Seals and sealing devices are an important component of hydraulic equipment. Their operational reliability and service life are important indicators for evaluating the quality of a hydraulic system. Except for clearance seals, all other types use seal components to control the gap between two adjacent mating surfaces below the minimum gap through which the liquid to be sealed can pass.
In contact seals, there are two types: self-sealing compression type seals and self-sealing tension type seals (i.e., lip seals).