789B Off-Highway Truck Hydraulic System Caterpillar

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Sudden movement of the machine or release of air or oil under pressure can cause possible injury or death to persons on or near the machine. To prevent possible injury or death, do the procedure that follows before testing and adjusting the Hydraulic System.

Note: Permit only one operator on the machine. Keep all other personnel away from the machine or in the operator's sight.

1. Move the machine to a smooth, horizontal location. Move away from operating machines and away from other personnel.

2. Move the transmission control lever to NEUTRAL. Stop the engine.

3. Engage the parking brake.

4. Put wheel blocks in front of the wheels and behind the wheels.

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Illustration 1	g00282855
Retaining cable

5. Fully raise the dump body and connect the retaining cable to the rear of the truck.

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Illustration 2	g00328223
Hoist control linkage

6. Disconnect the hoist control linkage. Remove the cotter pin and remove the pin that connects the rod to the hoist lever.

7. Make sure that the transmission rotary selector spool is in the "N-1" position.

8. Make sure that all air pressure and all oil pressure is released before you perform any work on the hydraulic system.

Note: The hydraulic system involves the hoist, the torque converter, the brakes, and the brake cooling. For more detailed information about the torque converter, about the brakes, or about brake cooling, see the following modules:

• Testing and Adjusting, SENR6327, "789B Off-Highway Truck Power Train"

• Systems Operation/Testing and Adjusting, SENR6329, "789B Off-Highway Truck Steering System"

• Systems Operation/Testing and Adjusting, SENR6331, "789B Off-Highway Truck Air System and Brakes"