Tapered roller bearing, a tapered roller bearing assembly and a pinion-shaft supporting assembly using the same

A tapered roller bearing comprising:

• an outer ring;
• an inner ring;
• a plurality of tapered rollers interposed between these rings;
• and a retainer for retaining the tapered rollers, wherein
• a roller loading ratio represented by z·DW/(π·dm) is in a range of 0.7 to 0.92, and a ratio of roller length to roller diameter as represented by LWR/DW is in a range of 1.1 to 1.7, provided that z denotes a number of rollers, LWR denotes an effective length of the roller, DW denotes a mean diameter of the roller, and dm denotes a Pitch Circle Diameter (PCD) of the roller, and wherein
• raceways of the outer ring and the inner ring and a rolling contact surface of the tapered roller are each provided with a crowning;
• a total crowning amount (=an outer-ring crowning amount+an inner-ring crowning amount+a roller crowning amount) is 50 μm or more;
• an outer-ring crowning rate (=the outer-ring crowning amount/the total crowning amount) is 40% or more;
• and
• a roller crowning rate (=(the roller crowning amount×2)/the total crowning amount) is 20% or less.

A vehicular pinion-shaft supporting apparatus comprising tapered roller bearings disposed on a pinion-gear side of a pinion-shaft and on an end of the pinion shaft opposite the pinion-gear end, wherein a tapered roller bearing disposed on the pinion-gear side includes:

• an inner ring;
• an inner ring;
• a plurality of tapered rollers interposed between these rings;
• and
• a retainer for retaining the tapered rollers;
• and
• oil inflow restricting means for restricting the inflow of oil, the restricting means being disposed at an axial one end of space between the inner ring and the outer ring, wherein
• a roller loading ratio represented by z·DW/(π·dm) is in a range of 0.7 to 0.92, and a ratio of roller length to roller diameter as represented by LWRIDW is in a range of 1.1 to 1.7, provided that z denotes a number of rollers, LWR denotes an effective length of the roller, DW denotes a mean diameter of the roller and dm denotes the Pitch Circle Diameter (PCD) of a roller, and
• an outer-ring crowning parameter (=RCO/LRO) is in a range of 30 to 150, and an inner-ring crowning parameter (=RCI/LRI) is in a range of 50 to 260, provided that RCO denotes a radius of an outer-ring crowning, LRO denotes a raceway length of the outer ring, RCI denotes a radius of an inner-ring crowning, and LRI denotes a raceway length of the inner ring.