Experimental rolling contact traction data for the nominal point contacts of a steplessly variable ratio drive are presented. Operation is in the elastohydrodynamic lubrication regime with peak contact pressures of 1.5 to 3.0 GPa. Good agreement with the measurements is demonstrated by a visco-plastic lubricant model, and contrary to the conclusions of other recent work it is shown that the effects of elastic compliance of the fluid and rolling elements are small. The ability of the theory to account for the influence of the main operating variables, and its simplicity, should facilitate the solution of certain transmission design problems.
