1, hydraulic pump or motor noise

(1) suction is one of the main reasons for the high noise of hydraulic pump. When the oil is mixed with air, it is easy to form the cavitation phenomenon in the high pressure area, and it is transmitted in the form of pressure wave, which causes the oil oscillation, which results in cavitation noise. The main reasons are:

Hydraulic pump oil filter, oil inlet pipe blockage or oil viscosity is too high, can cause the pump into the mouth of the vacuum is too high, so that the air infiltration.

Hydraulic pump, the end of the pilot pump shaft seal damage, or poor seal into the pipe, causing air to enter.

Fuel tank oil level is too low, so that the hydraulic pump directly into the suction tube. When the hydraulic pump in the work of high noise, the above should be the first to check the site and found problems in a timely manner.

(2) the internal components of the hydraulic pump excessive wear, such as hydraulic pump cylinder and valve plate, and with blade rotor parts wear, tear, make a serious leak in the hydraulic pump, when the hydraulic pump output pressure and flow pulsation will produce small flow oil, causing high noise. At this point, the deflection angle of the pilot system can be increased to improve the effect of internal leakage on the pump output. The piston of the hydraulic pump to control the flow will also be due to local wear, strain, so that the piston in the process of moving the pulse, resulting in fluctuations in the output flow and pressure of the hydraulic pump, resulting in large vibration and noise at the exit of the pump. At this time can be worn, strained parts of the brush plating or replacement.

(3) the valve plate is one of the most important components of the noise. In the use of the plate in the use of surface wear or sludge deposition in the unloading tank opening, will make the unloading groove shorter and change the unloading position, resulting in trapped oil phenomenon, and then lead to higher noise. In the normal repair process, the flat grinding repair of the flow plate will also appear to reduce the consequences of unloading tank, this time if it is not appropriate in a long time, it will produce a greater noise. In the assembly process, the large discharge tank must be installed in the high pressure chamber of the pump, and the direction of its sharp angle and cylinder rotation must be relative, otherwise it will bring greater noise to the system.

2 relief valve noise relief valve is prone to high frequency noise

The pilot valve is mainly caused by the instability of the performance, that is, the pilot valve cavity pressure oscillation caused by high frequency vibration caused by air vibration. The main reasons are:

(1) the air is mixed in the oil, the cavitation phenomenon is formed in the cavity of the pilot valve, which results in the high frequency noise. At this point, it is necessary to exhaust the air in time and prevent the air from entering.

(2) the needle valve in the use of the process of frequent opening and excessive wear, so that the valve cone and the valve seat can not be closed, resulting in the pilot flow instability, resulting in pressure fluctuations caused by noise, this time should be repaired or replaced.

(3) pilot valve because of spring fatigue deformation caused by the pressure regulating function is not stable, so that the pressure fluctuations caused by noise, this time should replace the spring.