Peterbilt Motors Co. will display a hybrid-electric medium duty truck – outfitted with a fully integrated bucket lift body – at the Hybrid Truck Users Forum National Meeting in San Diego this month.

The Class 7 Model 335 is ideal for municipal and utility applications and features advanced technologies that provide improved fuel economy while reducing noise and emissions.
The hybrid Model 335 will be in limited production in 2007.
“Peterbilt and parent company Paccar Inc are on the forefront of developing hybrid vehicle technologies that benefit both customers and the environment,” says Dan Sobic, Peterbilt general manager and Paccar vice president.
Sobic says the hybrid Model 335 is powered by the new Paccar PX-6 engine, which is compliant with the Environmental Protection Agency emissions standards that go into effect Jan. 1, 2007.
According to Peterbilt Chief Engineer Landon Sproull, the truck uses a parallel hybrid system that was developed with Eaton Corp. A parallel hybrid system has 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. The system also stores energy during idling and uses it to power the vehicle’s PTO.
“We expect the hybrid Model 335 will result in a 30 to 40 percent reduction in fuel use through the combined improvement of on-road fuel economy and stationary jobsite operation,” Sproull says. “The fuel savings, combined with reduced maintenance requirements, will significantly impact our customers’ bottom line.”
The reduced maintenance requirements, Sproull says, result from less wear on the engine, as its workload is supplemented by the electric engine, and the brakes, since the charging of the batteries retards the motion of the vehicle.
The hybrid Model 335 on display at the HTUF meeting Nov. 14 through 16 will be equipped with a Terex body and 55-foot aerial. Peterbilt and Terex have jointly developed the fully integrated chassis and body combination. The body was specially designed to allow for installation of the hybrid components on the chassis during manufacturing, allowing the vehicle to drive off the assembly using hybrid power. The design also allows for easy access to hybrid components for improved serviceability.
The truck and body communicate through a new J1939 digital controller. This interface senses hydraulic demand from the body and automatically engages the hybrid system. Under a full charge, the PTO can operate for about 25 minutes at which time the vehicle will automatically start the diesel engine and recharge the hybrid’s batteries. “It takes about three minutes to fully recharge,” Sproull says. “So, during eight hours of operation, the diesel engine will run for less than an hour.”
Also on display at the meeting will be a Peterbilt Model 320 featuring Hydraulic Launch Assist hybrid technology. The Class 8 vehicle is specifically spec’d for refuse applications and uses its kinetic energy to conserve fuel and assist in acceleration.
The Hydraulic Launch Assist technology was also developed in partnership with Eaton. The system is particularly beneficial in heavy stop-and-go applications, such as refuse collection. In addition to the enhanced fuel economy, brake wear can be reduced by more than 50 percent, improving serviceability requirements and reducing operating expenses.
Hydraulic Launch Assist works by recovering a portion of the energy normally lost as heat by the vehicle’s brakes, in the form of pressurized hydraulic fluid. This fluid is stored in an on-board accumulator until the driver next accelerates the vehicle.
Fuel savings occur when the stored energy is then used to launch the vehicle during the initial, high fuel consumption start from stop, followed seamlessly by power from the primary engine. In performance mode, the stored energy is released and blended with engine power at launch. This can significantly improve acceleration due to the high power density of hydraulics.