Patent ID: 7488270

Claim:
A toroidal continuously variable transmission comprising: an input disc having a concavely curved raceway portion in one side; an output disc having a concavely curved raceway portion opposing to the raceway portion of the input disc in one side; and a roller rotatably sandwiched between the raceway portions of the discs for transmitting torque between the discs by a traction force between the circumference of the roller and the raceway portion of each of the discs, wherein, at least rolling contact portion of at least one transmitting member of the input disc, the output disc and the roller is formed of a bearing steel which contains: C: 0.8-1.5 wt %; Si: 0.5-2.5 wt %; Mn: 0.3-2.0 wt %; Cr: 1.9-2.5 wt %; Mo: 0.3-1.0 wt %; and a total of 1.0 wt % or more of Si and Mo; with the balance being iron and unavoidable impurities; and wherein a residual austenite in a range of depth Z=1.0L, where L is the major axis of a contact ellipse of the traction contact portion, from the surface of the rolling contact portion is 15 wt: % or less, and the hardness of the range is HRC 58-62; and wherein, an oxide particle size in the range of depth Z=1.0L from the surface of the rolling contact portion formed of the bearing steel is less than 20 μm.