Fault Phenomenon: Putzmeister M47 pumps smoothly when cold. After reaching operating temperature (oil temp 80℃), outlet pressure fluctuates, and the reversing impact is strong, with a noise alarm on the dashboard.

Troubleshooting Process:
– Checked accumulator nitrogen pressure: pressure normal, bladder intact.
– Checked reversing proximity switches: signal triggers sensitively, position accurate.
– Checked displacement sensor shielding: exterior intact, ground normal.
– Measured displacement sensor feedback at operating temperature: found high-frequency noise interference on the feedback signal.

Root Cause: Poor grounding of the displacement sensor shield, affected by electromagnetic interference from the hydraulic pump.

Required Parts: Main cylinder displacement sensor and shielded ground wire.