Hoisting Machine for Excavating Earth
Spring-loaded boxes and a cord-and-semicircle mechanism sized against the weight of the earth cut.
The sheet works out a machine for lifting boxes of excavated earth: at the top, cases are hoisted by pulleys and a wheeled winch, while a central spring-and-cord device reverses a pair of semicircles and a rod between fixed points. Leonardo diagnoses a 'defect of the Pesaro pull' that wastes travel and time when the box must be raised an extra half-braccio to drop onto its hook. He then treats the load itself as civil engineering, sizing a cut of earth 4 braccia high at 3600 pounds, trimming a superfluous sixth to leave 3000, and applying the same rule to an embankment. The fifth (angled) side of the box is set to project outward so the earth spills out by itself.
On this page
Defect of the Pesaro pull
The thirteenth point notes a fault in the Pesaro pull: the box must be raised a half-braccio higher so it can then drop onto the hook. That half-braccio consumes one sixth of the wheel's travel and another sixth in the lowering, amounting to 10 paces lost, or 3 and 1/3 units of time.
Box with a spring behind it
At the top of the sheet a case is drawn with a spring set behind it. The spring is part of the tipping or release action of the hoisted box.
Cord-and-semicircle reversing mechanism
Cord a is fixed at d e and cord b at r t. When cord a f h e g, fastened at d c, is pulled, semicircle p moves into the place of semicircle q and q into p; the rod n passes to the opposite side into m and m into n, while the short cord a takes the place of cord b and b returns into a. Pulling cord b then restores the parts, and n m return to their first positions.
The fifth side of the earth box
Lettered a - a - b, this box has a is the fifth side of the case. It should project further outward at the top than at the foot by 1/6 of a braccio, or better a half-braccio, so that the loaded earth falls out of the box by itself.
Weight of a cut of earth, trimmed by a sixth
A cut of earth 4 braccia high, 1 braccio wide and 1/2 thick weighs 3600 pounds. The extra 600 are superfluous, so remove them by height, thickness or width alike; taking away a sixth of the whole from any place leaves 3000 pounds.
Embankment, reduced by a seventh
For an embankment 4 braccia high with a thick cut, remove a seventh of it, whether taken from the width. The note breaks off, extending the trimming rule to earthworks of a different section.