| The International Standards Organization (ISO) will soon approve ISO/DIS 6336 "Calculation of Load Capacity of Spur and Helical Gears" as an international standard for gear rating. The purpose of this thesis was to compare ISO/DIS 6336 to the equivalent American Gear Manufacturers Association (AGMA) standard - AGMA 2001-B88.; The method of comparison was a factorial study of 48 different gear meshes which were analyzed for both pitting and bending fatigue failure modes, using software written at the University of Waterloo. The variational parameters were: through-hardened and case-carburized steel; 0{dollar}spcirc{dollar}, 15{dollar}spcirc{dollar} and 30{dollar}spcirc{dollar} helix angles; 20{dollar}spcirc{dollar} and 25{dollar}spcirc{dollar} pressure angles; 17 and 26 pinion teeth; and transverse modules of 4 and 10 mm. Further detailed studies considered the effect of: pitch-line velocity on the dynamic factor: pinion aspect ratio on the face load distribution factor; profile-shift on the bending geometry factor; number of load cycles on the life factors; and gear hardness on the work-hardening factor. The standards were shown to be satisfactory, in general, although some discrepancies were found.; Distinct patterns are exposed which explain the source of the discrepancies; although no simple rule was found which can convert the strength ratings (which often differ by more than 40%). The difference in ratings are sensitive to the tooth loading levels and the helix angle, due to the different trends shown in the AGMA and ISO standards. Many factors show significant discrepancies, but the most severe is the excessively high values of the ISO load distribution factors for the lower tooth loads typically associated with through-hardened steel gears. Extensive analytical data is included in the thesis to support all conclusions.; The comparison fulfilled purpose of the thesis; the analysis does not judge either standard to be less conservative, less adequate or less accurate, but rather strives to offer an objective presentation using actual results. |
