Abstract: A ball bearing includes an inner ring, an outer ring, a plurality of balls rollably provided between the inner ring and the outer ring, and a cage configured to hold the plurality of balls at equal intervals in a circumferential direction. The cage includes a plurality of pockets configured to hold the balls. The plurality of pockets include at least two types of pockets including a first pocket and a second pocket. A gap on each of an outer circumferential surface side and an inner circumferential surface side of the cage between the ball and an inner circumferential surface of the second pocket is larger than a gap on each of the outer circumferential surface side and the inner circumferential surface side of the cage between the ball and an inner circumferential surface of the first pocket.

Abstract: A ball bearing includes an inner ring, an outer ring, a plurality of balls rollably provided between the inner ring and the outer ring, and a cage configured to hold the plurality of balls at equal intervals in a circumferential direction. The cage includes a plurality of pockets configured to hold the balls. The plurality of pockets include at least two types of pockets including a first pocket and a second pocket. A gap on each of an outer circumferential surface side and an inner circumferential surface side of the cage between the ball and an inner circumferential surface of the second pocket is larger than a gap on each of the outer circumferential surface side and the inner circumferential surface side of the cage between the ball and an inner circumferential surface of the first pocket.

Abstract: In an HDD actuator pivot bearing unit 10, an axial inner surface 22a of a shield cap 22 is formed into a stepped shape so that an axial minimum gap a1 with a shield member 14e of one bearing 14 is narrower than an axial minimum gap a2 with an outer ring 14b and so that an axial minimum gap a3 with a boundary position 14b3 between an axial end face of the outer ring 14 and an annular groove 14b1 is narrower than the axial minimum gap a2 with the outer ring 14. By doing so, the amount of air passing through an interior of the bearing can be reduced to thereby reduce outparticles.

Abstract: In an HDD actuator pivot bearing unit 10, an axial inner surface 22a of a shield cap 22 is formed into a stepped shape so that an axial minimum gap a1 with a shield member 14e of one bearing 14 is narrower than an axial minimum gap a2 with an outer ring 14b and so that an axial minimum gap a3 with a boundary position 14b3 between an axial end face of the outer ring 14 and an annular groove 14b1 is narrower than the axial minimum gap a2 with the outer ring 14. By doing so, the amount of air passing through an interior of the bearing can be reduced to thereby reduce outparticles.

Abstract: There is provided a roller bearing for a hard disk swing arm, which is configured to improve the response characteristics of the swing arm by reducing a change in torque hysteresis of a swing arm retaining force with respect to time passage in a HDD drive state. The roller bearing (14, 16) is configured to swing and rotatably support the swing arm provided in a hard disk drive. The roller bearing (14, 16) includes: an inner ring (14a, 16a); an outer ring (14b, 16b); a plurality of rolling elements (14c, 16c) disposed between the inner ring (14a, 16a) and the outer ring (14b, 16b); and a retainer (14d, 16d) that retains the plurality of rolling elements (14c, 16c). The inner ring (14a, 16a) and the outer ring (14b, 16b) have a surface hardness of 700 HV or more and less than 800 HV, and each of the rolling elements has a surface hardness of 945 HV or more and less than 1060 HV.