The rigid coupling is simple in structure and cheap in price. It is suitable for two axes with good concentricity.

The structure of elastic coupling is relatively complex and its price is high. It is suitable for the case of two shafts with poor concentricity and torsional vibration (vibration reduction).

Coupling is a mechanical part used to connect two shafts (active and driven shafts) in different mechanisms and rotate them together to transfer torque. When the machine is running, the two axles can not be separated. Only when the machine parks and disconnects the connection, the two axles can be separated. In high-speed and heavy-load power transmission, some couplings also have the functions of cushioning, vibration reduction and improving the dynamic performance of shafting. The coupling consists of two parts, which are connected with the driving shaft and the driven shaft respectively. Generally, power machines are mostly connected with working machines by means of coupling.