A coupling is a device used to connect two shafts together at their ends to transfer power. Their primary purpose is joining two pieces of rotating equipment together while permitting some degree of misalignment, end movement, or both.
Couplings are most commonly used to transfer power from a motor to a pump, connect shafts of two machines manufactured separately, provide mechanical flexibility, prevent shock and vibrations from transferring from one piece of equipment to another, and potentially slip when torque overload occurs.
They typically feature two rigid parts that fit around the end of two shafts to form a sleeve. A hub sits between the teeth to provide the buffer between each coupling half. Flexible couplings provide similar results with a one-piece aluminum body design to shift under differential torque loads.