On analysing certain, typically intractable, six-bar linkages

A pair of six-bar linkages, one of long vintage and the other very recent, are used as exemplars for considering their overall structures and the nature of their articulations. The two issues raised are the installation of an effective means for analysing a six-bar's gross mobility, and the extent to which exchanges might be made between linear and non-linear screw joints. Although the analytical tool applied is the well-known algebra of displacement—closure equations, it is the novel form of the relationships employed here that results in a successful outcome.