1, the component of the circuit itself generated by bad action and mutual interference of the system circuit, as well as a component monomer abnormal action.

2. In the failure of hydraulic components, the failure rate of hydraulic pump is high, accounting for about 30% of the failure rate of hydraulic components, so enough attention should be paid to it.

3, due to improper selection of working media and poor management caused by hydraulic equipment failure is also very much. About 70% ~ 80% of all faults of hydraulic equipment are caused by hydraulic oil pollutants, and about 90% of faults caused by hydraulic oil are caused by impurities. Impurities are very harmful to hydraulic equipment. They can aggravate component wear, increase leakage, decrease performance, shorten life, and even lead to component damage and system failure.

4. Some hydraulic equipment failures are gradual, such as equipment disrepair, parts wear, corrosion and fatigue and aging seals;

5, some are sudden failure, such as components due to foreign bodies suddenly stuck, action failure caused by; Some faults are caused by comprehensive factors, such as the selection of component specifications, unreasonable configuration, due to improper installation, adjustment and setting;

6. Some are caused by mechanical, electrical and external factors. All these factors increase the difficulty of hydraulic equipment fault diagnosis.

7, because the hydraulic station system in the various hydraulic components of the action is mutual influence, so a fault removed, often there will be another fault, therefore, in the inspection, analysis, troubleshooting, must pay attention to the tightness of the hydraulic equipment.