A spring-driven clock escapement tooth
One tooth of the escapement that turns wheel S, kept pressed by a spring (molla)
The verso is given to a clockwork escapement: Leonardo draws and describes one of the teeth of the 'time' that drives the wheel marked S, made with two unjointed teeth so that the escapement moves the wheel rather than the reverse, as in clocks. The tooth is of one piece with its rings o and r, its shaft f, n, g is a single piece, and a spring (molla) on the opposite side always pushes the tooth m against n. Two large drawings show the disc S above a toothed wheel with a weight hanging in a box, together with a detail of the tooth-and-spring assembly.
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One tooth of the escapement driving wheel S
The figure shows one of the teeth of the 'time' (escapement) that moves the wheel above S. Its two teeth are made unjointed, as required for the escapement to move the wheel rather than the wheel the escapement; the tooth is of one piece with its rings o and r, and its shaft f, n, g is likewise a single piece, as shown in clocks.
A spring holds the tooth m against n
Joined to the shaft on the opposite side, facing n, is a spring (molla) that always pushes the tooth m back against n. The spring's constant return force keeps the escapement tooth seated.
Escapement wheels S with hanging weights
Two large drawings show a disc lettered S set above a fine-toothed wheel on a shaft, each with a weight hanging by a cord into a box, and a lower detail of the tooth-and-spring assembly. The mechanisms illustrate the weight-driven, spring-returned escapement.