February 20, 2006

NTN Develops Ultra Low-torque Tapered Roller Bearings
with Rotating Torque Reduced by 1/2

[Innovatively Low Torque While Maintaining Current Fatigue Life and Rigidity!]

NTN Corporation (NTN) has responded to demands for improved energy and fuel efficiency in general industrial machinery and automobiles with the development of Ultra Low-torque Tapered Roller Bearings, featuring half the rotating torque of conventional bearings, while maintaining the same fatigue life and rigidity.

Tapered roller bearings have greater load capacity and rigidity than ball bearings. For this reason, they are widely used in general industrial machinery, construction machinery, and automobiles. However, tapered roller bearings have greater rotating torque than ball bearings. There has been demand to reduce this rotating torque in order to improve energy efficiency.

Thus, NTN developed an optimized design that greatly reduces Elastohydrodynamic Lubrication(EHL) rolling resistance and sliding friction resistance. This bearing also features cage pocket shape that reduces agitation resistance by optimizing the oil flow inside the bearing in order to reduce rotating torque under oil lubrication. We also applied our unique FA heat treatment technology and high load-capacity design. As a result, we were able to develop a bearing with torque reduced to half that of its conventional counterpart under the same operating conditions, while maintaining the same fatigue life and rigidity.

[Features]

1. Low torque (half the rotating torque of conventional bearing)
   1. Optimized design greatly reduces EHL rolling resistance and sliding friction resistance.
   2. New cage pocket shape reduces agitation resistance of oil.
2. Same fatigue life as conventional bearings (compared to previous NTN product)
   • Application of NTN's proprietary FA heat treatment technology (fine austenite strengthening treatment) and high load-capacity design with maximized roller count bring about the same fatigue life and rigidity as conventional bearings by counterbalancing reduced load-capacity when low-torque specifications are applied.
     (Lower torque specifications are preferable to save energy. In general, however, as specifications allow for lower-torque, rated load capacity is reduced.)
3. Same rigidity as conventional bearings (compared to previous NTN product)
   • Application of high load-capacity design with maximized roller count.

[Applications]

1. General industrial machinery:
   • Construction machinery, transportation equipment, hydraulic machinery, etc.
2. Automobiles:
   • Transmissions, differentials, etc.

[Photograph of product]

[Features]

Lower torque: 1/2 previous product Smaller bearing: More than 10% reduction in bearing outer diameter (Same fatigue life/rigidity as previous product)

[Challenges and Solutions]

Challenge 1: Achieve low torque

Solution:	Optimized design
	New cage pocket shape reduces oil's agitation resistance

Challenge 2: Same lifetime as conventional bearings

Solution:	FA heat treatment
	2.8 times longer lifetime than conventional 4T product under pure oil conditions

Challenge 3: Same rigidity as conventional bearings

Solution:	High load capacity design
	roller count maximized by bringing cage closer to outer ring

[Performance]

Achieves 1/2 the torque of previous product at commercial range of 500-2,000 rpm.

Nearly same rigidity between previous and new products

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