Spring-driven forge hammers
Rod- and cord-spring mechanisms for self-lifting trip hammers
Two joined sheets show designs for mechanical forge hammers, the upper drawn as a radial array of hammer arms around a central toothed disc and a perspective device below. Brief notes explain that the two rods serving as a spring need only just enough force to barely raise the hammer after each blow, since it almost lifts itself. One hammer is set to strike sand under water, and the design at left is called the last and best because its cord springs never tire, their weights never diminishing. The word iron labels a part within the drawing; the companion sheet 67b recto is without writings.
On this page
Rod springs that let the hammer lift itself
The two rods that act as a spring, Leonardo notes, need not be very strong: it is enough that they have just enough force to barely raise the hammer after the blow, since it almost rises of its own accord.
A hammer striking sand under water
Beside one of the hammers he directs that it strike on the sand under water, a note attached to a second hammer variant among the array.
Cord springs that never tire
The design at left is judged the last and the best, because here the springs made of cords never tire, since the weights of those cords never diminish — a mechanical advantage over the rod springs above.