A roller bearing includes an inner race ring, an outer race ring, and a roller arranged between and in contact with the inner and outer rings. The bearing has a flange on the inner race ring at one axial end, and a flange on the outer race ring at an opposite axial end. At least one of the flanges, or an end of the roller, has a profile including a principal segment with a reference point C defining a contact location between the roller and the flange, the principal segment having a continuously changing radius of curvature, on both sides of reference point C, that decreases as a distance from the reference point C increases.

A tapered roller bearing is provided in which, in order to prevent a sharp rise in temperature and rotate the bearing smoothly even when the bearing is used under sever lubrication conditions, a grinding undercut has an undercut width A of 0.5 mm or less from a reference point to a large flange surface, the reference point being the intersection point of the imaginary line extending from the generatrix of the raceway surface of the inner ring toward the grinding undercut, and the imaginary line extending from the generatrix of the large flange surface toward the grinding undercut.

A bearing assembly includes a roller bearing unit, an inner race and an outer race. The roller bearing unit is formed of polycrystalline super-hard material having a mean mass density of at most 4.5 g/cm.sup.3 and a volume-weighted arithmetic mean thermal conductivity of at least 100 W/m.Math.K.

A motor including a rotor, a first arm, a mount, a stator, a first bearing, and a second bearing. The motor is configured to rotate the rotor. The mount connected to the first arm. The stator coupled to the mount. The first bearing located between and connecting the rotor to the stator. The second bearing located between and connecting the rotor to the mount. The first arm prevents movement of the stator and the mount.

A follower bearing 1 includes: an inner member 10 including a first body 50 and a flange 52; an outer ring 20; a plurality of rolling elements 40; and a first sealing member 30A including an annular first portion disposed between an outer peripheral surface 52A of the flange 52 and a first surface 22A and at least partially forming a sealing structure between the first portion and the outer ring 20. The first portion has an outer diameter that gradually increases toward a first end surface 52B at an end opposite to a first rolling surface 51A of the flange 52 in an axial direction.

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.

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.