Abstract: In a U-cup based seal of a rod, the basic body of the U-cup 3 is recessed relative to a square cross-sectional shape in the region of a radially inner outer edge 18 on the low pressure side in order to obtain a space 17 between the U-cup 3 and the opening, i.e. the passage opening 16 of a sealing gap 15, leading into a rectangular groove 4 guiding the U-cup 3. This space 17 remains at least partially also upon pressurization such that the U-cup 3 completely remains in the groove 4 upon pressurization and is not extruded into the sealing gap 15. This considerably reduces wear of the U-cup 3.

Abstract: A sealing device is arranged in a groove between a first machine component and a second machine component. If the sealing device, comprising the sealing ring and the biasing element, is subjected to a hydraulic pressure from the high pressure side and/or should an axial motion of a machine component take place, the sealing ring pivots towards the low pressure side in such a fashion that an angle .alpha. is reduced and an angle .beta. is increased. Through this pivoting effect a sealing edge is formed. Thereby a wedge-shaped gap forms between the peripheral surface and the surface of the sealing ring lying across therefrom, the gap being open towards the low pressure side.