793B Off-Highway Truck Hydraulic System Caterpillar

Illustration 1	g01041360
Front view of hydraulic tank (1) Hydraulic section (Torque converter, hoist and brake section) (2) Transmission section (3) Rear brake oil cooler relief valves (4) Front brake oil cooler relief valve

The hydraulic tank is divided into two sections by a wall which is inside the tank. This wall separates the hydraulic section (torque converter, hoist and brake section) (1) from transmission section (2). Hydraulic section (1) contains SAE 10 W oil. This oil is used in several systems: the torque converter system, the brake cooling system, the hydraulic brake system and the hydraulic hoist system. Transmission section (2) contains SAE 30 oil.

Hydraulic section (1), the torque converter case, and the pump drive gearbox are vented to a filter. Transmission section (2) and the transmission case are vented to an air breather. The air breather and the filter are located on the vertical frame member on the right side of the truck.

Tank Ports

Illustration 2	g01030480
Rear view of hydraulic tank (5) Breather ports for the transmission section (6) Breather port for the torque converter, hoist and brake section (7) Return port from the transmission scavenge pump (8) Return port from the torque converter scavenge pump (9) Return port for the torque converter relief valve (10) Return port for the relief valve (torque converter cooler) (11) Return ports for the brake oil coolers (12) Drain port for the parking brake and secondary brake control valve (13) Drain port for the lip seal case of the parking brake (14) Drain port for the brake makeup oil tank (15) Drain port for the pilot valve (hoist) (16) Return ports for the relief valves for the rear brake oil coolers (17) Return port for the hoist control valve (18) Suction port for the transmission (19) Drain port for the transmission section (20) Suction ports for the hoist pumps (21) Suction port for the pump (transmission cooler) (22) Drain port for the torque converter, hoist and brake section (23) Suction port for the pump (torque converter cooler) (24) Suction port for the torque converter pump