Coupling

A coupling is a device that is used to connect two shafts together at their ends for transmitting power. It couples two drive elements which enabled motion to be transferred from one element to another.
Types of couplings
• Rigid coupling: it is used to connect two shafts that are perfectly designed. Rigid coupling has three types:
1. Sleeve or muff coupling: This coupling contains a pipe whose bore is finished to the required tolerance based in the shaft size.
2. Clamp or split-muff or compression coupling: The sleeve is made of two halves, which is divided or split along a plane passing through the axes of the shafts.
3. Flange coupling: It has two separate cast iron flanges. Each flange will be mounted on the shaft end and keyed to it. The two flanges are coupled together with bolts or nuts.

• Flexible coupling: It transmits torque from one shaft to another when two shafts are having both lateral and angular misalignment. Flexible coupling has three types:
1. Bushed pin type coupling: it has pins and works as a coupling bolts. The rubber or leather bushes are used over the pins.
2. Universal coupling: It is a coupling joint in a rigid rod to bend the rod in any direction and is commonly used in shafts.
3. Oldham coupling: It has three discs, one coupled to the input and other coupled to the output and a middle disc that is joined to the first two by tongue and groove.

Uses of coupling
They are used to reduce the transmission of shock loads from one shaft to another, to connect driving and driven part, to introduce protection against overloads, to alter the vibration characteristics of rotating units.