Roller bearing

A roller bearing, comprising:

• an outer race with a convex-shaped outer raceway formed on the inner peripheral surface thereof;
• an inner race with a convex-shaped inner raceway formed on the outer peripheral surface thereof;
• a plurality of substantially cylindrical-shaped rolling elements respectively interposed between said outer raceway and said inner raceway;
• and,
• a collar portion formed so as to extend along one of an axial-direction end portion of said outer raceway and an axial-direction end portion of said inner raceway,
• wherein the outer peripheral surface of each of said rolling elements being formed of a concave-shaped bus, and the end faces of said rolling elements are formed as a convex-shaped spherical surface,
• wherein the central portion of one of said outer and inner raceways, and the outer peripheral surface of each-of said rolling elements is formed of a first bus which has a given radius of curvature and, two end portion sides adjoining said central portion are each formed of a second bus having such a radius of curvature that causes the two end portion sides to part away from the other of said outer and inner raceways, and said outer peripheral surface of each of said rolling elements, and
• wherein the collar surface of said collar portion is formed as a concave-shaped spherical surface.