Eaton's electric-drive system is the one usually used by truck manufacturers who offer a medium-duty hybrid, including Freightliner, Freightliner Custom Chassis, Kenworth, Peterbilt and Navistar International. One builder that doesn't make hybrids is Ford Motor - but it does supply

chassis for conversions. Eaton used a Ford F-550 to install a plug-in version of its electric system for demonstration purposes, and like all hybrids, this one was an interesting drive.

The F-550 with its Altec public-utility body is a demonstration vehicle that was shown to President Obama last summer. He was no doubt impressed with this American-designed and -built product that promises considerable fuel savings and emissions reduction. Not present during that show-and-tell was the engineer who has overseen the vehicle's development, Helene Cornils. Too bad, because she could've told him about using the F-550 hybrid to drop her two kids off at school one morning after having the truck at home overnight. "The other kids said, 'Oooh, what a cool ride,'" the native of France said. "I was a cool mama."

The kids were impressed by the truck's big look and feel, but more importantly, it saves fuel and cuts exhaust emissions even more than the Power Stroke V-8 diesel's 2007-spec particulate filter and other advances already achieved. The plug-in feature supplements hybrid action by topping off the lithium-ion batteries while the truck's parked overnight. This extends battery life and allows the truck to go farther and work on electric-only power first thing in the morning.

Driving impressions

Like most F-550s, this one's engine was mated to a TorqShift 5-speed automatic transmission, making it very easy to drive during an early autumn spin around Eaton's proving grounds near Marshall, Mich. Cornils and I found that the truck took off on diesel-only mode more often than expected. She was puzzled at this behavior, but guessed the batteries had run down a bit since they were last plugged in.

Sure enough, a series of sharp stops out on the track apparently juiced them up so the truck then launched repeatedly on electric-only power. With a light foot on the pedal, it accelerated to 15 or 20 mph before the engine cut in. And it climbed a steep test grade several times while emitting only an eerie whine, like a futuristic car in an early 1950s sci-fi movie.

How it works

As with any diesel- or gasoline-electric hybrid, an electric motor-generator on the driveline drags down the truck's speed during braking and converts road motion to electricity, which goes to the batteries mounted in the utility bed (they'd be elsewhere in the body in a working truck). An inverter wired into the batteries has a cord that can be plugged into a 110/120-volt outlet for overnight charging. (House current was convenient for the demo truck, but working trucks would feed on faster-charging 220-volt circuit).

Electric launch reuses some of that power, saving diesel fuel. On a "trouble truck" like this one, even more savings come when repair line crews operate the man bucket and power tools from an electric-over-hydraulic system while the engine is shut down. This also reduces noise and diesel emissions, pleasing both crewmen and neighbors. The engine automatically restarts when the controls sense the batteries are running down, and it spins the generator to recharge them. Should the engine fail to start, a lineman could grab the cord and go to a nearby house and ask permission to plug it in. (Hey, it could happen!)

This prototype truck retains engine-driven power steering, air conditioning and other accessories. But later generations will run those with electric power, allowing the engine to shut down more often.

Hybrid potential

Under a three-year program funded by the federal Department of Energy, hundreds of Ford F-550s will be fitted with Eaton hybrid systems and will work in various parts of the country, according to Bill Van Amburg at WestStart-Calstart, which manages the industry-government Hybrid Truck Users Forum. Planners chose the Class 5 F-550 because it's a popular model with municipalities and utility companies, who will benefit from what's learned.

Critics say the plug-in mode transfers pollution to whatever power plant makes the electricity for the outlet, but emissions from power generation plants are strictly regulated, whether they consume coal or anything else. This will become a bigger issue as more plug-in hybrids and all-electric vehicles go to market, and as politicians continue to discuss countermeasures to climate change.

Hybrids can save 30 percent to 60 percent in fuel, but constitute an iffy business case unless buyers seek grants and tax credits to offset their 30 percent to 50 percent higher acquisition costs. Van Amburg said HTUF partners are lobbying Congress to extend federal tax credits, and action was pending at this writing. It will probably be a one-year extension of the existing program that was to expire on Dec. 31. It allows $6,000 to $12,000 in credits for buying a qualifying hybrid.

Eaton says its plug-in hybrid will be available for sale in about a year.

Oh - there's a rumor out there that electric hybrids shut down at 4 degrees above zero Fahrenheit (or is it 4 below zero? - the story teller couldn't recall). Then the hybrid truck runs only on diesel, so there go your fuel savings in any cold climate. That rumor's not true, Eaton says, because hybrid trucks operate reliably in the northern U.S and Canada. Two are in Edmonton, Alberta, where winter temps drop as low as 40 below. Now, that's cool.

From the February 2010 issue of Heavy Duty Trucking.