Depending on the application, you may need a two- or three-piece Shrink Disc design to create a secure shaft-hub connection. Ringfeder Power Transmission recently offered insight to some of their key similarities and differences to help you select the right one.

A modern method for creating a mechanical shrink fit, Shrink Discs offer an even distribution of locking forces and eliminate fatigue-prone keyed connections in light- and heavy-duty applications. Each Shrink Disc consists of one or two outer rings with tapered bores and a mating tapered inner ring. After placing the device over the hub and shaft, simply tighten the locking screws — compressing the hub tightly around the shaft.

Characterized by a shallow tapered single cone, two-part Shrink Discs transfer the necessary torque in a similar way to an interference fit. The screws on the discs can be tightened without using a torque wrench, and the installation is complete once the inner and outer ring surfaces are flush, enabling you to mount the units quickly and easily. The two-piece design is inherently better balanced and is therefore better suited for high-speed applications.

Characterized by a steeper double cone, three-part Shrink Discs transfer the required torque in a similar way to an interference fit and can be assembled and disassembled quickly. The Shrink Disc itself is not in the flow of forces, and the distance between the flanges enables simple function checking. You can adapt these function values specifically to your application requirements by varying the screw-tightening torque.

Ringfeder's three-piece Shrink Discs, which include a top and bottom outer ring, inner ring and screws, are the company's most popular design. Available models, along with their characteristics, include:

4073 — light-duty units usually used in shaft-seal applications

4051 — light-duty units with lower torque ratings

4061 — standard-duty units available in 14 to 200 millimeters

4071 — standard-duty units available in 220 millimeters and up

4081 — the same as the 4061 and 4071 series, except these units use grade 12.9 screws instead of the standard 10.9

4091 — heavy-duty units with a higher torque rating

Two-piece Shrink Discs, which include an outer ring, inner ring and screws, are ideal for high-speed applications. Available models, along with their characteristics, include:

4161 — standard-duty units available in 18 to 200 millimeters

4181 — standard-duty units available in 220 millimeters and up

4191 — heavy-duty units with a higher torque rating

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