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U-Cup Lip Seals for Pistons
The U-Cup series lip seals are asymmetric and symmetric dynamic sealing solutions designed to guarantee absolute fluid retention in hydraulic and pneumatic cylinders. The flexible pre-loaded lip geometry exploits internal system pressure to proportionally increase the radial contact force against the piston bore. The range includes O-ring energized profiles for low-pressure environments and pure polyurethane or rubber configurations engineered to resist mechanical wear, high friction, and extrusion.
| Profile | Geometric description and typical application |
|---|---|
| TTU Type | Universal symmetric profile with identical extruded lips, optimized for both rod and piston configurations in medium-duty hydraulic systems. |
| TTE Type | Asymmetric variant featuring a shorter and stouter outer lip, specifically engineered to maximize static stability on the piston head. |
| TTO Type | Inverted asymmetric profile designed for highly compact hardware housings with excellent residual oil film preservation. |
| TTU/O Type | Geometric evolution pre-loaded with an inner elastomeric O-ring energizer in the lip cavity, ideal for ensuring flawless leakage control at zero pressure. |
| GUM Type | Classic configuration manufactured entirely from NBR elastomer without reinforcing inserts, ideal for industrial pneumatics and low-friction automation. |
| Material / compound | Velocity | Temperature | Max pressure |
|---|---|---|---|
| Hydrolytic Polyurethane Tecnopolymer | Up to 1.0 m/s | −35 / +110 °C | 40 MPa 400 bar |
| NBR Nitrile Rubber 80 ShA GUM Type | Up to 0.5 m/s | −30 / +100 °C | 16 MPa 160 bar |
| FKM Fluoroelastomer / Viton | Up to 0.5 m/s | −20 / +200 °C | 25 MPa 250 bar |
Traditional mineral oils, synthetic hydraulic fluids, ester-based lubricants, and water-glycol emulsions. Profiles are manufactured in absolute compliance with standard housing dimensions specified by DIN ISO 5597 and ISO 6547 international regulations for piston sealing cavities.
- Calibrated Geometric Profile: the dynamic sealing edge is razor-cut with high precision to minimize idling friction.
- Self-Energizing Mechanism: increased system pressure boosts radial interface contact, neutralizing micro-leakages.
- Flexible Elastomeric Shell: fully rubberized design eliminates bare metal contact, preventing damage to inner housings.
| Manufacturer | Standard profile (TTU / TTE) | Energized profile (TTU/O) |
|---|---|---|
| Net Seals | TTE / TTU Series | TTU/O Series with O-Ring |
| Freudenberg (Simrit) | T20 / NI300 Profile | O-Ring Loaded U-Cup Profile |
| Parker Prädifa | Profile B3 / E5 | PolyPak Type SP Profile |
| Dichtomatik | NIP / KN Profile | KNDA Profile |
| Kastas Sealing Tech. | K22 / K32 Profile | K33 Profile |