Planar closed loop double chain linkages

This paper deals with the planar closed loop double chain linkages consisting of a series of scissor like pairs connected by hinges. The chain is made of a serious of loop parallelograms, i.e., in the assemblies each set of four neighbouring hinges form a parallelogram. Three cases of mobile assemblies have been identified: the chains with intersecting and non-intersecting pairs as well as a mixture of both pairs. The corresponding mobility conditions are derived. Physical models were made which demonstrates that our proofs are correct.