Together with the design of the installation spaces, the selection of seals is one of the most important factors in ensuring functional, long-lasting hydraulic cylinders. Therefore the following parameters must be taken into account very carefully in the dimensioning and selection of seal systems: 

  • temperature
  • piston speed
  • fluid
  • operating pressure



The seals used in AHP Merkle cylinders are dimensioned for a maximum piston speed of 1 m/s (3.28 feet/s). Thanks to decades of experience and the systematic implementation of new technologies and innovative equipment, the range of applications for the seals used by AHP Merkle is correspondingly broad and diverse.


  • Standard seals: -15 °C to 80 °C (5 °F to 176 °F)
  • Viton®: -15 °C to 180 °C (5 °F to 356 °F)

In the AHP Merkle catalog range the seals are designed for HL or HLP oils; for HFC or other fluids the data sheet of the fluid manufacturer should be noted. The compatibility of the hydraulic fluid with the sealing materials must be checked.

Use of zinc-free HLP oils in combination with certain sealing materials may result in increased wear of sealing elements and running surfaces.

With very short strokes we recommend the use of special seal variants.



When selecting seals it is always essential to take into account the extent to which pressure spikes occur, or a particularly low pressure level is present.
At particularly low pressures the danger of leaks is increased because due to the residual stress or the mode of action the seals only function „properly“ starting with a certain pressure.
Additional seal solutions for non-standard parameters are available on request.




In hydraulic cylinders from AHP Merkle, the number, placement and design of the guide rings are adapted to the specific loads. Through the use of especially high-quality guides and optimized design, some product groups have been adapted for special high-load applications. These include, for example, the stamping cylinders (STZ).



Guides are dimensioned purely for the motions of the cylinder, not to absorb side forces.