SHIELD AS 3892999 - Caterpillar

Illustration 1 g00695970
(1) Final drive planetary for the drum. (2) Charge pressure port for the brake. (3) Drum drive motor.The final drive takes power from the drum drive motor (3) and the power is sent to the drum. Final drive planetary (1) is attached to the drum drive plate. The final drive provides 80 to 1 gear reduction through the use of planetary gears. 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. When the parking brake is applied, the passage for charge oil (2) is open to the hydraulic tank. The springs in the planetary housing push on the brake piston. This compresses brake plates to the brake discs. At this point, the drum will not turn.When the parking brake is released, the charge oil is routed to the charge pressure port (2) by the brake valve. The charge oil enters the brake piston cavity. The charge oil pressure overcomes the force of the springs. This moves the brake piston away from brake plates and brake discs. At this point, the drum is free to turn.