The present invention relates to a bearing shaft provided with an outer peripheral surface that includes a raceway surface (side surface) on which a rolling element rolls. The bearing shaft is made of steel containing carbon of 0.7% or more. The raceway surface is forming with a nitrogen-enriched layer. The absolute value of compressive residual stress in the surface of the nitrogen-enriched layer (i.e., the surface of a hardened layer which is formed on the side surface of the bearing shaft by shot peening) is 600 MPa or more and 1700 MPa or less. Thereby, it is possible for the present invention to prolong the operation life of a bearing.

A thrust roller bearing includes rollers arranged in a radial manner, an annular cage that retains the rollers such that the rollers are rollable, an annular outer race located on one side of the cage in an axial direction of the cage and having a first raceway on which the rollers roll, and an annular inner race located on the other side of the cage in the axial direction and having a second raceway on which the rollers roll. At least one of the first raceway and the second raceway has a Vickers hardness that is greater than or equal to 800 and less than or equal to 950. The outer circumferential surface of each of the rollers has a Vickers hardness that is greater than or equal to 697 and less than 800.

A thrust bearing cage including an improved lubrication feature is disclosed. The thrust bearing cage includes a first rim and a second rim with a plurality of crossbars extending therebetween to define rolling element pockets. Each crossbar of the plurality of crossbars includes: a first radial flange extending from the first rim; a second radial flange extending from the second rim; and a medial radial flange connecting the first radial flange and the second radial flange. The medial radial flange is axially offset from the first radial flange and the second radial flange. At least one of the first radial flange, the medial radial flange, or the second radial flange includes a protrusion defining at least one ramped surface. The ramped surface creates a hydrodynamic effect, which guides the thrust bearing cage away from an adjacent surface, and ensures that a lubricated state is maintained.

A thrust bearing cage includes a piloting feature to radially locate a thrust bearing with respect to one of the shafts. Specifically, the bearing cage includes an axial extension at an outer diameter that extends beyond the rollers and around an outer diameter of end of the shaft. This feature permits elimination of a washer.

A thrust roller bearing cage (11) of the present invention is included in a thrust roller bearing (20) and includes a plurality of pockets (21) accommodating rollers (13). The thrust roller bearing cage (11) includes: a first cylindrical portion (36) extending in a direction of a rotation axis (12); a first disc portion (31) continuous with the first cylindrical portion (36) and extending in a radially outward direction; and a second cylindrical portion (37) continuous with the first disc portion (31) and extending in the direction of the rotation axis (12). The first cylindrical portion (36), the first disc portion (31), and the second cylindrical portion (37) are formed in an area located radially inside the pockets (21). The height (H36) of the first cylindrical portion (36) in the direction of the rotation axis is smaller than the height (H37) of the second cylindrical portion (37) in the direction of the rotation axis.

A cage for a thrust bearing assembly is disclosed. The cage includes a radially inner flange, a radially outer flange, and a plurality of crossbars extending therebetween that define a lower portion of a plurality of rolling element pockets. The radially inner flange includes a first plurality of retention bars extending radially outwardly, and the radially outer flange includes a second plurality of retention bars extending radially inwardly. The first plurality of retention bars and the second plurality of retention bars each partially define an upper portion of the plurality of rolling element pockets.

A cage for a thrust bearing assembly is disclosed. The cage includes a radially inner flange, a radially outer flange, and a plurality of crossbars extending therebetween that define a lower portion of a plurality of rolling element pockets. The radially inner flange includes a first plurality of retention bars extending radially outwardly, and the radially outer flange includes a second plurality of retention bars extending radially inwardly. The first plurality of retention bars and the second plurality of retention bars each partially define an upper portion of the plurality of rolling element pockets.

A thrust roller bearing cage (11) includes a thrust roller bearing (20) and a plurality of pockets (21) accommodating rollers (13). The thrust roller bearing cage (11) includes: a first cylindrical portion (36) extending in a direction of a rotation axis (12); a first disc portion (31) continuous with the first cylindrical portion (36) and extending in a radially outward direction; and a second cylindrical portion (37) continuous with the first disc portion (31) and extending in the direction of the rotation axis (12). The first cylindrical portion (36), the first disc portion (31), and the second cylindrical portion (37) are formed in an area located radially inside the pockets (21). The first disc portion (31) has a through hole (53).

A rolling-element bearing cage or segment configured to guide at least one rolling element includes a first circumferential ring connected to a second circumferential ring by a plurality of axially extending bridges. A first one of the bridges includes a first axial portion that has a cross-section perpendicular to the axial direction and a cross sectional area and a peripheral length. The peripheral length of the cross section of the first axial portion is greater than a peripheral length of a smallest rectangle bounding the cross section.

A thrust roller bearing cage (11) includes a thrust roller bearing (20) and a plurality of pockets (21) accommodating rollers (13). The thrust roller bearing cage (11) includes: a radially outer area bent portion (41) formed by bending an area located radially outside the pockets (21) inward in a radial direction; and projecting portions (44) that are formed in a tip end of the radially outer area bent portion (41) at positions aligned with the pockets (21) and project inward in the radial direction beyond radially outer edges of the pockets (21) so as to contact end faces (16) of the rollers (13) accommodated in the pockets (21). The projecting portions (44) have a width that is or more and or less of the width of the pockets (21).