797 Off-Highway Truck Hydraulic System Caterpillar

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Front view

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Section A-A

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Rear view

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Front view without cover plate

(1) Breather port for the hydraulic tank

(2) Fill port for the hydraulic tank

(3) To complete the seal, cross the ends.

(4) Torque for 14 bolts ... 30 ± 7 N·m (22 ± 5 lb ft)

(5) Port for the full warm switch for the Wiggins system (if equipped)

(6) Port for the full cold switch for the Wiggins system (if equipped)

Note: Do not exceed 70 kPa (10 psi) of pressure in the tank when the air test kit is connected to the port for the full cold switch.

(7) Fill port for the steering hydraulic tank

(8) Breather port for the steering hydraulic tank

(9) Port for the oil level sensor

(10) Return port for the fan drive, for the steering system, and for the motor that drives the brake cooling pump sections

(11) Port for the oil temperature sensor

(12) 7B-3039 Spring

Length under test force ... 26.2 mm (1.03 inch)

Test force ... 14.3 to 16.8 N (3.22 to 3.78 lb)

Free length after test ... 36.6 mm (1.44 inch)

Outside diameter ... 19.8 mm (0.78 inch)

(13) Torque for the plugs on the drain valves ... 50 ± 7 N·m (37 ± 5 lb ft)

(14) Return port for the hoist system

(15) Suction port for the brake actuation pump section

(16) Return port for front brake cooling

(17) Supply port and return port for the pump section for the piston motor that drives the rear axle oil pump

(18) Port for the dead engine hydraulic oil level switch for the Wiggins system (if equipped)

(19) Return port for brake actuation oil

(20) Supply port for rear brake cooling pump sections

3K-4056 Spring at the end of the screen

Length under test force ... 17.48 mm (0.688 inch)

Test force ... 222.5 ± 22.2 N (50.02 ± 4.99 lb)

Free length after test ... 34.14 mm (1.344 inch)

Outside diameter ... 59.64 mm (2.348 inch)

(21) Suction port for fan drive

(22) Piston motor that drives the brake cooling pump sections

(23) Supply port for front brake cooling pump section

3K-4056 Spring at the end of the screen

Length under test force ... 17.48 mm (0.688 inch)

Test force ... 222.5 ± 22.2 N (50.02 ± 4.99 lb)

Free length after test ... 34.14 mm (1.344 inch)

Outside diameter ... 59.64 mm (2.348 inch)

(24) Fill port for the body hoist section of the hydraulic tank for the Wiggins system (if equipped)

(25) Suction port for hoist pump

(26) Suction port for steering pump

(27) Fill port for the steering hydraulic tank for the Wiggins system (if equipped)

(28) Suction port for the piston pump for the piston motor that drives the brake cooling pump sections

(29) Return ports for rear brake cooling oil

(30) Return ports for front brake cooling oil

(31) Four screens for the hoist return lines.

Torque for the two locknuts for the screens ... 20 ± 5 N·m (15 ± 4 lb ft)

(32) Screen for the return line for the fan drive, for the steering system, and for the motor that drives the brake cooling pump sections

Torque for the locknut for the screen ... 20 ± 5 N·m (15 ± 4 lb ft)

(33) Two relief valves

Note: Refer to the Braking System Specifications, "Relief Valve (Brake Oil Cooler)".

(34) Screen for the supply line for the rear brake cooling

(35) Screen for the supply line for the front brake cooling

(36) Front brake cooling pump sections

(37) Rear brake cooling pump sections

Hydraulic Tank Mounting

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(1) Torque for mounting bolts ... 900 ± 100 N·m (664 ± 74 lb ft)

(2) 8X-2576 Shim Pack

Shim Pack thickness ... 1.64 mm (0.065 inch)

Note: Bolt the cap to the frame without the hydraulic tank in place. Measure the vertical diameter. Measure the diameter of the pipe assembly on the hydraulic tank. Subtract the first measurement from the second measurement. Install the shims at each bolt so that the gap is equal to 0.00 to - 0.12 mm (0.000 to - 0.005 inch).