Freightliner previews SuperTruck II

Freightliner SuperTruck II.

Daimler Truck North America LLC (DTNA) has debuted the SuperTruck II from Freightliner.

As part of the SuperTruck program co-funded by the Department of Energy (DOE) with the aim to reduce emissions from on-road freight transportation, DTNA engineers were able to investigate next-generation technologies for heavy-duty commercial trucks and to clear the technical pathway for their development and potential integration into series production.

With a major priority of the project to increase operational efficiency for fleets, a clear focus was given to the development of new technologies on the most promising core components and systems to improve this outcome on the truck.

Enhanced aerodynamics, low-rolling resistance tyres, powertrain improvements and energy management with advanced technologies were identified as areas for technology innovations that could potentially enter production for customers in the future.

“Our decision to focus on improvements to core truck components was based on the objective to maximise freight efficiency for our customers while helping to reduce the carbon footprint of trucks and engines,” said Rainer Mueller-Finkeldei, Senior Vice President of Engineering and Technology, DTNA.

“Taken all together, the combined innovations developed for the Freightliner SuperTruck II have provided us the opportunity to explore the technologies needed to meet stringent and forthcoming Greenhouse Gas reduction requirements in the coming years.”

Building on the success of SuperTruck I, which overachieved DOE requirements in 2015, SuperTruck II surpassed expectations in aerodynamics, tyres, powertrain and energy management, while doubling the freight efficiency of the base vehicle from the start of the SuperTruck program.

In close collaboration between the design and engineering departments, the teams were able to overachieve in aerodynamic improvements and reduce the aerodynamic drag of SuperTruck II by more than 12 per cent over SuperTruck I.

Instead of radically changing the structure of the truck, the design goal for SuperTruck II was to redefine the existing shape of the market-leading Cascadia to maximise aerodynamic efficiency and simultaneously employ advanced design language to convey that efficiency.

“We wanted to create a shape that makes efficiency exciting,” said Jeff Cotner, Chief Designer at DTNA.

The designers imagined the surfaces of the truck being carved away by the wind.

“Nature has a way of creating the perfect sculptural shape, when the material is light and airy like snow or sand. This was our inspiration in creating the new expressive form language for the Freightliner brand,” said Cotner.

“Sometimes what the eye sees is not what the air sees. We let the areas most critical to aero performance design themselves and integrated the more expressive lines in the places where the drag is neutral,” he continued.

“Our goal was to gain as much freight efficiency as possible and create a beautiful looking truck at the same time. It was important to us that we didn’t change something just for the sake of changing it.”

The redesigned hood, bumper and chassis fairing all work well with the existing cab structure and now allow the air to flow undisturbed around the truck.

The grille, air intakes and doors were redesigned to be as seamless and clean as possible; no sharp edges compromise the aerodynamics or beauty of the truck.

Other critical areas were refined in an iterative approach between the design studio and engineering team.

Active side extenders and a roof spoiler system closes the trailer gap by up to 4 inches at highway speeds and an enhanced Aerodynamic Height Control lowers the truck just inches off the ground for additional aerodynamic improvements.

By removing the exterior mirrors and integrating a mirrorless camera system, like the one used by stablemate Mercedes-Benz on the Actros, the aerodynamic drag of SuperTruck II was significantly reduced.

SuperTruck II features the most efficient powertrain Freightliner has integrated into a truck.

The highly efficient powertrain enables a 5.7 per cent fuel consumption reduction over SuperTruck I.

With a non-certified prototype Detroit 13-litre engine featuring two-stage turbo and interstage cooling and a 13-speed overdrive transmission, the powertrain is able to achieve lower downspeeding and greater fuel savings through reduced drag overdrive.

One key powertrain feature of SuperTruck II is split cooling. This system consists of high temperature and low temperature cooling circuits, working in tandem with two-stage turbocharging and Exhaust Gas Recirculation (EGR) cooling on the engine.

Together, these technologies result in further efficiency gains enabling more aggressive downspeeding.

A smart engine lubrication circuit minimises internal pumping losses, thus reducing engine parasitics by actively proportioning flow to the most sensitive components.

Adaptive tandem axles allows for increased torque from the powertrains and automatically shifts from 6×4 to 6×2 at highway speeds which benefits the driver when manoeuvring in low speed.

DTNA again collaborated with SuperTruck I partner Michelin on the development of brand new tires specifically designed for adaptive tandem axles to not only reduce vehicle energy consumption but also to reduce maintenance downtime due to minimised wear and tear on the tyres.

Tyres play a critical role to achieving that goal according to DTNA. By lowering the friction on the road, less fuel is needed to maintain the truck speed.

The engineers were able to significantly reduce the rolling resistance by 12 per cent over SuperTruck I.

In co-development with DTNA, Michelin designed tyres specifically for the steer, drive and tag axles of SuperTruck II. The introduction of dynamic load shift further increased efficiency and fuel savings.

SuperTruck II features an innovative 48-volt electrical system with lithium-ion batteries, enabling a new electric steering system to adjust demand as needed, whether the operator is manoeuvring at low speed or driving at highway speeds, or to operate during EcoSail while the engine is off.

The intelligent EcoSail feature can turn the engine off when drive power is not needed, without requiring any intervention from the driver. At the same time, if the truck is coasting down a hill while the engine is off, features like air conditioning remain in operation.

As soon as power is needed, the engine will restart automatically for a seamless experience for the driver. More 48-volt features result in decreased fuel consumption and increased driver comfort like a new electric air conditioning system that consumes 50 per cent less energy than SuperTruck I and continues seamless operations while the engine is turned off.

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