Fuente: WIPO "rice" Large flat blades are put on the ends of long lever arms to maximize the torque produced at a central vertical shaft. Pivoting each blade on its own axis allows it to be positioned to best advantage as it rotates around the central vertical shaft. The positioning is accomplished by gearing the blade to a central control gear. By simply attaching a weather vane to the central control gear, the direction of the entire windmill is controlled.