The invention has an object of providing grease reduced in an amount of the flying grease and an amount of the outgas, and superior in low-temperature characteristic, an antifriction bearing using the grease, an antifriction bearing device, and an information recording/reproducing device. A grease includes a base oil, and a thickener, the base oil includes mineral oil and poly-α-olefin, the poly-α-olefin is higher in mass than the mineral oil, the poly-α-olefin includes poly-α-olefin higher in kinetic viscosity than the mineral oil, the kinetic viscosity of the base oil at 40° C. is in a range of 40 through 90 mm.sup.2/s, and worked penetration is in a range of 200 through 250. Further, an antifriction bearing, an antifriction bearing device, and an information recording/reproducing device use the grease.

A fluid dynamic bearing device 1 includes: a shaft member 2; a bearing sleeve 8 that has the shaft member 2 inserted into the inner periphery thereof; a housing 7 that holds the bearing sleeve 8 on the inner periphery thereof and has a bottomed cylindrical shape having an opening at an end portion on one axial side; and a seal member 9 provided at the opening of the housing 7. The seal member 9 has a disk portion 9a disposed on one axial side of the bearing sleeve 8, and a protrusion (cylindrical portion 9b) protruding to the other axial side from an outer diameter end of the disk portion 9a. An outer peripheral surface 9c of the seal member 9 is fixed to an inner peripheral surface 7a1 of the housing 7.

A tolerance ring having a first axial end, a second axial end, and a central axis, the tolerance ring including an annular band; a plurality of protrusions, all of the plurality of protrusions extending from the annular band; and a guide portion extending from the annular band towards the first axial end of the tolerance ring, where the guide portion includes a guide surface that is curved in an axial section.

According to one embodiment, a disk device includes a disk-shaped recording medium, a base accommodating the recording medium, the base including a bottom wall, a sidewall on a peripheral portion of the bottom wall, and a rib on a part of an upper surface of the sidewall and extending along an entire circumference of the sidewall, a first cover on a part of the upper surface of the sidewall, and a second cover on a first surface of the rib and above the first cover. The rib includes a first region with a first width, a second region with a second width less than the first width, and the first surface with a fixed width around an entire circumference of the rib. The first region and the second region are located corresponding to a side portion of the recording medium.

Provided is a fluid dynamic bearing device, including: a shaft member; a bearing sleeve (18) having the shaft member inserted along an inner periphery thereof; and dynamic pressure generating grooves (26) configured to support the shaft member in a relatively rotatable and non-contact manner with pressure of an oil film formed in a radial bearing gap defined between an outer peripheral surface of the shaft member and an inner peripheral surface (24) of the bearing sleeve (18). The dynamic pressure generating grooves (26) include: the large number of polygonal hill portions (27) arranged in a pattern on the inner peripheral surface (24) of the bearing sleeve (18) ; and polygonal groove portions (28) formed in such a manner as to surround the polygonal hill portions (27).

A spindle motor includes a shaft fixed to a base portion and a hub rotatably supported by the shaft. The hub is a cold-forged product made of low-carbon steel having a carbon content of 0.23 mass % or less.

A rolling bearing capable of achieving reduction in torque is provided. The rolling bearing includes an inner ring and an outer ring disposed coaxially with each other, a rolling element disposed between the inner ring and the outer ring, a seal member configured to cover an area between the inner ring and the outer ring from an outside in an axial direction, and filled grease disposed between the rolling element and the seal member. The filled grease includes a first ring-like part which extends to form a circumferential shape centering on a common axis of the inner ring and the outer ring, and which has contact with one of the inner ring and the outer ring, and a second ring-like part which extends to form a circumferential shape centering on the common axis, which is connected to the first ring-like part at an outer side in the axial direction, and which has contact with the seal member.

The present invention relates to a manufacturing method for a fluid dynamic bearing device, the method involving: forming an axial clearance 14 having a clearance width δ equal to a total amount of clearance widths of two thrust bearing clearances δ1, δ2 between a second bearing surface C of a bearing member 22 fixed to an outer periphery of a shaft member 21 and a sealing member 9; relatively moving the shaft member 21, the shaft member 22, and the sealing member 9 with respect to a housing 7 while the clearance width δ of the axial clearance 14 is maintained after forming the axial clearance 14; and fixing the sealing member 9 to the housing 7 at a time when a first thrust bearing surface B of the bearing member 22 comes into contact with a bottom surface 7b of the housing 7.

A tolerance ring includes a base formed of a strip-like member approximately wound around into a ring shape, and a plurality of projections provided along a winding direction of the base so as to protrude in a radial direction from an outer peripheral surface of the base, wherein each of the projections has edges serving as a boundary with the base and at least one of the edges in a width direction orthogonal to the winding direction has a shape intersecting the winding direction.

A fluid-dynamic bearing system comprising a stationary bearing component (12, 16, 18) and a bearing component (14, 14a) rotatable about a rotation axis, wherein, during operation of the bearing, the stationary and rotary components are separated from each other by a bearing gap (20) filled with a bearing fluid, wherein at least one fluid-dynamic radial bearing (22, 24) and at least one fluid-dynamic thrust bearing (28) or, alternatively, at least one conical fluid-dynamic bearing are arranged along the bearing gap (20), and wherein the bearing gap (20) comprises first and second open ends sealed by a first sealing gap (34) and a second sealing gap (36). The second sealing gap (36) exclusively extends normal to the rotation axis (40).