This engine is able to convert the reciprocating motion of the pistons into the required rotary motion of the crankshaft. The rotation is obtained by the rocking action of a harmonic beam mechanism located in the centre of the engine between the opposing cylinders. This design feature proved to be more complicated and expensive to produce and technically les efficient than the connecting rod and crank system. As a result, the engine was never incorporated in production motorcycles.
© Science Museum / Science & Society Picture Library