Provided is a double-row self-aligning roller bearing including: an inner ring; an outer ring having a spherical raceway surface; and rollers arranged in two rows and interposed between the inner ring and the outer ring, wherein a ratio of a contact angle θ1 in one row to a contact angle θ2 in the other row falls within a range of 0.25≤θ1/θ2≤0.5, and a ratio of distance B1 in a bearing width direction from an end face of the bearing on a side of the one of the rows to an intersection of two lines of action defining the contact angles of the two rows, relative to a distance B2 in the bearing width direction from an end face of the bearing on a side of the other of the rows to the intersection falls within a range of 0.5≤B1/B2≤0.6.

In the tapered roller bearing, at least any one of an outer ring, an inner ring, and a plurality of tapered rollers includes a nitrogen enriched layer. An oil retaining hole is provided in a larger annular portion of a cage. 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 a 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 a larger flange surface of the inner ring. A ratio R.sub.process/R is than not lower 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.

The invention relates to a gas bearing for contactlessly bearing a rotatable element (50). The gas bearing comprises: a housing (100) having an opening for receiving the rotatable element; and at least two sliding films (200), which are arranged on an interior (110) of the opening without overlap and which each have a first end portion (210) and a second end portion (220) for support on the housing (100). The sliding films (200) are designed to radially support the rotatable element relative to the housing (100) only by means of the first and second end portions (210, 220), the second end portion (220) providing frictional contact with the interior (110) and the first end portion (210) being fastened to the housing.

A rolling bearing includes an inner ring, an outer ring, and a plurality of balls interposed between the inner ring and the outer ring. The inner ring and the outer ring are made of stainless steel. A raceway surface with which the ball is in rolling-contact in each of the inner ring and the outer ring and is a superfinished surface and a coating layer made of a solid lubricating film is formed on the superfinished surface.

An electroconductive roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The density of peaks S.sub.pd of the surface of the surface layer is equal to or greater than 93,406 (1/mm.sup.2), and is equal to or less than 153,027 (1/mm.sup.2).

Provided is a tapered roller bearing (1, 1′, 21) which is to be used for a pilot portion and an idler portion of a synchronous mesh-type transmission in which a component corresponding to a bearing outer ring (3, 23) is formed of a gear (34, 43), wherein a ratio L/Dw of a roller length (L) of a tapered roller (4) serving as a rolling element to a roller diameter (Dw) is set to 1.7 or more, wherein a rolling surface (6) of the tapered roller (4) includes a straight portion (6a) in a center portion of the rolling surface (6) in an axial direction and crowning portions (6b, 6c) extending from the straight portion (6a) to both end portions, and wherein the crowning portions (6b, 6c) are each formed of logarithmic crowning.

A bearing member 1 is provided with a coating layer 3 on an inner circumferential surface of a shaft hole 1A into which a shaft body 2 is to be fitted. The coating layer 3 is composed of a metal base material 3A and a heat conductive material 3B that is dispersed in the base material 3A and that has a thermal conductivity relatively higher than that of the base material 3A. The heat conductive material 3B has lengths Lb and Lc in directions B and C along a surface of the coating layer 3, longer than a length La in a thickness direction A of the coating layer 3, whereby thermal conductive characteristics in the directions B and C along the inner circumferential surface of the shaft hole 1A are enhanced. Thus, heat dissipation is improved, whereby temperature rise due to sliding contact with the shaft body 2 is suppressed, and seizure resistance is improved.

A rolling contact bearing, wherein the surface of the raceways of an outer member and/or an inner member are randomly formed with an innumerable number of microconcavelike pits, the surfaces are provided with said pits having a surface roughness value smaller than 0.25 microns and a skewness Rsk value such that −3.5<Rsk<−1.0.

A tapered roller bearing includes an inner ring having a tapered raceway surface and a large-collar surface on a large-diameter side of the raceway surface, and tapered rollers. Each of the rollers has a large end surface guided by the large-collar surface. When R represents a set curvature radius of the large end surface and R.sub.BASE represents a base curvature radius from a vertex of a cone angle of each of the tapered rollers to the large-collar surface, the base curvature radius R.sub.BASE is 100 mm or less, and a ratio R/R.sub.BASE of the set curvature radius R to the base curvature radius R.sub.BASE is set to 0.90 or less. When R.sub.ACTUAL represents an actual curvature radius of the large end surface of each of the tapered rollers, a ratio R.sub.ACTUAL/R of the actual curvature radius R.sub.ACTUAL to the set curvature radius R exceeds 0.5.

A sliding member includes a resin overlay layer on a sliding surface side coming into sliding contact with a mating member. The resin overlay layer has a surface roughness parameter Rk satisfying 0.4≤Rk≤1.2, and a surface area ratio S=S2/S1 calculated when an area of an arbitrary measurement field of view is designated by S1 and a surface area of the measurement field of view is designated by S2 satisfies 2.5≤S≤4.5.