Wal-Mart eyes Class 8 diesel-electric drivetrain

ArvinMeritor has entered into an agreement with Wal-Mart Transportation to develop a dual-mode, diesel-electric drivetrain for a Class 8 tractor.

ArvinMeritor has entered into an agreement with Wal-Mart Transportation to develop a dual-mode, diesel-electric drivetrain for a Class 8 tractor. The vehicle will be based on the Class 8 ProStar model tractor from International, with an engine from Cummins supplying the diesel power. Like ArvinMeritor, both companies are current suppliers to Wal-Mart and also partners in the new project.

Dual-mode diesel-electric drivetrains have both mechanical and electrical propulsion systems, not just an electrical launch assist, according to Garrick Hu, recently promoted to vp of engineering for ArvinMeritor's Commercial Vehicle Systems (CVS) business. They use the electric motor drive primarily for periods of high demand under low-speed, high-load operating conditions. Once moving, the mechanical propulsion system begins to blend its power with the electric motor until it reaches highway speeds (over 30 mph), where it phases to completely mechanical drive. The electrical system can also provide additional power during hill climbing.

In addition to its work at highway speeds, the engine also charges an onboard energy storage system, which provides power to the electric motor when demand is high. Energy that is generated during braking is captured and stored using regenerative braking.

“We've been working on development of hybrid drivetrains for some time,” said Carsten J. Reinhardt, president of ArvinMeritor's (CVS) business. “This Class 8 project is a major step in our continuing work in alternative drivetrain development — for power transmission and emissions — and holds tremendous promise for the worldwide heavy-duty trucking market in a number of important environmental and economic ways.”

According to Hu, the new vehicle will feature a long list of environmentally friendly enhancements, including: sufficient on-board battery power to handle overnight hotel loads, avoiding the need for shore-power or engine idling during rest periods; the ability to operate at low speeds for sustained periods of time without the use of the diesel engine; the elimination of engine idling during stops; and improved emissions through lower fuel consumption.

It will also include a number of technology-enabled safety enhancements, such as air disc brakes for improved stopping capability, an advanced anti-lock braking system, roll stability control, blind spot detection, and collision warning and mitigation. The project's ultimate potential, however, goes beyond even this list, according to Hu. “The things that can come from this are so exciting,” he noted.

ArvinMeritor will provide the tandem axle, regenerative braking system, air disc brakes and advanced ABS with integrated stability control and driver assistance systems (from Meritor WABCO Vehicle Control Systems), software, electronic controls, transfer case and motors, as well as the battery power from a third party.

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