Hands on with Navistar’s latest transmission options

The side-by-side test drives involved two ProStar tractors, one with an Eaton AMT and the other with Allison’s fully automatic TC10.The side-by-side test drives involved two ProStar tractors, one with an Eaton AMT and the other with Allison’s fully automatic TC10.

There’s a lot going on behind the scenes at Navistar these days.

The priority is still transitioning from an exhaust gas recirculation-only approach for meeting emissions regulations to a full selective catalytic reduction integration throughout its product line. But there’s other product refinement taking place, says Steve Gilligan, vice president of product and vocational marketing.

As evidence, he pointed out the advanced aerodynamic refinements and the transmissions on the two ProStar test trucks I had come to evaluate at International’s Melrose Park Test Center and Engine Plant, west of Chicago, earlier this year.

Gilligan said automated transmissions are being ordered on almost 30 percent of new International trucks. For some truck manufacturers, it’s approaching 50 percent, he said – another strong indication that the days of manual gearboxes may be numbered.

Moreover, he noted that a revived relationship with Cummins has allowed International to take a leadership role with the Cummins-Eaton SmartAdvantage integrated drivetrain. Gilligan hinted that International was working with Eaton to develop a new integrated drivetrain with its proprietary MaxxForce 13-liter engine.

“The improvement in average fuel economy is undeniable,” Gilligan said. “Because as good as automated manual transmissions are by themselves in terms of driver comfort and safety, we know they’re also a key enabler for reaching higher levels of average fuel efficiency in heavy-duty trucks. I think we’re rapidly approaching the point where 8 or even 9 mpg will become the new industry baseline for fuel economy, and integrated drivetrains are absolutely vital for attaining and maintaining those numbers. International intends to achieve this integration through close partnerships with our component supplier partners.”

In addition to the Cummins-Eaton drivetrain, I also would be evaluating Allison’s new TC10, a fully automatic transmission featuring a torque converter instead of an electronically actuated clutch. Gilligan said Allison designed the TC10 to compete with the new wave of AMTs.

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First up was the SmartAdvantage-equipped ProStar. Unfortunately, Chicago traffic gave me little opportunity to reach and maintain typical long-haul cruise speeds. But it was clear, even in stop-and-go traffic, that the Cummins ISX15 and the Eaton AMT were delivering smooth, precise shifts and were more than capable of getting a heavily loaded tractor-trailer up to speed in a timely manner. Drivers will enjoy the confidence of knowing the engine performs exactly the way it would with a manual transmission – and hitting perfect shifts every time, to boot.

Likewise, my ProStar daycab with the Allison TC10 and MaxxForce 13 power proved equally capable. I was expecting the Allison to shift smoother than an AMT since that is a prime benefit of a torque converter, and the Allison delivered on that front. But – and this is a credit to today’s AMT design – I doubt most drivers would see a noticeable difference.

The Allison certainly shined in heavy stop-and-go traffic. It delivered plenty of low-end torque in such a way that made me forget I’d driven the same route with a 15-liter under the hood just a little earlier.

It will be interesting to see if Allison adopts an “integrated drivetrain” version of the TC10. For now, it’s clear that International is taking the new heavy-duty transmission push seriously.