Model: Helical Worm Gear Pair [Endless Screw]
This gear pair model was created by the Illinois Gear & Machine Co Chicago. Cornell University acquired a set of 15 models around 1950. A similar set can be found at Ohio State University. The so-called "endless screw" is a very old mechanism and can be found in machine drawings of Renaissance artist-engineers such as Francesco di Giorgio Martini and Leonardo da Vinci. The worm drive converts high speed motion about the horizontal axis [as shown in the model] into slower rotary motion about a horizontal axis perpendicular to the drive axis. The straight or right angle worm drive is generally not back drive-able; i.e. one can only move the pair through the helical screw. However, the helical worm gear pair can be driven from either the higher-speed helical worm or though the larger slow-speed gear with helical teeth. [See also the Cornell Reuleaux-Voigt model C-9]

Francis Moon 2005-00-00