Grade Control Valve Contamination Caterpillar

Problem:

The grade control valves may not respond properly during automatic operation due to silting of the spool area.

Solution:

The valves can be flushed of contamination using the following procedure.

1. Remove 137-3603 Grade Control Valve from 136-5748 Control Manifold.

2. Remove the small orifice from the bottom side of the valve and reinstall the valve to the manifold. Note location of the orifice.

3. Start the machine and cycle the tow point valve top to bottom ten times to flush material from the cylinder.

4. Disconnect the hoses from the tow point cylinder, cap the cylinder using two 6V-9829 Caps and connect the cylinder hoses together using two 6V-8397 O-rings and one 6V-8730 Connector.

5. Locate the tow point jog switch and install a small jump wire from terminal number (1) of the switch to terminal number (2) of the switch.

6. Start and run the machine for a minimum of 30 minutes to allow the oil to flush the control valve.

7. Stop the machine. Remove the jump wire and reinstall the hoses of the cylinder.

8. Remove the control valve. Reinstall the orifice and the valve onto the machine.

9. Repeat the procedure for other side of the machine as necessary.

10.Warm the machine and recalibrate offsets using the appropriate Operations and Maintenance Manual, KEBU7008 for the Premier Grade and Slope System or KEBU7009 for the Topcon Grade and Slope System.

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