Beam that raises itself by rocking on a toothed post
Lifting each end in turn up a vertical rack — the quickest method
A long beam is balanced across a vertical toothed rack fixed on a cross-shaped base, tilting like a see-saw; a strip of saw-tooth rack is detailed at upper right and a bracket at left. The note explains that the beam raises itself simply by being rocked, lifting first one end and then the other up the ratchet. Leonardo calls this the easiest and briefest way of raising a beam.
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Beam rocked up a toothed vertical post
The beam raises itself on high merely by being rocked, lifting now one extremity, now the other, so that it climbs the vertical toothed post step by step. Leonardo names this the easiest and briefest method that can be done.
Saw-tooth rack detail
At the upper right a short strip is drawn showing the profile of the rack's teeth, whose ratcheted edges catch the beam at each rock and prevent it from slipping back down the post.