Brand: Ringfeder

Ringfeder RfN 8006 Locking Elements, Shafts 6-1000 mm

Name: Ringfeder RfN 8006 Locking Elements – Datasheet & Quote
Brand: Ringfeder
SKU: RfN 8006

Description

Locking elements that turn your own flange and screws into a keyless joint

The RfN 8006 is not a ready-to-fit locking assembly but a pair of tapered thin rings, the RINGFEDER locking element. You place one or several elements between shaft and hub bore, push them together with a thrust flange and customer-supplied clamping screws, and the elements expand into a friction joint. Because the design leaves the screw layout to the user, one element size can be adapted to most surface pressures, materials, hub and shaft dimensions and mounting spaces. RINGFEDER offers solid and slit versions; sizes up to 8 mm and some other small sizes are generally slit.

The joint has no keyway, so fatigue strength under reversing torque is high, it is free of backlash, and the connection can be adjusted to any axial or angular position on the shaft before clamping. RINGFEDER calls the elements wear and maintenance free, with unlimited life when designed and used correctly. Releasing the screws frees shaft and hub completely.

Technical specifications

Parameter	Specification
Manufacturer	RINGFEDER POWER TRANSMISSION GmbH, Groß-Umstadt, Germany
Series	RINGFEDER RfN 8006 locking element, solid and slit versions
Shaft diameter d	6 to 1000 mm; more sizes on request
Outside diameter D	9 to 1050 mm
Overall length L / ring width L3	4.5 to 80 mm / 3.7 to 73 mm
Reference torque T100	2.5 Nm (6 mm) to 1,377,741 Nm (1000 mm), at shaft pressure p = 100 N/mm2
Reference axial force Fax100	830 N (6 mm) to 2,755,482 N (1000 mm), at p = 100 N/mm2
Maximum transmissible torque Tmax	7.8 Nm to 2,057,223 Nm
Elements in series	Up to 4; torque and axial force multiplied by m = 1.555 / 1.86 / 2.03 for 2 / 3 / 4 elements
Weight per element	0.0015 kg to 50.6 kg
Surface finish	Shaft and hub bore Ra 1 um or better
Recommended fits	Shaft h6 / hub H7 up to d = 38 mm; shaft h8 / hub H8 above 38 mm
Self-centring	No; concentricity depends on the centring and care of the installation

Selected sizes from the tech paper

The table runs from 6 to 1000 mm. T100 and Fax100 are reference values at a shaft pressure of 100 N/mm2; FA’ is the clamping force needed for that pressure. For a solid element the screws must apply FA = FA’ + F0, and for a slit element FA = FA’.

d x D (mm)	L (mm)	FA’ (kN)	T100 (Nm)	Fax100 (kN)	Tmax (Nm)	Weight (kg)
10 x 13	4.5	6.3	7	1.4	12	0.0018
20 x 25	6.3	18	40	4.0	103	0.0082
30 x 35	6.3	27	90	6.0	252	0.012
50 x 57	10	73	405	16.2	948	0.05
100 x 114	21	317	3,520	70	7,950	0.4
200 x 224	38	1,180	26,200	262	37,870	2.3
400 x 440	65	4,000	178,000	890	258,373	13.5
1000 x 1050	80	12,400	1,377,741	2,755	2,057,223	50.6

Designing the screw set and the series

The torque capacity is proportional to the clamping force, so the product paper includes a screw table. For grade 10.9 screws, M10 gives 69 Nm tightening torque and 36,900 N initial force, M12 gives 120 Nm and 54,000 N, M16 gives 295 Nm and 102,000 N, M20 gives 580 Nm and 160,000 N, and M24 gives 1,000 Nm and 230,000 N, with oiled screws. Where two to four elements are placed in series, torque and axial force rise by a factor of 1.555, 1.86 or 2.03, and the clamping force and surface pressure per element may be reduced by the same factor while keeping the transmitted values.

Because the elements are narrow they mostly serve to transmit large torques and axial forces and are not self-centring, so accurate concentricity depends on the shaft and hub fits and on careful assembly. Fits are shaft h6 and hub H7 up to 38 mm shaft diameter, and h8 and H8 above. A spacer sleeve is listed for each size. Confirm before ordering: torque, hub material and wall thickness, space for a thrust flange and screws, and whether a solid or slit version is needed.

Documents and quotation

The attached PDF is the RINGFEDER tech paper for the RfN 8006 (01.2023). Related drive components are listed under Electric Motors and Gear Units. Send the shaft and hub dimensions, torque and available mounting space for a calculation.

Datasheets & Documents

Technical Data RINGFEDER RfN 8006 tech paper (EN, 01.2023) 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

Family	Examples
Couplings & Shaft Locking Devices	RfN 4051 Light Shrink Disc, RfN 4061 Standard Shrink Disc, RfN 4091 Heavy-Duty Shrink Disc, RfN 7003 Self-Centring Locking Assembly, RfN 7005 Three-Piece Locking Assembly, RfN 7006 Locking Assembly with Collar, RfN 7012 Locking Assembly, RfN 7013.0 Self-Centring Locking Assembly and 5 more

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.