Kabushiki Kaisha Riken

Yoshiyuki Hirade

Hiroyuki Yabune

Kentaro Miyagawa

A side rail forms an oil control ring together with a spacer expander, and includes: an outer peripheral surface; an inner peripheral surface having a vertically symmetrical shape in an axial cross section; a first side surface; and a second side surface. The inner peripheral surface includes an inner tip portion satisfying following Condition 1 in an axial cross section.0.7≤1/0≤1.1  Condition 1: In the expression, R1 represents a curvature radius (unit: mm) of a curve forming the inner tip portion, and h0 represents a height (unit: mm) of the side rail.

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Kashiwazaki, Japan

Yoshiyuki Hirade