ROLLING ELEMENT FOR CONTINUOUSLY VARIABLE TRANSMISSION AND ITS MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To solve a problem of a toroidal type continuously variable transmission (CVT) that lowering of a fatigue life of a rolling element might occur since a bearing groove part of a power roller receives high surface pressure, traction force and radial directional load. SOLUTION: This rolling element is used for a CVT having such a construction that a power roller inner ring 7 is contacted with discs 3 and 12 through lubricating oil and, for example, a nickel (Ni) based coat with its coat thickness of 0.1-20μm is applied to a bearing groove part 7a, which is a rolling surface of the power roller inner ring 7 of a rolling element. The possibility of micro metal-to-metal contact is lowered and penetration of hydrogen into a substrate is restrained by forming a protecting coat with low hydrogen permeability. Thus, short life peel-off due to hydrogen embrittlement is inhibited and the rolling fatigue life is improved.