if the solenoid pilot valve into the exhaust hole blocked by sludge and other debris, not tightly closed, the movable iron core clamping circuit failure, which can lead to the valve does not change. The pilot valve should be cleaned and the activity of sludge and impurities on the core of the former 3 cases. The circuit fault is generally divided into two types of control circuit fault and electromagnetic coil fault. Before checking the circuit fault, the valve should be turned on the manual knob several times, to see whether the nominal pressure of the valve can be normally reversed, if the normal commutation, the circuit is faulty. When the inspection, the instrument can be used to measure the voltage of the electromagnetic coil, to see whether the rated voltage, if the voltage is too low, it should be further check the power supply in the control circuit and the associated trip switch circuit. If the rated voltage of the valve can not be normal commutation, it should check the electromagnetic coil connector (plug) is loose or contact is not real. Method is to pull the plug, measure the coil resistance, if the resistance is too large or too small, indicating that the electromagnetic coil is damaged, should be replaced.。对此，应先检查油雾器的工作是否正常；润滑油的粘度是否合适。必要时，应更换润滑油，清洗换向阀的滑动部门，或更换弹簧和换向阀。检查时，可用仪表丈量电磁线圈的电压，看是否达到了额定电压，假如电压过低，应进一步检查控制电路中的电源和相联系关系的行程开关电路。而电路故障一般又分为控制电路故障和电磁线圈故障两类。方法是，拔下插头，丈量线圈的阻值，假如阻值太大或太小，说明电磁线圈已损坏，应更换。
the reversing valve can not reverse or change the slow action, generally due to poor lubrication, the spring is stuck or damaged, oil or impurities stuck sliding part and other reasons. In this regard, we should first check the oil mist is working properly; the viscosity of the oil is suitable. If necessary, replace the lubricating oil, clean the sliding part of the valve, or replace the spring and the valve.
Bending machine hydraulic system faults are: valve can not change or change the slow action, leakage, electromagnetic pilot valve failure, etc..
(2) for a long time after the use of the valve spool valve sealing ring wear, stem and valve seat damage phenomenon, resulting in leakage of the valve, the valve action is slow or not normal commutation failure. At this point, the sealing ring should be replaced, the stem and the valve seat, or to replace the valve.