Degree Name

Doctor of Philosophy


Department of Mechanical Engineering


This Thesis is the result of a fifteen year involvement in both the theoretical and practical aspects of spur and helical gear design. Over this period of time, the evolution of the computer, has rendered its use in gear design to be almost mandatory. However, the greatest problem faced in writing the necessary software, has been the analysis of the Lewis parabola inscribed within the gear tooth profile. The tenet of this Thesis, is the presentation of an original analytical method for the calculation of the height and width of the Lewis parabola. This theory has been adopted, both in an analytical and graphical format, by the Australian Standards Association Gear Committee ME/11, and has been distributed as AS 2938-1987, being a supplement to AGMA 218.01 Dec 1982. An adaptation of the theory, has resulted in the production of software for the rating and/or design of gears to AGMA 218.01. The package is designed to be used by a person unfamiliar with gear design, whilst at the same time, the program has sufficient flexibility to satisfy the needs of an experienced gear designer. To complement the theory, and as part of the ongoing program of gear research being conducted at the University of Wollongong, a gear testing rig was designed and manufactured. Although four gear sets do not provide sufficient evidence from which to draw categorical conclusions, the trends were towards a verification of the theory, for modified addendums, in combination with minimum specific sliding velocities.