Hydraulic transmission system has been widely used in various fields due to its unique advantages, which has extensive process adaptability, excellent control performance and lower cost. Because objective element, auxiliary parts quality is not stable, and the subjective use and maintenance are improper, and the components and working fluid in the system are within the closed oil circuit work, it is not as intuitive as machinery and equipment and also don't like electric equipment that can use various instrumentation easily measure various parameters. In hydraulic equipment, it only uses a few pressure gauges and flowmeters to indicate the the working parameters of some parts of the system. Other parameters are difficult to measure, and generally there are many possible fault source, which brings certain difficulty for the hydraulic system fault diagnosis.

On the production site, the fault diagnosis personnel are required to accurately, conveniently and efficiently diagnose the fault of hydraulic equipment due to the restriction of production plan and technical conditions. For maintenance personnel use of existing information and the scene of the technical conditions, reducing the mounting workload and saving time and cost of maintenance as far as possible, with the most simple technology, in the shortest possible time. Finding accurately out the cause of the failure positions and failure and repairing to make the system back to normal operation, and striving to the same failure will not happen in the future.