The Odometer was designed to measure the distance travelled by the small cart. It was done through a series of gears which turned a wheel holding pebbles, these being released into a bucket beneath the carts framework. Counting the pebbles at the end of the journey allowed the distance travelled to be calculated.
The history of the odometer is a long one stretching back to Alexander the Great when he used an unknown device to measure the distance of his travels with great accuracy. Following that a Roman device that used the principle later picked up by Leonardo was described by Vitruvius as using a Roman Chariot wheel 4 feet diameter at the heart of the system that counted pebbles dropped into a bin after so many wheel rotation.
It would seem that Leonardo’s design using square toothed gears failed to work.
I have used the alternative worm gear on Leonardo’s alternative design to produce a model that will work.
Odometer - Codex Atlanticus Folio 1r
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I have put together a package of files that define the design in 2D and 3 D.
I have included PDF files of the 2D drawings that has all the parts laid out and dimensioned. Most of the parts are drawn at 1:1 scale so that they can be used as patterns to cut out the profiles.
I have also included DXF files so the relevant parts can be CNC machined. 3D files have been included in IGS and STP format so that they can be input to your own CAD program.