Wheel that Drives a Screw Now Right, Now Left
A wheel turned always one way reversing the rotation of its screw
The folio is dominated by a large rope-wound drum carried on an upright timber frame, driven through a horizontal ring-gear and worm screws with a vertical shaft descending below. Leonardo's note describes a device in which turning a wheel continuously in one and the same direction makes the screw it drives turn now to the right and now to the left. It belongs to his sustained study of screw-and-gear mechanisms in this manuscript.
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Reversing a screw from a one-way wheel
Leonardo sets out a method whereby, by turning a wheel in one and the same direction, the screw that is turned by that wheel reverses, going now to the right and now to the left.
Rope drum on a ring-gear frame
The drawing shows a large cylindrical drum wound with many coils of rope, mounted between uprights, engaging a broad horizontal toothed ring below by way of worm screws, with a vertical shaft running down through the frame.