Coupling can be divided into rigid coupling and flexible coupling.

　　Rigid coupling does not have the ability of buffering and compensating the relative displacement of two axes,which requires the two axes to be aligned strictly.However,this kind of coupling has simple structure,low manufacturing cost and assembly and disassembly.,easy to maintain,can ensure the two axes have a high pair of neutral,transfer torque is large,widely used.Flange coupling,sleeve coupling and clamp coupling are commonly used.

　　Flexible couplings can be divided into inelastic flexible couplings and elastic flexible couplings.The former type only has the ability to compensate for the relative displacement of two axes,but cannot buffer and reduce vibration.After a class because of containing elastic element,in addition to have the ability to compensate for two axes relative displacement,but also has cushioning and vibration damping,but transfer torque strength by elastic component,generally less than without the elastic element flexible coupling,common column elastic sleeve pin couplings,elastic dowel pin shaft coupling,plum coupling,tyred coupling and snake-like spring coupling and coupling reeds,etc.