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| Illustration 1 | g01361873 |
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Cross Section of the Final Drive (1) Brake passage (2) Brake piston (3) Brake piston chamber (4) Disks and plates (5) Second stage sun gear (6) Brake coupling (7) Brake springs (8) Connection shaft | |
The parking brakes are spring applied and hydraulically released. These wet brakes are engaged through the compression of a series of disks and plates. The disks are splined to the brake coupling. The plates are splined to the housing. The brake plates and disks are splash lubricated.
Oil from the auxiliary hydraulic pump is used in order to release the parking brakes. When the brakes are engaged, the brake solenoid opens the brake passage to the hydraulic tank. The brake springs move the brake piston against the brake disks and plates. This action compresses the disks and plates, so the brake coupling cannot rotate.
When the brakes are released, auxiliary pressure is directed into the brake piston chamber. Auxiliary pressure acts against the brake piston. This action works against the brake springs. The auxiliary pressure overcomes the spring force, and the brake piston moves. This movement releases the compressive force on the disks and on the plates.