Fault Phenomenon: Schwing S600 hydraulic system functions normally when cold. During high-pressure pumping (operating temperature), the hydraulic system pressure pulsates, the pressure gauge needle swings, and eventually loses power.

Troubleshooting Process:
– Checked hydraulic pump pistons: wear normal, no scoring.
– Checked valve plate: surface smooth, no burning.
– Checked accumulator: pressure normal, bladder intact.
– Measured hydraulic pump flow at operating temperature: found excessive flow pulsation.

Root Cause: Fatigue of the hydraulic pump piston springs causes delayed return under thermal conditions.

Required Parts: Hydraulic pump piston assembly and springs.