Mack Trucks and the U.S. Air Force Advanced Power Technology Office displayed a prototype hybrid electric powertrain for Class 8 heavy-duty trucks in Washington, D.C. on Wednesday, Sept. 28.
The powertrain is mounted in an Air Force R-11, a 6,000-gallon-capacity refueler truck built on a Mack RD 6×4 chassis.
Diesel hybrid electric vehicles combine the power of an electric motor with a diesel engine. The electric motor assists the diesel in launching the vehicle and regenerates energy during braking. This energy is stored as electrical energy and used in place of diesel fuel. Anticipated advantages of hybrid technology include better fuel economy, reduced emissions and noise, longer engine and brake system service intervals, and lower overall operating costs.
The refueler was developed in Hagerstown, Md., and funded by a $1.2 million Department of Defense contract Mack received through the Southwest Research Institute in 2003. Enova Systems supplied the motor, motor control and battery system used in the vehicle. Kovatch Industries manufactured the refueler tank and pumping station.
The vehicle is actually a mild hybrid. Mild hybrids assist in launching the vehicle and recover braking energy. The project’s goal is to develop a full hybrid system that can launch a heavy-duty truck with only electric power. Full hybrids do not require the engine to idle while stopped.