Fault Phenomenon: The XCMG XCA4000 exhibits unsmooth action and occasional stuttering during main boom extension.

Troubleshooting Process:
– Check hydraulic oil level: Normal.
– Check extension cylinder: No internal leakage.
– Check boom sliders: Slight wear.
– Check electro-proportional valve: Valve spool slightly sticking.
– Cleaned valve body and restored normal operation.

Root Cause: Slight sticking of proportional valve spool.

Required Parts: Proportional valve cleaning kit, hydraulic oil.