Pile-Driver Raised by a Man with Pulley and Rope
Pull at a right angle to lift the most; a quarter-circle in a square above
A tall pile-driver dominates the sheet: a rope runs over a pulley at the top to lift the ram, while a small figure at the lower left hauls on the rope. Leonardo argues that one man pulling here does the work of two, and that the puller must keep a right angle with his rope, for the more obtuse the angle the less he lifts. He also notes that when the two rope-ends leaving the pulley are equally placed, the mover's power equals its resistance. A small square enclosing a quarter-circle is sketched at the upper left.
On this page
Quarter-circle inscribed in a square
A little diagram in the top corner sets a quarter-circle inside a square, its diagonal drawn across. It sits apart from the mechanical study that fills the rest of the sheet.
Keep a right angle with the rope to lift the most
By the fifth proposition of the 'Theory,' a pulls as much weight alone as two men would at b. In whatever spot he stands, the puller should make a right angle with the rope he draws; the more obtuse that angle, the less weight he will raise.
Equally placed rope-ends make power equal resistance
When the two ends of the rope leaving the pulley are equally situated, the power of the mover equals that of its resistance. The more unlike the positions taken by the cords issuing from the pulleys, the more the mover's power differs from its resistance.
The pile-driver, pulley and hauling man
A rope runs over a single pulley at the top of a tall frame to raise the ram, whether the pull is vertical or oblique. A small figure at the foot of the frame hauls the line down.