Chain Couplings
Morse roller-chain couplings join shafts through a double-strand chain wrapped over two hardened sprockets. A simple, serviceable design for moderate torque and speed.
A chain coupling connects two shafts using a hardened sprocket on each shaft and a length of double-width roller chain wrapped around both. A connecting link closes the chain, so the drive can be broken and remade without moving either machine, which is why chain couplings are common where a pump or gearbox has to come out for service. The clearance between chain and sprocket teeth absorbs a small amount of misalignment, and the whole assembly runs inside a grease-filled cover.
Also known as: chain coupling, chain coupler, roller chain coupling, double roller chain coupling
Series in this category
Related guides: Coupling types compared, Cross-reference help
| Specification | What it means |
|---|---|
| Nominal torque | The continuous torque the coupling is rated to transmit. Compare it against the driven load with a service factor already applied. |
| Chain size | The ANSI roller chain pitch used, which sets the sprocket tooth form and the coupling's torque class. |
| Maximum bore | The largest shaft diameter a sprocket can be bored to while leaving enough material around the keyway. |
| Number of teeth | Teeth per sprocket. More teeth spread the load over more rollers and raise the torque the coupling carries. |
| Maximum speed | The rotational limit for the coupling, set by chain mass and the ability to keep grease on the teeth. |
| Overall length | The axial space the assembled coupling and cover occupy between the two machines. |
A small amount of angular and parallel offset, absorbed by the clearance between the chain rollers and the sprocket teeth. It is a tolerance for practical installation error, not a license to skip alignment, and running persistently misaligned wears the chain and teeth quickly.
No, and they usually do not have it. Each sprocket is bored for the shaft it mounts on, so a motor shaft and a gearbox input of different diameters are the normal case rather than the exception.
The chain and sprocket teeth are a sliding, loaded contact that has to stay lubricated, and the cover is what retains the grease around them. It also guards a chain moving at shaft speed, so it matters for safety as much as for coupling life.
Yes, and that is the main reason to choose one. Removing the connecting link frees the chain and separates the drive in place, so a pump or gearbox can be pulled without disturbing the alignment of either shaft.
