HRS MA41 - U-rings

Type/Ref.: Rod seal
Pressure (bar): 40/400
Temperature (°C): -40 to +100
< +40 in HFA, HFB, HFC
Speed (m/s): <0.5

Piston rod seal with asymmetrical seal lips which are cut at an angle of less than 45°. There is a second seal edge on the inner diameter and the seal unit has an integrated support ring.

Standard material

Polyurethane TPU92
Polyoxymethylene POM

Area of application

reciprocating movements
extreme loads


The HRS MA41 is a single function piston rod seal in the form of a U-ring. Its excellent suitability for extreme loads, which is for example required for application in the working cylinders of heavy earth-moving machines, is provided by the synergy between the geometric of this seal and the special material characteristics of polyurethane. It guarantees effective sealing at low and zero pressures as well as the most difficult operational conditions which would overload conventional elastomer or fabric seals. The second seal lip supports the sealing function on the upward stroke of the rod and also wipes remaining dirt from the atmospheric side on the downward stroke of the rod. The semi-active support ring on the inner diameter protects against fission extrusion.


Hydraulic oils ace. DIN 51524/51525, lubricating oils, mineral oil based lubricating fats, non-flammable hydraulic fluids HFA, HFB, HFC ace. VDMA24317

Operational application limits

Pressure (MPa/bar): 40/400
Temperature (°C): -40 to +100
< +40 in HFA, HFB, HFC
Running speed (m/s): <0.5


The HRS MA41, from an inner diameter of 25 mm and a thin profile, can always be installed in cut housing. Due to the high tensile resistance of polyurethane, it is necessary to use installation tools for thick seals. With an inner diameter of less than 25 mm, we recommend axially accessible housing.

To push the cylinder head and seal over the piston rod without damaging it, an lead-in chamfer C ace. to the following table is required:

Profile width (mm) Lead-in chamfer C (mm)
4 2
5 2.5
7.5 4
10 5
12.5 6.5
15 7.5
20 10
25 10

The service life of the seal is lengthened if the housing is provided with a metallic fitting on the side opposite the pressure. Within the operating parameters given above, depending on the pressure, a metallic wedge can be fitted between the cylinder head and piston rod ace. to the following table:

Pressure (MPa) Radial wedge G (mm)
5 1.0
10 0.8
20 0.6
30 0.5
40 0.4

Please also follow the general installation instructions.


In addition, we are able to supply other dimensions required. For operating conditions other than the standard applications, further polyurethane materials are available.