Troubleshooting of excavator's sudden inaction

(1) Fault phenomenon

A modern 220LC-5 hydraulic excavator suddenly failed to respond to all operations while the engine was running normally in use.

(2) Troubleshooting

During maintenance, open the side cover at the operating handle of the hydraulic lock. There is a light touch two position switch inside. The switch works normally after testing. Then open the side cover of the main hydraulic pump of the excavator, unplug the plug of the pilot valve coil, start the engine, release the handle of the hydraulic lock, and the measured terminal voltage of the pilot valve plug is 27V, which is normal.

Then the resistance of the solenoid coil of the pilot valve is measured to be 18M Ω (the normal value is 27 Ω), indicating that the solenoid coil is damaged.

Because the coil of the same model can not be purchased locally and the price is high, it was decided to rewind the coil by itself. The measured coil resistance was 28 Ω. Then, connect the plug of the original coil with the connector of the new coil. After the coil was soaked, insulated and dried, install it back on the excavator. Test the machine, and the machine works normally.