INDUSTRY NEWS
Companies are beginning to integrate hybrid technol- ogy into heavy-duty applications. Mack developed a Class 8 tractor with a diesel-electric powertrain for operation at Dover Air Force Base. The truck operates a regional pick-up and delivery route running between Dover and Western Pennsylvania and also serves as a mobile power station for other equipment.
THE BUSINESS OF BIG HYBRIDS Industry begins development of heavy-duty hybrids and other alternatives
BY AMANDA M. KLEMP A s the U.S. EPA continues to inch toward regulation of greenhouse gases (GHG) and forecasts predict rising fuel prices, heavy-duty truck manufactur- ers have continued to search for newer ways to develop cleaner trucks that use less fuel. Fuel economy has always been a goal for manufacturers, but the likeli- hood of GHG regulations combined with the fact that the only way to reduce such emissions is burning less fuel, has added some additional urgency to the quest. As a result, manufacturers — aided by a wide array of government- sponsored grants and development programs — are looking more serious- ly at technologies such as larger diesel- electric hybrids and other alternatives. While hybrid powertrains have begun making some real inroads in medium-duty applications, such as delivery and utility vehicles, heavy- duty trucks pose some specific chal- lenges. Hybrids have shown to be quite capable in vehicles with high start/stop duty cycles. The majority of Class 8 trucks operate on long-distance, over- the-road duty cycles, reducing many of the hybrid benefits, such as regen- erative braking. Another significant hurdle involves the size and weight of both the vehi- cles and the hybrid technology. In most segments of heavy trucking, reducing vehicle weight is critical, as it allows for more cargo to be hauled. Energy storage systems cap- able of driving a Class 8 truck are based on groups of large batteries that are generally both heavy and costly. Yet work is ongoing at many truck manufacturers to meet those chal- lenges. One of the ongoing develop- ments involves ArvinMeritor, which has partnered with Navistar, Cummins and Wal-Mart. ArvinMeritor developed its
12 DIESEL PROGRESS NORTH AMERICAN EDI TION February 2010
Meritor hybrid diesel-electric powertrain as a proof-of-concept for a Wal-Mart Class 8 truck used in line-haul serv- ice. The system is also applicable for drayage, regional and off-highway vehicles, the company said. The Meritor dual-mode hybrid drive- train combines both mechanical and electrical propulsion systems. Under 48 mph, the truck is propelled through anelectricmotorpoweredbylithiumion batteries. The batteries are charged by an engine-driven generator and through regenerative braking. For higher speeds, the drivetrain transitions to an engine-driven sys- tem with the electric motor providing power only as needed. Along with helping drive the vehicle, the batter- ies also supply power for the trucks’ hotel loads, reducing the need to idle the engine. Tammy Packard, product manager, hybrid, at ArvinMeritor said the truck has shown an average of 7 to 15% improvement in fuel efficiency. Mack, part of the Volvo Group, has developed the Granite diesel- electric hybrid tractor for the Dover Air Force Base in Delaware. The base is a transportation hub for cargo planes, and the Granite truck
