When the hydraulic pump is working, if the resistance of the oil suction pipeline is large, enough oil can not be sucked, and the oil can not fill the empty pump cavity, a vacuum will be formed in the local part of the pump, resulting in local low pressure. When the pressure is low enough to separate the air in the oil, a large amount of air dissolved in the oil will decompose. Form free bubbles. When the pressure is as low as the saturated vapor pressure of the oil, the vapor of the oil itself will also precipitate, and the oil will boil.

With the operation of the hydraulic pump, bubbles mixed in the oil are brought into the high pressure area. When the pressure rises, bubbles burst, shrink, dissolve and disappear. When the bubble bursts, it produces high-frequency impact force, and the pressure is very high, which can reach 150-200MPA, accompanied by local high temperature. On the one hand, the metal surface of hydraulic components appears cavitation phenomena such as peeling and pitting. On the other hand, it produces great high-frequency noise and vibration.

This is the source of vibration and noise in the excavator system.