Hydraulic and pneumatic seals

Thanks to highly developed sealing systems today the fluid power enables to build compact and efficient hydraulic and pneumatic systems. Piston and rod sealing systems assembled from sliding ring, O-ring and metal spring work mutually and unilaterally and fit into standardized and special equipment rooms.

The sophisticated material combination and the chemical, physical and mechanical properties of hydraulic and pneumatic seals have:

- excellent tribological properties – low friction
- and wastage, high durability
- high compressive strength with an optimized gap extrusion resistance
- does not adhere to the sealing surface
- good dry running properties
- no gap extrusion of the O-ring
- insensitive towards dirt
- reliable function within a high pressure, speed and temperature ambit

Hydraulic sealing systems

Pneumatic sealing systems

Piston and rod compact seals

Consist of a primary seal, a dynamic sliding ring of polymer materials and a secondary seal, a static O-Ring of elastomer. The sliding ring has all the advantages of crystalline polymer materials and prevents the extrusion of the O-ring into the mechanical clearance. Compact seals can be assembled into opened and closed slots.


The function of the compact seal is based on the approved system of the elastic O-ring. The O-ring statically seals the slot base and presses the dynamic sliding ring on to the dynamic sealing surface. Build-up of pressure at the sealing surface is enabled because the statically sealing O-ring is set in a precharge pressure and empowers, within a depressurised state, the base pressure of the dynamic sliding ring. The item’s pressure affects the elastic O-ring and therefore triggers a radial pressure component on the dynamical sliding ring and enables an ideal sealing surface compression.


Spring-backed seals

Exposed to extreme conditions such as high and low temperatures as well as aggressive and special agents the elastomer O-ring loses its good-natured properties and therewith its efficacy. Pre-stressed metal springs replace the statically elastic O-rings and fulfil the required function and efficacy, similarly as described above. Seals that are reinforced by metal springs are more efficient then those supported by the O-rings. They can only be installed into open slots.


Piston and rod guidances

Guidance rings of polymer materials have the function to perfectly guide both, pistons and piston bar and to assimilate appearing crossing components. They impede a metallic contact between piston and cylinder liner or rather between piston bar and bush. Its width and number is conforming to the upcoming shear forces. Due to its grit finish the guidance rings can be inserted into closed slots.


Scraper rings

Scraper rings are indispensable machine elements for hydraulic pneumatic cylinders. Its assignment is to wipe off dirt of the sealing surfaces of the pulling in and pulling out piston bar. If the scraper rings were missing within the hydraulic and pneumatic cylinders, the medium would get dirty and consequently the sealing systems and surfaces would be damaged. Scraper rings are single and double-acting. Material, construction and arrangement are geared for the requirements.


O-rings

O-rings are circularly closed rings with a circular cross-section and made of elastomer materials. They are inserted into open and closed slots and are self-acting and double-acting sealing elements for the static and dynamical sealing. O-rings are defined through an inner diameter and a profile diameter. The jacking force caused by the installation in radial and axial direction is overlaid by the system pressure. A total compression of the seal occurs that depends on the total system pressure.


Back ring (anti-extrusion ring)

Among drilling and trunnion or rather shaft, O-rings when under pressure tend to a gap extrusion. Using standard elastomer strength at low system pressures the gap extrusion can already occur. It is therefore favourable to insert a back ring that works unilaterally and mutually into the slots of static and dynamic applications.