992K Wheel Loader Electrohydraulic System Caterpillar

The ride control valve uses pilot oil pressure in order to shift the diverter ride control valve. The pilot oil is supplied to the ride control valve from the pilot pump. The flow of pilot oil to the ride control valve is controlled by the solenoid valve (ride control).

When the solenoid valve (ride control) is energized, pilot oil flow to the end of the diverter valve spool is blocked by the solenoid valve. The end of the diverter valve spool is connected to the hydraulic tank. The spring on the end of the spool shifts the diverter valve spool. The head end of the lift cylinders is connected to the ride control accumulators and the rod end of the lift cylinders is connected to the tank.

The signal pressure for the ride control is measured from a port on the diagnostic plate. The diagnostic plate is located on the right side of the hitch area.

Illustration 1	g06220393
Diagnostic plate (1) Pressure tap for ride control valve

Before proceeding to the test procedure that follows, complete the procedures:

Reference: For additional information about preparing the machine for troubleshooting the machine, refer to the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.

Reference: For additional information about releasing the system pressure in the machine, refer to the Service Manual module Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

1. Attach a 8T-0850 Gauge ( 4000 kPa (580 psi)) to the port for the ride control. The port for the ride control is located on the diagnostic plate.

2. Engage the parking brake.

3. Shift the transmission to neutral.

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

5. Run the engine at low idle.

6. Move the ride control switch to the MIDDLE position which is the OFF position. Record the gauge reading.

7. The gauge reading should be 3500 ± 150 kPa (508 ± 22 psi). The gauge reading is the pilot pressure during engine operation.

8. Release the pressure in the pilot system.

   Reference: For additional information about releasing the system pressure in the machine, refer to the Service Manual module Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

9. Remove the gauge from the port for the ride control (1) on the diagnostic plate.