A method for heat treating a crankshaft surface on a crankshaft for a vehicle propulsion system includes heating the crankshaft surface to a first temperature and heating the crankshaft surface to a second temperature that is higher than the first temperature.

A double row tapered roller bearing includes: an outer ring having an annular shape; an inner ring disposed on an inner circumferential side of the outer ring and having an annular shape; and rollers. The inner ring has an outer circumferential surface facing the outer ring and having two rows of grooves having a bottom surface serving as a raceway surface. The rollers are tapered rollers disposed in the grooves in contact with the raceway surface of the inner ring and are also in contact with the outer ring. At outer circumferential surface of the inner ring, a region adjacent to the groove includes a hardened region extending from the inner peripheral surface of the groove to the region adjacent to the groove, and an unhardened region located at a position farther from the groove than the hardened region and being smaller in hardness than the hardened region.

When a rod-shaped workpiece (W) having an outer peripheral surface with a circular cross section is inductively heated to a quenching temperature while being conveyed at a predetermined velocity along an axial direction of the rod-shaped workpiece (W), the rod-shaped workpiece (W) being currently conveyed is heated to a predetermined temperature equal to or lower than the quenching temperature by a first heating coil (2A), which is electrically connected to a first high-frequency power supply (3) and has a constant output. Then, the rod-shaped workpiece (W) being currently conveyed is heated so as to be maintained at the quenching temperature by a second heating coil (2B), which is electrically connected to a second high-frequency power supply (4) and has a constant output.

A double row tapered roller bearing includes: an outer ring having an annular shape; an inner ring disposed on an inner circumferential side of the outer ring and having an annular shape; and rollers. The inner ring has an outer circumferential surface facing the outer ring and having two rows of grooves having a bottom surface serving as a raceway surface. The rollers are tapered rollers disposed in the grooves in contact with the raceway surface of the inner ring and are also in contact with the outer ring. At outer circumferential surface of the inner ring, a region adjacent to the groove includes a hardened region extending from the inner peripheral surface of the groove to the region adjacent to the groove, and an unhardened region located at a position farther from the groove than the hardened region and being smaller in hardness than the hardened region.

There is prepared a formed body constituted of steel and having an outer circumferential surface having an annular groove having a bottom surface to serve as a raceway surface of the bearing ring. In the step of forming a heated region, the formed body is induction heated to form a heated region including the bottom surface of the groove and heated to a temperature of at least an A.sub.1 point. In the cooling step, the whole of the heated region is simultaneously cooled to a temperature of not more than an M.sub.s point. The step of retaining the formed body in a state in which heating is stopped is performed after the step of forming a heated region before the step of cooling. In the step of retaining, dispersion in temperature in the heated region in the circumferential direction is suppressed to not more than 20 C.

A method for producing a bearing ring of a double row tapered roller bearing includes the steps of: preparing a formed body; forming a heated region; cooing; and removing. In the step of forming a heated region, an induction heating coil arranged to face part of the groove and induction-heating the fixated body is relatively rotated along the circumferential direction of the groove to form a heated region including the bottom surface of the groove and heated to a temperature of at least an A.sub.l point. In the cooling step, the whole of the heated region is simultaneously cooled to a temperature of not more than an M.sub.s point. After the step of forming a heated region before the step of cooling, the method further includes the step of retaining the formed body in a state where heating is stopped.

A bearing unit having a stationary radially outer ring, a radially inner ring rotatable about a central rotation axis (X) of the bearing unit is provided with at least one raceway and, in an end portion thereof, with at least two circular sector segments, at least one row of rolling elements interposed between the radially outer ring and the radially inner ring, and a concentric collar for clamping the radially inner ring on a rotating shaft, where an induction-hardening heat treatment is applied to a portion of the radially inner ring that overlaps with at least a portion of the at least one raceway.

A bearing ring of a rolling-element bearing includes a raceway for rolling elements and at least one flange for guiding the rolling elements, the flange merging into a bearing ring shoulder and extending to a height above the raceway. A free space such as a recess is formed between the bearing ring shoulder and the flange such that the flange is freestanding over its entire height.

A member for guiding an element mobile in oscillation or rotation is presented. The member has a body made of a hardened metallic material, provided with a bore for assembling the mobile element, having cavities that are distributed discontinuously in the bore and capable of acting as grease reserves, and having optional grease supply. In the bore are defined a bearing surface outside of the cavities and the grease supply, and a non-bearing surface in the cavities and the grease supply. The bore includes at least one zone with: cavities having a depth of between 2 and 5 mm, and a quantity of grease in the cavities per bearing surface of between 0.05 and 0.3 g/cm.sup.2. A mechanical system having such a member and a method for manufacturing such a member is also contemplated.

A wheel bearing assembly for a vehicle includes at least one rolling-element bearing having a first bearing ring and a second bearing ring defining therebetween a bearing interior, rolling elements disposed in the interior, and a seal assembly for sealing the bearing assembly. The seal assembly includes a sleeve-shaped element connected to the second bearing ring such that the sleeve-shaped element rotates with the second bearing, and the sleeve-shaped element includes a flange that forms an axial stop for the rolling elements. A carrier element is connected to the first bearing ring such the carrier element rotates with the first bearing ring, and the carrier element includes a radially extending annular flange. The radially extending annular flange supports a radially encircling seal having at least one seal lip, and the seal lip extends toward the second bearing ring and sealingly abuts on the sleeve shaped element.