HRS MA39 - U-rings

Type/Ref.: Rod seal
Pressure (bar): 40/400
Temperature (°C): –40 to + 100
Speed (m/s): = 0.5

Piston rod seal with asymmetrical sealing lips which are cut at an angle of less than 45°. There is a second seal edge on the inner diameter.

Standard material

Polyurethane TPU92

Area of application

reciprocating movements
extreme loads


The HRS MA39 is a single function piston seal in the form of a U-ring. Its excellent suitability for extreme loads 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 edge 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.


Hydraulic oils acc. DIN 51524/51525,
lubricating oils, mineral oil based
lubricating fats, non-flammable
hydraulic fluids HFA, HFB, HFC acc.
VDMA 24317.

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 MA39, from an inner diameter of 25 mm and a thin profile can always be installed in cut housing. Due to the high strength 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 piston body and seal over the piston rod without damaging it, a lead-in chamfer C acc. 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

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

Pressure (MPa) Radial wedge G (mm)
5 0.6
10 0.5
20 0.35
30 0.3
40 0.25

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, other polyurthane materials are available.