1. Check whether the hydraulic pump can output hydraulic oil. If it is a new hydraulic pump without hydraulic oil output, it may be that the pump body has casting defects (shrinkage cavity, sand hole, etc.), which connects the oil suction chamber and oil pressure chamber and loses the oil pressure capacity. It should be replaced by the manufacturer in time. If it is not a new hydraulic pump and there is no hydraulic oil output, the steering of the pump may be wrong, and the parts may be seriously worn or damaged. Replace them in time.

2、若液压泵有油液输出，查看溢流阀工作是否正常。若不正常，则可能是压力油路中的某个阀有污物或其他原因卡住，处于回油位置，致使压力油路与溢流回路短路，也可能是管接头松脱，或处于压力油路中的某些阀泄漏严重，或液压缸、液压马达的密封损坏，严重泄漏。

2. If the hydraulic pump has oil output, check whether the overflow valve works normally. If it is abnormal, it may be that a valve in the pressure oil circuit is stuck due to dirt or other reasons and is in the oil return position, resulting in a short circuit between the pressure oil circuit and the overflow circuit, or the pipe joint is loose, or some valves in the pressure oil circuit leak seriously, or the seals of the hydraulic cylinder and hydraulic motor are damaged and leak seriously.

排除方法：拆开有关阀进行清洗，检查密封间隙的大小及各种密封装置，密封装置损坏应更换。

Troubleshooting: disassemble relevant valves for cleaning, check the size of sealing gap and various sealing devices, and replace the damaged sealing device.

3、若液压泵输出流量随压力升高而显着减小，且压力达不到规定值，则是由于液压泵磨损后间隙增大所致。

3. If the output flow of the hydraulic pump decreases significantly with the increase of pressure, and the pressure cannot reach the specified value, it is due to the increase of clearance after the hydraulic pump is worn.

排除方法：测定液压泵的容积效率，即可确定该泵是否能继续使用，对磨损严重的零件，应进行修配或更换。

Troubleshooting: determine the volumetric efficiency of the hydraulic pump to determine whether the pump can continue to be used. Repair or replace the severely worn parts.

4、若整个液压系统能建立正常压力，而某些管路或液压缸（或液压马达）中无压力，则可能是由于管路、小孔或节流阀、换向阀等部位堵塞。此时，应逐段检查压力和有无油液通过，找出原因，加以排除。

4. If the whole hydraulic system can establish normal pressure, but there is no pressure in some pipelines or hydraulic cylinders (or hydraulic motors), it may be due to the blockage of pipelines, small holes, throttle valves, directional valves and other parts. At this time, the pressure and the passage of oil should be checked section by section to find out the cause and eliminate it.