Discussion: “Constrained Fatigue Life Optimization of a Nasvytis Multiroller Traction Drive” (Coy, J. J., Rohn, D. A., and Loewenthal, S. H., 1981, ASME J. Mech. Des., 103, pp. 423–428)

in life as the geometry is changed from the optimum. Fig. 8 shows the variation in drive life and component lives with location on the ratio constraint boundary. The maximum life is achieved as a trade-off among the component lives. The sun and driven track of the first row rollers increase in life while the remaining components decrease in life as B and C increase. The loss of life for the smaller values of (B, Q was due to high stress on the high-speed sun element. The loss of life at the higher values of (B, Q was due to high stress caused by less effective toggle action and the resultant need for higher normal loads to preclude slip at the planet/planet and planet/ring contacts. The multiroller traction drive reported in [5] had a [B/d6, C/d6] = [0.322, 0.194]. The calculated drive life was 94 percent of the optimum.