In the hydraulic system of the waste paper baler, cavitation and cavitation are most likely to occur at the inlet of the oil pump. This is because the oil pump rotates fast, sucks oil by vacuum, and the local pressure is low, so bubbles are most likely to escape. Therefore, the oil suction height should be shortened as much as possible, especially in the oil inlet pipeline, the flow rate should not be too fast, and as few valves and fine filters as possible, in order to increase the local pressure of the waste paper baler oil suction. It is generally not recommended to use a "positive pressure fuel tank" that passes pressure gas into the fuel tank. The occurrence of cavitation and cavitation will cause the discontinuity of the liquid flow and destroy the normal operation of the waste paper baler. Insufficient oil absorption at the inlet of the pump and reduced outlet flow will cause the metal in the oil suction cavity to be oxidized and corroded, causing noise and shocks. In the hydraulic system of the waste paper baler, when the oil circuit is changed rapidly or the oil circuit is opened and closed, the oil speed will change greatly, and the oil pressure in the waste paper baler system will change drastically and generate high pressure. This is Hydraulic shock phenomenon. The maximum pressure generated is called impact pressure. The pressure is often several times higher than normal pressure. This phenomenon is often seen in daily life. For example, when you suddenly turn off the tap, you hear the click sound, which is the hydraulic shock of the waste paper baler. Hydraulic shock is harmful to the equipment and measures should be taken to prevent it. The easiest way is to add a high-pressure hose where impact is prone to occur. There are also buffer ports on the valve structure to delay the opening and closing time, and there are also safety valves and stepped pressure reduction methods.