Structural form of hydraulic seals

The commonly used self sealing compression hydraulic seals are mainly O-shaped sealing rings, circular sealing rings, and square sealing rings. They have the advantages of simple structure, easy manufacturing, and low cost. Therefore, they are widely used dynamic and static sealing components in hydraulic transmission systems. They usually generate 10-25% radial compression deformation when installed in the sealing groove, and generate higher initial contact stress on the sealing surface, thereby preventing the leakage of pressureless liquid.
When the hydraulic cylinder is in operation, the pressure liquid squeezes the self sealing compression type hydraulic seal, causing it to further deform and producing a significant pressure on the sealing surface with the pressure liquid, strictly speaking, it should be pressure. The increased additional contact stress, together with the initial contact stress, prevents the leakage of the pressure liquid. But when the working pressure is greater than 10Mpa, in order to prevent a part of the self sealing hydraulic seal made of synthetic rubber from being squeezed into the sealing gap and being cut off during the reciprocating movement of the hydraulic cylinder, causing leakage, it is necessary to set a synthetic resin retaining ring on the compression side of the self sealing hydraulic seal made of synthetic rubber, such as nylon retaining ring, polyoxymethylene retaining ring, and filled PTFE retaining ring.
Due to the significant compression deformation of self sealing hydraulic seals made of synthetic rubber during operation, their static friction resistance is particularly high, usually more than twice that of their dynamic friction resistance. Such a large static friction resistance is bound to cause adverse phenomena such as low pressure crawling and operation difficulties in some low-pressure hydraulic transmission systems, which is precisely why self sealing compression hydraulic seals are rarely used as dynamic seals alone.