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| Illustration 1 | g00691715 |
(1) Coupling (2) Final drive housing (3) Gear in the rear cover (4) Outer planetary gears (5) Outer sun gear (6) Carrier (7) Inner sun gear (8) Inner planetary gears (9) Spindle (10) Ring gear (11) Brake discs (12) Brake plates (13) Stationary housing (14) Passage for charge oil (15) Brake piston | |
The final drive takes power from the drum drive motor and the power is sent to the drum. Final drive housing (2) is attached to the drum drive plate. The final drive provides two-stage gear reduction through the use of planetary gears.
Power from the drum drive motor is sent to the final drive by the motor output shaft. Coupling (1) connects the output shaft to outer sun gear (5). Outer planetary gears (4) mesh with gear teeth of the outer sun gear. The rotation of the outer sun gear causes the outer planetary gears to turn. The planetary gears move around the inside of the gear in the rear cover (3) .
The movement of the planetary gears around the rear cover causes carrier (6) to turn. The carrier is connected to inner sun gear (7) by splines. The rotation of the outer carrier and the inner sun gear causes inner planetary gears (8) to turn.
The inner planetary gears are mounted on spindle (9). As the spindle is held stationary, the inner planetary gears rotate ring gear (10). This movement causes gearbox housing (2) 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 (1). Brake plates (12) are splined to stationary housing (13) .
When the parking brake is applied, the passage for charge oil (14) is blocked at the brake interlock valve. The springs push on brake piston (15). This compresses brake plates (12) to brake discs (11). At this point, coupling (1) is locked to stationary housing (13) and the drum will not turn.
When the parking brake is released, the charge oil is routed to the passage for charge oil (14) by the brake interlock valve. The charge oil enters the brake piston cavity and the charge oil acts against brake piston (15). The charge oil pressure overcomes the force of the springs. This moves the brake piston away from brake plates (11) and brake discs (11). At this point, the drum is free to turn.