Kinematic chain
Kinematic chain is defined as the combination of kinematic pairs in which each links forms a part of two kinematic pairs and the relative motion between the links is either completely constrained or successfully constrained.
Examples: slider-crank mechanism
For a kinematic chain
N = 2 P – 4 = 2 (j + 2) / 3
Where N = no. of links, P = no. of Pairs and j = no. of joints
When,
LHS > RHS, then the chain is locked
LHS = RHS, then the chain is constrained
LHS < RHS, then the chain is unconstrained