Fault Phenomenon: The Zoomlion ZCC3200NP crane body drifts noticeably to the left during straight-line travel, requiring constant steering correction.

Troubleshooting Process:
– Check track tension: Tension is consistent on both sides.
– Check travel motor: Motor operation sounds normal.
– Check travel reducer: Internal planetary gear wear found.
– Check counterbalance valve: Left travel counterbalance valve spool wear causing internal leakage and slow pressure build-up.
– Replaced left travel counterbalance valve.

Root Cause: Internal leakage in single-side travel counterbalance valve causing insufficient driving force.

Required Parts: Travel counterbalance valve, seal rings.