OEMs put heavy, medium-duty hybrids on display

WASHINGTON, D.C. — Mack Trucks and International Truck and engine are showcasing pilot hybrid electric powertrain for Class 8 heavy and medium-duty trucks this week.

Mack Trucks, in conjunction with the United States Air Force Advanced Power Technology Office (APTO), is displaying on Capitol Hill a prototype hybrid electric powertrain for Class 8 heavy-duty trucks. The powertrain is mounted in an Air Force R-11 6,000 gallon capacity refueler truck built on a Mack RD 6×4 chassis.
A likely commercial use for full hybrid technology is a refuse hauler based on a Mack platform.

The work was done under a $1.2 million Department of Defense contract Mack received through Southwest Research Institute in 2003.

The vehicle is what is referred to as a mild hybrid, which assist in launching the vehicle and recover braking energy.

Mack, military prototype hybrid electric truck

“The development of this technology is in line with our goals of enhancing our nation’s military capabilities, supporting the Air Force’s environmental policy requirements and reducing our dependency on foreign energy sources,” said APTO Chief Mike Mead.

Diesel hybrid electric vehicles combine the power of an electric motor with that of 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 is then used in place of diesel fuel. Anticipated advantages of hybrid electric technology include better fuel economy, reduced emissions and noise, longer engine and brake system service intervals, and lower overall operating costs, Mack says.

Meanwhile, International is launching what they say is the largest medium truck diesel-electric hybrid utility pilot program

The pilot truck program, sponsored by WestStart’s Hybrid Truck Users Forum (HTUF), a hybrid commercialization project bringing together truck fleet users, truck makers, technology companies, and the U.S. military, will field-test 24 utility trucks with an integrated hybrid power-train solution jointly developed by International and Eaton Corporation. Commercial operations such as utilities gauge their success in terms of fuel savings, rather than the miles-per-gallon measure that traditionally is used by over-the-road truck fleets. The pilot is slated to begin by year-end.

It was designed to anticipate how trucks in the field test will be used on a larger scale and thus can be considered a sneak preview of some of the benefits the utility industry can expect to see. Beyond that, this hybrid technology built on a medium platform can translate to many other commercial uses. Specifically, it’s ideal for applications with frequent start-and-stop operations, significant idle time and those that need exportable power, such as retail delivery (food, beverage, etc.), package car, government, ambulance and schoolbus. Utilizing the power-take-off (PTO) functionality will benefit additional applications such as propane and fuel oil, vacuum trucks and paper shredders, International says.

The drive system in the utility trucks is a parallel hybrid configuration, with the permanent magnet motor mounted directly in front of the transmission, behind the engine and clutch. Power from the engine is used to drive the conventional drive-train directly or converted into electrical energy and stored for use as needed. Electric torque can be blended with engine torque to improve vehicle performance and to operate the engine in the most fuel-efficient range for a given speed or to operate the vehicle with electric power only. The system recovers kinetic energy during braking, charging the batteries while the truck is slowing down which provides additional power for acceleration. This truck also can operate the utility bucket in electric-only mode, with the engine off, significantly contributing to improved fuel economy.

Independent test results involving the type of truck being used in the pilot, measured against driving and work cycles typical of the utility industry, showed a decrease in the amount of fuel used of 40 to 60 percent, as well as emissions-reduction benefits, significantly exceeding expectations, the truckmaker says.

“These early results are very promising. While we will need to test these trucks on a larger scale and over a longer period of time, we continue to see indications that these vehicles are commercially viable and will deliver real value to customers,” said Bill Van Amburg, senior vice president at WestStart.

“These initial findings support our vision of making diesel-electric hybrid trucks a viable option,” said George Survant, director of fleet services, Florida Power and Light Company, and the chairperson of the HTUF Utility Working Group of WestStart. “The other benefits we expect, such as extended maintenance intervals and fewer brake changes, further illustrate the promise of this technology.”