The number of circuits and branches in the fourbar linkage depends on its Grashof condition and the inversion used. A nonGrashof, triple-rocker fourbar linkage has only one circuit but has two branches. All Grashof fourbar linkages have two circuits, but the number of branches per circuit differs with the inversion. The crank-rocker and double-crank have only one branch within each circuit. The doublerocker and rocker-crank have two branches within each circuit. Table 4-1 summarizes these relationships)2]