Fault Phenomenon: SANY STC750 when lifting heavy loads, the main winch moves slowly and is weak, accompanied by abnormal noise from the hydraulic pump.

Troubleshooting Process:
– Checked hydraulic oil level: level low.
– Checked suction filter: found severely clogged.
– Tested main pump output pressure: pressure only 60% of rated value.
– After cleaning the filter and replacing the hydraulic oil, pressure returned to normal.

Root Cause: The hydraulic suction filter was clogged, causing the main pump to cavitate, reducing output flow.

Required Parts: Hydraulic suction filter, anti-wear hydraulic oil.