The reason that the running speed of hydraulic cylinder slows down

After a certain period of application, the hydraulic cylinder appears to run at a slower speed. In general, when the working pressure reaches the regulating pressure of the relief valve, the relief valve begins to overflow and the movement speed of the hydraulic cylinder slows down. The slower the moving speed of the hydraulic cylinder affects the working speed of the whole hydraulic system, so that the whole machine will become slow when it works.


The internal leakage of the hydraulic cylinder itself is serious when the hydraulic cylinder moves, the pressure oil in the high pressure cavity of the hydraulic cylinder leakage to the low pressure cavity. The reason for the leakage is that the gap between piston and cylinder is too large because of wear, or the piston seal ring is broken.


1. The motion speed of the hydraulic cylinder is the ratio of the flow rate of the input cylinder to the effective area of the piston. The hydraulic cylinder movement speed is reduced due to the reduction of the actual flow of the piston movement due to the leakage. At this time, the piston shall be replaced to ensure a reasonable clearance between the piston and the cylinder barrel. If the piston seal ring is damaged, replace it with a new one.


2. The pressure oil of the hydraulic system is supplied by the hydraulic pump due to insufficient flow of the hydraulic pump. Generally, the proper pump is selected to avoid insufficient oil supply. Due to the oil pollution, the oil filter is blocked and other reasons, the oil suction of the pump is insufficient, so the pump flow must be insufficient. The serious wear and tear of the parts, the serious internal leakage and the sharp decline of the volume efficiency are also the reasons for the insufficient oil discharge of the pump.


3. The internal leakage of the directional valve is serious. The inner seal of the reversing valve is guaranteed by the clearance between the valve core and the valve hole. Due to various reasons, the gap between the valve core and the valve hole increases, so when the pressure oil from the pump enters the directional valve, it will flow from the inner annular gap into the low pressure cavity from the high pressure cavity to the low pressure cavity, which greatly reduces the oil flow rate through the directional valve, thus reducing the flow rate flowing into the hydraulic cylinder.