Among Leonardo’s many machines, we must make a distinction between those destined for actual civil, military or artistic use and those that were purely theoretical. This apparatus was drawn on one of the most beautiful pages in the entire Codex Atlanticus (folio 30v) related to mechanics. Its purpose is to transform the alternating movement of a human being operating a lever into the rotating and continuous movement of the pivot, which lifts a weight attached to a rope. Activating the lever causes the two larger internal wheels to move. Each of these wheels has two metallic cogs, which alternately engage the external cogged wheels by pushing them and rotating the small caged gear connected to the central pivot. This mechanism would later be applied to many of Leonardo’s machines. We find it for example in the engine complex of the Paddle Boat and the internal mechanism of the Harpsichord-Viola.