Re-construction of a Cam Hammer, from a drawing by Leonardo da Vinci, in the Madrid Codex I, folio 92 v. Leonardo applied a cam to this simple mechanical device for transforming rotary motion into intermittent motion. The energy that moves this device so that the hammer continuously strikes the anvil is derived directly from the hand crank, its rotary motion directly activating the cam: the hand crank is inserted into the side of the axis of the same and has a circular profile with a sudden break in it. By turning this, the lever to which the hammer is attached tilts forward, returning to its initial position when the hand crank has done a complete turn. Using the law of gravity, the hammer continues to fall heavily on the anvil; an automation process that relieves human fatigue. After having been long used in automatic meshes, the cam is now widely used in car engines, which deliver power by activating a camshaft.. Leonardo da Vinci (1452-1519), Italian artist and polymath