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

Illustration 1	g00302043
(1) Pressure compensator valve (2) Steering pump (4) Plug

Illustration 2	g00302023
(1) Pressure compensator valve (2) Steering pump (3) Pump drive (4) Plug

Illustration 3	g00430304
(5) Pressure tap

The following test covers the setting of the pressure compensator valve.

Pressure compensator valve (1) is mounted to the steering pump (2). The steering pump (2) is mounted to the pump drive (3). The pump drive (3) is located on the inside of the right frame rail near the torque converter.

The pressure setting of the pressure compensator valve (1) is 17580 ± 345 kPa (2550 ± 50 psi).

In order to check the pressure setting of the pressure compensator valve, use the following procedure:

1. Remove the cap from pressure tap (5). Pressure tap (5) is located on the steering accumulator.

2. Install a 8T-0859 Pressure Gauge on pressure tap (5) .

3. Start the engine and operate the engine at low idle.

4. The pressure reading on the gauge should go up to 17580 ± 345 kPa (2550 ± 50 psi).

5. Stop the engine. If the setting of the pressure compensator valve (1) is incorrect remove plug (4) .

6. If the pressure setting is low, increase the thickness of the shims behind plug (4) .

7. If the pressure setting is high, decrease the thickness of the shims behind plug (4) .

8. Install plug (4) and repeat Steps 3 through 7 until the proper pressure is attained.

9. Remove the test equipment and replace the cap on pressure tap (5) .

Leakage

A leakage oil test for the condition of the steering pump is made on a hydraulic test bench. The Leakage Oil Chart has the information that is needed for the test.

The steering pump has too much wear if the leakage oil is more than the value found on the Leakage Oil Chart and the pump output is less than the value found on the Leakage Oil Chart.