Ringfeder RfN 4181 Heavy-Duty Shrink Disc, 220-800 mm

Heavy-duty shrink disc for the highest torques, tightened by route control

The RfN 4181 is the size-extended version of the RfN 4161 for larger shaft diameters and maximum torques. RINGFEDER describes it as a two-part heavy-duty shrink disc with an additional guide mechanism for the inner ring, made for transmitting the largest torques. Inner diameters run from 220 mm to 800 mm, and the product paper lists transmissible torques from 160,000 Nm to 8,390,000 Nm. It is applicable to static, dynamic and impact loads.

Assembly is route-controlled: the screws are tightened to a defined displacement path of the thrust ring, so the clamping is independent of the friction in the screws. Both rings are in contact in the clamped state, which gives very good concentricity, and the tightening status can be checked visually, which minimises faults during assembly. The shrink disc works without any positive locking, so it is fully replaceable.

Technical specifications

Selection should start from the torque and bending load on the shaft, then confirm the hub material and wall thickness at the shrink disc seat. Check the shaft and bore tolerances against the values in the Ringfeder technical paper, and tighten the screws in the sequence and to the torque given there so that the contact pressure is evenly distributed around the hub.

Selected sizes from the tech paper

The table does not list screw counts for this series. Each size is tabulated for three shaft diameters; the 260 x 430 disc covers 190, 200 and 220 mm shafts at 247,000, 277,000 and 340,000 Nm. The tech paper adds Tmax values for every row, for example 304,700 Nm for the 260 x 430 at 200 mm.

Limits and neighbouring series

The RfN 4161 route-controlled series is replaced by the RfN 4181 from an inner diameter of 220 mm, and the tech paper requires a hub with a yield strength Rp0.2 of at least 360 N/mm2. RINGFEDER also stresses that only plain shaft and bore diameters are needed, and that a visual check of the tightened state keeps assembly errors low.

For this series the function values apply to MoS2-lubricated screws and cones and a lightly oiled shaft, with the shaft solid, finished to Ra 3.2 um and the permitted clearance S fully used; the largest sizes allow 0.090 mm at 180 to 250 mm, 0.123 mm at 400 to 500 mm and 0.154 mm at 630 to 800 mm. Additional loads or hollow shafts call for RINGFEDER engineering. Confirm before ordering: shaft diameter within the dw range, hub strength and wall thickness, whether the 12.9 screws and route-controlled fitting suit your procedure, and torque with shock factor. For a friction-controlled standard series in the same size range look at the RfN 4071.

Related Ringfeder products: Ringfeder RfN 4091 Heavy-Duty Shrink Disc, 50-500 mm, Ringfeder RfN 4071 Standard Shrink Disc, 220-500 mm, Ringfeder RfN 4051 Light Shrink Disc, 125-500 mm, Ringfeder RfN 4061 Standard Shrink Disc, 14-200 mm, Ringfeder RfN 4073 Mini Shrink Disc, 14-160 mm and Ringfeder RfN 4161 Shrink Disc, Route-Controlled, 18-200 mm.

Documents and quotation

The attached PDF is the RINGFEDER RfN 4181 tech paper (10.2024). Related locking devices are listed under Couplings & Shaft Locking Devices. Send shaft diameter, hub dimensions and torque for a size proposal.