Gear-tooth durability and a device to lock a power
Pyramidal toothing, power and resistance at a and b, and a large hoisting crane
On this recto Leonardo notes how to reckon a gear train's power and resistance, taking the pinion's thickness at a and the wheel's width at b, and observes that a 'pyramidal' toothing is the most durable of all because of the great quantity of contact between pinion and wheel, though its teeth do not wear evenly. A further note labels a mechanism for releasing or locking a power. The page is dominated by a large braced-timber crane hoisting weights on pulleys, which is drawn but not covered by the transcription.
On this page
Pyramidal toothing lasts longest through greater contact
This pyramidal toothing is more durable than any other, solely because of the great quantity of contact that the pinion has with its wheel; but these teeth do not wear equally.
Reckoning power and resistance from pinion thickness a and wheel width b
The calculation of power and resistance is taken in this way: the thickness of the pinion is measured at a, and the width of the wheel at b. The two measures are marked a and b on the figure.
A mechanism to release or to lock a power
A short note identifies one of the drawn devices as a way of releasing or else of locking (serrare) a power, apparently the lever-and-disc arrangement at the upper part of the sheet.
A large braced-timber crane hoisting weights on pulleys
The lower and central part of the sheet is filled by a big timber gantry crane with diagonal cross-bracing, from which two weights hang on pulley falls. This lifting structure is drawn in detail but is not addressed by the transcribed notes.