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Our pressure‑responsive packing set for rods, glands and pistons. Popular with operators of older hydraulic plant.

  • Hydraulic sealing
  • Reciprocating plant

Our Twinset packing set comprises an endless U-ring firmly supported by a header ring. The lips of the U-ring are slightly flared to provide an interference fit for initial sealing. When system pressure is applied, the sealing force is increased significantly by reaction within the tongue-shaped cavity of the U-ring.

Under slight axial compression, the header ring also spreads the U-ring lips slightly to improve low pressure sealing efficiency.

Although we recommend our more advanced designs for many traditional Twinset applications, this product remains a firm favourite with many operators of older hydraulic plant, and boasts a record of success stretching back over 50 years.

  • Very well proven on reciprocating plant worldwide
  • Readily available in traditional inch and metric sizes for older plant
  • Suitable for adjustable and non-adjustable axial length housings

Twinset was developed for vertically reciprocating hydraulic shafts and rams. Current applications include the main rams of upstroking/gravity return presses and downstroking/prefilling type presses. It is also successful on press drawback rams, hydraulic piston heads, jacks and hoists, and hydraulic valves.

Note: This packing set should not be used under abrasive conditions or for heavy-duty applications (e.g., forging or extrusion presses), or on rams subjected to shock loads or side loads. In such cases, please contact us to recommend a suitable product.

  • Maximum operating pressure: 34 MPa (4931 psi)
  • Maximum temperature (standard materials): +100°C (+212°F)
  • Maximum surface speed: 0.5 m/s (98.4 fpm)


  • Standard materials: cotton fabric proofed with a blend of synthetic rubbers

Header ring

  • Standard materials: nylon or similarly hard composite

Spring-loaded header ring

  • Header rings of 6.5mm section and above can be supplied with multiple coil springs for the automatic compensation of wear when used in non-adjustable housings

Standard materials are suitable for use with most mineral-based hydraulic fluids, lubricating oils and greases at temperatures up to +100°C (+212°F). They are also resistant to water and air.

The standards materials prove satisfactory for use with a number of fire-resistant fluids, including many of the phosphate ester type. Although swell will occur, most users find that this does not impair plant performance. Where fire-resistant fluids are used, it is essential to advise us of the type and designation.

  • Endless rings only, up to 1675 mm (66 inch) OD, with sections from 5 mm (0.19 inch) upwards. Please state whether housings are adjustable or non-adjustable.
  • For sizes above 1675 mm (66 inch) OD, please contact us
  • Fitting instructions are supplied with every set
Related Downloads

Twinset fitting guide

English pdf (176 KB) Download

Twinset datasheet

English pdf (297 KB) Download

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