The design of GAMMA seal TRB/9RB is based on many years of experience, the sealing lip total axial pressing force depends on the pre elongation of the rubber body, and sealing lip elasticity and deformation, and the sealing lip deformation depends on the sealing lip with respect to the friction surface assembly location. The metal case protects the seal against the hard object and plays the other polluting medium by centrifugal force, and has a good drain capacity after dipping the liquid. The shape of the metal shell creates an additional dust barrier through the installation of the labyrinth in the groove, which is very effective for heavy use.