9 - AHP Merkle GmbH

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Tip
In short
Hydraulic cylinders – just like the hydraulic system as a whole – have to be vented carefully before they are
put into operation. In order to make sure that there is no air remaining in any part of the hydraulic system,
the application and the cylinders should be actuated a number of times with as low a pressure as possible;
this will facilitate complete venting. For this reason AHP Merkle offers optional vents for almost all hydraulic
cylinders.
The detailed procedure for venting hydraulic cylinders is provided in the chapter „Operating and maintenance
instructions“
Because under certain circumstances air dissolved in the hydraulic fl uid may be
released, it is advisable to vent the system again when maintenance is performed.
To allow complete venting of hydraulic cylinders, the venting screws should be
placed at the highest point.
2.6 Seals, guides
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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
● fl uid
● operating pressure
Seals
The seals used in AHP Merkle cylinders are dimensioned for a maximum piston speed of 0.5 m/s (1.64 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
● Standard seals: -15 °C to 80 °C (5 °F to 176 °F)
● Viton ® : -15 °C to 200 °C (5 °F to 392 °F)
In the AHP Merkle catalog range the seals are designed for HL or HLP oils; for HFC or other fl uids the data
sheet of the fl uid manufacturer should be noted.
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.
Guide elements
In hydraulic cylinders from AHP Merkle, the number, placement and design of the guide rings are adapted to
the specifi c 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.
Cylinder parameters en
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