The Effect of Inaccuracy of Spacing on the Strength of Gear Teeth

Abstract

Abstract In a paper presented before the Society in 1912, Professor Guido H. Marx reported results of an extended series of tests to determine the strength of gear teeth at pitch velocities from 0 to 500 ft. per min. During the discussion of this paper it was suggested that further tests he made in order to obtain definite data as to the effect of inaccuracy of spacing on the strength of the teeth at high speeds. At the instance of Professor Marx the authors undertook such a series of tests, the results obtained and a description of the apparatus and procedure employed being given in the present paper. Among other things the authors found that, in a broad way, at pitch velocities of 1000 ft. per min. and upward, gears whose inaccuracies of spacing do not exceed 0.001 in. will carry twice the load of those having inaccuracies of spacing of 0.006 in.; and that the strength of gears having inaccuracies of spacing of the order of 0.002 in. is about half-way between the two. An error of 0.006 in. in the size of teeth tested is much more than will ordinarily be found in first-class commercial cut gears.