A roller bearing system comprising a rolling element having a cylindrical outer raceway; said rolling element is housed inside an outer ring to the bearing system; said outer ring having an inner and an outer diameter surface, is connected to a rotatable shaft from one end, said inner diameter surface of the outer ring having a non-symmetric convex shaped profiling facing the rolling element to facilitate maximum contact area during any operational condition.

A roller bearing includes an outer raceway, an inner raceway, and a roller positioned between the outer and inner raceways. The roller bearing also includes a relief contour between the roller and at least one of the outer and inner raceways. The relief contour defines a slope along its length. The slope of the relief contour defines at least one inflection region.

A cross shaft joint includes a cross shaft including four shaft parts, needle rollers rolling on outer peripheral faces of the shaft parts, bearing cups each having a cylindrical part, and a bottom part, and externally fitted to the shaft parts via the needle rollers, and yokes provided with bearing holes into which the bearing cups are inserted. The needle rollers are maintained in a tight fit state between the shaft parts and the bearing cups. Each cylindrical part is provided with a projected part projected radially inward of the cylindrical part in a curved shape, at an inner peripheral side thereof, and an apex of the projected part is in contact with the needle roller within a range in an axial direction of the needle roller, the range containing an axial center of the needle roller in the axial direction.

A roller is provided that is configured to support of a rotary platform. The roller includes at least one side flange including an inner surface, a rolling surface to be in contact with a flat running surface of an upper rail member fixedly connected to the rotary platform and a flat running surface of a lower rail member stationary arranged. The roller includes a circumferential recess connecting the rolling surface to the inner surface of the side flange and that the circumferential recess has a depth such that the flat running surfaces of the upper rail member and the lower rail members are out of contact with a bottom surface of the circumferential recess at a potential angle deviation between the flat running surfaces of the rail members and a rotation axis of the roller.

In the tapered roller bearing, at least any one of an outer ring, an inner ring, and a plurality of tapered rollers includes a nitrogen enriched layer. An oil retaining hole is provided in a larger annular portion of a cage. A value of a ratio R/R.sub.BASE is not smaller than 0.75 and not greater than 0.87 where R represents a set radius of curvature of a larger end face of the tapered roller and R.sub.BASE represents a distance from a point which is an apex of a cone angle of the tapered roller to a larger flange surface of the inner ring. A ratio R.sub.process/R is than not lower 0.5 where R.sub.process represents an actual radius of curvature after grinding of the larger end face of the tapered roller and R represents a set radius of curvature.

A roller is provided that is configured to support of a rotary platform. The roller includes at least one side flange including an inner surface, a rolling surface to be in contact with a flat running surface of an upper rail member fixedly connected to the rotary platform and a flat running surface of a lower rail member stationary arranged. The roller includes a circumferential recess connecting the rolling surface to the inner surface of the side flange and that the circumferential recess has a depth such that the flat running surfaces of the upper rail member and the lower rail members are out of contact with a bottom surface of the circumferential recess at a potential angle deviation between the flat running surfaces of the rail members and a rotation axis of the roller.

The contact portion of the end face of a conical roller, which is a portion to be slidingly contacted with a collar portion, is ground such that the outer contour line of the section thereof has a continuously curved line which passes through at least not only the first point but also between the third position and fourth position.

In the tapered roller bearing, at least any one of an outer ring, an inner ring, and a plurality of tapered rollers includes a nitrogen enriched layer. An oil retaining hole is provided in a larger annular portion of a cage. A value of a ratio R/R.sub.BASE is not smaller than 0.75 and not greater than 0.87 where R represents a set radius of curvature of a larger end face of the tapered roller and R.sub.BASE represents a distance from a point which is an apex of a cone angle of the tapered roller to a larger flange surface of the inner ring. A ratio R.sub.process/R is than not lower 0.5 where R.sub.process represents an actual radius of curvature after grinding of the larger end face of the tapered roller and R represents a set radius of curvature.

A double-row self-aligning roller bearing has rollers interposed, in two rows aligned in a bearing width direction, between an inner ring and an outer ring. The outer ring has a spherical raceway surface. Each of the rollers has an outer circumferential surface having a cross-sectional shape that matches the raceway surface of the outer ring. Either or both of shapes and contact angles of the rollers are different from each other. An attachment hole to which a protrusion prevention jig is attachable is provided in an end surface of at least either one of the inner ring and the outer ring. The protrusion prevention jig prevents protrusion of the end surface of the inner ring in the bearing width direction with respect to the end surface of the outer ring.

A tapered roller bearing includes inner and outer rings having tapered raceway surfaces. The inner ring also includes large-collar and small-collar surfaces respectively on large-diameter and small-diameter sides of its raceway surface. A plurality of tapered rollers are arrayed between the raceway surfaces. Each of the tapered rollers has a large end surface that contacts and is guided by the large-collar surface. A set curvature radius (R) of the large end surface of each of the tapered rollers and a base curvature radius (R.sub.BASE) from a vertex of a cone angle of each of the tapered rollers to the large-collar surface has a ratio R/R.sub.BASE in a range of 0.75 to 0.87, and when R.sub.ACTUAL represents an actual curvature radius of the large end surface, a ratio R.sub.ACTUAL/R is equal to or larger than 0.5.