A coupling is a type of mechanical device that connects similar or dissimilar shafts in machines to transmit power and motion. Generally, a coupling is used as a temporary connection, but can be made permanent, if necessary. More than that, couplings are easy to remove for servicing and replacement, and they are typically rigid or flexible in nature.As there are a wide range of designs available on the market, there are many unique differences in the design and function of couplings. For instance, some couplings can connect to a shaft without moving the shaft itself, while others necessitate shaft movement for installation. In most cases, couplings do not change the direction of motion or angular velocity, and they cannot be connected or disconnected mid-operation.Essentially, couplings are only capable of transferring torque over short distances, whereas torque over long distances can be achieved with chain drives and belt drives. In many applications, couplings are used alongside lead screw assemblies to connect the screw shaft in-line to a motor. Moreover, couplings can withstand an array of loads and accommodate for misalignment without permitting any relative motion between shafts.