A simpler variation is Deere's 644K. It uses a 6.8L, 300-hp engine and pump drive but just one generator and motor. The motor powers a three-speed powershift transmission and mechanical axles. This hybrid also tosses out the torque converter, says Randy Swanson, a Deere drivetrain manager. Eliminating that device is “one of the areas where we get our significant efficiency improvement over a standard wheel loader,” he says.

The electric parts, which are based on switched-reluctance technology rather than permanent magnets, are common for both platforms. The generators produce roughly 270 hp each, while the motors crank out about 130 hp. With this arrangement, Deere foilows LeTourneau Inc., which produces diesel-electric wheel loaders of up to 2,300 hp and 53 cu yd of bucket capacity. It, too, uses switched reluctance to drive the wheel motors.

Deere's two-platform hybrid strategy wasn't always a sure thing. The project began more than four years ago, when fuel prices were skyrocketing, under a research program Deere calls its Accelerated Innovation Process. Then came the recession, which gave engineers pause.

“A lot of people said, 'Whoa, let's throttle back on this,' ” says Joe Mastanduno, who runs drivetrain marketing for Deere's construction and forestry division. In the end, the team assumed that fuel prices would bounce back, and they did. “It was full steam ahead, and it was the right decision,” Mastanduno says. Nationwide, highway diesel costs about $4 per gallon compared to $3 a year ago, according to the U.S. Dept. of Energy.

Back to the Future

Both loaders work more like a mining truck or freight train—the basic technology has been around for more than 50 years—than a hybrid car. Many construction machines operate on repetitive movements, making energy storage an ideal way to boost efficiency.

But batteries present size, weight and cost challenges, so many of the early construction hybrids are skipping the battery. In 2009, Caterpillar began selling its ">D7E bulldozer, a series hybrid that combines a diesel engine with electric motors to power the tracks. It does not offer battery storage; most of its efficiency comes from downsizing the engine and running it at a steady speed.

Earlier this year, Komatsu began selling domestically its ">PC200LC-8 hybrid excavator. It captures regenerative braking energy whenever the superstructure swings and stores it briefly in capacitors, which are like batteries that provide short bursts of energy. In 2008, Volvo showed a concept loader at CONEXPO that used a battery, but that model has not gone into production. Deere's loaders do not offer battery storage—at least not yet.

“Battery technology is moving very quickly, and it will continue to accelerate due to the automotive business,” Mastanduno says. “There will be a point where this makes sense,” he says, noting that batteries will boost a machine's fuel economy by another 5% to 10%.

In the case of Cat and Komatsu, the technology costs about 20% to 30% more. Deere isn't talking hard prices yet, but its own internal research has identified a strong customer base that is interested in boosting efficiency and willing to pay a premium up front for machines that save money over time.