The tank body and the return oil pipe extend from the outside of the tank body to the inside of the tank body, and the return oil pipe is arranged at the opening of the tank body with a filter element, of which the filtering precision of the filter element is less than 20 microns. By making the filter precision of filter element 7 less than 20 microns, the impurity particles with a diameter of 20 microns or less in the hydraulic pressure can be filtered by the filter element, so that these impurity particles will not enter the clearance of the steering valve, thus avoiding the damage of the impurities particles to the steering device and ensuring its normal operation.

To tank and its medium-duty truck and steering system, power steering oil tank, including tanks, tank cover, screw, fuel cap, filter assembly and fastener component, fastener components include buckles of tank and tank cover buckles, tanks and tank cover by buckles of tank and tank cover buckles the spin riveting between extrusion of plastic deformation and the sealing connection, can cover zerk with outward, fuel cap cover part of the matching connections for fitting, female connection of fuel cap into the fitting, and thread sleeve connection, filter assembly put in tanks, maneuverability to connect to the thread. Utility model can be cancel installation clearance between tank and tank cover, on the one hand, can be solved between tank and tank cover seal failure caused by the leakage and improve the vehicle's direction and safety performance, cancelled the seal on the other hand, reduced the number of parts and components, in addition, the outer surface of the tank and tank cover, no sludge, improve the quality of the whole tank appearance.