Kinematic Chain

The kinematic pairs are joined in such a way that the last link is connected to the first link, in order to transmit motion in a desired direction. We can say that kinematic chain is a combination of rigid bodies which provides completely or successfully constrained motion.

Relation between number of links (l) and number of pairs (p) in a kinematic chain can be expressed as

l = 2p – 4

Relation between number of joints (j) and number of links (l) in a kinematic chain can be expressed as

j = (3/2)l – 2

Both the above equations are applicable for kinematic chains having lower pairs.

Following types of joints are usually found in a kinematic chain.

(a). Binary joint – In this type, two links are joined at a connection.

(b). Ternary joint – Three links are connected at a connection.

(c). Quatenary joint – Four links are connected at a connection.

There are three types of Kinematic Chains.

(a). Four bar chain – It has four turning pairs.

(b). Single slider crank chain – It has one sliding and three turning pairs.

(c). Double slider crank chain – It has two sliding and two turning pairs.