Ringfeder RfN 4071 Standard Shrink Disc, 220-500 mm

Standard shrink disc for large shafts and very high torque

The RfN 4071 is the large-diameter extension of the RINGFEDER standard shrink disc family. According to the tech paper it takes over from the RfN 4061 at an inner diameter of 220 mm and carries the same concept up to 500 mm, with transmissible torques of 95,000 to 1,455,000 Nm in the product paper. RINGFEDER calls the standard series the most popular shrink disc. A slit inner ring is drawn onto the shaft by the thrust rings when the locking screws are tightened, and the outer ring presses on the hub, so a key, step or spline is no longer needed.

The disc is available as a two-part or three-part design. The preload can be set to the application through the screw tightening torque, and the slit inner ring keeps forces and pressures on hub and shaft low. RINGFEDER states that small tolerance errors are compensated and that the joint is suitable for static, dynamic and impact loads.

Technical specifications

Selected sizes from the tech paper

Every size is tabulated for three shaft diameters at slightly different torques. The values above are the middle shaft row of each size; the 220 x 370 disc, for example, lists 95,000 Nm for a 160 mm shaft, 102,000 Nm for 165 mm and 110,000 Nm for 170 mm, which is how one disc covers neighbouring shaft sizes. Tmax rises from 118,750 Nm to 137,500 Nm across those rows.

Characteristics and what to check

RINGFEDER’s list of benefits for this series starts with simple manufacture, since plain shaft and bore diameters with an easily achieved finish will do, and continues with free replacement because no form fit is involved, mounting with standard screws and standard tools at any axial position or angle, and self-release after the screws are slackened. Once tightened, the contact surfaces are pressed together and resist dirt and moisture.

Torque and axial force in the tables hold under stated test conditions: screws and cones lubricated with MoS2, lightly oiled shaft surfaces (friction 0.12) and steel hub and shaft with an elastic modulus of 210,000 N/mm2. The shaft is solid and finished to Ra 3.2 um. Hollow shafts, or extra tension, thrust or bending loads, change the values and should be taken up with RINGFEDER engineering. For this size range the tech paper allows a maximum clearance S between shaft and bore of 0.090 mm at 180 to 250 mm, 0.101 mm at 250 to 315 mm, 0.111 mm at 315 to 400 mm and 0.123 mm at 400 to 500 mm. Confirm before ordering: shaft diameter within the dw range, hub outside diameter and strength, and drive torque with a shock factor. Below 220 mm inner diameter RINGFEDER points to the RfN 4061, and the heavy-duty RfN 4181 reaches higher torques.

Documents and quotation

The attached PDF is the RINGFEDER RfN 4071 tech paper (10.2024) with the full size table. Related locking devices are listed under Couplings & Shaft Locking Devices. Send shaft diameter, hub dimensions and torque for a size check.