Rod seals are key components in hydraulic and pneumatic sealing technology. They seal the moving piston rod of a cylinder against the outside environment and prevent the working fluid (e.g., hydraulic oil or compressed air) from escaping the system. At the same time, they must prevent the ingress of dirt, dust, and moisture from the outside.

Their function is crucial for the leak-free operation, efficiency, and service life of a hydraulic or pneumatic system.

 

Designs

There are different designs, depending on the application and load:
• Single-acting rod seals: Seal in one direction (inward to outward)
• Double-acting rod seals: Seal in both directions – under alternating pressure loads
• Combination seals: Combination of primary and secondary seals to optimize sealing performance
• Profile and groove seals: With special lip profiles to adapt to operating pressure and medium

Elastomers rod seals – FiLomer^®

• Properties: good elasticity, adapts to surfaces, reliable recovery forces
• Advantages: easy installation, good sealing performance, cost-effective
• Disadvantages: limited temperature and media resistance
• Applications: standard hydraulics, pneumatics, mechanical engineering

Polyurethane rod seals – FiPur^®

• Properties: high mechanical strength, abrasion and extrusion resistance, good resilience
• Advantages: very durable, resistant to high pressures and dynamic loads
• Disadvantages: limited chemical resistance to hot water and acids
• Applications: mobile hydraulics, construction machinery, agricultural machinery

PTFE rod seals – FiKumer^®-F

• Properties: very low coefficient of friction, high chemical and thermal resistance
• Advantages: ideal for high speeds and temperatures, low wear
• Disadvantages: no inherent elasticity – usually combined with elastomer preload elements (e.g., O-ring)
• Applications: high-performance hydraulics, chemical plants, precision systems