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.

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.

In a tapered roller bearing (10), the surface roughness of at least a rolling surface (13c) and a large diameter-side end surface (13b) of a tapered roller (13) is 0.02 to 0.17 μm in reduced peak height Rpk, 0.12 to 0.21 μm in core roughness depth Rk, and 0.07 to 0.43 μm in reduced valley depth Rvk and the average recessed portion area in the fine irregularities on the surface of the tapered roller (13) is 5 μm.sup.2 or less. As a result, oil film formability can be improved under dilute lubrication and a decline in lubricating oil viscosity and surface damage at a rolling contact part and an increase in friction at a sliding contact part can be suppressed at the same time.

A transport-securing unit for retaining a plurality of rollers in a rolling-element bearing cage during transportation may include an annular region and a plurality of axially extending, circumferentially spaced projections extending from the annular region. Also, an assembly of the transport-securing unit, a rolling-element cage and a plurality of rollers in pockets of the rolling-element bearing cage, where the transport-securing unit is formed separately from the rolling-element bearing cage, and where the projections extend inside the cage and limit radially inward movement of the rollers relative to the cage.

A rolling sliding member includes a base part and a surface layer. The base part has a composition that includes 0.30 mass % to 0.45 mass % of carbon, 0.15 mass % to 0.45 mass % of silicon, 0.40 to 1.50 mass % of manganese, 0.60 mass % to 2.00 mass % of chromium, 0.10 mass % to 0.35 mass % of molybdenum, 0.20 mass % to 0.40 mass % of vanadium, and 0.005 mass % to 0.100 mass % of aluminum, and a remainder of iron and inevitable impurities. The surface layer is positioned around the base part. The surface layer has a Vickers hardness of 700 to 800 and a retained austenite content of 25 volume % to 50 volume %. The thickness of a grain boundary oxide layer satisfies Formula: thickness of grain boundary oxide layer≤equivalent diameter of rolling sliding member×1.4×10.sup.−3.

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.

The present disclosure discloses a polymer joining ring for a bearing assembly and is configured to retain a first inner ring and a second inner ring together to the bearing assembly. The polymer joining ring includes an outer surface and an inner surface. The outer surface includes a W or E shaped geometry throughout and includes a pair of flanges extending radially outwards at corners from outer surface, and a semi-circular protrusion extending at middle of the polymer joining ring. The pair of flanges are placed in tapered narrow grooves of the first inner ring and the second inner ring, and the semi-circular protrusion is placed in a triangular shape space produced between the first inner ring and the second inner ring can be tightly connected to each other. The joining ring is made of a polymer material that facilitates ease in assembling and accurate positioning of the inner rings.

A rolling element for use in a rolling-element bearing is proposed, including an outer casing and a bore hole. The bore hole is provided along a center line of the rolling element. The rolling element has at least one sensor arranged in the bore hole for load measurement and a radio module for transmitting the data measured by the sensor, wherein the rolling element has a micro-generator to provide the energy required for operation of the sensor and/or of the radio module.

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.