Hoists, a Screw Conveyor, and Interlocking Locking Beams
Lifting gear and a notched timber joint that clamps itself tight
The sheet gathers construction and lifting machinery: a tripod hoist with pulleys raising a bucket, a large toothed half-wheel on a vertical post driving a horizontal screw conveyor, and box-like molds or hoppers with a small furnace at the lower left. Notes describe a joint of interlocking beams, each cut with three notches, in which one member twists back, receives the other on top, and then springs shut to lock tight. A second note reckons the mechanical advantage by which a weight of some twenty pounds is raised by a one-ounce counterweight working through a counter-lever.
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Interlocking beams A and b with locking notches
Two beams are cut with three notches each, gentler than those below. The member A is forced to twist backward; the member b is set on top of it and fitted together; then A is released and clamps the joint firmly shut.
A twenty-pound weight raised by a one-ounce counterweight
A note reckons that a load of about 20 pounds is lifted by a counterweight of only one ounce, obtained through a counter-lever. It states, without completing the calculation, the great mechanical advantage of the arrangement.
Joint elements labelled a - a
Two mating elements of the timber joint are each marked with the letter a, keying the parts that fit together in the interlocking construction described above.
Tripod hoist and toothed-wheel screw conveyor
At the upper left a tall A-frame supports a beam and pulleys lifting a bucket by a counterweighted cord. To its right a large half-wheel cut with gear teeth turns on a vertical post to drive a long horizontal cylinder fitted with helical vanes, a screw conveyor for moving loose material on a work site.