To reduce the rate of metallic contact so as to enhance the traction property of a traction drive by keeping thin the thickness of an oil film between both rolling elements.
The traction drive includes a metallic input side rolling element 3 secured to an input shaft 2, and a metallic output side rolling element 5 fixed to an output shaft 4 and to which motive power from the input side rolling element 3 is transmitted via oil filled between the output side rolling element and the input side rolling element 3. Of the input side rolling element 3 and the output side rolling element 4, at least one rolling element 3 has a circumferential three-dimensional fine groove 6 provided on the outer peripheral surface 3a thereof, with the depth of the groove bottom 6a of the three-dimensional fine groove 6 varying along the circumferential direction.
KOMATA MASAHIRO
OTA MINORU
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