Shaft Coupling
A shaft coupling is a device that connects two rotating shafts, typically a driver such as a motor and a driven machine such as a pump or gearbox, to transmit torque. Rigid couplings require precise alignment, whereas flexible couplings accommodate limited angular, parallel and axial misalignment. Flexible types include jaw (elastomeric spider), tyre, gear, grid, disc and diaphragm couplings; disc and diaphragm couplings are common on API-standard rotating equipment because they need no lubrication. Selection considers nominal and peak torque, speed, shaft diameters and keyways, misalignment capacity, torsional stiffness, damping, service factor and spacer length, which allows seal maintenance without moving the machines. Couplings on process pumps and compressors may be specified to API 610 or API 671. Rotating couplings must be fitted with guards.
Examples
- Jaw coupling between a motor and a small pump
- Spacer disc coupling on an API process pump
- Gear coupling on a heavy-duty mill drive