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Brand: Ringfeder
Ringfeder RfN 4161 Shrink Disc, Route-Controlled, 18-200 mm
Description
Route-controlled shrink disc that is tightened without a torque wrench
The RfN 4161 is a proven standard series with small dimensions for transmitting high torque. Its distinguishing feature is route-controlled assembly: the screws are tightened until the thrust ring reaches a defined displacement path, so no torque wrench is needed and the clamping does not depend on the friction in the screws. RINGFEDER notes that this saves installation time, which pays off in serial production. Because both rings touch in the clamped condition, concentricity is very good.
The forged outer pressure ring gives good stress distribution and efficient use of material. The slit inner ring keeps pressure on hub and shaft modest, small tolerance errors are compensated, and static, dynamic and impact loads are within scope. No key, step or spline is needed.
Technical specifications
| Parameter | Specification |
|---|---|
| Manufacturer | RINGFEDER POWER TRANSMISSION GmbH, Groß-Umstadt, Germany |
| Series | RINGFEDER RfN 4161 shrink disc, route-controlled standard series |
| Inner diameter d | 18 to 200 mm |
| Transmissible torque T | 80 Nm to 124,000 Nm (product paper range) |
| Maximum torque Tmax | 121 Nm (18 x 44) to 136,400 Nm (200 x 340) |
| Locking screws | ISO 4014/4017, strength 12.9; M6 to M16 |
| Weight | 0.15 kg to 34 kg |
| Hub yield strength | Rp0.2 of 360 N/mm2 or more |
| Surface finish | Shaft Ra 3.2 um or better |
| Ordering example | RfN 4161 150 263 (d = 150 mm, D = 263 mm) |
Selected sizes from the tech paper
| d x D (mm) | Shaft dw (mm) | L (mm) | TA (Nm) | T (Nm) | Fax (kN) | Screw | Weight (kg) |
|---|---|---|---|---|---|---|---|
| 18 x 44 | 16 | 19 | 12 | 110 | 14 | M6 | 0.15 |
| 30 x 60 | 25 | 24 | 12 | 320 | 25 | M6 | 0.3 |
| 40 x 80 | 35 | 29.3 | 35 | 880 | 50 | M8 | 0.7 |
| 50 x 90 | 40 | 31.3 | 35 | 1,700 | 87 | M8 | 0.8 |
| 200 x 340 | 155 | 95.5 | 290 | 116,000 | 1,500 | M16 | 34 |
The table does not list screw counts for this series. Each size is tabulated for several shaft diameters, for example 15 and 16 mm in the 18 x 44 disc.
Limits and neighbouring series
Because assembly is route-controlled, the fitter does not depend on a torque wrench or on a calibrated tightening value: the displacement path of the thrust ring is what defines the clamping condition. Tabulated torque T and axial force Fax in the sizes above are the transmissible values from the tech paper, so the selection step is to compare them with the drive torque multiplied by a shock factor for the application.
The RfN 4161 is replaced by the larger RfN 4181 from an inner diameter of 220 mm. The tech paper requires a hub with yield strength Rp0.2 of at least 360 N/mm2. The function values assume lubricated screws and cones and lightly oiled contact surfaces (friction 0.12), and the shaft must be finished to Ra 3.2 um; maximum clearance S is 0.069 mm for shafts of 80 to 120 mm and 0.079 mm for 120 to 180 mm. Hollow shafts and additional tension, thrust or bending loads must be discussed with RINGFEDER.
The tech paper lists 12.9 screws for the RfN 4161, against 10.9 for the RfN 4051, 4061 and 4091. Confirm before ordering: hub yield strength, shaft diameter within the dw range, and torque with shock factor.
The product paper distinguishes two designs. Two-part shrink discs have an extremely flat single cone and act in the manner of a taper interference fit, and their screws can be tightened route-controlled without a torque wrench. Three-part discs have a steep double cone, and the distance between their flanges allows a simple function check; their values can be tuned by changing the tightening torque.
Documents and quotation
The attached PDF is the RINGFEDER tech paper for the RfN 4161 (10.2024). Related drives are listed under Electric Motors and Gear Units. Send shaft diameter, hub dimensions and torque for a size check.
Datasheets & Documents
- Technical Data RINGFEDER RfN 4161 tech paper (EN, 10.2024) Download
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About brand
RINGFEDER is a German maker of power transmission components and vehicle couplings, founded in 1922 in Krefeld to exploit patents for the ring spring, a friction spring first used in railway buffers. The same friction-ring principle later led to keyless locking devices and shrink discs. RINGFEDER POWER TRANSMISSION is part of the Swedish VBG Group, with its commercial office and R&D in Krefeld.
Seven Star LLC is an independent supplier in Muscat. We list Ringfeder RfN series from the official tech papers and quote them for machine builders and maintenance teams in Oman and the GCC.
Ringfeder company profile
| Founded | 1922, Krefeld, Germany |
|---|---|
| Origin | Patent exploitation of the ring (friction) spring for railway buffers |
| Headquarters | Krefeld, Germany |
| Ownership | VBG Group, Vänersborg, Sweden |
| Acquisitions | TSCHAN shaft couplings (Neunkirchener Tschan GmbH) |
| Product families | Locking assemblies and shrink discs, TNM, TND and POSIMIX couplings, damping springs and friction springs, trailer couplings for trucks and agricultural vehicles |
Milestones
- 1922: RINGFEDER is founded in Krefeld around the ring spring patent.
- Later: The friction-ring principle is applied to keyless shaft-hub connections (locking assemblies and shrink discs).
- Today: RINGFEDER operates within the VBG Group, with TSCHAN couplings added to its range.
Ringfeder product series
Locking assemblies fit between shaft and hub bore: RfN 7012 for shafts from 19 to 1000 mm, the self-centring RfN 7013.0 and RfN 7003, the heavy torque RfN 7014, RfN 7015.0, the three-piece RfN 7005 and RfN 7515, RfN 7006 with collar, the miniature RfN 7061 and the compact RfN 7110. Shrink discs clamp a hollow hub onto a shaft from the outside: light RfN 4051, standard RfN 4061 and RfN 4071, mini RfN 4073, route-controlled RfN 4161 and heavy-duty RfN 4091 and RfN 4181. RfN 8006 locking elements cover shafts from 6 to 1000 mm.
All of these are keyless friction connections, so there is no keyway to weaken the shaft and no backlash. Each tech paper lists sizes, transmissible torque and axial force, screw tightening torques and tolerances.
Where Ringfeder connections are used
Gear wheels, sprockets, pulleys, couplings and brake discs on shafts; hollow-shaft gear units on conveyors, mills and crushers; and drives in mining, cement, wind energy and general machine building.
Ringfeder products we list
Ordering Ringfeder products: what we need
Give the RfN series and size, or the shaft diameter, hub bore and hub outside diameter, the torque and any axial or bending loads, and the material or surface finish required.
Facts checked against RINGFEDER catalogues, VBG Group information and German trade press, October 2026.
Browse Ringfeder products by category: Couplings & Shaft Locking Devices.
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Frequently Asked Questions
What does route-controlled mean?
The screws are tightened until a defined displacement path is reached, with no torque wrench needed.
Which size range does the RfN 4161 cover?
Inner diameters 18 to 200 mm, 80 to 124,000 Nm.
What hub strength is required?
Yield strength Rp0.2 of at least 360 N/mm2.
Which series takes over above 200 mm?
The larger RfN 4181 from 220 mm inner diameter.
Which screws are used?
ISO 4014/4017 with strength 12.9, thread M6 to M16.
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