The contribution of roller compliance to elastohydrodynamic traction

EHL traction behavior in the high-pressure, low slide-to-roll ratio regime, where the response may be described as linear, is of importance for the operation of toroidal continuously variable transmissions that must reduce the mechanical loss by operating in or close to this regime and for defining the torque losses of a rolling element bearing. In this article, we take a novel approach to the problem by comparing traction in this low slide-to-roll regime for dry and lubricated contacts. New experimental measurements show that for very high contact pressures along with low slide-to-roll ratios, the lubricated traction curve varies little from that obtained in dry sliding contact. Longitudinal sliding, transverse sliding, and spin are investigated and the results are compared to the theory of Kalker The implications for the calculation of traction from material properties and for the advantageous manipulation of the linear traction gradient are explored.