SWING MOTION IS IMPOSSIBLE IN ONE DIRECTION SWING MOTION IS IMPOSSIBLE IN ONE DIRECTION 3) 3) MACHINE SWINGS BUT DOES NOT STOP MACHINE SWINGS BUT DOES NOT STOP 4) 4) 5-11 Does symptom YES change when LH YES and RH port relief valves are exchanged Does swing control NO YES valve spool move smoothly by hand? Is MCV pilot NO pressure same for LH and RH? YES Check if pilot piping is not clogged or does NO not have oil Clogged or oil leakage. leak. Cause Remedy Swing port relief valve is faulty. Shuttle valve is faulty. Swing control valve spool is stuck. Pilot valve is faulty. Disassemble and repair. Disassemble and repair. Disassemble and repair. Disassemble and repair.
Clean pilot piping interior or repair piping. YES Is MCV pilot Is gear pump pilot YES YES pressure within pressure within standard value? standard level? NO Does swing control YES valve spool move smoothly by hand? NO Is swing control valve's return spring normal? NO NO Cause Remedy Pilot relief valve is faulty. Disassemble and repair or replace. Disassemble and repair. Disassemble and repair. Disassemble and repair. Disassemble and replace. Gear pump is broken. Pilot valve is faulty. Swing control valve spool is stuck. Return spring is faulty.