1, Abnormal noise
The oil pump has abnormal noise during operation.It is generally caused by the pump suction air or oil pump damage. First, check the oil quantity in oil tank.maybe it is too low.Or the oil filter is blocked by dirts; secondly, check the oil suction pipe,maybe it is loose; finally, check the pump,maybe it is damaged. If the pump is damaged, pump body is so hot in most cases .
2,The Piston Stroke Slow
First, check if the oil quantity is too low, or low pressure oil filter is blocked by dirt; Secondly, check whether the card or oradjusting screw is loose, which would result in fluid pressure become low;Thirdly, check if the poppet of hydraulic control one-way is stuck by dirt. Lastly, check if the pump is damaged.
3,Pressure Rises Slowly When It Boost
First, check the combination valve spool ,maybe it is stuck by dirt ; Secondly, check the pressure relief valve adjustment screw ,maybe it is loose, whether the valve is dirtstuck, adjusting spring failure; Thirdly, check if the poppet of hydraulic control one-way is stuck by dirt ;Lastly, check if the pump is damaged.
4, Pressure-maintaining Performance is Not Good.
Firstly, maybe the ring to the pipe inspection is damaged, or the fasteningbolts is loose. Secondly, check the high, low pressure one-way valve and the hydraulic control one-way valve,maybe it is losing the sealing effect, if the sealing surface of the valve, valve seat is damaged, it should be regrinding.Secondly, check if the pipe connector "O" type sealing ring or gasket leaks.Finally, check if the oil of the sealing ring of the hydraulic cylinder is leaking.