Reviving the PK56 Robust Hydraulic Piston Seal for Tough Conditions

Reviving the PK56 Robust Hydraulic Piston Seal for Tough Conditions

An enduring example of a classic seal design for harsh conditions where shock loads and pressure spikes present an issue is the PK56 profile (or PK58 with bearing/backup rings), which in recent times has been overlooked by seal suppliers and manufacturers all over the world.

Wilhelm Prinz, Managing Director of Oz Seals, supports the continued use of the compact double acting PK56 seal,

“We believe the PK56 piston seal is worthwhile continuing, as it is very robust for rough and tough conditions. It is true that it’s an old robust design, but it deserves to stay.”

Oz Seals supply the robust PK56 and PK58 hydraulic piston seals in super polymer, rather than the traditional rubber and fabric combination, which can delaminate. The super polymer makes it a long lasting, wear resistant seal for a wide variety of applications with the bonus of superior performance. These applications include hydraulic cylinders for general hydraulic systems and presses, agricultural machinery and mobile hydraulic systems. The efficiency of this heavy duty seal benefits from the low friction provided by the triple lubricated properties in Oz Super Polymer.

The PK56 and PK58 comes in a wide range of sizes listed under the Sealnet web store, or custom sizes are also machined upon request. Under the harshest of conditions, the PK56 piston seal design has proven itself over many years to be an effective and contamination-tolerant solution to hydraulic sealing.

PK56/PK58 Hydraulic Seal vs Old 56 Seal
PK56/PK58 Hydraulic Seal vs Old 56 Seal


What’s improved?

  • Improved super polymer compound for higher performance
  • Lower friction
  • 4x Higher tensile strength than the old seal design
  • Better availability
  • Reasonably priced
  • Key advantage: The old seal material was only suitable for open or split pistons, while the super polymer seal material can even be used for closed pistons.