Abstract: The present invention is concerned with the formation of rollers in a rollingtraction toroidal-race type of continuously variable ratio transmission device (“variator”). Specifically, it concerns variators of the “full-toridal” type in which the variator rollers (48) are permitted to adopt a position in which their centres are close to—or even coincident with—the center line of a toroidal cavity defined by races (30, 32, 42). It has been recognised that the roller centres do not, in such a variator, lie precisely upon the centre line of the variator cavities. Consequently in order to optimise roller performance there is provided, in accordance with the present invention, a roller (70) having an outer perimeter which, viewed in a sectional plane containing the roller axis, has a convex profile which is not symmetrical about any plane perpendicular to the roller axis.

Abstract: For extension of service lives of rollers and discs of a toroidal continuously variable transmission, input discs, output discs and rollers are formed of a heat-resisting bearing steel. At least a roller has its peripheral surface subjected to a shot peening for achieving a compressive residual stress of 0.6 to 1.2 GPa and a hardness of HRC 63 to 66 at the outermost surface.

Abstract: For extension of service lives of rollers and discs of a toroidal continuously variable transmission, input discs, output discs and rollers are formed of a heat-resisting bearing steel. At least a roller has its peripheral surface subjected to a shot peening for achieving a compressive residual stress of 0.6 to 1.2 GPa and a hardness of HRC 63 to 66 at the outermost surface.