Preload Lip type
Preloaded lip piston seals, also known as Loaded U-Cups, are the ideal solution for hydraulic systems where maintaining a positive seal at zero or low pressure is critical. By integrating an elastomeric O-ring or quad-ring energizer into the seal profile, the lips are mechanically flared against the cylinder bore. At Carlock Sealing, we engineer these seals to provide consistent sealing force, effectively preventing "bypass" during long-term static holding or unpredictable pressure fluctuations.
Q: When should I choose a preloaded piston seal over a standard U-cup?
A: Carlock Sealing recommends preloaded designs for applications like holding cylinders or systems with frequent "stop-start" cycles. The internal energizer acts as a permanent spring, ensuring the lips stay active even when there is no system pressure to flare them, thereby eliminating initial leakage.
Q: Can preloaded piston seals handle bi-directional pressure?
A: Most preloaded lip seals are uni-directional. For bi-directional service, they must be installed back-to-back in a twin-groove configuration. If space is limited, please consult our engineering team for Compact Piston Seals or Coaxial PTFE designs that offer bi-directional capabilities in a single groove.
Technical Disclaimer: Preloaded seals exhibit higher breakout friction due to the constant radial load on the cylinder bore. Ensuring proper surface finish (Ra) is critical to minimize heat build-up.
