In recent years, powertrain integration has become increasingly prevalent. Fleets are focused on operational efficiency, and what could be more efficient than each major powertrain component working in concert?
Today, nearly every OEM offers its own proprietary powertrain combination—Freightliner and Western Star sport Daimler’s Detroit engine, transmission and axles; Kenworth and Peterbilt are powered by PACCAR engines that integrate intimately with Eaton transmissions; Volvo has its line of engines and transmission; and Mack recently showed off its refreshed integrated powertrain that touts its MP series engines, mDrive transmissions, and Mack axles. While Cummins continues to hold the most market share—you can find Cummins and Eaton’s SmartAdvantage integrated powertrains, along with Dana axles, in practically every make—proprietary integrated powertrains are gaining ground within the segment.
Mack Trucks, for example, continues to report increased numbers of integrated powertrains for each of their truck models. For Pinnacle trucks, 80% of axle-back and 60% of axle-forward models are spec’d with Mack-made integrated powertrains; for Titan models, it’s 30%; and for Granite trucks it’s 20%. The latter two have each had just one year of availability with mDrive transmissions, so Mack expects those numbers to grow in the future.
To support this growing trend, the 2017 versions of Mack’s 11-liter MP7 and 13-liter MP8 engines bring several new features including an updated wave piston design that raises the compression ratio and enables more complete combustion of fuel, a common-rail fuel system that injects fuel more precisely and a two-speed coolant pump. According to Mack, this will increase MP7 fuel efficiency by between 2.5% and 5.1%, and MP8 fuel efficiency by between 2.5% and 5% (with the higher number being possible through the use of downspeeding).
Additionally, the 445-HP MP8 engine will be available with turbo compounding. The extra power this system generates can result in an estimated 8% to 8.8% fuel economy improvement with as low as 900 RPM (with full torque). This is only available with Mack’s Super Econodyne downspeeding package.
“It’s not a new engine,” says Stu Russoli, Mack’s manager of highway and powertrain products marketing, “but we’re making improvements to get us to that next level.”
In August 2017, Mack’s recently announced 13- and 14-speed mDrive HD automated manual transmissions will be available. mDrive is already standard for Mack’s Pinnacle, Titan and Granite models. The 13-speed mDrive HD, available in direct- or overdrive configurations, is designed for easier starting on steep grades or when the truck is under heavy load, according to the company, while the 14-speed version is available only in an overdrive configuration, and adds a second ultra-low-speed reduction gear designed for curb pouring applications or low-speed, heavy-haul maneuvering.
These now include Mack Predictive Cruise, an intelligent cruise control system contained in the transmission unit. Predictive Cruise learns the topography of the road and uses GPS to match topography with the location. It anticipates the upcoming topography of the road and adjusts the vehicle’s speed, torque and gear based on this information to save fuel.
“This can result in up to 1% fuel economy savings,” Russoli says, before summing up the powertrain’s 2017 improvements: “Everything we’ve done here comes down to fuel efficiency, better performance and maintenance.”
