Oil Press and Studies of Screw Threads
Operating an olive press; square- versus triangular-threaded screws; a double-acting screw
The sheet gathers Leonardo's studies of screws and presses. At the centre a horse-driven olive press is drawn with its screw, crank and cross-bar; around it are worm-screws whose nut travels back and forth, a screw cut on a lathe, and comparisons of square-threaded and triangular-threaded screws with reasoning about their strength. A caliper or gauge appears at upper left, crossed-out sketches at upper right, and a brief note on "a method of water" at the foot. The dense mirror-script text is transcribed in full.
On this page
Operating the horse-driven olive press
To turn the screw one first removes the cross-bar (marked a) above the cages and tightens the cages with the crank as far as possible, then replaces the bar and harnesses a horse to the larger lever. Leonardo promises the olives will be pressed almost dry. He warns the press must be far stronger than usual so it is not overcome by, but resists, the horse's force.
Cutting a screw on the lathe
A short caption at top centre reads "a way of making a screw on the lathe." A nearby note describes chests whose lids raise by themselves. These accompany the small mechanism sketches in the upper register.
Double-acting screw: the nut advances and returns
A grooved worm-screw is numbered 1 through 23. Turning always in the same direction, the nut both goes and returns: in going it pushes and in returning it pulls with great force. The channel's outward path from 1 to 23 is the same path the nut must retrace.
A return stroke that holds its load
A similar screw, also numbered 1 to 23 and labelled "spring" (Molla), likewise sends the nut out and back with one direction of turning. Here, though, on returning it holds what it had pushed, so that a load driven home by force cannot slide back to where it started.
Square threads stronger than triangular
The square-threaded screw is judged stronger and able to bear more weight because its threads present three faces where common screws present two, and its section is uniform rather than wide and weak at the top. Leonardo cites having seen a common iron screw whose nut-threads all broke under a modest load. The companion triangular-threaded screw is weaker but runs more easily, since its nut touches only two faces.
A method of water
A brief note at the foot of the sheet announces "a method of water," apparently a heading for a water device beside the mechanical studies. No developed drawing accompanies the phrase in the transcription.