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Oshkosh Truck Corp. is developing a diesel-electric hybrid truck for heavy loads. It promises to be quieter and even to carry an extra passenger.
Oshkosh Truck Corp. is developing a diesel-electric hybrid truck for heavy loads. It promises to be quieter and even to carry an extra passenger.

It's still heavy, but it's a hybrid

OSHKOSH, Wis. -- At the top of a 10-foot mound of dirt, Gary Schmiedel takes in the silence. The military truck he's driving barely hums just before it careens down a steep incline into a muddy pool.

Normally the vehicle -- a heavy expanded-mobility technical truck, or HEMTT -- would be so loud the occupants wouldn't be able to talk to each other, said Schmiedel, vice president of product engineering for Oshkosh Truck Corp. But this version is about as loud as a standard sedan, with a smooth ride, splashy computer screens, and a comfortable interior.

This isn't a bumpy, loud gas guzzler; it's a hybrid made for the Defense Department.

Oshkosh Truck, the military's exclusive provider of the Army's cargo-hauling HEMTT vehicles, is finishing up prototypes of its electric hybrid. It not only increases gas mileage by about 20 percent from the standard 3 or 4 miles per gallon, it generates enough electricity to power a city block or hospital.

The company, based in this city about 100 miles north of Milwaukee, just signed a contract to produce a prototype of a similar vehicle for the Marines.

It's not clear how the hybrid technology will affect prices for the military vehicles, whose diesel version costs from $200,000 to $400,000, said Schmiedel. Even modest reductions in gas mileage help, he said, pointing out that 70 percent of military payloads is fuel.

The hybrid technology can be far-reaching, Schmiedel said. Commercial vehicles such as garbage trucks and emergency vehicles could benefit from using less fuel. The Department of Energy has said it hopes to double the fuel economy of garbage trucks by 2010.

The ability to generate power could be another selling point, Schmiedel said. The technology captures energy that would otherwise dissipate in the braking process. The generator can produce up to 300 kilowatts -- enough to run 50 homes for an indefinite period, he said. In response to Hurricane Katrina, Oshkosh took a hybrid truck to New Orleans and used it to pump out a hospital basement.

``First and foremost it's a truck. If it has the flexibility to act as a generator in a pinch, that's a heck of a disaster-recovery attribute," Schmiedel said.

The military is working with several companies to get power systems into its hybrid vehicles, said Paul Mehney, communications officer with the US Army Tank Automotive Research, Development, and Engineering Center, in Warren, Mich. Hybrid generators would eliminate the need to haul in a diesel generator, he said.

``It comes in real handy in the field. You can power an operation center out of that. You can power water purification systems off that," Mehney said.

While manufacturers such as Honda and Nissan have said they may slow production of hybrid vehicles, due to sluggish sales, development for military and commercial use doesn't seem to be waning, Schmiedel said. FedEx recently said it would add 75 diesel-electric hybrids to its fleet of 18, and refuse and recycling hauler Waste Management Inc. has worked with three companies, including Oshkosh Truck, to develop hybrid technology and alternative fuels for its 22,000 vehicles.

Schmiedel and others at Oshkosh have been working since 1999 on the technology, called ProPulse. The company has made two trucks. It plans to make a few more and turn them over early next year for government testing, a process that could take a year, he said.

Though hybrid technology has been around for several years in passenger vehicles, adapting it for larger vehicles isn't easy, Schmiedel said. Military vehicles must often carry thousands of pounds of cargo -- 13 tons for the HEMTT -- and endure hills, a lack of pavement, and angles that few standard vehicles can handle.

In tweaking the ProPulse technology, Schmiedel said, engineers created dozens of other perks, such as reducing vehicle weight and placing engines in a way that eases maintenance . A specialized technician used to spend up to 24 hours swapping an engine, but now any mechanic can do it in 20 minutes.

``What we think will drive hybridization is when there is some benefit over and above saving fuel," Schmiedel said.

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