LAS VEGAS — For the $20 million it spent on the Freightliner Cascadia SuperTruck II program, Daimler Truck North America expects some of the advanced technology to find its way into production.
This followed SuperTruck I, an $80 million split between DTNA and the Department of Energy that took place between 2010 and 2015. DOE matched DTNA’s $20 million for SuperTruck II.
The investment from the first SuperTruck program has paid off. The current-generation Freightliner Cascadia features a windshield that debuted on the SuperTruck I. The aerodynamic, fuel-saving features from the project appeared as options on the New Cascadia, which debuted as a 2020 model.
“We want to focus on those things that have the best chance for production,” said Derek Rotz, DTNA’s director of engineering, who worked on the SuperTruck I and leads the SuperTruck II program. “With the SuperTruck II, we’ve built on that knowledge. We didn’t need to start with a clean slate and explore every last corner of the car.”
Even as the SuperTruck II results were revealed at the Manifest supply chain conference, DTNA was already working on the SuperTruck III program to develop a hydrogen-powered fuel cell electric tractor for long-haul transportation that retains maximum cargo capacity.
The SuperTruck III results are scheduled to be revealed in 2027, around the time Daimler Truck and Volvo Group expect to introduce production fuel cell trucks from their cell-oriented joint venture.
4 focus areas in SuperTruck II
For the SuperTruck II, designers and engineers tried to stay close to the architecture of today’s Cascadia when choosing what to leave in and what to leave out. Four areas received attention: improved tractor aerodynamics, powertrain improvements, energy management and low rolling resistance tires.
Each has set benchmarks for cargo efficiency and a reduced carbon footprint, the overall goals of the SuperTruck program.
“All of these technologies combined have allowed us to more than double the efficiency of hauling cargo with a tractor that doesn’t look radically different, but performs better,” said Derek Villeneuve, manager of advanced vehicle systems.
It’s not a pull
Aerodynamic drag — a measure of how well it slides through air currents — proved to be 12 percent better than the SuperTruck I. Engineers didn’t calculate the number against the current production truck because it wouldn’t be an apples-to-apples comparison, Rotz said.
A redesigned front hood, bumper and chassis fairing complement the existing cab structure, providing undisturbed airflow around the truck. The grille, air intakes and doors were redesigned to be as seamless and clean as possible.
At highway speeds, the tractor and trailer are automatically lowered a few inches. When the platform slows down, the tractor is raised back up.
DTNA-developed side extenders and a roof spoiler also automatically activate at highway speeds to close the gap between the tractor and trailer by up to four inches. They look like aftermarket extenders from Truck Labs, but Villeneue said DTNA is working on its own version.
The bulky side mirrors were replaced by the Stoneridge mirror camera system. Federal regulations prohibit factory installation of the system today, but they are getting closer. DTNA now connects manufacturing cascades to facilitate their addition to the aftermarket, which regulators allow.
Engine efficiency
DTNA claims the SuperTruck II features the most efficient powertrain Freightliner has integrated into a truck. The SuperTruck II consumes 5.7% less fuel than the SuperTruck I. A prototype 13-liter engine from Detroit features a two-stage turbo and intercooler, mated to a 13-speed overdrive transmission.
The SuperTruck II features a split cooling system that consists of high-temperature and low-temperature cooling circuits working in tandem with a two-stage turbocharger and engine exhaust gas recirculation cooling. Navistar introduced a similar system to the S13 integrated powertrain offered in the International LT, which goes into production later this year.
A key advantage is lower engine speeds.
“Typical highway speeds are around 1,100 rpm. We find that the SuperTruck II is around 950,” Villeneuve said. “Because the revs are lower, it’s quieter in the cabin.”
48-volt electrical system
High-powered 48-volt electrical systems are too expensive for most production trucks today. They appear in autonomous trucks, where computing systems require vast amounts of electricity. A 48-volt system powered by lithium-ion batteries offers significant advantages in a research vehicle such as the SuperTruck II.
Take power steering for example.
“The typical steering system is really designed for low speed when you park the truck,” Villeneuve said. “You have to have a big pump to give you a lot of boost to drive the vehicle.”
But power steering systems tend to be over-engineered and ineffective for highway driving where little steering effort is required.
“With this system, we’re able to control it so that we run high pump revs to incredibly easy low-speed handling, and then on the highway you don’t need a lot of boost. We bring all that power back [into the battery] so you don’t consume extra energy.
The 48-volt battery powers the steering at all times, even when the truck is moving with the engine off. (Yes, you read that right.)
DTNA’s EcoSail feature can shut down the engine when propulsion power is not needed, such as on a long descent. The driver doesn’t have to do anything. The 48-volt system keeps functions such as the air conditioner running. As soon as power is needed, the motor automatically restarts.
But there is more.
The 48-volt starter turns the engine on with more power and speed. It operates sleeper cabin hotel features such as opening a microwave and entertainment systems without the engine running, while supplying 12-volt power for cabin lighting and the instrument panel.
When the rubber meets the road
As with the SuperTruck I, DTNA partnered with Michelin to develop adaptive tandem axle tires that reduce energy consumption and maintenance time due to less tire wear.
By reducing road friction, less fuel is needed to maintain the truck’s speed. Engineers reduced the tractor’s rolling resistance by 12% compared to the SuperTruck I. Michelin designed tires specifically for the SuperTruck II’s steering, drive and steering axles.
Dynamic load shifting, which moves part of the load automatically from the drive axle to the drive axle, further increases efficiency and fuel economy by taking advantage of the low rolling resistance of the rear tires. New treads and compounds resulted in 20% less wear and tear on the drive tire and significantly improved rolling resistance.
Efficiency as an art form
Jeff Cotner, head of design development and lead designer, and his team strive to bring artistry to the truck while working with the engineers.
“We were inspired by the way the wind can blow through surfaces like snow and sand to create the perfect shape,” Cotner said. “The wind will tell you the shape it wants to be, and we thought that was an excellent way to make the SuperTruck happen. You can actually see the efficiency in the shapes you’re looking at.”
And how about this colorful packaging?
“The truck underneath is silver, and we needed something to make it stand out,” Cotner said.
Mission accomplished.
Related articles:
SuperTruck II’s efficiency efforts could increase the range of electric trucks
Paccar, Daimler, Volvo get most of $127 million in SuperTruck III funding
Daimler Trucks GenH2 is more than just a fuel cell
Click for more FreightWaves articles by Alan Adler.