There is little knowledge of related shafts

(1)CouplingType characteristics
Rigid coupling: rigidCouplingIt does not have the ability to compensate for the relative deviation of the axis of the coupled two shafts, nor does it have shock absorption performance; but the structure is simple and the price is cheap.Rigid couplings can only be used when the load is stable, the speed is stable, and the relative deviation of the axes of the two shafts to be coupled is minimal.
Flexible coupling without elastic elements: large load-bearing capacity, but also does not have cushioning and shock absorption performance, and there will be impact noise at high speed or unstable rotation or frequent forward and reverse rotation.It is suitable for occasions with low speed, heavy load and stable speed.
*Coupling: The structural feature is that there is a safety link (such as a movable pin connection, etc.), which can only bear a limited load.When the actual load exceeds the previously limited load, the insurance link changes, cutting off the transmission of motion and power, so as to protect the rest of the machine from damage, that is, it plays a protective role.
(2) The function of the coupling
Coupling is a component that connects two shafts axially and transmits torque and motion. It has a certain ability to compensate for the deviation of the two shafts. In order to reduce the vibration of the mechanical transmission system and reduce the impact peak load, the coupling should also have a certain The cushioning and shock absorption performance.The coupling sometimes also has an overload* protection function. 
(3)CouplingThe selection principle:
Alignment: For good alignment, choose a rigid coupling, and when compensation is needed, choose a flexible coupling;
Assembly and disassembly: Considering the convenience of assembly and disassembly, choose a coupling that can directly move radially;
Environment: If working at high temperatures, couplings with non-metallic components are not available;
Cost: Under the same conditions, try to choose a coupling with low price and simple maintenance