Mechanical Loom: Gear Train and Treadle Timing
Wheels, pinions and springs for an automatic weaving machine.
This sheet works out an automatic weaving loom, which the notes call an invention 'second only to the printing of letters' and of even greater profit. Leonardo specifies the gearing: the wheel of the first motion drives two treadles on one side, while on the other a single tooth turns a small six-toothed pinion, which in turn drives a twelve-toothed wheel. Marginal notes give the tooth spacing in half-ounces and relate a toothed cylinder's circumference to a one-ninth-braccio diameter. A cord anti-recoil device and a spring-loaded bobbin are drawn and labelled below.
On this page
Gear train of the first motion
The wheel of the first motion carries two teeth on its right to work the two treadles, and a single tooth on its left to turn a small pinion of six teeth. That pinion then drives a third wheel of twelve teeth, matching the pinion's tooth spacing and length. The counts fix the timing of the whole loom.
A weaving machine to rival the printing press
Leonardo judges the machine second only to the printing of letters, and no less useful. He calls it more profitable and a more beautiful and subtle invention. Dimensions of half an ounce and twelve teeth, with 'height' and 'bottom', are noted beside the mechanism.
Toothed cylinder: circumference and diameter in braccia
In the right margin a toothed cylinder is analysed by measure: eight half-ounce teeth make four whole ounces around its circumference, which equals one third of a braccio. From this its diameter is given as one ninth of a braccio. The note ties the tooth pitch to the wheel's size.
Cord anti-recoil device and spring bobbin
A device in the left margin is made of cord so that, as its spring straightens, the treadle does not recoil too far. In the lower half a bobbin is fitted with a spring so that it does not slip. Both details keep the moving parts under control.