COLUMBUS, Ind. — Cummins Engine has introduced its latest electronic torque management technology, STx, a variation on the company’s “Smart Torque” (ST) product.

The basic ST technology tailors the engine’s torque output to specific transmission gear ratios. In the first examples of the ST strategy, Cummins recently introduced 10 engine models that will provide an extra 100 or 200 pound feet of torque in the top two gears by controlling fuelling rates gear by gear.

STx essentially does the reverse. Instead of adding torque, it limits torque output in the lower gears and retarding mode.

This makes it possible to spec lighter — and less expensive — drive axles with Signature 600 engines.

Meritor Automotive is the first to take advantage of it, offering its RT-140 40,000- and RT-160 46,000-pound tandem drive axles with the STx version of the 600-horsepower Signature engine. These pairings, available now, are possible because the STx strategy selectively limits the engine’s 2050 pound feet of torque. Weight savings over the heavier axles that would be required without STx can be several hundred pounds, and the cost saving is as much as US$3000 at data book prices.

In the STx Signature 600, torque output is limited to 1650 in the first three gears, then 1850, and by the time you shift into high range you’ve got all 2050 pound feet. STx is also available in the Signature 565, where torque is restricted to 1650 pound feet to launch the truck, and 1850 pound feet thereafter.

Meritor’s RT-40-140 series tandem axle — designated RT-40-149 — is approved for gross weights up to 80,000 pounds with the Signature 600 STx. For higher weights, the RT-40-160 and RT-46-164/16H — designated RT-40-169 and RT-46-169/16H — can be spec’d.