The rod seal is a crucial element in fluid power systems, as it prevents fluid leakage from the hydraulic cylinder. Such leaks undermine equipment performance and service life but can be avoided by attention to seal characteristics that meet the specifications for a given application.

The appropriate elastomeric rubber for fluid movement, vibration isolation or other use is defined based on system pressure, chemical compatibility, temperature regime, friction and economic considerations for single- or double-acting seals. The distinguishing requirement for a single- or double-acting seal is pressure direction: Single-acting seals take pressure from one side only and are used between fixed components while double-acting seals handle pressure from both sides and are installed between parts that are in relative motion.

Rod seals supplied by Seals-Shop are available as O-ring energized polytetrafluoroethylene (PTFE) products and polyurethane (PU) U-cups, all from Trelleborg Sealing Solutions. The design and material focus is on low friction, compact form and simple installation.

Turcon®, a proprietary PTFE-based sealing material, is compatible with almost all chemicals, making it suitable for use in equipment where seals are likely to be exposed to demanding media. These materials deliver excellent low friction and self-lubricating characteristics for dynamic and rotating applications. The low-friction properties reduce power loss while positional accuracy and control are enhanced by the elimination of stick-slip movements and conditions.

Different grades made with special processing methods and incorporating fillers can be fabricated to achieve specific operating properties. For example, Turcon® Stepseal® 2K is a single-acting O-ring energized rod seal designed to provide high static and dynamic sealing results. It can be installed together with other seals in a tandem configuration for advanced static and dynamic tightness and is marked by high-extrusion resistance, low friction with no stick-slip, minimal break out force and high wear resistance.

A double-acting O-ring energized rod seal for dynamic applications also offers low friction with no stick-slip, minimal break out force and high wear resistance. The trapezoidal cross-section of the Turcon® Glyd Ring® T provides very good static leak-tightness and the angles of each lip are designed to provide improved leakage control and better resistance to extrusion.

Another high performance polymer family for sealing service is available in a range of compounds, additives and hardness levels to optimize sealing element compatibility and performance with diverse industrial fluid media types. The Zurcon® line of injection and cast molded polyurethanes is designed to meet the rigorous demands of hydraulic and pneumatic sealing systems. High mechanical strength and abrasion resistance as well as the ability to withstand petroleum oils are hallmarks of this material.

The Zurcon® Rimseal is a single-acting rod seal energized by an elastomer O-ring, providing high static and dynamic leak tightness and high wear resistance. It functions as a suitable secondary element to ensure reliable sealing of thin oil films at low secondary pressures.

The Zurcon® U-Cup RU9 can be specified for applications requiring very high sealing performance with lower friction and lower heat generation than standard U-cups. The trimmed lip design allows for outstanding wear and extrusion resistance. Compatible with virtually all media, it also has a wide operating temperature range (from minus 35 degrees Celsius to 110 degrees Celsius).

Proper hydraulic-cylinder operation hinges on choosing the best seal for the job. A good working knowledge of available seal options and application parameters — such as fluid pressure range, temperature range, stroke speed and fluid type — helps achieve that goal.

For more information on rod seals and for installation guides, you can visit Seals-Shop.