Franz Reuleaux wanted to give mechanical engineering a scientific groundwork. His goal was the analysis and the classification of mechanical motion. He speaks of element pairs
that can be put together in kinematic chains
.
He had more than 800 models built that represent the connection of element pairs\: For example, a control unit that is operated via a friction brake acting upon a wheel, the transfer of circular motion via belts and a cantilever used in steam engines.