Wheel for Perpetual Motion: Rebound of the Counterweight
An overbalancing toothed wheel, and why the striking blow fails to keep it turning
A large toothed wheel carries jointed arms radiating from its hub, each tipped with a round weight and arranged to hang out farther on one side of the axle than the other, an overbalancing design meant to turn of itself; a small quadrant diagram labelled 1, 2 and 3 sits at the right. The note weighs whether a descending counterweight a, striking its opposite part at n and driving it forward by the rebound of the blow, could make the wheel ever easier to turn, citing propositions 'on percussion' and 'on weights'. Leonardo concludes that although two-thirds of the impact seems gained, the remaining third of the blow steals a third of the wheel's proper motion, and so the scheme is spoiled.
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Why the rebounding blow spoils the wheel's motion
A descending counterweight a strikes its opposite part at n and shoves it forward by the rebound of the impact, so that however little the wheel turns it should descend more easily. Yet though two-thirds of the impact seems to remain to advantage, by the propositions cited 'on percussion' and 'on weights', the remaining third of the blow takes away a third of the motion proper to the wheel, and this ruins the invention.
Overbalancing toothed wheel with weighted arms
A large sawtooth-rimmed wheel carries jointed arms radiating from the hub, each ending in a round weight, set to swing out farther on one side of the axle than the other. A crank-like arm projects to the lower left of the rim.
Quadrant force detail
At the upper right a small quarter-circle diagram carries the numerals 1, 2 and 3 on radiating lines, apparently analysing the direction and leverage of the striking weight discussed in the note.