Powertrain integration emerged as a focused truck marketing pitch several years ago, and the concept has quickly become an industry standard. Simply, it makes sense: link engines, transmissions, and even axles together into a single, seamless package and reap the benefits of fuel savings and improved vehicle performance. Mike Roeth, executive director of the North American Council for Freight Efficiency (NACFE), says that such integration also goes far beyond fuel savings and engine responsiveness. In his view, a range of benefits from maintenance-related cost savings to safety are possible as a result of increased integration.
“Once you electronically connect the powertrain, the door is wide open to all sorts of future enhancements that you can gain [without] making mechanical changes to a truck,” Roeth explains.
He points to the group’s recent work analyzing the potential benefits of automated manual transmissions (AMTs). On the conservative side, fuel savings of 1% to 3% are possible; however, Roeth says there is potential for additional savings because the electronics underpinning the AMT can generate benefits when integrated with electronics within the truck’s engine, axles, and other systems. “What we’re finding is that AMTs are many times an ‘enabler’ for greater fuel savings, as they are integrated with the truck’s other systems,” he says. “It’s like buying a smartphone to get better cell phone capability and then realizing it can do a lot more like surf the web and access email.”
Brad Williamson, manager of powertrain marketing for Daimler Trucks North America (DTNA), notes that powertrain integration development must include a more holistic view of single-system capability.
“In the past, the electronics would be combined but never developed together,” he explains. “Today, integration means understanding what the end goal of the system is and beginning development with that end in mind. It is also looking at the entire system—engine, axle, transmission, driveline, truck, etc.—and developing a truly integrated [package] that meets drivers’ needs for performance and owners’ needs for profitability and uptime.”
The safety aspect comes into play with systems like Detroit Assurance, which offers active brake assist and adaptive cruise control by integrating a truck’s brakes, radar and sensor technology with Detroit-branded engines and transmissions.
“It’s really about the feel, the smoothness, and how we can better integrate the intelligent controls with the truck,” explains Williamson. “That’s the main piece.”
It’s important not to forget the back-end benefits of powertrain integration when it comes to warranty coverage, maintenance service and parts support, he adds.
“[Integration] is really about looking at the entire truck ownership experience and making it a better product for the customers’ ownership life,” Williamson says. “What that also does for customers is make the dealer a true one-stop shop for all things integrated. This eliminates the need to send an engine with repairs to an engine distributor or axle issues to an axle supplier.”
MORE THAN MESHING
The real driving force behind powertrain integration efforts, notes Mario Sanchez, director of technical sales support for engine-maker Cummins, is the software linkage between engine and transmission along with potentially other components.
“It is more than just better meshing of the transmission and engine,” he says. “The engine and transmission are linked, constantly communicating and adapting to the operating conditions due to critical data sharing. That leads to more efficient operation with more time spent in the sweet spot of the [engine’s] rpm band, which means fuel cost savings. The operational efficiency an AMT provides also means less driver fatigue and an easier overall driving experience.”
Since 2013, Cummins has partnered with Eaton Corp. to develop several SmartAdvantage integrated engine/AMT packages, which combine Cummins ISX15 or ISX12 diesel engines with the Eaton Fuller Advantage 10-speed AMT.
For natural gas engines, Eaton and Cummins Westport, a joint venture between Cummins and Canada’s Westport Innovations, offer an integrated powertrain package that combines the Cummins Westport ISX12 G engine and the Eaton UltraShift Plus AMT.
Ryan Trzybinski, product planning manager for the Eaton Vehicle Group, notes that integrated powertrains hinge on what he calls “highly optimized control logic” to deliver fuel savings of between 3% and 6% on a consistent basis.
Eaton is now working with Paccar Corp., parent company of Kenworth Truck and Peterbilt Motors, and Navistar on similar integrated packages. The linkup with Paccar’s MX-13 is called Fuller Advantage with Small Step S-Ratio at Kenworth and dubbed APEX at Peterbilt.
Anthony Gansle, marketing manager for on-highway product at Peterbilt, notes that APEX is a fundamental part of the OEM’s EPIQ fuel efficiency package, which aims to improve overall fuel efficiency by up to 14%. The package is available exclusively on the Peterbilt Model 579 tractor.
“In the past, traditional methods to improve fuel economy usually resulted in a trade-off of reduced performance. For instance, lowering the rear axle ratio typically meant lower startability and less power,” he explains. “Today, improved technology has helped minimize those trade-offs. The proprietary communication software developed for APEX is proof of that, resulting in both improved fuel efficiency and performance.”
OEMs are deploying such powertrain integration packages with the goal of delivering increased fuel savings. Navistar, for example, relies on two such integrated packages for its ProStar ES highway tractor unveiled late last year. Through a combination of the powertrain packages and other initiatives, the ES offers up to 11% better fuel economy versus a 2010 ProStar model equipped with a 13L MaxxForce engine and 10-speed manual transmission, says Jodi Presswood, vice president-heavy-duty truck product line at Navistar.
