Studies of screws, levers, pulleys and foundations

Ropes on a pulley act as a lever from the center

Though the ropes mS and mt are both fastened at m, they exert force only as if attached to a lever whose length equals a line drawn from the center to touch the rope at equal angles. The note reduces the pulley to an equivalent lever arm.

Triangular threads and the double screw

A screw one braccio long is judged easier to work with triangular threads than square ones, 'because they are so many more,' while a double screw set in a frame is of doubled difficulty and speed because the upper and lower nuts climb their threads at once. Another figure notes a screw stronger from the right than the left because its half-threads lengthen the line of resistance.

Lever arms and the pull of many men

Along a lever lettered r-a-b-c-d-e, Leonardo places a man pulling with equal force at each of the parts a, b, c, d, e and asks how much force they together make at r. A companion figure notes that the greater the circle a horse harnessed to the rope of a lever makes about the center, the more slowness and strength results.

Doubling a foundation beneath the door-jambs

The foundation must be doubled in width beneath the jambs of the doorways, because where there is more weight the more it sinks in; being of doubled weight, it makes doubled resistance. A small drawing of a building's footing accompanies the rule.

In alto, carrucola con due corde e le lettere:

A sinistra figura di vite doppia in un telaio:

Verso il centro, disegno:

A destra disegno di vite:

Più in basso, analoga figura:

Al centro, quadrante di cerchio colle lettere:

A sinistra, corda con contrappeso che rizza una colonna:

In centro, braccio di leva con:

Altro braccio di leva colle lettere:

Altro braccio di leva colle lettere:

In basso a destra, braccio di leva entro cerchi concentrici, colle lettere:

Al centro del margine inferiore, disegno di fondamenta di edificio:

A sinistra in basso, scuri battute da martelli, colle lettere:

Sul margine destro:

Above, a pulley with two ropes and the letters:

On the left, a figure of a double screw in a frame:

Toward the center, a drawing:

On the right, a drawing of a screw:

Further down, an analogous figure:

At the center, a quadrant of a circle with the letters:

On the left, a rope with a counterweight that raises a column:

At the center, a lever arm with:

Another lever arm with the letters:

Another lever arm with the letters:

At the bottom right, a lever arm within concentric circles, with the letters:

At the center of the lower margin, a drawing of the foundations of a building:

At the bottom left, axes struck by hammers, with the letters:

On the right margin:

Studies of screws, levers, pulleys and foundations

On this page

Ropes on a pulley act as a lever from the center

Triangular threads and the double screw

Lever arms and the pull of many men

Doubling a foundation beneath the door-jambs