Circuits and branches of single degree-of-freedom planar linkages

Improved definitions for circuits and branches of mechanisms are proposed and discussed in application to planar linkages. The difficulty of circuit and branch identification of multi-loop planar linkages is introduced. The nomenclature used by various authors is correlated with the definitions proposed here. The danger of confusing circuits with branches is illustrated by demonstrating that mechanisms satisfying published branch criteria may actually require disassembly to reach all desired positions, rendering them useless in practice. Furthermore, a change of branch within a circuit is shown to be irrelevant to some applications.