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Zurcon® U-Cup RU9

Product Announcement from Trelleborg Sealing Solutions

Zurcon® U-Cup RU9-Image

Due to its special design, behind the dynamic seal lip, the Zurcon® U-Cup RU9 with its structure of slide segments interspersed by back-pumping channels features excellent back-pumping ability across the entire pressure range. The dynamic seal slide segments also have a micro-structure with excellent tribological and sealing characteristics. As well as increasing the sealing ability of the U-Cup RU9, this also ensures a constant lubrication film underneath the seal sliding surface, reducing breakaway force even after prolonged periods of rest and reduces dynamic friction force.

Slide segments

· Patented micro-structuring of the slide segments

· Back-pumping channels

· Cut seal lip

The Zurcon® U-Cup RU9 also generates less heat than conventional seals. The combination of the FEM seal geometry with the highly wear-resistant Zurcon® polyurethane sealing material also provides increased protection against extrusion.

Product features

  • Grooves according to DIN/ISO 5597
  • Can be installed in closed grooves

Hydrodynamic back-pumping across the entire operating range is possible due to the patented micro-structuring of the seal sliding surface. This gives rise to other benefits provided by the Zurcon® U-Cup RU9, including:

  • Reduced friction
  • Less heat generation
  • High extrusion resistance
  • Outstanding dynamic and static sealing performance due to trimmt seal lip
  • Smooth seal lip ensures optimum sealing characteristics

The high static sealing performance is achieved by:

  • Interference fit at the external diameter
  • The special shape of the trimmt seal lip

The special Zurcon® Z20/Z22 polyurethane ensures:

  • High wear resistance
  • Lower compression set
  • Wider temperature range


The friction force of U-cups dramatically increases between 2.5 and 10 MPa. The Zurcon® U-Cup RU9 has a unique feature. As the system pressure increases, the contact surface between the U-cup and the piston rod increases. Once a specific system pressure is reached, the seal deforms to such an extent that its entire friction-generating inside surface gets in contact with the piston rod. Due to the special design of Zurcon® U-Cup RU9 there is improved pressure distribution on the rod. The resulting tribological benefits restrict the increase in friction. When we compare the friction values of conventional U-cups with those of the Zurcon® U-Cup RU9 the results are self-evident.

The New Profile

The innovative profile and surface design have several advantages: friction forces are significantly lower than on conventional U-cups. The back-pumping ability of the seal is ensured across the entire field of application.