Today, u-Cups are used primarily as seals for piston rods in hydraulic cylinders. u-Cups in polyurethane are proven elements, due to their good mechanical properties, for standard cylinder

construction, particularly for mobile hydraulics under rough operating conditions. The u-Cup ru2 is a double lip seal in a compact design. 




The compact u-Cup type ru2 is designed for small grooves. it is thus particularly suitable for use in space-saving designs. The compact form provides a high sealing effect even with low system pressures. The u-Cup has two sealing lips in the dynamic sealing zone. The compact form with two sealing lips provides an improvement in the leakage behavior at low system pressures.


Due to the incorporation of an oil trap between the two sealing lips, friction at pressures above approximately 10 MPa is reduced. Furthermore, the second sealing lip prevents the entry of dirt from the atmosphere side.




The sealing effect of the u-Cup comes from the intrinsic preload of the seal body and from the compression of the

seal lips during installation. in operating conditions, the radial mechanical contact forces are superimposed by the system pressure.


at low stroke speeds, u-Cups can tend to have a stick-slip effect due to an inadequate lubrication film formation in the seal clearance and to their material properties. This behavior corresponds to the Stribeck curve described in the relevant literature.



Pressure: Max. 35 MPa

Speed: up to 0.5 m/s

Temperature: use in mineral oils: -35 °C to +110 °C

Media: Mineral oil-based hydraulic fluids.


 - good sealing effect at high and low pressures

 - good abrasion resistance, wear-resistant

 - unaffected by sudden loads

 - Suitable for small grooves

 - Simple installation