Gradual development of S-shaped gears

Search for an improved gear tooth flank shape arose from heavy industry problems rolling mills. Original involute gears suffered severe damages. So, better teeth flanks should improve contact circumstances, decrease the pressure, and enhance a lubrication film. This was achieved by curved, pole symmetric path of purely graphical methods. And developed gears, proven in applications, showed highly properties. Specimens both geometries, which were made tempered nitrided alloy steel, tested on FZG testing machine, results confirmed theoretical foundations S-gears. Then it necessary to replace method numerical one define tool. rack profile defined parabolic-type function, turn finally with arbitrary number teeth. Many applications S-gear shape, e.g., helical, crossed, planetary various worm drives, etc. concept also used polymer high transmission ratio gears. Lately, this develop crossed helical drive perpendicular shafts. Such drives are often centrifuge (e. g. Alfa-Laval) implementation module m = 5 mm uses large driving 60 (with left-handed helix angle 30°) horizontal shaft smaller driven 20 right-handed 60°) vertical shaft. paper is tribute work Professor Jože Hlebanja (1926-2022) whose research dedicated properties, namely