A power roller bearing of a toroidal-type continuously variable transmission
unit
that is used for a transmission of an automobile or the like comprises a power
roller, an outer race, balls, a retainer, etc. Annular raceway grooves are formed
individually on the respective opposite end faces of the outer race and the power
roller. Treated-surface layers for enhancing the endurance of the power roller
bearing are formed individually on the respective surfaces of the raceway grooves.
The treated-surface layers include super-finished surfaces with the surface roughness
of 0.05 Rad or less, formed individually on the raceway grooves, and low-friction
layers formed individually on the super-finished surfaces. Alternatively, the treated-surface
layers include residual compression stress layers formed on the respective surface
layer portions of the raceway grooves by shot-preening.
