793C Off-Highway Truck Power Train Caterpillar

New wheels or retrofitted wheels will have the high capacity bearings. All 793C Off-Highway Trucks should now have the high capacity bearings. The part numbers for the high capacity bearings are 135-2666 Cones and the 135-2667 Cups or the part numbers for the high capacity bearings are 175-3769 Cones and 175-3770 Cups.

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NOTICE
Improperly adjusted wheel bearings or loose wheel bearings can affect the life of the wheel bearings. Use the correct wheel bearing adjustment procedure.

Releasing The Parking Brakes

Illustration 1	g00532854
Typical example Location of the purge valve for the parking brake ("P")

Note: During the wheel bearing adjustment, you will need to release the parking brakes.

In order to release the parking brake, connect a manual hydraulic pump or an electric hydraulic pump to the "P" port. Continue to operate the pump until the brake is fully released. The amount of pressure that is required to release the brakes is 4690 ± 200 kPa (680 ± 30 psi). To learn more about releasing the parking brakes, refer to the information about towing that is located in the following service manuals.

• Towing Information in the Operation and Maintenance Manual

• Air System and Brakes Systems Operation, "Towing"

• Air System and Brakes Testing and Adjusting, "Towing the Machine - Preparation"

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NOTICE
If it becomes necessary to use an outside hydraulic source to release the parking brake, do not exceed the relief pressure of the parking and secondary brake control valve. Exceeding the relief pressure can damage seals and other parts in the circuit.

Refer to the Power Train Disassembly and Assembly, "Final Drive, Brake and Wheel (Rear) - Assemble" in order to perform the wheel bearing adjustment procedure. These procedures are intended for the machines with the high capacity bearings.