Aaron Peterson, chief performance engineer at Navistar, notes that the setups include the Cummins/Eaton SmartAdvantage combination and a combination of Navistar’s 13L N13 engine with the Eaton Fuller Advantage 10-speed AMT. Both offer a 3% to 6% fuel economy boost.
Kurt Swihart, marketing director at Kenworth, adds that the need to boost fuel economy while simultaneously improving drivability rests at the heart of OEM powertrain integration efforts.
“On the fuel economy side, software calibrations between the engine and transmission optimize rpm during acceleration, deceleration, pulling hills, and coasting down hills to maximize fuel economy,” he says. “In addition, targeting low engine rpm allows transmissions and axles—both with optimized gear ratios—to minimize parasitic losses throughout the powertrain, improving fuel economy.”
On the drivability side, Swihart continues, those same shared calibrations improve vehicle control at slow speeds and when pulling hills, for example. “The end result is a more fuel-efficient truck that provides an improved driving experience. This helps customers increase their profitability,” he notes.
Swihart also believes that the benefits of powertrain integration can be gained regardless of whether truck owners follow the proprietary or non-proprietary path.
John Moore, manager of product marketing for Volvo Trucks in North America, adds that maintenance savings are another benefit that shouldn’t be overlooked.
“Integrated powertrains streamline maintenance because electronic diagnostic tools, service repair information, and training are integrated with common hardware and software,” he points out. “Also, given the complexity of electronics in today’s trucks, symptoms may be related to or generated by connected controllers and not necessarily the host controller.”
Moore thinks vertically integrated powertrains offer an extra advantage because they give the OEM control over more components and reduce diagnostic time. “All of this reduces repair costs and puts the truck back on the road [quicker],” he says. “As for warranty, integration provides one stop for administration, streamlining the process.”
But truck buyers demand concrete dollar savings before considering the oftentimes higher price tag for a fully integrated powertrain. NACFE research indicates AMTs alone cost anywhere from $3,000 to $5,000 more than a comparable manual transmission.
Linehaul truck operators can save around $600 for every 1% of fuel economy improvement, explains Eaton’s Tryzybinski. “The SmartAdvantage package delivers 3% to 6% improved fuel economy over current production, non-integrated Cummins ISX and Eaton UltraShift Plus combinations. The MX-13 integrated package delivers 2% to 4% better fuel economy, and the N13 integrated package delivers 5% better fuel economy,” he says. “Those are real dollars back into the pockets of operators.”
Trzybinski adds that Eaton Fuller Advantage AMTs are lighter by 82 lbs. and eliminate the need for an external cooler, helping reduce maintenance expenses and saving test customers as much as $40 per truck per year as a result.
Roy Horton, director of product marketing for Mack Trucks, notes that similar fuel savings are available with the OEM’s Super Econodyne package. He says the package can improve fuel efficiency up to 4% compared to a standard MP7/AMT package. The SE package features a 405-hp. MP7 engine leashed to the OEM’s proprietary overdrive-equipped 12-speed mDrive AMT (the twin to Volvo’s I-Shift AMT) and Mack’s C125/126 axles.
A similar integrated powertrain package featuring Mack’s bigger MP8 engine instead of the leaner MP7 offers a 3.5% fuel economy savings.
“[Integration] allows our customers to maximize payloads, save on fuel, and increase their return on investment—all without compromising power,” Horton says.
Volvo already offers integrated XE downspeeding drivelines with its I-Shift AMT for its D11, D13 and D16 engines, explains Moore. “Now, our latest focus in powertrain integration is delivering integrated packages tailored to our customers’ specific applications,” he says.
Starting this year, for example, Volvo plans to offer XE-Adaptive Gearing options for its D11 and D13 engines.
“This powertrain package will offer two drivelines for applications—bulk haulers, liquid tankers, flatbeds and end dumps, for example—that typically go out loaded and return empty,” Moore explains. “By picking up a rear suspension pressure signal and sending this information to the powertrain, the engine and transmission know when a load is present and will lock out the 12th gear and run as a direct drive in 11th gear, enhancing performance while loaded.”
Once the load is delivered, the system becomes a “super overdrive” powertrain with a 2.47 rear axle ratio with the ability to cruise on home at 1,050 rpm at 65 mph.
“It’s the best of both worlds,” Moore explains. “And it could not have happened without an integrated powertrain.”
DTNA’s Williamson thinks combining such direct and indirect savings will convince customers to eventually step through the powertrain integration doorway.
“As we look forward, customer demands for fuel economy efficiency will continue to increase, and other demands on the industry, such as driver and technician shortages, will require more efficient products that contribute to ease of driving, ease of maintenance and service, improved drivability, and improved cost of ownership,” he explains.”
“The acceptance of powertrain integration will grow as the products continue to prove themselves and the overall value of vehicle integration is demonstrated,” Williamson says.