Patent ID: 8186887

Claim:
A double row tapered roller bearing unit having a double structure comprising: an outer bearing comprising: an integral outer-side outer ring member, having formed on an inner circumferential surface thereof a double row of outer ring raceways each having a partially conical concave surface inclining in a direction such that an inner diameter increases toward an end in an axial direction; an outer-side inner ring member comprising a pair of outer-side inner ring elements each having an inner ring raceway of partially conical convex surface formed on an outer circumferential surface, and a plurality of tapered rollers, rollably disposed between both outer ring raceways and both inner ring raceways; and an inner bearing comprising: an eccentric integral inner-side outer ring member, having formed on an inner circumferential surface thereof a double row of other outer ring raceways each having a partially conical concave surface inclining in a direction such that an inner diameter increases toward an end in the axial direction, an inner-side inner ring member comprising a pair of inner-side inner ring elements each having another inner ring raceway of partially conical convex surface formed on an outer circumferential surface, and a plurality of tapered rollers, rollably disposed between both of the other outer ring raceways and both of the other inner ring raceways; and wherein the pair of outer-side inner ring elements are externally fitted onto the inner-side outer ring member in a state where respective ends of smaller outer diameter of both inner ring raceways oppose each other, and both outer-side inner ring elements apply preload to the respective tapered rollers by pressing forces acting from both sides in the axial direction by an outwardly-directed, flanged collar formed on an outer circumferential surface of one end among both ends in the axial direction of the inner-side outer ring member and by a holding ring fitted onto the other end of the inner-side outer ring member, or by a pair of holding rings fitted onto respective ends in the axial direction of the inner-side outer ring member, wherein each holding ring engages an end surface of a respective one of the outer-side inner ring elements and is urged against and fastened to the respective end of the inner-side outer ring member at an adjustable position in the axial direction by a fastener such that the outer-side inner ring elements are adjustably spaced along the outer circumferential surface of the inner-side outer ring member to adjust the preload.