① first check the hydraulic oil level is normal, if the oil level should be added to the specified location; restart the motor to observe the vacuum gauge reading is normal.
② stop state, open the main power supply, press the pump button to see if the control of the pump solenoid valve action, if not normal should be further identified as a line fault or solenoid valve coil damage or spool stuck. If it is normal, check the action of the hydraulic directional control valve.
③ the main cylinder in the commutation position does not move, you can determine the trip switch may be a problem.
④ Check the main pump system pressure, if not reach the specified value, you should check the relief valve and the main pump.
⑤ hydraulic oil temperature is too high, resulting in increased leakage, oil pressure drop, work weakness. Should repair the cooling system to ensure good heat dissipation.