Unloaded U-Cups

The rod style unloaded twin lip U-cup features a secondary “bump” or lip on the inside heel of the seal that provides additional stability in the seal groove. The increased stability enhances the long-term performance of the seal. In rod seal leakage tests, the twin lip rod U-cup had better performance than the conventional U-cup. This is due to the initial leakage of the seal being reduced by the secondary sealing lip.