Piston seal, double-acting

The double-acting piston seal type KD 04 is a two-piece seal, consisting of a profile ring and an O-ring as a preload element. It is optimally suited for applications in the low pressure range and is used primarily in truck-mounted cranes and standard cylinders.

A low coefficient of friction and small installation height are the decisive advantages of this seal. It also possesses a high wear resistance, good service life and also a very good chemical and thermal resistance.

While the PTFE profile ring seals dynamically against the cylinder surface, the elastic O-ring ensures uniform contact pressure of the PTFE profile ring onto the cylinder surface, and at the same time, a static sealing between profile ring and groove base.

Even with low pressures, the piston seal shows good sealing effect due to the inherent preload of the PTFE profile ring and the contact force of the preloaded O-ring. At higher system pressures, the medium pressurizes the O-ring causing it to press the PTFE seal with enhanced force against the cylinder surface.

With the different material combinations, the piston seal can be used reliably across the whole pressure, speed and temperature range.

Application media

  • Mineral oil-based hydraulic liquids
  • Water
  • Air
  • Environment-friendly bio-oils
  • Flame-resistant hydraulic liquids
  • Other media, depending on the O-ring material

Application range

Pressure: up to 16 Mpa (160 bar)
Speed: approx. up to 2 m/s
Temperature: – 30 °C to + +100°C (depending on the O-ring material)


Roughness depthRaRt
Running surface≤ 0,3 µm≤ 2,5 µm
Groove base≤ 1,6 µm≤ 6,3 µm
Groove flank≤ 3,0 µm≤ 15,0 µm

Installation dimensions

Cylinder ø D
overtoGroove base ø DGroove width L +0,2
922ø d – 6,13,2
2255ø d – 7,24,0
55150ø d – 12,27,5

PTFE profile ring material

Weitere mögliche Werkstoffe finden Sie in unserer PTFE-Werkstoffübersicht unter Downloads.

PTFE + bronze

The standard for hydraulic applications, good gliding behavior, particularly pressure and abrasion resistant, cannot be used in aqueous solutions or acids

O-ring material

Nitrile rubber NBR: Temperature range − 30 °C to + 120 °C

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