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| Illustration 1 | g00424196 |
Steering Clutch and brakes (1) Clutch housing. (2) Clutch piston. (3) Brake housing. (4) Belleville springs. (5) Brake piston. (6) Passage for brake pressure oil. (7) Input hub. (8) Passage for clutch pressure oil. (9) Output hub. (10) Passage for lubrication and cooling oil. (11) Clutch plates and discs. (12) Brake plates and discs. | |
The steering clutches and brakes are modular, multiple discs. The steering clutches and brakes are also cooled by oil. The steering clutches and brakes transfer power from the bevel gear to the final drives. The functions of the clutches and brakes are hydraulically controlled by a control valve that is mounted on the bevel gear case. The steering clutch is hydraulically engaged by pressure oil that is sent from the steering and brake control valve. The brakes are engaged by Belleville springs (4) and the brakes are released by pressure oil that is sent from the steering and brake control valve. This arrangement gives an automatic brake application if hydraulic pressure is lost.
Power from the bevel gear is sent through an inner axle shaft to input hub (7) . Input hub (7) is connected to clutch housing (1) by clutch plates and discs (11) . Clutch housing (1) is fastened to output hub (9) by bolts. Stationary brake housing (3) is connected to output hub (9) by brake discs and plates (12) .
During straight movement of the machine, pressure oil from the steering clutch and brake control valve is sent through two passages in brake housing (3) . Pressure oil from one passage is sent to passage (6) . This pushes brake piston (5) against Belleville springs (4) in order to sustain the brakes in the released position. Pressure oil from the other passage is sent to passage (8) and pushes against clutch piston (2) in order to engage the steering clutches. This connects input hub (7) to clutch housing (1) and output hub (9) . The splines inside the output hub turn the outer axle shaft and power is sent to the final drives.
When resistance is felt in the steering control lever, the pressure oil to the respective clutch is stopped. When this oil stops the clutch is released. (This occurs with the right clutch or with the left clutch.) The inner axle shaft still turns input hub (7) and the clutch discs, but no power is sent through the clutch to clutch housing (1) and to output hub (9) . Pressure oil is still flowing to the respective brake. This keeps the brake released. The result is a gradual turn.
When the steering control levers are pulled back all the way, the steering clutch is released, as previously described. The pressure of oil to the brake decreases to approximately 225 kPa (33 psi). This allows Belleville springs (4) to push brake piston (5) in order to engage the brake. Output hub (9) connects with stationary brake housing (3) . Rotation of the outer axle shaft stops. Movement of the tracks stop. A fast, abrupt turn will result.
When the foot brake is pushed, the flow of pressure oil to the brakes is stopped. This allows the Belleville springs to engage the brake. The flow of pressure oil to the steering clutches is not stopped, so the steering clutches remain engaged. For this reason, all components are stopped and the components cannot turn. The machine is completely stopped in the converter stall condition. On machines with direct drive transmissions, the engine will stall unless the transmission clutch is disengaged.
If hydraulic pressure is lost, the flow of oil to the steering clutches and brakes is stopped and the brakes are applied by the action of the Belleville springs.
Lubrication of Steering Clutches and Brakes
Oil for the lubrication of the steering clutches and the brakes and for the cooling of the steering clutches and the brakes comes from the steering clutch and the brake lubrication section of the power train oil pump. The oil flows through a passage in brake housing (3) . The oil then flows through internal passages (10) to the discs and to the plates.