MARSHALL, MI. Truck operators have more options for integrated Cummins-Eaton ISX15 SmartAdvantage Powertrains, including a new direct drive ratio. To highlight that, the companies recently let reporters drive some tractor-trailers sporting different SmartAdvantage configurations — two of them, for the first time, with Cummins' 2017 ISX15 diesel being readied for the market to meet new emissions standards.

Some of the trucks came from Cummins' Redefining Tour fleet showcasing the capabilities of the current and upcoming ISX15 engines. The tour trucks together logged nearly 77,000 miles in the United States and Canada.

Mario Sanchez-Lara, director of on-highway communications and technical sales at Cummins, said the tour made believers of the drivers involved — including one who he said found the new trucks' fuel economy, ease of operation and comfort so convincing it opened up the possibility of returning to a former career as an owner-operator.

While the companies wouldn't yet talk specifics about fuel economy of the 2017 engine, Mike Taylor, Cummins' general manager of global powertrains, said Cummins expects the new ISX15 will provide "best-in-class uptime with best-in-class fuel economy." Also, "with maintenance — and I can't say a whole lot more about this — it's going to be game-changing," he said.

Here's a quick look at an International ProStar+ equipped with a 2017 Cummins ISX15 diesel in its SmartAdvantage Powertrain — which, yes, delivered on the hype — heading for a trip around the Eaton Proving Grounds oval track:

 

SmartAdvantage portfolio expanded

New SmartAdvantage Powertrain options include direct drive transmissions that optimize performance and fuel economy for regional and less-than-truckload carriers whose trucks cruise at speeds below 62 mph, according to Cummins and Eaton. SmartAdvantage small-step overdrive powertrains, which are aimed at line-haul applications with cruising speeds above 62 mph, are now available with additional horsepower ratings. 

When the SmartAdvantage Powertrains were released for 2014, the companies claimed they provided fuel economy gains of 3-5%, noted Ryan Trzybinski, Eaton's global product strategy manager for line haul commercial powertrains. "We keep saying how we're not done — this is a collaboration," he said.

"Since then, we've added SmartCoast, which is a neutral-coasting feature, and we're up another 2% in fuel economy. We have done testing, and we're up to 7% [fuel economy advantage] over competitive integrated powertrains," Trzybinski contended.

Cummins and Eaton have continued to refine the SmartAdvantage integrated powertrains by sharing more data between the engine and transmission, he explained, adding, "That's part of what enables us to increase fuel economy and give the performance we can; we're optimizing our shifting for each environment."

The direct drive transmission options include 2.26 and 2.28 axle ratios with ISX15 engines rated at 400 and 450 HP and use engine down-speeding to maximize fuel efficiency. The original small-step overdrive powertrain also employs down-speeding technology and has a 2.64 axle ratio and ISX15 with a 450 HP rating; the small-step tranny configuration is now available with ISX15s with 400 and 420 HP ratings.

With the small-step powertrain's 2.64 axle ratio, "that's going to cruise in the 1,140 [RPM] range," Trzybinski said. "And now with the direct drive with those axle ratios we mentioned, we can run a direct drive as low as about 1,240 RPM at 65 mph. So we're getting down not quite to the overdrive level in terms of down-speeding, but you're also running it in direct, which brings in some new opportunities.

"We're the only integrated powertrain to offer both" the direct drive and small-step overdrive transmission options, he added.

"If you're going to go faster, like your typical line haul, and spend more time in top gear, the small-step SmartAdvantage product that we've had available since 2014 is still going to be your best fuel economy option," Trzybinski said. "But if you're going to go a little slower, maybe with a cruise speed of 62 mph and below, our options with the SmartAdvantage direct drive transmission perform better from a fuel economy standpoint."