A shaft coupling joins a driving shaft to a driven one and, in every type except a rigid coupling, takes up some misalignment between them. The group divides first into lubricated and non-lubricated designs. Gear couplings and chain couplings run in grease under a cover and carry the highest torque for their size. Disc couplings, elastomeric couplings and jaw couplings need no lubrication: disc couplings flex stainless steel packs, elastomeric couplings drive through rubber or urethane, and jaw couplings drive through an insert between two hubs. Rigid sleeve and bushed couplings hold two shafts as one. Fasteners, seal kits and coupling grease are listed alongside.
Also known as: shaft couplings, flexible couplings, motor couplings, coupling hubs, power transmission couplings
Series in this category
Related guides: Coupling types compared, Cross-reference help
| Specification | What it means |
|---|---|
| Coupling type | Gear, disc, elastomeric, chain, jaw or rigid, which sets whether the coupling is lubricated and how it takes up misalignment. |
| Coupling size | The size designation within a line, such as KD 204 or a 3 1/2 gear coupling, which fixes the torque rating and bore range. |
| Torque rating | Continuous torque in lb-in or lb-ft, which must exceed the selection torque after the service factor is applied. |
| Bore type and maximum bore | Rough, finished or bushed bore, and the largest shaft the hub can be bored to. |
| Configuration | What the listing is: a complete coupling, a full flex or flex-rigid gear coupling, a half coupling, a hub or a sleeve. |
| Maximum speed | The rpm limit for the size, sometimes stated separately for balanced and unbalanced assemblies. |
| Lube or non-lube | Whether the coupling runs in grease under a cover, as gear and chain couplings do, or needs no lubrication. |
In five steps: determine the application type and its service factor; calculate selection torque as the service factor times application torque; verify the coupling's torque rating is at least that; verify its bore capacity covers both shafts; and check the balance chart for the type to see whether it can be used as manufactured. For a 500 hp motor at 700 rpm the application torque is 45,000 lb-in.
Among the stocked types, the Morse Morflex elastomeric coupling is rated for angular misalignment up to 10 degrees, and gear couplings are listed for good misalignment and slide capability. Disc couplings are listed with limited misalignment capacity, and jaw couplings with low misalignment capability, so those two need careful alignment at installation.
The elastomeric group: the Kop-Flex MAX-C K2 drives urethane blocks in compression and is made for shock absorption, torque reversals and start-stop service, and the ELASTOMERIC and Morflex couplings cushion shock and vibration through their rubber elements. Grid couplings are the lubricated alternative for shock loading.
The catalog states that its gear couplings are interchangeable by half coupling with the equivalent sizes from other manufacturers, and that grid couplings interchange by part. Confirm the size, flange pattern and bolt circle against the existing half before ordering one side only.
