The efficiency and friction of plastic cylindrical gears Part 2: Influence of tooth geometry

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In Part I the influences of materials and material combinations on the efficiency of plastic gears were investigated. In this paper, the effect of changes to plastic gear tooth geometry is investigated. Using a gear tooth form of standard proportions as the benchmark gear, gears were moulded to a number of different specifications. These changes in geometry included speed ratio, module, pressure angle, addendum, integer contact ratios and tip relief. Sensitivity to centre distance variations was investigated on the benchmark geometry. A helical gear was also tested for comparison with a spur gear of comparable specification. Using measured efficiencies, coefficients of friction were determined for a number of the gear geometries examined.


Original languageEnglish
Pages (from-to)93-103
Number of pages11
JournalInstitution of Mechanical Engineers. Proceedings. Part J: Journal of Engineering Tribology
Publication statusPublished - 1 Jan 2002


  • coefficients of friction, spur gears, recess action, module, pressure angle, polymer composites, helical gears, efficiency, tip relief, gears