The machine is powered by the two symmetric springs. While one spring would be enough to move the device, two symmetric springs probably looked like a more "logically perfect" solution. Leonardo has been well aware the powering force drops significantly as the spring unwinds. In order to deliver smooth and stable motion, the machine features balance wheel, as used in clocks. The control mechanism is quite complex and allows to follow the pre-programmed path automatically. The machine also features a mechanism similar to differential that also allows to set the turning angle.