Movement No. 140 demonstrates the toggle-joint mechanism arranged for a punching machine — one of the most powerful force-multiplying arrangements in mechanical engineering. A toggle joint consists of two links connected end-to-end at a central pivot, with the outer ends attached to fixed and moving parts respectively. A lever on the right side acts on the central joint of the toggle through a horizontal connecting-link. When the lever pushes the connecting-link, it moves the central joint of the toggle sideways, causing the two toggle links to straighten from a bent position toward a straight line. As the links approach alignment, a small sideways input force is amplified into an enormous downward force on the punch — because near the straight position, the mechanical advantage of the toggle approaches infinity. This force multiplication makes the toggle-joint ideal for punching, stamping, and pressing operations where very high force is needed at the end of the stroke with modest input effort.
140. The toggle-joint arranged for a punching machine. Lever at the right is made to operate upon the joint of the toggle by means of the horizontal connecting-link.