Rotating seal is installed on the hydraulic pump and hydraulic motor axis, to prevent work medium leakage along the axis to the casting then together with the outer dust reverse invade the body inside.General oil seal pressure ability is poorer, generally 0.2 0.3 MPa, fluorine rubber pressure seal bearing capacity is 0.25 to 0.25 MPa, Othello seal of high pressure oil seal maximum pressure is 40 MPa.