Simple examples of dual coupling networks

Most mechanisms are both underconstrained and overconstrained. The motions attributable to underconstraint can be seen so that they are easily imagined from a drawing whereas actions attributable to overconstraint cannot. Dual coupling networks have the property that the action and motion systems of one are transposed in the other. So, by finding the dual of a mechanism, actions attributable to overconstraint become motions in its dual that can be imagined. Earlier work cited explains the methodology and validates the theory mathematically: this paper provides some simple examples.