Edited by Mike Santora
Ringfeder recently updated its TND Series of steel disc couplings, which feature backlash-free torque transmission and excellent positioning accuracy in machines that involve synchronous operation, frequent starts, and stops or reversing operations. Typical drive applications include printing and packaging machines, compressors, pumps, and variable speed drives.
Using in-depth finite element analysis (FEA), Ringfeder optimized the redesign of these couplings, which now includes two coupling types: High Deflection (HD), which offers strong shaft misalignment compensation, and High Torque (HT), which incorporates a higher power density.
Corrosion-resistant disc pack design
The functional centerpiece of the TND coupling’s design is a disc pack, which consists of several circular, torsionally flexible discs made from stainless spring steel. The discs are connected via sleeves that incorporate special relief grooves, reducing the load peaks that can affect the outer discs whenever the shaft misaligns. In addition, screws alternately connect the disc packs to the hub’s input and output sides, enabling the steel discs to transmit torque reliably and accurately. This design also allows the coupling to compensate for angular, axial and radial shaft misalignments at minimum restoring forces.
Creating a Friction-Fit Shaft-Hub Connection
You can mount TND coupling hubs onto shafts via keyways (DIN 6885-1) or our Shrink Discs. This latter mounting option offers benefits like a 360-degree connection, which is suitable for smooth shafts that require greater contact pressure. By creating a friction fit, this option also achieves reliable torque transmission.
A single-disc pack or spacers with one disc pack screwed into each side function as the connecting elements between the hubs. Coupling types with the single disc pack feature single-jointed designs and can compensate for angular and axial shaft misalignments. Double-jointed designs with two disc packs can compensate for angular, axial, and radial misalignments. To bridge longer shaft distances, spacers are available in standard and custom lengths up to three meters.
Superior concentricity and operational reliability
Thanks to their high material quality, compact design, and tight tolerances, TND Series couplings achieve superior concentricity, maximum operational reliability, smooth operation, and low vibration levels — even in the presence of fast rotational speeds or irregular rotational forces. They also avoid wear, don’t require cleaning or lubrication, and offer a long service life when properly installed.
These shaft connections also provide maximum performance and reliability under extreme thermal loads due to their all-steel construction. You can use these couplings in temperatures ranging from -20° to 240°C, making this series suitable for applications involving high-temperature pumping systems. For use in explosive areas, we can supply units with ATEX compliance according to Product Directive 2014/34/EU and DIN EN ISO 80079-36:2016.
Other notable product features include:
Wear- and maintenance-free operation.
Modular design for maximum flexibility.
Available in eight types and eleven sizes each.
Bore diameter range: 25 to 215 millimeters.
Nominal torques up to 130,000 Newton-meters.
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