Toothed wheels, pin-gear wheels, and pinions

The toothed wheel, pin-gear wheel, and pinion played a key role in Renaissance technical application. Mills, machine tools, hoists, and many other devices were nearly always fitted with gears of this type. Leonardo tried to give a strictly methodical description of the nature and performance of these devices. He focused on the teeth profiles and accurately classified the different types of motion produced by various combinations of toothed wheels, pin-gear wheels and pinions.

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