A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end movement or both. In a more general context, a coupling can also be a mechanical device that serves to connect the ends of adjacent parts or objects. Couplings do not normally allow disconnection of shafts during operation, however, there are torque limiting couplings which can slip or disconnect when some torque limit is exceeded. Selection, installation and maintenance of couplings can lead to reduced maintenance time and maintenance cost.
Shaft couplings are used in machinery for several purposes. A primary function is to transfer power from one end to another end (eg: motor transfer power to pump through coupling). Other common uses:
- To alter the vibration characteristics of rotating units
- To connect driving and the driven part
- To introduce protection
- To reduce the transmission of shock loads from one shaft to another
- To slip when an overload occurs