On the basis of shaft alignment. Couplings can be classified into two types;
- Rigid Coupling
- Flexible Coupling
It is used to connect two shafts having no misalignment, ideally co-axial shaft. They are further classified into following types;
- Sleeve or Muff Coupling
- Clamp or Compression Coupling
- Flange Coupling
Sleeve Coupling is one of the basic type of rigid coupling. It consists of a cylindrical sleeve keyed to the shafts to be connected.
Clamp Coupling consists of two half cylinders which are placed over the ends of the shafts to be coupled and are held together by two bolts.
Flange Coupling is widely used rigid coupling. It consists of two flanges which are keyed to the shafts and bolted where the bolts are equally spaced.
It is used to connect two shafts which have some amount of misalignment. They are further classified into following types;
- Bushed Coupling
- Universal Coupling
- Oldham Coupling
It is one of the commonly used flexible couplings in which torque is transmitted from one flange to another through a flexible bush put around the bolt. This type of coupling used only when there is small amount of misalignment.
It is mainly used to handle relatively large angular misalignment. It consists of two forks and a key screwed to the shaft. These two forks ends are connected to a center piece through which two pins pass usually perpendicular axis.
It is used to handle both lateral and angular misalignment to some extent. It consists of two flanges having slots on the faces and these flanges which are keyed or screwed to the shafts. The central portion is called the disc which is a cylindrical piece having a narrow rectangular race portion running across each face at right angle to each other. A disc is placed between the flanges so that the raced portion fit into the slots of the flanges.