Difference between rigid and flexible coupling

What is Rigid coupling?

Rigid coupling some cases called sleeve or muff coupling are economical and mostly designed for the aligned shafts only. 

What us Flexible coupling?

A flexible coupling is used to transmit torque from one shaft to another which is slightly misaligned. 

Let us have a deep insight into the comparison between the rigid and flexible coupling. 

Difference between rigid and flexible coupling :

• Flexible coupling couple with rotating members such as motors and driveshafts, while allowing misalignment in either angular or parallel offset orientation while rigid coupling couple with rotating members such as shafts. 
• A rigid coupling is simple and inexpensive while the flexible coupling is comparatively costlier due to additional parts.
• A rigid coupling can not tolerate misalignment between the axis of shafts used only when there is precise alignment between two shafts while flexible elements like bush or disk can tolerate 0.5⁰ of angular misalignment and 5 mm of axial displacement between the shafts.
• The flexible elements in the flexible coupling absorb shocks and vibrations while the motion is free of shocks and vibrations in the rigid coupling.
• Rigid couplings have limited application compared to flexible couplings because rigid couplings do not have the ability to compensate for shaft misalignment and are therefore used where shafts are already positioned in accurate lateral and angular alignment.
• Rigid coupling does not allow for angular or parallel misalignment while flexible coupling does.
• Deflection is less in rigid coupling while flexible coupling has more.

Explore more information : 

• Why flexible coupling is preferred over rigid coupling?
• What is coupling?
• What are the disadvantages of muff coupling?