Ringfeder RfN 4091 Heavy-Duty Shrink Disc, 50-500 mm

The heaviest shrink disc series for extreme loads

The RfN 4091 is the heaviest, most robust shrink disc in the RINGFEDER range. A wider body with particularly strong outer rings gives it, in RINGFEDER’s words, maximum transmission values even at extreme loads. The tech paper lists inner diameters from 50 mm to 500 mm and torques from 1,800 Nm up to 1,940,000 Nm in the product paper, in both two-part and three-part forms.

Its function is the same as the lighter series: a slit inner ring, drawn onto the shaft by the thrust rings, produces a friction fit without key or spline, so there is no keyway to weaken the shaft and no backlash. The preload can be targeted to the application through the tightening torque.

Technical specifications

Selected sizes from the tech paper

Each size is tabulated for three shaft diameters; the 75 x 145 disc covers shafts of 55, 60 and 65 mm with torques from 4,600 to 7,000 Nm. The full table continues to the largest sizes.

Comparing rows shows the step in capacity: the 50 x 95 disc is tabulated at 2,100 Nm with seven M8 screws, while the 110 x 185 disc reaches 12,900 Nm with twelve M10 screws and an axial force of 338 kN. Use the shaft diameter column first, then check the torque against the application and the wall thickness of the hub that will carry the pressure.

When to choose the heavy series

The heavy series gets its capacity from a wider body and stronger outer rings. A 100 x 170 disc is tabulated at 10,000 Nm for a 75 mm shaft with ten M10 screws, and the 125 x 215 disc at 17,500 Nm with ten M12 screws. Choose it for drives with extremely static or dynamic loads, where the lighter RfN 4051 or the standard RfN 4061 would not have enough margin.

Order by series with d and D. Confirm before ordering: shaft diameter within the dw range, hub strength and wall thickness, and torque including shock factor.

A shrink disc connection suits almost any hub on a shaft or axle: gear wheels and sprockets, levers, cam discs, pulleys, brake discs, couplings, flanges and rotors, replacing keys, polygon connections and splined shafts. RINGFEDER notes that the disc itself is not in the load path and that few other shaft-hub connections combine such permanent rotational stability with excellent concentricity.

Because the tech paper tabulates every size for three shaft diameters, the same disc can serve neighbouring shafts, so state the exact shaft diameter, hub bore and required torque when requesting a quotation.

Documents and quotation

The attached PDF is the RINGFEDER RfN 4091 tech paper (10.2024). Related drives are listed under Electric Motors and Gear Units. Send shaft diameter, torque and load type for a size proposal.