Three Types Of Hydraulic Seals

The hydraulic seals commonly used in hydraulic cylinders mainly include O ring, lip seals and compact seals.

1. O ring

The cross section is "O" type, the shape is simple, the material is rubber, and the wear resistance is not as good as PU, so it is mainly used for static sealing in hydraulic systems.

2. Lip seals

U cup seals: U cup seal has better sealing performance, but it is easy to roll when used alone, and its frictional resistance is relatively large and increases with the increase of working pressure. Therefore, U cup is only suitable for hydraulic cylinders with lower working pressure or lower moving speed.

V ring: The V ring must be used with the support ring and the pressure ring. The sealing performance of the V ring is better. The number of the sealing rings used can be determined according to the working pressure. The sealing ring can be compensated by adjusting the pressure ring. The shortcomings of the wear and tear are that the structure is complex and the friction resistance is relatively large. Therefore, the V ring is only suitable for hydraulic cylinders with lower moving speed and higher working pressure.

YX U cup seals: YX u cup seal has a cross-sectional width and its height ratio greater than 2, and based on the requirements for stability in use, the working lip of the YX u cup is shorter than the non-working lip, so it is divided into piston seal YxD and rod seal Yxd. It will not roll when used, so is suitable for high-pressure and high-speed hydraulic cylinders.

3. Compact seals

Glyd ring: Glyd ring is composed of PTFE ring and O ring. It can be divided piston glyd ring and rod glyd ring, but sealing principle is the same, and its deformation produces a higher initial contact stress on the sealing surface to prevent the leakage of pressureless liquid. When the hydraulic cylinder is working, the pressure oil causes the elastic deformation of the O-ring to squeeze the square sealing ring to make it close to the sealing surface, and together with the initial contact stress to prevent the leakage of the pressure oil.

Step Seal: It is also composed of PTFE ring and O ring. It can be divided into piston step seal and rod step seal. sealing principle is the same as glyd ring, but step seal is single-acting seals. The common feature of step seals and glyd ring is that it is filled with PTFE material, has low friction, no creep, and long life.