oil. | |
The final drive takes power from the drum drive motor and the power is sent to the drum. Final drive housing (1) is attached to the drum drive plate. The final drive provides three-stage gear reduction through the use of planetary gears.
Power from the drum drive motor is sent to the torque hub by the motor output shaft. Outer planetary gears (6) mesh with outer gear of input shaft (7). The rotation of input shaft (7) causes outer planetary gears (6) to turn. The planetary gears move around the inside of ring gear (4).
The movement of the planetary gears around the ring gear causes outer carrier (5) to turn. The outer carrier is connected to inner sun gear (8) by splines. The rotation of the outer carrier and the inner sun gear causes inner planetary gears (2) to turn.
Inner carrier (3) is connected to inner sun gear (9) by splines. As the inner carrier (3) is held stationary, inner planetary gears (2) rotate inside ring gear (4). This movement causes gearbox housing (1) to turn. This transfers the power to the drum drive plate.
The final drive has a separate oil supply. All components get lubrication oil as the gears move through splash lubrication.
The parking brake is spring applied and pressure released. Brake discs (11) are splined to coupling (13). Brake plates (8) are splined to output housing (12) .
When the parking brake is applied, the passage for charge oil (15) is blocked at the brake interlock valve. The springs push on brake piston (14). This compresses brake plates (10) to brake discs (11). At this point, coupling (13) is locked to stationary housing (12) and the drum will not turn.
When the parking brake is released, the charge oil is routed to the passage for charge (15) by the brake interlock valve. The charge oil enters the brake piston cavity and the charge oil acts against brake piston (14). The charge oil pressure overcomes the force of the springs. This moves the brake piston away from brake plates (10) and brake discs (11). At this point, the drum is free to turn.