A perpetual motor with pistons
On the verso of folio 1062 of the Codex Atlanticus, Leonardo describes a model that differs from his other studies in his attention to materials. It is an overbalanced motor with two cylinders, and two pistons connected by a hydraulic circuit moving between them. In the drawing, the wheel is fitted with a pair of these systems mounted at right angles to each other. However, Leonardo envisaged fitting four on the same axle, so as to have a cylinder—and thus a motive force—every 30 degrees. Moving downward, the piston pushes the water contained in the system into the other cylinder. This increases the imbalance and so facilitates rotation. The wheel movement is regulated by a verge escapement (foliot).