The document is a catalog for the Merkel U-Ring TM 20, a single-acting rod seal designed for use in hydraulic cylinders. It features asymmetrical sealing lips, offers excellent media resistance, and functions effectively across a wide temperature range. The catalog includes specifications on materials, dimensions, operating conditions, and installation recommendations for various applications including injection molding machines and heavy machinery.

1. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
Hydraulics | Rod Seals | Merkel U-Ring TM 20
Merkel U-Ring TM 20
Asymmetrical sealing lips
PU profile ring
Fig. 1 Merkel U-Ring TM 20
Product description
Merkel U-ring with asymmetrical profile,
inner lip set back and press fit at the out-
side diameter.
Product advantages
Single-acting rod seal for hydraulic
cylinders. With new production technol-
ogy even special sizes can be manufac-
tured quickly and flexibly
Good media resistance
Wide operating temperature range
Very good static and dynamic
tightness
Use as an individual seal or as a
secondary seal in sealing systems
possible
Large range of dimensions
No moulding tools.
Application
Injection moulding machines, presses,
heavy machinery manufacture, large
cylinders.
Material
Ø range <500
Material Code Hardness Colour
Polyurethane 95 AU V142 95 Shore A Blue
Ø range >500
Material Code Hardness Colour
Polyurethane 93 AU V168 93 Shore A Red
Operating conditions
Material 95 AU V142 93 AU V168
Temperature range in °C
Hydraulic oils HL, HLP –30 … +110 –25 … +100
HFA fluids +5 … +50 +5 … +60
HFB fluids +5 … +50 +5 … +60
HFC fluids –30 … +40 –25 … +40
HFD fluids – –
Water +5 … +50 +5 … +60
HETG (rapeseed oil) –30 … +60 –25 … +60
HEES (synthetic ester) –30 … +80 –25 … +80
HEPG (glycol) –30 … +50 –25 … +50
Mineral greases –30 … +110 –25 … +100
Pressure p in MPa 40
Running speed v in m/s 0,5*
* If TM 20 is fitted in a sealing system as a secondary seal, higher running speeds can be allowed.
Surface quality
Surface roughness Ra Rmax
Sliding surface 0,05 … 0,3 µm ≤2,5 µm
Groove base ≤1,6 µm ≤6,3 µm
Groove flanks ≤3,0 µm ≤15,0 µm
Percentage contact area Mr >50% to max. 90% at cutting depth c = Rz/2 and reference line C ref = 0%.
Design notes
Please observe our general design notes
in → Technical Manual.
Merkel U-Ring TM 20

2. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
Tolerance recommendation and dimension D2
D2 "System" is based on the use of Merkel TM 20 as a secondary seal in a sealing
system. The specified D2 dimensions are based on the use of Merkel fabric-base
laminate guide ring SB or metal guide. They provide high security against gap extru-
sion and also metal tarnish. → Technical Manual. If the stated operating parameters
range is not fully exploited or only for a short period, larger D2 dimensions may be
selected. With high lateral forces or high deflection we recommend a metal guide.
Lead-in chamfers
Dimension C → Technical Manual.
Fitting & installation
The rod seals can be fitted into plunge-
cut grooves by hand or with a fitting
tool. In the case of different housings,
e.g. in old plant, please ask our advisory
service.
Housing recommendations for new designs
Merkel U-Ring TM 20 primary seal
d D L c
>320 … 600 d + 30 25 11
>320 … 720 d + 40 32 12
>720 … 2000 d + 40 40 16
Merkel U-Ring TM 20 secondary seal in the sealing system
d D L c
>320 … 650 d + 20 16 8
>650 … 950 d + 25 20 10
>950 … 2000 d + 30 25 11
Tolerance recommendation for SB Guide Ring
<10 MPa
Nominal Ø d S DF d D2
≤190 ≤15 H8 f8 H10
>190 … 320 ≤15 H7 f8 H9
>320 … 600 15 H7 f8 H8
>320 … 720 20 H8 f8 H8
>720 … 2000 ≥25 H8 f8 H8
<25 MPa
Nominal Ø d S DF d D2
>105 … 320 ≤15 H7 f8 H8
>320 … 600 15 H6 f7 H7
>320 … 720 20 H7 f7 H7
>720 …2000 ≥25 +0,05 f7 H7
<40 MPa
Nominal Ø d S DF d D2
>85 … 320 ≤15 H6 f7 H7
>320 … 600 15 H6 f6 H7
>320 … 720 20 H6 f7 H6
>720 … 2000 ≥25 +0,05 f6 H6
System
Nominal Ø d DF** d** D2
<320 – – H11
>320 – – +0,4
* Profiles in accordance with "housing recommendations for new designs"
** Use fit or tolerance level of primary seal
Hydraulics | Rod Seals | Merkel U-Ring TM 20

3. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
Hydraulics | Rod Seals | Merkel U-Ring TM 20
Article list
d
Ø
L +0,2
H
S
Ø
D > 400 +0, 4
400 H11≤
DØ 2 DØ 1 DØ FC
R1
0,4
20°
H9
Rounded and free of burrs
d D H L Profile C Fitting Material Article No.
320 340 14,6 16 10 10 S 95 AU V142 24357237 DD
320 350 22,8 25 15 11 95 AU V142 24359549 DD
320 360 29,1 32 20 14 95 AU V142 24359550 DD
330 360 22,8 25 15 11 95 AU V142 24359743 DD
350 370 14,6 16 10 10 S 95 AU V142 24357238 DD
350 380 22,8 25 15 11 95 AU V142 24359746 DD
350 390 29,1 32 20 14 95 AU V142 24359747 DD
360 380 14,6 16 10 10 S 95 AU V142 24359719 BB
360 400 29,1 32 20 14 93 AU V168 24359748 DD
370 400 22,8 25 15 11 95 AU V142 24359749 DD
380 400 14,6 16 10 10 S 95 AU V142 24359750 DD
380 410 22,8 25 15 11 95 AU V142 49001346 DD
380 420 29,1 32 20 14 95 AU V142 24359751 DD
390 420 22,8 25 15 11 95 AU V142 24359752 DD
400 420 14,6 16 10 10 S 95 AU V142 24359753 DD
400 430 22,8 25 15 11 95 AU V142 24359755 DD
400 440 29,1 32 20 14 95 AU V142 24359754 DD
410 430 14,6 16 10 10 S 95 AU V142 24357239 DD
420 460 29,1 32 20 14 95 AU V142 24359757 DD
430 460 22,8 25 15 11 95 AU V142 24359758 DD
440 460 14,6 16 10 10 S 95 AU V142 24357240 DD
440 470 22,8 25 15 11 95 AU V142 24370501 DD
450 470 14,6 16 10 10 S 95 AU V142 24359760 DD
450 480 22,8 25 15 11 95 AU V142 24359761 DD
450 490 29,1 32 20 14 95 AU V142 24359763 DD
480 500 14,6 16 10 10 S 95 AU V142 24357241 BB
500 520 14,6 16 10 10 93 AU V167 24359767 DD
500 530 22,8 25 15 11 93 AU V168 24359768 DD
500 540 29,1 32 20 14 93 AU V168 24359769 DD
520 560 29,1 32 20 14 93 AU V168 24359770 DD
530 560 22,8 25 15 11 93 AU V168 24359771 DD
540 580 29,1 32 20 14 93 AU V168 24359772 DD
550 570 14,6 16 10 10 S 93 AU V168 24357242 DD
550 590 29,1 32 20 14 93 AU V168 24359204 DD
560 600 29,1 32 20 14 93 AU V168 24359773 DD
BB Available from stockAvailable from stock DD On request: Tool is available, delivery at short noticeOn request: Tool is available, delivery at short notice
S = only as secondary sealS = only as secondary seal

4. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
d D H L Profile C Fitting Material Article No.
580 610 22,8 25 15 14 93 AU V168 49001720 DD
580 620 29,1 32 20 14 93 AU V168 24359774 DD
600 620 14,6 16 10 10 S 93 AU V168 24359775 DD
600 630 22,8 25 15 11 93 AU V168 24359776 DD
600 640 29,1 32 20 14 93 AU V168 24359777 DD
620 640 14,6 16 10 10 S 93 AU V168 24359551 DD
630 670 29,1 32 20 14 93 AU V168 24359778 DD
640 660 14,6 16 10 10 S 93 AU V168 24358387 DD
670 695 18,2 20 12,5 11 S 93 AU V168 24359552 DD
670 710 29,1 32 20 14 93 AU V168 24359779 DD
710 750 29,1 32 20 14 93 AU V168 24359780 DD
720 745 18,2 20 12,5 11 93 AU V168 49004523 DD
720 760 29,1 32 20 13 93 AU V168 24359781 DD
720 770 36,4 40 25 16 93 AU V168 24357182 DD
750 800 36,4 40 25 16 93 AU V168 24359782 DD
800 825 18,2 20 12,5 11 S 93 AU V168 24359783 DD
820 870 36,4 40 25 16 93 AU V168 24357250 DD
830 855 18,2 20 12,5 11 93 AU V168 49003544 DD
900 925 18,2 20 12,5 11 S 93 AU V168 24359788 DD
900 950 36,4 40 25 16 93 AU V168 24359789 DD
950 975 18,2 20 12,5 11 S 93 AU V168 24359554 DD
1000 1030 22,8 25 15 11 S 93 AU V168 24359555 DD
1000 1050 36,4 40 25 16 93 AU V168 24359792 DD
1040 1070 22,8 25 15 16 93 AU V168 49017258 DD
1050 1100 36,4 40 25 16 93 AU V168 24359793 DD
1070 1120 36,4 40 25 16 93 AU V168 24359794 DD
1150 1200 36,4 40 25 16 93 AU V168 24359795 DD
1200 1250 36,4 40 25 16 93 AU V168 24362258 DD
1250 1300 36,4 40 25 16 93 AU V168 24359556 DD
BB Available from stockAvailable from stock DD On request: Tool is available, delivery at short noticeOn request: Tool is available, delivery at short notice
S = only as secondary sealS = only as secondary seal
Hydraulics | Rod Seals | Merkel U-Ring TM 20

5. © Merkel Freudenberg Fluidtechnic GmbH | Seals for Fluid Power Catalog 2007
Merkel Freudenberg
Fluidtechnic GmbH
Industriestr. 64
D-21107 Hamburg
Tel.: +49(0)40/75 30 6-0
Fax: +49(0)40/75 30 6-440
E-mail: merkel@freudenberg.de
www.merkel-freudenberg.de
The catalog details are based on the
experience of many years of research
in the development and production of
seals in the Freudenberg Group and
correspond to our current level of know-
how.
The sealing action of many catalog
products is, however, not only created
by the component itself. In many
cases – depending on the specific
application – it depends significantly on
the other parameters, such as installa-
tion point, counter surface, pressure,
operating temperature, media to be
sealed, lubrication, effects of vibration
and any ingress of dirt from outside.
These and other unknown factors in
practical use may noticeably influence
the functioning of the seals. Against this
background generalised statements
on the function of the catalog products
are not possible. Details in this catalog
merely represent general and non-bin-
ding reference values which make no
claim to be valid for every application.
We therefore recommend you to always
discuss specific applications with our
consultancy service. In the event of very
high and special loads, for example due
to aggressive media, the seal should be
selected in co-operation with us; trials to
check the functional reliability are often
indispensable.