Can Stepseal be improved any further?

In terms of dynamic tightness modern step seals produce a triangular compression curve between the seal and the rod, with a sharper rise occurring at the edge of the sealing surface on the pressure side. This of course also applies to the tried and tested Stepseal® sealing edge. It has a sharp compression gradient on the pressure side and a flat gradient on the side away from the pressure. Under normal operating conditions this ensures that the film of oil discharged with the piston rod on the forward stroke is fully backpumped to the cylinder on the return stroke.

Demanding applications call for a tandem arrangement consisting of a primary and secondary seal. The individual elements have to be coordinated to each other in terms of sealing performance and wiping behavior. Only then is it guaranteed that the oil film discharged is backpumped completely. However, with critical operating conditions the balance between discharge/return may not always work out properly, e.g.:

• With a fast forward stroke and a slow return stroke
• With cylinder applications involving long strokes
• When the sealing edge of the primary seal has lost its original profile due to wear or damage.
  

A hazardous pressure level may then build up between the primary and secondary seal stroke by stroke - in adverse conditions possibly even exceeding the maximum operating pressure of the hydraulic cylinder. This interface sealing pressure may irreparably damage the entire sealing system and result in premature failure, for example of injection molding machines, hydraulic presses or excavators.

The Stepseal® V promises safety for such operating conditions. It is based on the well-proven sealing profile of the Stepseal® 2K and is equipped with an integrated non-return valve. If the pressure between the primary and secondary seal exceeds a design-specific limit, the valve will open and reduce the interface sealing pressure via the pressure relief channel. After ventilating, the channel is closed automatically by the O-ring, and the valve shuts. And this is what makes it different to other ventilating seals. In the Turcon® Stepseal® V the pressure relief channel and O-ring form a non-return valve with precisely defined switching points and a fast response time. This patented design has advantages to offer:

• The closing delay of the non-return valve and thus a premature rise in the interface sealing pressure is extremely small.
• Leakage via the auxiliary seal or the pressure relief channel is impossible.
• Operation of the non-return valve is pressure-controlled, regardless of stroke speed or length.
• In addition, the Stepseal® V offers the following technical characteristics:
• The back bevel improves backpumping of the oil film on the return stroke.
• The stabilization edge before the actual sealing edge protects the sealing edge during fitting and when in operation.
• The Stepseal® V is manufactured from Turcon® and Zurcon® materials offering excellent slide and wear characteristics.
• Use in grooves as per DIN/ISO 7425/2.
• Available as a rod or piston seal.
  

The Stepseal® V offers all customer benefits of the Stepseal® 2K as well as safety reserves for any unexpected modes of operation. This means there no longer is any obstacle to increasing operating safety/reliability and machine availability.