The troubleshooting sequence is :oil pump motor unit, reversing sensor switch, reversing valve, overflow valve, hydraulic cylinder seals

A: Check oil pump and motor unit,start up motor and oil pump, observe  whether the oil sunction tube of piston pump enter oil, if no, the phase of three-phase power supply has changed (motor reversed)

Oil pump and motor abnormal solution:

1. exchange the positon of random two input (output)wire of breaker

2. maintenance or change oil pump and motor, enter oil pump and motor is normal, processing the next step checking

B: Check the reversing Hall switch ,Turn on the power,  do not start up the motor and oil pump, take out the Hall switch , approach the Hall swithc to the magnet in turn(pay attention to the polarity,Try with both ends of the magnet), the hall switch indicates whether the light is on/off corresponding . At the same time,observe whether the relay which connected with the Hall switch has action. Can not light on/off, Hall switch damage,please replace;The relay  no action, relay dagamed, solution: replace new replay could turn on/off corespondingly; Hall switch no damage/the relay is normal, proceed to the next inspection

C. Check the reversing valve ,Turn on the power, do not start up the motor and oil pump, approach the Hall switch to the magnet in turn,and at the same time sense whether the solenoid valve stem of the reversing valve moves by hand.it can be repeated serveral times, to make sure the steability. Valve stem not moving and reversing valve working abnormal 

solution:1. cleaning the poppet valve and valve body;

2.replace new valve, valve stem movement,reversing valve normal, proceed next inspection.

D. Check the overflow valve, Turn on the power, do not start up the motor and oil pump, press the high pressure start knob, using your hand to sense whether the solenoid valve stem of overflow moves. It can be repeated many times to make sure the steability.

Valve stem not moving, overflow valve abnormal working solution：

1. clean the poppet valve and valve body 

2. replace new valve. Valve stem moving and overflow valve working normal, proceed the next inspection.

E .Check the hydraulic cylinder seal, start up the oil pump and motor( pay attention: do not open the high pressure), hold the two Hall switch in the hand,approach them to the magnet respectively, at the same time pay attention to the movement in the hydraulic cylinder, and observe whether there is oil leakage in the peephole behind the two baffles. Both two ends no movement or in one of the direction no movement, seals on the piston are failed.

Solution: disassembly the hydraulic cylinder, take out the piston, replace with new seal assy. At the same time, replace the oil seals in  the baffles which there is leaking