Schaeffler Group (Germany, parent of INA / FAG Bearings) announced it has developed a next-generation quad-row ball bearing, designed to replace tapered roller bearings in automotive wheel bearing applications.

The four-row angular contact ball bearing, called "Twin Tandem," offers lower startup torque and lower running drag than the traditional tapered roller bearings it is designed to replace. The units also potentially offer improved service life without sacrificing load capacity.

TT was a main attraction in INA/FAG's Hannover Messe stand.
Hannover Messe virtual trade show booth for INA/FAG
The key impact from employing TTs is lower fuel consumption, claimed at up to 1.5% for each pair installed in larger vans, trucks, and SUVs.

Tapered roller bearings carry loads via line contact along the rolls, while ball bearings have point contact. The net difference is a claimed 50% reduction in internal friction between equivalent ball and tapered roller bearings.

INA/FAG also claims the TT design has a lower operating temperature, contributing to longer service life of the bearing itself and also extending the service life of the lubricant used.

Finally, the TT design is claimed to offer superior deflection stiffness, meaning it wobbles less under side loading than the comparable TRB.

The greatest differences are expected against the larger TRB applications such as trucks and SUVs, but Schaeffler said it will continue to develop the bearings with an eye toward potential use in higher-volume automotive applications.

Envelope dimensions have been established such that TT wheel hub units will be directly interchangeable with current hub units employing TRBs. TTs are also designed to keep the same ABS and wheel speed sensor operating and output parameters.

Beyond automotive applications, Schaeffler indicated it is developing TT units oriented toward heavy manufacturing, steelmaking, machine tools, paper mills, and wind energy.

Schaeffler claims approximately 7 million vans, SUVs and trucks are manufactured each year which would be suitable candidates to use TT wheel bearings in place of TRBs.

INA / FAG's bearings are similar to SKF's X-Drive asymmetrical ball bearings, now used in several OEM wheel hub applications.

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