X-ring is the most commonly used seal in the hydraulic cylinder, it is a typical lip seal, whether used for piston or piston rod can obtain a good sealing effect, U-ring in the case of low pressure, only rely on the interference deformation of the lip to produce a seal, due to small contact area, friction force is relatively low, as the pressure rises, the lip elastic deformation increases, stretching, stretching, etc. With the increase of compression and bending stress, the radial compression force of the U-ring automatically increases, and the length of contact with the sealing surface continues to increase, until the entire axial length of the U-ring contacts the sealing surface, so as to ensure good sealing under high pressure.
The X-ring is a double acting seal with elastic sealing ability. The sealing function is achieved by the radial or axial contact stress and system pressure superimposed by the pre-compression during the initial installation.
The sealing force after superposition increases with the increase of system pressure. Under pressure, the star seal acts like a fluid with a high surface tension. The pressure can be evenly transmitted to all surfaces.
The X-ring is widely used, but it is mainly used for dynamic sealing, but its use is limited by pressure and speed.