Spring-driven gear drum with tempered spring and turning spool
A barrel motor whose spool may be columnar or pyramidal, mounted on a fixed axis
The large central drawing shows a spring-powered gear train rising from a cylindrical drum, with concentric toothed wheels and a coiled spring labeled inside the barrel. The note explains that the turning spool may be shaped either as a column or a pyramid, and that the instrument drawn above demonstrates how the spool is movable upon its axis. Leonardo stresses that the axis itself does not rotate with the spool but simply carries it upward.
On this page
Gear train raised on a spring drum
A stack of concentric toothed wheels turns above a cylindrical drum that houses the motor spring. The upper detail shows the same assembly so that the working of the spool upon its axis can be read. The mechanism belongs to the manuscript's study of spring-driven machine elements.
The tempered spring inside the barrel
Words written on the face of the drum label the coiled element as a tempered spring, the store of force that drives the gearing. The spool that carries it may be built either as a column or as a pyramid. Its axis does not revolve with it but bears it upward.