for helical gear the helix angle generally ranges from 45°.
for helical gear the helix angle generally ranges from?
45°
Na
Na
a worm gear is a species of helical gear, but its helix angle is usually somewhat large (close to 90 degrees) and its body is usually fairly long in the axial direction. these attributes give it screw like qualities. the distinction between a worm and a helical gear is that at least one tooth persists for a full rotation around the helix. if this occurs, it is a 'worm'; if not, it is a 'helical gear'. a worm may have as few as one tooth. if that tooth persists for several turns around the helix, the worm appears, superficially, to have more than one tooth, but what one in fact sees is the same tooth reappearing at intervals along the length of the worm. the usual screw nomenclature applies: a one-toothed worm is called "single thread" or "single start"; a worm with more than one tooth is called "multiple thread" or "multiple start". the helix angle of a worm is not usually specified. instead, the lead angle, which is equal to 90 degrees minus the helix angle, is given.
gear