Traction drive rotary assembly and process for producing rolling element thereof

A rotary assembly for traction drives, comprising:

• a plurality of rolling elements having a rotation axis and traction contact surfaces around the rotation axis and associating with each other to transmit a motive power between the rolling elements via a traction oil film formed between the traction contact surfaces;
• at least one of said traction contact surfaces having a microstructure with irregularities which sizes are larger than a thickness of the traction oil film,
• wherein the microstructure is represented by an unfiltered primary profile curve including alternately arranged recesses and top-flat lands,
• wherein the unfiltered primary profile curve is measured using a surface roughness tester, each of said lands of the unfiltered primary profile curve including a portion located higher than a center line with respect to the unfiltered primary profile curve, said portion having either one shape selected from a generally trapezoidal shape, a generally trapezoidal shape with rounded corners, a generally trapezoidal shape with chamfered corners, a generally crowning shape, a generally elliptic arc shape, a generally sinusoidal shape and a generally triangular shape with a rounded apex,
• wherein a height difference between a top of each land and a bottom of each recess is within a range of 2.0-2.5 μm.

A rotary assembly for traction drives, comprising:

• a plurality of rolling elements having a rotation axis and traction contact surfaces around the rotation axis and associating with each other to transmit a motive power between the rolling elements via a traction oil film formed between the traction contact surfaces;
• at least one of said traction contact surfaces having a microstructure with irregularities which sizes are larger than a thickness of the traction oil film,
• wherein the microstructure is represented by an unfiltered primary profile curve including alternately arranged recesses and top-flat lands,
• wherein the unfiltered primary profile curve is measured using a surface roughness tester, each of said lands of the unfiltered primary profile curve including a portion located higher than a center line with respect to the unfiltered primary profile curve, said portion having either one shape selected from a generally trapezoidal shape, a generally trapezoidal shape with rounded corners, a generally trapezoidal shape with chamfered corners, a generally crowning shape, a generally elliptic arc shape, a generally sinusoidal shape and a generally triangular shape with a rounded apex,
• wherein a height difference between a top of each land and a bottom of each recess is within a range of 0.8-1.2 μm.