Types of Links:
Each part of a machine, which moves relative to some other part is known as a kinematic link or simply link. A link may consist of several parts which are rigidly fastened together, so that they don’t move relative to one another. In order to transmit motion, the driver and the follower may be connected by the following three types of link in theory of machines.
1. Rigid Link: A rigid link is one which doesn’t undergo any deformation while transmitting motion. Strictly speaking, rigid links do not exist. However, as the deformation of a connecting rod, crank, etc of a reciprocating steam engine is not appreciable, they can be considered as rigid links.
2. Flexible Link: A flexible link is one which is partly deformed in a manner not to affect the transformation of motion.
Example: Belts, ropes, chains and wires are flexible links and transmit tensile forces only.
3. Fluid Link: A fluid link is one which is formed by having a fluid in a receptacle and the motion is transmitted through the fluid by pressure or compression only.