Abstract: A ball bearing includes a cage circular annular portion and a seal member. The cage circular annular portion has a cage-side sliding contact surface axially opposed to the seal member and configured to come into sliding contact with the seal member. The seal member has a seal-side sliding contact surface configured to come into sliding contact with the cage-side sliding contact surface. A plurality of axial protrusions each having an axially convex circular arc shape in cross sections along a circumferential direction are formed on one of the cage-side sliding contact surface and the seal-side sliding contact surface at constant pitches in the circumferential direction.

Abstract: An outer surface rubber portion is formed to cover the entire axially outer surface of a metal core. An inner surface rubber portion is formed with a circular annular opening through which the axially inner surface of the metal core is exposed on the same circumference passing on the radially outer side of minute protrusions; and circular arc-shaped openings through which the axially inner surface of the metal core is exposed on the same circumference passing on the radially inner side of the minute protrusions.

Abstract: A ball bearing is provided which includes a cage circular annular portion and a seal member. The cage circular annular portion has a cage-side sliding contact surface axially opposed to the seal member and configured to come into sliding contact with the seal member. The seal member has a seal-side sliding contact surface configured to come into sliding contact with the cage-side sliding contact surface. A plurality of axial protrusions each having an axially convex circular arc shape in cross sections along a circumferential direction are formed on one of the cage-side sliding contact surface and the seal-side sliding contact surface at constant pitches in the circumferential direction.

Abstract: A ball bearing is provided which includes a cage circular annular portion and a seal member. The cage circular annular portion has a cage-side sliding contact surface axially opposed to the seal member and configured to come into sliding contact with the seal member. The seal member has a seal-side sliding contact surface configured to come into sliding contact with the cage-side sliding contact surface. A plurality of axial protrusions each having an axially convex circular arc shape in cross sections along a circumferential direction are formed on one of the cage-side sliding contact surface and the seal-side sliding contact surface at constant pitches in the circumferential direction.

Abstract: 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/RBASE 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 RBASE 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 Rprocess/R is than not lower 0.5 where Rprocess 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.