Usage:
All D379B, D398B And D399 Engines So Equipped
It is our recommendation to check the operation of the hydramechanical shutoffs before the above engines are put back into service after a period of extended storage. The procedures which follow can be used to make sure the air shutoff and the rack shutoff work correctly.
Air Shutoff Group
1. Remove bolts (1) that hold the hydraulic cylinder or solenoid in place. See Illustration 1.
Illustration 1. Air shutoff group.
2. Remove the hydraulic cylinder or solenoid. When the cylinder or solenoid are removed, the plate assembly will automatically move to the fully closed position.
3. Turn knob (2) and check the movement of plate assembly (3). The plate assembly must move freely from the fully closed position to the fully open position. If the plate assembly moves freely, the hydraulic cylinder or solenoid can be put back in position. Make sure the shutoffs are in the open position.
If the plate assembly does not move freely to the fully closed position, see the next step.
4. Remove knob (2). Remove the cover assembly (4).
5. Install knob (2) and put penetrating type oil on the shaft, especially where the shaft goes into the housing. Turn the shaft until it moves freely.
6. Assemble the air shutoff group.
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Be sure both air inlet shutoff valves (one on each side of the engine) are open before the engine is started. Both valves must be open to prevent possible engine damage.
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Rack Shutoff Group (5N5792 Only)
1. Disconnect the oil supply tube assembly at the rack shutoff group.
2. Remove the rack shutoff group and three bolts (1) that hold it in place on the governor. Do not remove bolt (2) at this time. See Illustration 2.
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Spring pressure is present behind the cover. Make sure the cover and housing are held together while bolt (2) is removed. Gradually let the cover and housing separate.
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Illustration 2. Rack shutoff group.
3. While the cover and housing are held together, remove bolt (2). Gradually let the cover and housing separate.
4. Remove the spring and piston.
5. Check the condition of the seal on the end of the piston. If the seal is hard and/or cracked, install a new seal.
6. Make sure the piston moves freely in the housing.
7. Clean all the parts and the gasket surfaces of the rack shutoff housing and the governor drive housing.
8. Assemble the rack shutoff group and install it on the engine. Use new gaskets.
During normal operation, it is our recommendation that the operation of the hydramechanical shutoff be checked every 500 service meter units or 3 months whichever comes first.
If it is not possible to disassemble the components, this procedure can be used to check the operation of the hydramechanical shutoff after extended storage of an engine.
1. With the engine running, pull the red emergency knob. The engine must stop.
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Be sure both air inlet shutoff valves (one on each side of the engine) are open before the engine is started. Both valves must be open to prevent possible engine damage.
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2. Put both the air shutoff valves in the open position. They are located on each side of the engine.
3. Fasten the air shutoff valves in the open position. The knobs can be fastened with wire or held open manually by two servicemen.
4. Pull the red emergency knob. The engine must stop.
5. If the engine does not stop after either Step 1 or 4, see your Caterpillar dealer for the necessary repairs. The emergency shutoff system must work correctly for your engine to have protection during operation.