In use, the hydraulic transmission device may have many problems such as abnormality and leakage. In addition, during the operation of the equipment, many problems such as over-temperature will often occur, which will have a negative impact on the liquid in the equipment and reduce the characteristics.
1、 Basic principle of hydraulic control system
（1） Energy exchange
The principle of hydraulic transmission system is to use the pressure of the liquid to transmit power and pressure. It mainly uses the power element to convert the mechanical energy of the liquid into pressure energy, and then uses the actuating element to convert the pressure energy of the liquid into mechanical energy, so as to achieve the purpose of driving the working parts to move.
（2） Piston movement
The liquid substance moves in the system according to the efficiency of the gate valve in the internal structure of the machine and equipment, and then the liquid substance is upgraded through the hydraulic reversing valve and injected into the oil tank.
（3） Pressure control
In order to effectively control the hydraulic transmission device, it is also necessary to adjust the pressure and set up a safety valve to control the flow of liquid medium in the hydraulic cylinder. The hydraulic transmission device is an integrated system with various functions. It uses different adjustment methods to make the equipment move effectively and improve the transmission efficiency.
2、 Analysis of common faults
（1） Duality
The common faults of hydraulic control system are various. In the long use, there will not only be a single common fault, but also damage or incorrect operation of all machinery and equipment to parts with different internal structures, resulting in common faults. Some common faults will affect the overall operation of the mechanical system. Generally, industrial equipment errors will also lead to common faults in the operation of the electrical control system, making the whole processing process impossible.
（2） Diversity
The different nature of hydraulic press transmission fault results in different fault modes of hydraulic press transmission, which enhances the diversity of hydraulic press transmission fault and the difficulty of fault detection and fault handling. Therefore, for the first time, the cause of the hydraulic transmission system fault was uncertain, and the system abnormality could not be located. The common fault evaluation of the hydraulic control system was further complicated.
（3） Sharpness
Because the machine structure of the hydraulic transmission device is complicated and the internal structure is closed, it is not easy to notice the internal structure and parts. Once an exception occurs, it is difficult to determine the problem according to the immediate observation of the outside world. Be careful and clear it carefully, which also increases the time for troubleshooting.
3、 Common fault inspection
With the increase of service time, the probability of problems in the hydraulic control system will also increase, which will reduce the life cycle of the hydraulic control system. According to the phenomenon of various components of the hydraulic transmission system, the common faults of the hydraulic control system generally include abnormal vibration, noise, abnormal working pressure, oil leakage, etc., which can be further subdivided according to the severity of the common fault range. At present, the whole process of clinical diagnosis of hydraulic press system abnormality is basically as follows:
（1） Assignment determination
In case of failure, the maintenance manager should first clarify the job responsibilities and content assignment, define the inspection scope of each maintenance worker, and establish the work framework and objectives of fault handling.
（2） Field analysis
Before carrying out safety inspection on the system, the maintenance workers should communicate with the staff on the spot, investigate the operation status, check the equipment operation status, and establish the type and operation management status of the machine.
（3） Overall planning proposal
According to the basic causes and specific conditions of the fault analyzed on site, select the appropriate fault diagnosis method, prepare the detection equipment and components to be replaced in advance. At the same time, the following inspection methods and control points must be established, and the work orientation of maintenance workers must be established.
（4） Plan implementation
During the investigation, various methods should be used to determine the important reasons for the shortcomings. Then remove and replace the damaged components in the inspection process, upgrade the vulnerable components of the internal structure, tighten the anchor bolts, and apply oil to ensure the normal operation of the machine and equipment.
Source: Chengdu Zhengxi Group
