1. Structure type I: the lip has small pressure bearing area and can keep its rigidity at the same time, so it can be used under small diameter and medium pressure.
2. Structure type II has small deformation of lip under pressure, and the framework is designed as a whole under pressure, which can be used under large diameter and high pressure.
3. Structural type III the lip adopts the optimized structural design, and the oblique lip design makes the oil seal can adapt to the relatively high PV value: under the pressure of 200 kg, the rotation speed is required to be more than 0.75 m / s.