Development of low-torque thrust needle roller bearing
～Automotive transmission bearing with 50% less rotational torque～

JTEKT Corporation has developed a thrust needle bearing for automotive transmissions with significantly reduced rotational torque. This low-torque thrust needle bearing rotates with approximately 50 percent less torque than the conventional product, thus contributing to the improvement of automobile fuel efficiency.

Approximately 100 to 150 bearings are used in each automobile, and automakers, facing increased pressure from fuel efficiency regulations aimed at reducing CO₂ emissions, are seeking bearings of all types with less torque, smaller size, and lighter weight. In view of this situation, JTEKT has pursued the development of low-torque thrust needle bearings, some 10 of which are used in each automatic transmission on average, in order to improve driveline efficiency.

To achieve lower torque, focus was placed on improving sliding resistance between the roller end and the retainer pocket face. To achieve a structure enabling point contact between the retainer pocket face and the roller end center region, where rotational speed is low, a convex configuration was placed on the retainer pocket face and a convex configuration on the roller end. This structure has enabled a 50 percent reduction in rotational torque while maintaining life, high-speed operation, and wear characteristics equivalent to those of the conventional product.

Concerning this low-torque thrust needle bearing, JTEKT aims for sales of 1.2 billion yen in 2012.

Appearance of low-torque thrust needle roller bearing

 

Development point