The sealing between the moving ring and the shaft (shaft sleeve) and the static ring and the pressure cover is achieved by the auxiliary sealing ring. They are basically static seals. When the sealing end surface and the center line of the axis are not vertical, the moving ring sealing ring has a very small axial movement along the axial direction, and the displacement depends on the verticality error of the sealing end surface and the axis center, the number of movements and the shaft speed, etc. There are many kinds of auxiliary sealing rings, including synthetic rubber, PTFE and flexible graphite from the material perspective, and round, square, V, wedge and coveredsealrings (Figure 29).