Prospects of manufacturing spiroid gears with small gear ratios

Production of spiroid gears as alternatives to bevel and hypoid ones, when the gear ratio of the spiroid gear should be less than 10 (often less than 6) is traditionally related to problems of manufacturing multi-thread worms and hobs. Different versions of solving this problem in diversified series and mass production are considered. For the first case, improvements of traditional methods of analysis and the production technique are proposed basing on application of multi-thread hobs or multi-tooth assembled running-in cutting heads. For the second case, high production-efficient methods of gear machining of both gear elements are provided; they are implemented at simple and common lathes after their little modification. Features and restrictions of these methods are described. Numerical examples are given for the possible substitution of truck and tram hypoid gears by different versions of spiroid gears providing application of various methods of gearwheel tooth cutting while both keeping the same basic dimensions of parts and mounting dimensions and varying these dimensions. It is noted, that when choosing the parameters of spiroid gearing and machine-tool settings, there are methods of efficient control of operation and layout parameters of the gear, the level of contact localization and tool parameters.