The importance of axles
“Axles, once thought of as just a commodity, are now integral to achieving the company-targeted fuel efficiency levels,” Daimler’s Gedert said. “The Detroit captive engine rating and the Detroit DT12 are designed to work together with specific Detroit axle downsped ratios. A customer desiring the maximum fuel efficiency benefits must start looking at faster ratios in the future to achieve the savings. The new axle lubrication management [ALM] feature of Detroit drive axles most effectively manages the use of the transmission oil by eliminating excess ‘oil churning’ and provides that additional fuel efficiency benefit to the customer.”
“Mack drive axles can increase the fuel efficiency by 1.5% compared with competitive industry standard axles,” said Mack’s Barraclough. “In addition, they’re top-loaded, reducing driveline angularity to cut down on noise, vibrations and harmonics to provide a quieter, smoother drive.”
“Drive axles play an important role in fuel economy and powertrain performance,” Peterbilt’s Gansle said. “Spec’ing the right axle ratios is also important, and Peterbilt and its dealer network work closely with customers to spec the ratio that best meets their needs.
“The PACCAR axle provides Peterbilt customers with lower operating costs through reduced weight, improved fuel economy and outstanding durability,” he continued. “It is up to 150 lbs. lighter–the lightest-weight axle in its class–which means more payload. Its innovative design optimizes power distribution and has fewer parts for reduced maintenance and greater reliability. The PACCAR axle enhances fuel efficiency and is optimized for the PACCAR MX-13 and MX-11 engines.”
RELATED: Click here for more on the new PACCAR axle and 2017 MX Engines.
Dana Inc. worked with Cummins and Eaton to develop an optimized axle for the SmartAdvantage powertrain.
“Dana offers the fastest, lightest, and most flexible drivetrain system components available for the SmartAdvantage powertrain. Our axle ratios are compatible with both direct-drive and small-step overdrive configurations,” said Steve Slesinski, director of product planning for the commercial vehicle market at Dana Inc. “Dana’s solution includes the Spicer AdvanTEK 40 tandem axle — offering the industry’s fastest available ratio of 2.26:1— plus the SPL 350 driveshaft and SPL 250 inter-axle shaft.”
6×2 configurations
The adoption of the 6×2 axle configuration, despite having been rumored to be on the verge of mainstream acceptance, has stalled in the past year.
“The adoption of 6x2s will not see a significant increase in the market near team,” said Daimler’s Gedert. “There are two main factors limiting the acceptance of 6x2s: limited traction and minimal resale value.”
“We expect slow growth or stable demand of trucks spec’d in this configuration,” added Peterbilt’s Gansle. “North American customers prefer a liftable axle over an additional stationary axle.”
Mack’s Barraclough takes a more positive view of the future of the 6×2 configuration.
“The 6×2 axle configuration has its benefits: It’s 300–400 lbs. lighter than a 6×4, and it can be up to 3% more fuel efficient,” he said. “The customers that have them like them for this reason. At Mack, we’ve introduced our 6×2 with a liftable pusher axle. This system automatically lifts the non-driven pusher axle when the truck is lightly loaded for reduced rolling resistance, thus improving efficiency an additional 1% to 2%. Also, it can vary the load distribution between axles to enhance traction in low grip situations.”
It’s about partnerships
“It’s worth noting that these partnerships have opened up communication between our engineering teams,” Eaton’s Stucky said. “Collaboration with partners has provided access to industry experts and a deeper understanding of powertrain/ drivetrain capabilities. This high-level view of the powertrain system gives the engineers more levers to tune during powertrain integration activities.
“We’ve seen results of this effort in some recent developments with our partners. Some of those traditional technology barriers have been removed. By opening previously proprietary information with partners, we’ve been able to solve many mechanical and electrical challenges.”
Inside the integrated powertrain offerings
“For 2017, the new Detroit DT12 transmission will be available in Freightliner’s new Cascadia and the Western Star 5700,” said Daimler’s Gedert. “Detroit will be the first transmission manufacturer to industrialize the process of ‘super-finishing’ gears at the factory. The result will be a further reduction of parasitic loss in the DT12 due to improved gear mesh, ultimately driving additional fuel efficiency gains for the customers.
“With the latest release of Intelligent Powertrain Management (IPM4) the DT12 will utilize pre-loaded terrain maps to scan the road ahead to: more precisely select the proper gear, better use eCoast, utilize the engine brake more efficiently while using cruise control to leverage the truck’s momentum most effectively,” she continued.
“Peterbilt recently introduced enhancements to its 2017 MX engines as well as the new PACCAR tandem drive axle, rated at 40,000 lbs.,” Peterbilt’s Gansle shared. “These two powertrain components produce significant savings for our customers through reduced weight, higher fuel economy, greater uptime and extended service intervals.”
“2017 is a big year for Mack’s fully integrated powertrain,” said Mack’s Barraclough, “We updated our engines with a common rail fuel injection system, revised combustion system with the wave piston, along with a number of other enhancements, which have improved the fuel economy of our engines from 2% to 8.8%. Along with the engines, we’ve introduced our new ClearTech One single-unit exhaust aftertreatment system. This packages the aftertreatment components more efficiently, providing around 11 in. more frame space and a 17-lb. weight reduction compared with the previous system. Finally, we also introduced new variations of our extremely successful mDrive automated manual transmission. We’ve added 13- and 14-speed models with creeper gears ideally suited for dump, mixer, plow, roll-off and other vocational applications.”
For Volvo’s part, the OEM’s line of engines includes the D11, D13, and D16, as well as the D13 with turbo compounding, which according to the company has the potential for 6.5% fuel efficiency gains over the 2014 D13 engine.
Volvo also launched its latest I-Shift transmission, now available with Crawler Gears, which brings crawler functionality and start ability, making it ideal, according to Volvo, for vocational trucks requiring slow speed and maneuverability like the one pictured here. Volvo trucks spec’d with integrated powertrains reached an all-time high in 2015, with 94.5% of customers spec’ing a Volvo engine and 88.8% spec’ing a Volvo transmission.
Mack, meanwhile, says its customers spec integrated powertrains in 82% of Pinnacle trucks, 70% of Titan models, and 28% of Granite models.
Navistar recently announced that its new International LT over-the-road truck series will be available with the new 2017 Navistar N13 engine, a 13-liter engine that produces up to 475 HP and 1,750 lb./ft. of torque.
The concept of the integrated powertrain isn’t just limited to truck OEMs. For years, Cummins and Eaton have worked together on the optimized SmartAdvantage powertrain, combining the Cummins ISX series engines with the Eaton Fuller Advantage transmission.
“We’re deeply integrated with all of our partners powertrains—some good examples are the SmartAdvantage, MX and N13 optimized packages,” Eaton’s Stucky related.
“[Cummins’] 2017 engines have enhanced electronic control processing and capability to support remote connectivity, which will enable more features and real time adjustments,” Cummins’ Sanchez said. “We also saw a market demand for maximum fuel economy spec’d powertrains with higher performance ratings. To that end, we released SmartAdvantage powertrain ratings up to 1850 ft./lb. of torque and will introduce SmartAdvantage ratings up to 500 HP in 2017. These ratings offer more accessibility to integrated powertrains for customers that prefer the best fuel economy while still requiring a higher level of performance.”
