NASHVILLE, Tenn. — The downspeeding trend is likely to continue, and efforts to downspeed powertrains will become more aggressive, according to Steve Slesinski, director of global product planning, commercial vehicle driveline technologies with Dana.

“Downspeeding is here to stay,” he declared at the spring meeting of the Technology & Maintenance Council meetings. This is because every 100 rpm slower the engine turns translates to a 1% gain in fuel efficiency.

Slesinski said Dana is expanding its product offerings designed to handle the increased drivetrain torque downspeeding generates. Moving from a 3.55 rear axle ratio to 2.26, for example, increases drivetrain torque by 36%.

At the show, Dana announced the introduction of a new driveshaft specifically designed to support downspeeding. It weighs 30 lbs less than existing products, Dana announced. It also has fewer components and provides easier installation for OEM customers and easier maintenance for end users.

The driveshaft enables rear axle ratios lower than 2.26:1.

“Engine downspeeding is not a one-size-fits-all solution. Each OEM implements this efficiency-boosting strategy in its own way, resulting in very specific torque-handling requirements,” said Mark Wallace, executive vice-president of Dana. “This next-generation driveshaft is the result of our continuous drive to deliver flexible solutions to meet each customer’s unique needs while further reducing weight and improving efficiency in our products.”

The new driveshaft is available now for pre-production evaluation by OEMs.

Dana also announced its axle ratios are compatible with all seven configurations of SmartAdvantage powertrains from Eaton and Cummins. Dana says it worked with the two companies to develop the fastest, lightest and most efficient drivetrain available.

This includes the Spicer AdvanTek 40 155 Series tandem axle and the SPL 350 driveshaft and SPL 250 inter-axle shaft.

“The benefits of engine downspeeding are undeniable, and we are partnering with industry leaders to advance this efficiency-boosting technology,” said Wallace. “Our joint collaboration with Cummins and Eaton allows Dana to take a comprehensive systems approach, examining the integration of all components throughout the vehicle in an effort to fully optimize performance and make further drivetrain enhancements.”

Slesinski noted more downspeeding technologies are in development. A dual range disconnect axle, which converts to a 6×2 while in motion, has the potential to enable downspeeding as low as 900 rpm, he noted. This could provide another 2-5% fuel savings. The dual range disconnect has been in development for nearly four years and truck manufacturer field tests are currently underway, Slesinski added.