Four Bar Chain (quadratic cycle chain):
It has a four links and four pairs which are turning in nature.
The simplest and the basic kinematic chain is a four bar chain or quadric cycle chain, as shown in Fig.
It consists of four links, each of them forms a turning pair at A, B, C and D. The four links may be of different lengths.
A very important consideration in designing a mechanism is to ensure that the input crank makes a complete revolution relative to the other links.
Four Bar Chain (quadratic cycle chain):
The mechanism in which no link makes a complete revolution will not be useful.
In a four bar chain, one of the links, in particular the shortest link, will make a complete revolution relative to the other three links. Such a link is known as crank or driver.
