A simple calculation will now illustrate the important feature identified by Muller (1966) and noted by Naylor (1967). If it is imagined that the designer decided to increase the radius of curvature at the cam nose from 6mm to 13.7mm (not dissimilar to the situation identified in Figure 1) but retained the same ova.-an value of base circle radius plus maximum lift, then the importance of the consideration of not only stressing but also lubrication can be clearly illustrated. For the same load condition the maximum Hertzian stress (being inversely proportional to the square root of the radius of curvature) would fall by 34%. The calculation in Appendix 2 indicates, however, that the mean entraining velocity of the lubricant into the contact would fall to zero. On the basis of a quasi-static analysis, therefore, the predicted film thickness would be zero. The prognostication would be that there