Bench vise and a sectored-circle mechanism
Red-chalk studies of a screw-operated bench vise with a toothed star wheel below
In red chalk (sanguigna) Leonardo draws a bench vise (morsa da banco): an upright screw-and-handle clamp whose long turning bar and jaws are shown in perspective. Below it a small toothed star wheel or ratchet appears, described in the caption as a mechanical drawing based on a circle divided into sectors. The upper corner carries foliation and numeric notes rather than continuous prose.
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Bench vise (morsa da banco)
The principal drawing is a bench vise, worked by a horizontal handle that turns a threaded screw to open and close its clamping jaws. Leonardo renders the screw shaft, the turning bar with knobbed ends, and the mounting block in red chalk.
Star wheel from a sectored circle
Below the vise sits a small toothed disc, described as a mechanical drawing built on a circle divided into equal sectors. The lobed rim reads as a ratchet or star wheel derived from that geometric division.