992K Wheel Loader Electrohydraulic System Caterpillar

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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth, level surface. Lower the work tool to the ground and engage the parking brake. Stop the engine and remove the key. Block the wheels and install the steering frame lock.

The pilot oil comes from the fan pump and supplies oil to the pilot control valves on the main implement control valve. The pilot control valves allow pilot oil to shift the main control valve spools. The opening of the makeup valves will allow the bucket to float. The pilot oil is also used to shift the diverter valve in the ride control system. Pilot oil also flows to the actuator valves on the implement pump to control pump displacement.

The pilot pressure reducing valve controls the pressure of the pilot oil system. The pilot pressure reducing valve is on the right inside frame.

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Illustration 1	g06220367
Diagnostic plate for implement supply (1) Tap for pilot supply pressure

1. Connect the steering frame lock link.

2. Attach a 8T-0850 Gauge ( 4000 kPa (580 psi)) to pressure tap (1) on the manifold.

3. Engage the parking brake.

4. Shift the transmission to neutral.

5. Start the engine. Warm the hydraulic oil to a normal operating temperature of approximately 49 to 65°C (120 to 150°F).

6. With the engine at low idle, record the gauge reading.

7. The pilot oil pressure should be 3705 ± 605 kPa (537 ± 88 psi).

8. If the pilot pressure is not correct, the pilot pressure reducing valve setting must be adjusted.
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   Illustration 2	g06220369
   Right Side Frame (2) Pilot pressure reducing valve (3) Locknut (4) Adjustment screw for pilot pressure

9. Loosen locknut (3).

10. Turn adjustment screw (4) clockwise to increase the pilot pressure.

11. Tighten the locknut (3).

Perform Testing and Adjusting, "Pressure Reducing Valve (Pilot Oil) - Test and Adjust" again to verify the new pressure setting.