Hybrid trucks

June 1, 2007
PETERBILT continues to develop and test a full range of vehicles equipped with advanced hybrid technologies that increase fuel efficiency, reduce emissions,

PETERBILT continues to develop and test a full range of vehicles equipped with advanced hybrid technologies that increase fuel efficiency, reduce emissions, and improve service requirements. Earlier this year, the truck builder reviewed its hybrid technology progress.

The truck manufacturer is developing and testing four distinct hybrid technology vehicle applications, according to chief engineer Landon Sproull.

  • A hybrid electric heavy-duty Model 386 for long-haul applications.

  • A hybrid electric medium-duty vehicle for pick-up and delivery applications.

  • A hybrid electric medium duty vehicle equipped for stationary PTO applications.

  • And a hydraulic hybrid heavy-duty vehicle for vocational and stop-and-go applications.

The heavy duty hybrid electric Model 386, configured for on-highway use, is being developed in conjunction with Eaton and Wal-Mart Stores. It is currently in the testing and evaluation phase and is expected to be available in 2010.

During third-party testing, the Eaton Hybrid Power System has routinely achieved a 5% to 7% fuel savings versus comparable, non-hybrid models. The heavy-duty hybrid electric power system features an automated manual transmission with a parallel-type “direct” hybrid system, incorporating an electric motor/generator between the output of an automated clutch and the input to Eaton's Fuller UltraShift transmission. The system captures energy generated by the diesel engine and recovers energy normally lost during braking and stores the energy in batteries. That electric torque is then sent through the motor/generator and blended with engine torque to improve vehicle performance, operate the engine in a more fuel-efficient range for a given speed, and/or operate only with electric power in certain situations.

According to Sproull, in this heavy-duty application of Eaton's hybrid power technology, fuel efficiency and emissions reductions are best achieved both while the truck is rolling or standing still. The system's batteries power the heating, air conditioning, and vehicle electrical systems while the engine is off.

When the idle reduction mode is active, engine operation is limited to battery charging, an automatically controlled process that takes approximately five minutes per hour to fully charge the system. In the proposed system design, a proprietary feature minimizes engine vibration during start-up and shutdown during the recharge periods, allowing the driver to rest without interruption.

Peterbilt has engineered a hybrid electric system, developed in conjunction with Eaton Corporation, with its Class 6 Peterbilt Model 330 configured for local pick-up and delivery applications and its Class 7 Model 335 equipped with a fully integrated Terex bucket lift body.

The Model 330 is powered by the PACCAR PX-6 engine rated at 240 horsepower and 560 ft-lb of torque. With the hybrid system engaged, horsepower increases to 300 and torque to 860 ft-lb. The Model 335 is also powered by the PACCAR PX-6 engine, which regenerates lithium-ion batteries to electrically operate the PTO.

Fuel use, emissions, and noise are greatly reduced, and the crane apparatus can operate for up to 28 minutes solely on battery power. The engine automatically starts to regenerate the batteries, which takes approximately 4.5 minutes. During typical stationary operation of the PTO, the engine needs to run only about a sixth of the time versus non-hybrid vehicles.

Both medium-duty hybrid trucks are in limited production this year with full production expected for 2008.

The fourth area of development is hybrid Hydraulic Launch Assist (HLA) technology and is currently being evaluated for vocational and stop-and-go applications, such as refuse collection. This technology is also being jointly developed with Eaton and recycles a truck's kinetic energy to conserve fuel and assist in acceleration.

The system, currently integrated with Peterbilt's low-cab-forward Model 320, increases brake life and reduces engine and transmission wear, potentially extending component life and lowering service costs. It is also more environmentally friendly by decreasing exhaust emissions and noise.

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.

Bringing customers greater levels of fuel efficiency and ease of regulatory compliance, the proprietary Peterbilt ComfortClass system will be available as a factory-installed option by mid-year for select Peterbilt models.

The revolutionary new battery-based system provides heating, cooling, and 110-volt electrical power without the need for the engine to run for up to 10 hours. ComfortClass will be available for Class 8 vehicles equipped with a 70-inch Unibilt sleeper.

When the ComfortClass system is activated, the power pack batteries supply power to an electric fan blower in the cooling unit to circulate chilled air though the thermal storage unit and into the sleeper. Air temperature is regulated by adjusting a thermostat and fan speed dial conveniently located in the sleeper area, near the bunk.