The structure of the skeleton oil seal is simple, and generally consists of three parts: the oil seal body, the reinforced skeleton and the self-tightening spiral spring. The sealing body is divided into bottom, waist, cutting edge and sealing lip according to different parts. In general, in the Free State of the skeleton oil seal, its diameter is smaller than the shaft diameter, that is, with a certain“Interference”. Therefore, when the oil seal is put into the oil seal seat and the shaft, the pressure at the oil seal edge and the contraction force of the self-tightening spiral spring produce a certain radial tightening force on the shaft, therefore, the spring can be added to compensate for the self-tightening force of the oil seal at any time. Oil seals are classified according to the rotational speed of the shaft: oil seals can be divided into low speed oil seals (less than 6m/s) and high speed oil seals (more than 6m/s) .