21.2.2002
Allison Transmission showcases hybrid vehicle technology

The Electric DrivesTM EP System TM technology, developed by the Allison Transmission Division of General Motors, brings dramatically lower emissions and improved fuel economy to commercial-duty truck and bus applications.

A 40-foot hybrid transit bus powered by the Allison Electric DrivesTM EP SystemTM will be on display for legislators in the U.S. as part of an Allison-hosted event.

Buses equipped with the EP SystemTM produce much lower hydrocarbon and carbon monoxide emissions than conventional diesel buses, lowering particulate emissions by 90 percent and NOX emissions (nitrogen oxide) by 50 percent. Buses equipped with the Allison Electric DrivesTM system also deliver 50 percent better acceleration than a bus equipped with a conventional diesel powertrain.

The system can also be easily adapted to fit into existing vehicle platforms and delivers about 60 percent better fuel economy than a conventional diesel system in urban transit bus applications.

"The parallel hybrid electric system is the most efficient hybrid architecture available today," said Larry Dewey, President of Allison Transmission. "In addition to bringing the benefits of hybrid electric technology to commercial vehicles, the EP System is helping establish hybrid technologies as effective, practical and commercially viable. This system stands ready to revolutionize transportation as we know it."

Hybrid systems use two sources of power to move a vehicle - engine and battery. In the parallel hybrid system, the engine-generator combination works in parallel with the battery, furnishing electrical power to keep the battery charged. The engine is coupled to a drive unit that furnishes an infinitely variable ratio to the wheels. This allows an engine in a hybrid system to run more efficiently, quietly and cleanly. For example, when the bus accelerates from a stop, the batteries can supply a powerful acceleration. A hybrid bus uses the diesel engine to maintain speed after the vehicle is underway. In this mode the engine also charges the electric power source, making the vehicle capable of self-sustaining mobility.

The Allison Electric Drives EP SystemTM brings the benefits of advanced hybrid technology to a broad class of commercial transit and trucking applications. The EP SystemTM is designed to bring the "hybrid advantage" to vehicles such as articulated buses, suburban coaches, military vehicles and medium- and heavy-duty trucks. Designed in a compact, standardized platform that enables integration across a range of commercial vehicle types, the EP SystemTM is compatible with existing vehicle architectures. The EP SystemTM also is flexible and is easy-to-scale to a broad range of commercial applications.

Fred Cartwright, Program Director, Allison Electric Drives says: "By leveraging the benefits of GM's advanced technologies, Allison Transmission will continue to develop the type of environmentally responsible, viable and sustainable hybrid propulsion systems that today's commercial applications need."