The "Universal propeller": built by Paragon Engineers, Inc., Baltimore, Md
This is a 1922 technical report from the NASA Technical Reports Server, a set of engineering drawings of a variable-pitch propeller mechanism built by Paragon Engineers of Baltimore, Maryland, for aviation engineers. The first picture shows a split steel sleeve clamped about a propeller blade, with a detail of the propeller sleeve, crank shaft, spur gears and brake drum; the second shows the worm shaft, reversing idlers, jackshaft and brake shoes in a gear-train cutaway. A designer could take from them the clean line-drawing style of early mechanical diagrams with labelled callouts and exploded gear layouts.
