The principle of coupling needs should be considered based on six aspects: speed, torque, assembly and disassembly, neutrality, cost, and environment: coupling ((expansion sleeve)) selection principle: 

1: Rotation speed n: n ↑, flexible coupling of non-metal elastic element; 

2: Torque T: T ↑, choose rigid coupling, non-elastic element or flexible coupling with metal elastic element; T has impact vibration, choose flexible coupling with elastic element;

3: Assembly and disassembly: Considering the convenience of assembly and disassembly, choose a coupling that can directly move radially; 

4: Alignment: For neutral alignment, choose a rigid coupling, and when compensation is needed, choose a flexible coupling; 

5: Cost: Under the same conditions, try to choose a coupling with low price and simple maintenance;

6: Environment: If working at high temperature, couplings with non-metallic components are not optional;