What are the common noises of hydraulic components? How should one deal with it?

1. Noise from plunger pumps or motors

(1) The suction phenomenon is one of the main reasons for the excessive noise of the hydraulic pump. When air is mixed into the oil, cavitation is likely to form in its high-pressure area and propagate in the form of pressure waves, causing the oil to oscillate and resulting in cavitation noise in the system.

(2) Excessive wear of internal components of the hydraulic pump, such as the wear and scratches of the mating parts between the cylinder body and the distribution plate, the plunger and the plunger hole of the plunger pump, etc., causes severe leakage inside the hydraulic pump. When the hydraulic pump outputs high-pressure and low-flow oil, it will generate flow pulsation and cause high noise. At this point, the deflection Angle of the variable mechanism of the pilot system can be appropriately increased to improve the influence of internal leakage on the output flow of the pump. The valve core of the servo valve of the hydraulic pump and the piston that controls the flow may also be locally worn or scratched, causing the piston to pulsate during movement, resulting in fluctuations in the output flow and pressure of the hydraulic pump, and thus generating significant vibration and noise at the pump outlet. At this point, the components that are severely worn or scratched can be treated by brush plating and grinding or replacement.

(3) The distribution plate of the hydraulic pump is also one of the important components that are prone to causing noise. During operation, if the surface of the distribution plate wears out or oil sludge deposits at the opening of the unloading trough, the unloading trough will become shorter and the unloading position will change, resulting in trapped oil and subsequently causing high noise. During the normal repair process, the distribution plate that has been repaired by flat grinding may also experience a shortening of the unloading groove. If it is not appropriately lengthened in time at this point, it will also generate considerable noise. During the assembly process, the large unloading groove of the distribution plate must be installed in the high-pressure chamber of the pump, and its sharp corner direction must be opposite to the rotation direction of the cylinder body; otherwise, it will also cause significant noise to the system.

2. Noise from the relief valve

The relief valve is prone to generating high-frequency noise, mainly due to the unstable performance of the pilot valve. That is, the noise is caused by the high-frequency oscillation of the pressure in the front chamber of the pilot valve, which leads to air vibration. The main reasons are:

(1) Air mixed into the oil forms cavitation in the front chamber of the pilot valve, causing high-frequency noise. At this point, all the air should be promptly expelled and the re-entry of outside air should be prevented.

(2) During the operation of the needle valve, due to frequent opening, excessive wear occurs, causing the conical surface of the needle valve and the valve seat to fail to fit tightly, resulting in unstable pilot flow, pressure fluctuations and noise. At this time, timely repair or replacement should be carried out. Wear-resistant electrode

(3) The pilot valve's pressure regulation function is unstable due to the fatigue deformation of the spring, causing large pressure fluctuations and noise. At this time, the spring should be replaced.

3. Noise from the hydraulic cylinder

(1) When air is mixed in the oil or the air in the hydraulic cylinder is not completely discharged, cavitation occurs under high pressure, causing significant noise. At this point, all the air must be expelled in a timely manner.

(2) If the oil seal at the cylinder head is too tight or the piston rod is bent, noise will also be generated during movement due to the lack of force. At this point, the oil seal must be replaced in a timely manner or the piston rod straightened.