Hi everyone! I was called some time ago to perform a troubleshooting on a Hydraulic Crane which had all its functions working perfectly, except for its main winch lowering command. As it was operated to lower the hook, it was taking about 6 seconds to reach its maximum pressure and then manage to respond to the command. We have checked for obstructions, contamination, pressure, PLC configurations, exchanged valves but nothing changed a thing. Does everyone nows what could it be? That's an offshore Straight Crane, with an auxiliary and a main winch.
What type of controls, direct linkage, hydraulic pilot, electrical, electronic?
It may just take that long for it to build the pressure to compress the brake pack enough to start cabling down. Typically down is much slower than up. Cable up usually has a overrunning clutch so it won't have to compress the brake pack, only cable down will have that.