Regal Rexnord
Locking Assemblies & Shrink Discs
Regal Rexnord locking assemblies and shrink discs are precision mechanical devices that create high - force, zero - backlash, keyless connections between shafts and hubs — eliminating the fretting, backlash, and stress - concentration problems inherent in traditional keyed connections while providing the full torque - transmission capacity of an interference fit, but with the ability to be installed and removed with simple hand tools.These friction - based clamping systems consist of inner and outer rings with mating tapered surfaces; tightening the clamping screws drives the rings together, generating radial clamping forces that can exceed the yield strength of the shaft and hub materials, creating a joint that transmits torque through the full 360° contact surface without the stress risers of keyways or splines.Design engineers in heavy machinery, wind - turbine manufacturing, marine propulsion, mining equipment, and process industries specify Regal Rexnord locking assemblies and shrink discs — under the Tollok, Ringfeder, and Rexnord brands — when they require maximum torque capacity from a given shaft and hub diameter, need to index or phase a hub precisely on the shaft during assembly, or must eliminate the shaft fatigue failures that originate at keyway corners.With standard series covering shaft diameters from 5 mm to over 600 mm and custom designs for specific OEM applications, our locking device portfolio provides the keyless - shaft - connection reliability that enables more compact, more durable machine designs.
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Keyway - Free Connection for Maximum Shaft Fatigue Strength
Eliminating the keyway concentrates eliminates the 2.5x to 3x stress - concentration factor that causes shaft fatigue fractures, enabling smaller shaft diameters or longer service life for a given torque requirement.
Zero - Backlash, Precision Phasing
The 360° clamping connection allows infinite angular adjustment of the hub on the shaft during assembly, enabling precise timing of cams, gears, and coupling flanges without the incremental limitation of splines.
Full 360° Contact Torque Transmission
Load is distributed across the entire shaft circumference, eliminating the highly localized contact stress of a single - key or spline connection and maximizing the torque capacity of the shaft / hub interface.
Installation & Removal with Hand Tools
Tightening or loosening a ring of clamping screws produces the radial force, eliminating the need for heating, pressing, or hydraulic equipment during assembly and field service.
Standard & Corrosion - Resistant Materials
Carbon steel for general industrial use; stainless steel for food, marine, and chemical environments; special coatings for offshore and subsea applications where hydraulic activation is undesirable.
Wide Diameter & Torque Range
Standard series covering shafts from 5 mm to over 600 mm, transmitting torque from a few Nm to over 2,000,000 Nm — matching the torque demands of the smallest precision drives to the largest mill and marine propulsion shafts.
Keyless Locking Assemblies vs.Keyed Connections: Engineering & Cost Benefits
The keyed shaft - hub connection has been the standard for over a century, but it introduces fundamental engineering compromises: the keyway acts as a stress riser that reduces shaft fatigue strength by a factor of 2 to 3; the key must be sized for the full torque, creating a notch that often becomes the life - limiting feature of the shaft; backlash between the key and keyway grows with wear, creating impact loads that accelerate fatigue; and assembly requires accurate broaching or milling of the keyway, adding cost and lead time to shaft fabrication.Regal Rexnord locking assemblies eliminate all of these compromises.The shaft can be a simple ground cylinder — the least expensive and strongest shaft geometry possible.The hub bore is similarly simple, reducing machining cost.Assembly is faster than key - and - setscrew mounting, and the joint can be disassembled and reused multiple times without loss of clamping force.For OEM machine builders, the switch to keyless shaft connections reduces manufacturing cost, improves product reliability, and simplifies field service.For end - user maintenance teams, locking assemblies enable rapid component changes without the shaft and hub damage that often accompanies the removal of corroded or fretted keyed connections.
Shrink Discs for Wind Turbines, Marine Shafts & Large Drives
In the largest shaft sizes — 200 mm and above — external shrink discs provide the keyless connection method of choice.A shrink disc consists of a pair of heavy - walled rings with mating tapered faces; tightening the clamping bolts draws the rings together, compressing a thick - walled hub(typically a gearbox hollow shaft or a coupling flange) onto the shaft with extremely high radial force.This method is the standard for connecting wind - turbine main shafts to gearboxes, marine propeller shafts to flanges, and large mill pinion shafts to coupling hubs — applications where the torque exceeds 1,000,000 Nm and joint reliability directly impacts public safety and production continuity.Regal Rexnord Ringfeder and Tollok shrink discs are manufactured from forged, quenched and tempered alloy steels with the ductility to maintain clamping force through thermal cycling and the fatigue resistance for 20 + years of continuous service.For offshore wind, marine, and subsea applications, corrosion - protected and hydraulically - actuated designs eliminate the need for diver - accessible bolt tightening.The result is a joint that transmits more torque than would be possible with a keyed connection on the same shaft diameter, without the fatigue - life penalty that a keyway would impose.