What is a Coupling? What is its Purpose? Couplings are mechanical components used to connect two shafts together. Primarily, they serve to transmit energy from the driving side of a rotary system to the driven side. Secondary functions include compensating for misalignment or reducing vibration. There are two main types of couplings: flexible and rigid. Flexible couplings allow for more freedom of movement at the connection point, making them better suited to withstand lateral and axial forces compared to rigid couplings. This flexibility, however, results in a slight decrease in torque transmission, making these couplings best for applications where some degree of misalignment exists between shafts. Rigid couplings, on the other hand, create an inflexible connection between two shafts, allowing for more efficient torque transmission than flexible couplings. Since the coupling cannot compensate for misalignment, the shafts must remain precisely aligned. When proper ...