784C and 785C Off-Highway Truck/Tractors Steering System Caterpillar

Illustration 1	g00301062
(1) Steering crossover relief valve (2) Relief valves (3) Shims (4) Pressure taps

Illustration 2	g00430218
(1) Steering crossover relief valve (4) Pressure taps

The pressure setting of the steering crossover relief valve is 18270 ± 345 kPa (2650 ± 50 psi) at a flow of 7.57 ± 0.95 L/min (2.000 ± 0.251 US gpm).

Steering crossover relief valve (1) must be removed and tested on a bench in order to meet the flow requirements for steering crossover relief valve (1) .

A functional test of the steering check and relief valves may be performed on the machine.

1. Start the engine.

2. Steer the truck all the way in the left direction until the steering stop is reached.

3. Stop the engine.

4. Install Tool (A) to the test port for the left steering cylinder.

5. Attach Hydraulic Hand Pump (B) to Tool (A) .

6. Operate Tool (B) and pressurize the steering system.

7. If the pressure setting is low, add shims (3). If the pressure setting is high, remove shims (3). One 8J-7270 Shim will change the pressure setting approximately 504 kPa (73 psi).

8. Remove all tooling from the pressure tap for the left steering cylinder (4) .

9. Repeat Step 1 through Step 8 for the right steering check and relief valve.

10. For Step 9, steer the truck all the way in the right direction until the steering stop is reached.