LEONARDO DA VINCI - Techniques for regulating the force generated by springs - Spring and cone-shaped spindle
Madrid Ms. I (BNM), fol. 85r (detail)
If the spring's thickness is uniform, its force will diminish gradually. To avoid the negative consequences of this phenomenon, Leonardo imagined a solution that would proportionally diminish resistance. The drawing shows a cone-shaped spindle connected by a thread to the spring. The spindle maintains a constant force as the spring unwinds.