The present disclosure regards a spherical roller bearing having, an outer ring providing at least one inner raceway, an inner ring providing a first and a second outer raceway, a plurality of roller elements arranged in a first and second roller row disposed between the at least one inner raceway and the respective first and second outer raceway, the roller elements further providing axially inner ends. Moreover, the bearing includes a cage for one of guiding and retaining the roller elements in the first and second roller row, the cage including a plurality of cage pockets, wherein one of the roller elements is disposed within each cage pocket, and wherein the cage is roller centered by the axially inner ends.

A taper roller bearing includes: an inner ring, an outer ring, a plurality of taper rollers, and an annular cage which holds the plurality of taper rollers at an interval in the circumferential direction. The cage includes a small-diameter annular portion on one axial side, a large-diameter annular portion on the other axial side, and a plurality of column portions. An inner circumferential surface of the small-diameter annular portion includes a first inner circumferential surface portion and a second inner circumferential surface portion having a small diameter. An outer circumferential surface of the small flange included in the inner ring includes a first outer circumferential surface portion which opposes the first inner circumferential surface portion having a fine clearance, and a second outer circumferential surface portion which has a small diameter and opposes the second inner circumferential surface portion having a fine clearance.

A difference between a maximum value and a minimum value of arithmetic mean roughness Ra of an annular surface region in contact with a larger flange surface, in a larger end face of the tapered roller, is not greater than 0.02 μm. 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 the 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 the larger flange surface of the inner ring. A ratio R.sub.process/R is not lower than 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.

An angular contact self-aligning toroidal roller bearing comprising an inner ring, an outer ring, and a set of rolling elements formed of rollers arranged in an intermediate configuration between the inner and outer rings. Each roller is arranged to self orient in its axial direction in relation to the inner and outer rings in a loaded zone during operation. Furthermore, a method for determining dimensional parameters of structural members of an angular contact self-aligning toroidal rolling element bearing and a method for manufacturing an angular contact self-aligning toroidal rolling element bearing are described herein.

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 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 bearing system configured for use on a downhole tool including a rolling cutter member having a plurality of cutting structures thereon comprises a first plurality of bearings disposed between a head washer and an at least substantially planar shaft washer, and a second plurality of bearings disposed between the at least substantially planar shaft washer and a rolling cutter washer. A downhole tool, such as an earth-boring rotary rolling cutter drill bit includes such a bearing system between a rolling cutter and a head of a bit body. Methods of forming such a downhole tool include the assembly of such a bearing system between a rolling cutter and a head of a bit body.

Bearing systems configured for use on a downhole tool may include a tensioner bolt having a complementary nut, the tensioner bolt and nut sized and shaped to secure the rolling cutter member to a head. A radial bearing may include an annular sleeve sized and shaped to surround the head. A shaft washer may be sized and shaped to surround the head between an enlarged head of the tensioner bolt and the annular sleeve. A bearing element may be configured for positioning proximate the head, the bearing element comprising an upper surface configured for sliding, frictional contact with a lower surface of the shaft washer.

A tandem roller bearing assembly is provided that combines a tapered roller bearing with an angular contact ball bearing, yielding high load capacity with improved efficiency. A one-piece outer ring contains an outer tapered roller raceway and an outer angular contact ball raceway and can support an axial load in a single direction. A one-piece inner ring contains an inner tapered roller raceway and an inner angular contact ball raceway and can support an axial load in a single direction. Various rib configurations are implemented on the inner tapered roller raceway to achieve multiple friction and axial load support options.

The present invention provides a manufacturing method by which a good quality tapered roller can be obtained at low cost. An intermediate raw material (17) is obtained by grinding an outer-circumferential surface (15) of a preliminary intermediate raw material (14), which is obtained by plastic working of a metallic circular column shaped raw material, using a grindstone (16), with a large diameter-side end surface (10) of the intermediate raw material (14) as a reference. A final intermediate raw material (21a) is obtained by grinding the large diameter-side end surface (10) of the intermediate raw material (17) using a grindstone (20), and grinding the intermediate raw material (17) by a predetermined length instead of setting the intermediate raw material (17) to a predetermined length.