With hybrid technology poised to make inroads in the medium-duty truck market, Peterbilt has now shifted part of its environmental efforts towards Class 6-7 trucks.

In August, the truck manufacturer made its first delivery of medium-duty hybrid vehicles into the market and Peterbilt expects to launch into full production as early as March 2008, with two different specifications. The hybrid technology is the catalyst for what Peterbilt is expecting to be a very promising and green future.

“We’ve never been in a better position to take advantage of the medium- and heavy-duty markets,” said Bill Jackson, Peterbilt general manager and PACCAR vice-president. “People are talking a lot about the environment. Communities may drive this, but we don’t want regulations to force this. There are benefits to those trucks, so we don’t want to force them on the market.”

Peterbilt will offer two medium-duty hybrid configurations – the Model 330 hybrid-electric for pick-up and delivery applications; and the Model 335 hybrid-electric for stationary PTO applications.

“Customers who have already implemented our medium-duty hybrid systems into their operations have reported significant results of up to 40% greater fuel savings,” claimed Jackson.

Peterbilt’s Class 6 hybrid-electric system, developed in conjunction with Eaton Corporation, is a Model 330 for P&D applications.

The Model 330 is powered by the PACCAR PX-6 engine rated at 240 hp and 560 ft.-lb. of torque. With the hybrid system engaged, horsepower increases to 300 and torque to 860 ft.-lb. This configuration is ideal for stop-and-go use, such as urban P&D, with the hybrid system resulting in 30% to 40% greater fuel savings by using electric power to accelerate the vehicle from a stop.

Peterbilt’s Class 7 hybrid-electric system is a Model 335 for stationary PTO applications. The Model 335 is also powered by the PACCAR PX-6 engine, which regenerates lithium-ion batteries to electrically operate the PTO, ideal for municipal and utility applications. During typical stationary operation of the PTO, the engine needs to run only about one-sixth of the time versus non-hybrid vehicles. The engine automatically starts to regenerate the batteries, which takes approximately 4.5 minutes.

Both trucks use a parallel hybrid system with an electric motor that assists the mechanical diesel engine with supplemental torque for improved fuel economy. The system stores energy during stopping through a process called regenerative braking, and then reuses it for acceleration. In the case of the Model 335, in which the vehicle is equipped with a PTO, the system also stores energy during idling to power the PTO.

Heavy-duty hybrids

In addition to Peterbilt’s two medium-duty hybrid vehicles, the company is also actively developing and testing technology for two heavy-duty hybrid configurations – a hybrid electric heavy-duty vehicle for long-haul applications and a hydraulic hybrid heavy-duty vehicle for vocational and stop-and-go applications.

The first heavy-duty hybrid initiative includes the evaluation of an on-highway hybrid electric vehicle – an aerodynamic Model 386 configured for long-haul applications developed in conjunction with Eaton and Wal-Mart.

The Model 386 hybrid system has achieved a 5% to 7% fuel savings over non-hybrid models in third-party testing.

The Model 386 hybrid electric is expected to be available in 2010.

Peterbilt is also continuing development of the hybrid Hydraulic Launch Assist technology, currently being evaluated on Peterbilt’s low-cab-forward Model 320, for vocational and stop-and-go applications such as refuse collection. The system recycles a truck’s kinetic energy to conserve fuel and assist in acceleration. While in fuel economy mode, testing has proven a significant improvement in fuel efficiency and has also shown more than a 50% reduction in brake wear.

The Model 320 hydraulic hybrid is expected to be available in late 2008.