Screws that push and pull, and weight balanced on its pole
A screw that both drives and draws its nut, and why a body turns most easily when balanced about its pole
The sheet is dominated by two large helical screws (viti) drawn as tall spiralled cylinders, with smaller studies of a screw and its 'mother' (nut) below. The notes explain a screw that with a single turn both pushes and pulls its nut, advising that the threads be cut as narrow as possible for reliability, and show a way for a weight to travel up and down along a screw. Two accompanying mechanical propositions argue that a body turns more easily on its poles when its load is evenly distributed around the pole and when the pole lies near the center of gravity.
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A screw that both pushes and pulls its nut
Leonardo describes a screw that, with one and the same turn, both drives and draws its 'mother' (nut). He advises making the thread channels as narrow as possible so the device works better and more reliably.
Screw carrying a weight up and down
A short caption presents a way for a weight to go and return along a screw, moving up and down. The lower cross-hatched cylinder at right illustrates such a threaded travel.
Easier motion when weight is balanced about the pole
A weight is more easily set turning upon its poles when the load surrounding the pole is more evenly distributed. Likewise, a body whose pole lies nearer the center of its gravity will move more easily about that pole.