General particle size in the 10μm below the effect of pollutants on the pump is not obvious, and more than 10μm, especially in the 40μm above the pump service life has a significant impact. The solid pollution particles in the hydraulic oil are very easy to increase the surface wear of the relative moving parts in the pump, so it is necessary to install the oil filter to reduce the pollution degree of oil. Filtration Accuracy requirements: axial piston pump 10~15μm, vane pump for 25μm, gear pump for 40μm. The contaminated wear of the pump can be controlled within the allowable range. The use of high-precision oil filters is increasingly widely used, which can greatly prolong the service life of hydraulic pumps.