Rolling element for a continuously variable transmission (CVT), a CVT using the rolling element and a method for producing the rolling element

A continuously variable transmission, comprising:

• input and output disks arranged in a coaxial and spaced relation to each other;
• and
• a power roller interposed between the input and output disks, the power roller including an inner race, an outer race and a plurality of balls interposed between the inner and outer races, the inner race and the input and output disks having rolling contact portions coming into rolling contact with each other via lubricating oil, the inner and outer races having rolling contact portions coming into rolling contact with the balls via lubricating oil,
• wherein at least one of the rolling contact portions includes an outer surface layer having a surface microhardness of not less than Hv 750, a surface residual compressive stress of not less than 1000 MPa and a residual austenite content of not more than 10% by volume.

A method for producing a rolling element for a continuously variable transmission, the rolling element including a plurality of rolling members having rolling contact portions coming into rolling contact with each other via lubricating oil, at least one of the rolling contact portions including an outer surface layer, the method comprising:

• subjecting a workpiece to either one of carburizing-quenching and carbonitriding-quenching;
• subjecting an outer surface of the workpiece to shot peening;
• and
• subjecting the outer surface of the workpiece to finish grinding so as to provide the outer surface layer having a surface microhardness of not less than Hv 750, a surface residual compressive stress of not less than 1000 MPa and a residual austenite content of not more than 10% by volume.