Heavy-duty hybrid on the way

A new joint venture formed by truck maker Paccar and component supplier Eaton Corp. plans to develop a Class 8 hybrid truck by 2009. Eaton is providing the hybrid drivetrain system a traction motor married to a Fuller UltraShift 10-sp. automated transmission and four lithium ion batteries while Paccar subsidiaries Kenworth and Peterbilt provide the chassis, diesel engine and engineering assistance

A new joint venture formed by truck maker Paccar and component supplier Eaton Corp. plans to develop a Class 8 hybrid truck by 2009. Eaton is providing the hybrid drivetrain system — a traction motor married to a Fuller UltraShift 10-sp. automated transmission and four lithium ion batteries — while Paccar subsidiaries Kenworth and Peterbilt provide the chassis, diesel engine and engineering assistance to integrate everything.

“There will be an up-charge for buying a hybrid tractor, [but] we don't know [how much] yet,” Bill Jackson, Peterbilt's gm, told Fleet Owner. “But we see many opportunities as well: fuel savings, power assistance on hills, plus a way to operate the truck's heating/air-conditioning system without running the engine.”

Gary Moore, Kenworth's assistant gm, told Fleet Owner that although the fuel economy savings in a heavy-duty hybrid wouldn't be as great as those for hybrid medium-duty vehicles operating in P&D applications, payback is still there.

“Even a 1/10th improvement in fuel economy would be a huge savings to OTR fleets,” he said. “And then there are other benefits, such as power assist on hills, that can outweigh the additional weight a hybrid system would add to the vehicle.”

Todd Graham, Eaton's account manager for Peterbilt, explained that hybrid technology would only add about 300 lb. to a Class 8 tractor, mainly from the traction motor and power electric carrier (PEC), which holds four lithium ion batteries and replaces the standard batteries normally used to power the starter. Eaton is shooting for a five-year life cycle for the lithium ion batteries, he added.

Eaton's heavy-duty hybrid electric power system will be built using an automated manual transmission with a parallel-type “direct” hybrid system, incorporating an electric motor/generator located between the output of an automated clutch and the input to the transmission.

One benefit of this approach will be that braking energy captured and then stored as electric energy in the batteries can be used to provide torque from the electric motor and blended with engine torque to improve vehicle performance, operate the engine in a more fuel-efficient range for a given speed, or run the truck with electric power only.

Getting payback, of course, is the tricky part, he told Fleet Owner. “A hybrid's ROI is great in the medium-duty segment because owners keep their trucks 10 years on average,” Graham said. “In heavy-duty, however, many have a three-year trade cycle, so it's harder to accumulate the savings in that shorter time frame.”

Another key to a commercially viable Class 8 hybrid is eliminating idle time, said Landon Sproull, Peterbilt's chief engineer. With normal hotel loads, the hybrid's batteries would need recharging about once an hour, yet the diesel engine could fully recharge the system in about five minutes. He also noted Peterbilt has developed a “soft stop-start” algorithm for the diesel engine in order to minimize vibrations that could wake a sleeping driver.

Graham added that Peterbilt has built one Class 8 hybrid to date, which is being delivered to Wal-Mart Transportation for field testing, and plans to build a second one, while Eaton has two Class 8 test hybrids already on the road.

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