Defense contractor BAE Systems, whose series-hybrid drivetrains power more than 3,000 city transit buses in North America and Europe, is now offering a parallel-hybrid drive for medium and heavy-duty trucks.

"The expectation of the end-user is to see a payback in less than five years," said Mike Mekhiche, program director, at this year's World of Concrete. 
The company is targeting a 30% fuel-economy improvement at a time when the nation's first greenhouse-gas rules for large trucks will phase in. Fully-electric trucks will not be commercially viable for another 30 years, BAE officials said, so hybrids will fill the gap.
Announced last year, the hybrid drive went on sale at this year's concrete show. BAE says the fuel-sipping powertrain, which goes into production in the second quarter of 2013, will add about 20% to 30% to the cost of a truck, but no more than 20% when the program has reached "full volume," expected in 2020.
In an effort to keep costs down, BAE has inked a 20-year supply deal with Caterpillar to marry Peoria's six-speed automatic transmission with BAE's hybrid drive.
The electric drive unit is sandwiched between the diesel engine and transmission. It alone supplies up to 145 horsepower and 590 lb-ft of torque. Combined with a diesel, the system supplies a net 540 hp and 1,740 lb-ft of torque.
A parallel configuration means the hybrid drive can power the wheels with the diesel engine, electric motor or both. A computer selects the best combination to wring efficiency out of the truck. A 5.2 kilowatt-hour, lithium-ion battery pack stores energy captured through regenerative braking, which is used to launch the truck.
The drivetrain "draws from the electric system to provide that initial takeoff torque to launch the vehicle electrically, or provide that additional torque to climb a hill and keep the engine in an efficient operating mode," said Mekhiche.
BAE's HybriDrive can be placed on any brand of Class 6-8 truck, he adds.
"The system is designed to impact the vehicle in a very minor way," said Mekhiche, meaning that truck makers "do not have to redesign the chassis." BAE's HybriDrive adds about 882 pounds to the truck.
"This is a technology the world is crying for," said Doug Oberhelman, Cat's chairman and CEO, in a statement.