In my industry recently I have faced some problem with CCM turret arm lifting hydraulic system. during 100 MT load lifting hammering sound and metal to metal hammering sound observed and note for you that flow-Q meter used for load holding and arm down time and flow control valve, pilot operated check valve and rotary joint used. rotary joint have internal leakage. what is the reason of metallic sound please let me know. Thanks.

Hydraulic cylinder lifting time sound intensity is high. metal hammering sound. we changed pivoting pi or arm but problem not yet solved.