Previous work on load sharing in non-metallic gears indicated that the change in operating contact ratio is large enough to cause concern. Tests also show that premature contact between the gear teeth can lead to severe flank wear. This paper shows that predetermined amounts of tip relief are needed to minimize this form of wear from occurring. The tip relief suggested in this paper is compared to recommendations given in the British Standard. Finally, for non-metallic gears, allowances for backlash due to elastic deformation of the teeth are suggested.
WalkerH.Gear tooth deflection and profile modification. The Engineer, 1938, 319–412 and 434–436.
2.
MunroR. G.Profile and lead correction. BGA Data Item R/D 0101988.
3.
LinH. H., et. al. Dynamic loading of spur gears with linear or parabolic tooth profile modifications. Proceedings of the 1989 International Conference on Power transmission and gearing, Vol. 1, 1989.
4.
YelleH.BurnsD. J.Calculation of contact ratios for plastic/plastic or plastic/steel spur gear pairs. Trans. ASME J. Mech. Des., 1981, 103, 528–542.
5.
YelleH.BurnsD. J.Root bending fatigue strength of acetal spur gears—a design approach to allow for load sharing. Presented at AGMA Fall Technical Meeting1981.
6.
BreedsA. R.Non-metallic gears for power transmission. MPhil qualifying Thesis, The University of Birmingham, 1991.
7.
WaltonD.HookeC. J.MaoK.BreedsA.KukurekaS.A new look at testing and rating non-metallic gears. Third World Congress on Gearing and power transmission, Paris, 1992.
8.
BS 436: Part 2: 1970 Specification for spur and helical gears. Part 2: basic rack form, modules and accuracy (British Standards Institution, London).
9.
ISO/DIS1983, Parts 1–4 (Organization for International Standardizations, Belgium).
10.
BS 61681987Specification for non-metallic gears (British Standards Institution, London).
BS: 436 Part 3: 1970Specification for spur and helical gears. Part 3: method for calculation of contact and root bending stress limitations for metallic involute gears (British Standards Institution. London).
