Article

Hybrid Trucks

Manufacturers make progress on hydraulic systems while electric-drive trucks gain orders.

June 2008, TruckingInfo.com - Feature

by Tom Berg, Senior Equipment Editor, Senior Editor - Also by this author

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The world of hybrid trucks continues to move fast, with several manufacturers now building various configurations and others announcing plans for production. Meanwhile, the coordinating body for the hybrid movement says that two of its working groups have selected builders and suppliers to assemble prototype vehicles for field evaluations.

Walk-in van chassis with diesel-electric drive systems are currently available from Freightliner Custom Chassis Corp. and Workhorse Custom Chassis, while medium-duty cargo and utility trucks are available, or soon will be, from Freightliner, Navistar International, Kenworth and Peterbilt. One plug-in diesel-electric hybrid has come on the market, and a heavy trash collection truck using a diesel-hydraulic drive system is ready for production (see news items that follow).

As in automobiles and light trucks, hybrid-drive systems for commercial and military trucks offer great savings in fuel economy but carry hefty price premiums. Hybrids have cost 50 percent to 100 percent more than trucks with straight diesel powertrains, but costs have begun to come down as volume production gets unde way. In the meantime, federal tax rebates and other government support promise help for operators willing to try the new technology.

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The Hybrid Truck Users Forum says several of its working groups are proceeding toward acquiring specialty vehicles for evaluations by fleets, and that another working group continues to study test data and proposals for highway tractors. Suppliers for parcel delivery and trash trucks have been identified for ordering, with both electric and hydraulic hybrid systems represented.

"Hydraulic hybrids are coming on strong, and that provides some healthy competition" in the field, says Bill Van Amburg, HTUF's program executive and a senior vice president at Calstart-WestStart in Pasadena, Calif. "Hydraulics offer the potential for lower cost, but there is a weight penalty with the accumulators and other equipment, which developers are trying to improve. Overall, hydraulics are 18 to 24 months behind electric hybrid systems."

For various reasons, electric systems, primarily those from Eaton Corp., were the first to go into regular service for FedEx Express and United Parcel Service. FedEx now operates nearly 100 diesel-electric hybrid walk-in vans with Eaton electric-drive systems, assembled by Freightliner Custom Chassis. While the fleet saw some teething problems, Eaton and FCCC say the units now are 97 percent reliable, and FedEx reports considerable success in fuel economy and emissions reduction.

HTUF's Parcel Working Group will acquire three Class 6 diesel-hydraulic delivery trucks for testing by UPS, FedEx Ground and Purolator Courier. Hybra-Drive, the chosen supplier of the hydraulic hybrid system, says it hopes the vehicles will demonstrate a 60 percent reduction in fuel use. Ford will supply the chassis for the project. An evaluation vehicle will undergo dynamometer and other testing this fall, and it and the two others will begin field testing early next year.

FedEx Ground, a sister company to FedEx Express, has said it's going the hydraulic-hybrid route because the walk-in vans are bought by independent contractors who might be inclined to tinker with the drive mechanisms. That might be risky if they were high-voltage electric systems. FedEx Ground has other development projects in the works, as do the other test fleets, and will share their experiences with other HTUF members.

While most commercial hybrid trucks are diesel-powered, at least one, from Azure Dynamics and Ford, uses a 5.4-liter V-8 gasoline engine. FedEx Express has ordered several of these for use in California, where cleaner gasoline emissions are more acceptable to authorities.

Meanwhile, HTUF's Refuse Working Group has accepted proposals from industry teams to build six hydraulic and electric trash collection trucks for fleet testing. The group selected Crane Carrier Co. as the chassis builder; CCC is working with ISE Corp. on a diesel-electric system and with Bosch Rexroth Corp. on a diesel-hydraulic system. The ISE system is a series hybrid, meaning its engine never directly propels the truck; it drives an electric generator that charges batteries that propel the truck through motors.

Bosch Rexroth's hydrostatic system, which is successfully used in heavy articulated transit buses, is a parallel-type hybrid, meaning the truck will run on diesel or electric propulsion or both. The Bosch apparatus will replace the transmission in CCC's LET2 heavy low-cab-forward chassis, which will also be used for the ISE electric system.

The trucks are scheduled for testing starting early next year by sanitation departments in three cities, according to HTUF. New York City will take three electric and one or two hydraulic trucks, while Chicago and Houston will each take one electric hybrid truck.

Members of HTUF's Class 8 Working Group are discussing road tractors and how hybrid systems could best be used by them. Sleeper-cab tractors can readily use electric power produced through regenerative braking and an efficient diesel-generator setup. The one working example is Peterbilt's 386 Hybrid tractor that uses a Caterpillar C13 engine, an Eaton electric-drive system and a Delphi sleeper air-conditioning system; it's being evaluated by Wal-Mart Transportation.

Wal-Mart has ordered another diesel-electric hybrid tractor from a team consisting of International, which will supply a ProStar sleeper-cab, Cummins, which will provide an ISX or ISM diesel, and ArvinMeritor, which will supply an electric propulsion system. That tractor is scheduled to enter fleet testing sometime next year or in 2010.

This HTUF working group is also looking at a regional-service tractor whose greater amount of stopping and starting might be better able to take advantage of a hybrid's regenerative braking characteristics. It would probably be able to gain more fuel economy than the over-the-road sleeper-cab tractor, whose potential fuel economy gains are in the 5 to 7 percent range.

Public utility members of HTUF were the first to get prototype hybrid trucks into service for testing, with 23 units put into the hands of companies in the U.S. and one in Canada. Built by International on 4300-series chassis, the Class 6 "trouble trucks" have Eaton's electric-drive systems that feature regenerative braking and high-output generation of power from large alternators driven by the trucks' DT466 diesels. Tests show the hybrids save 14 to 60 percent in fuel, largely because they and their crews can work at job sites using power from batteries while the engines stay off. International has begun getting repeat orders for the trucks from satisfied users.

At least one plug-in hybrid truck is now on the road and more are headed for service. Odyne Corp., an electric-equipment manufacturer, and Dueco Inc., a Terex equipment dealer, assembled the trouble truck. Its batteries can store 35 kilowatt-hours of power, most of it taken on while plugged into a high-voltage outlet prior to a day's or night's work. An on-board electric generator is driven by the engine through the transmission's power take-off is for recharging in the field.

Finally, General Motors has begun selling its 2-Mode Hydrid system in Chevrolet Tahoe and GMC Yukon sport-utility vehicles. The system, with its highly sophisticated Electronically Variable Transmission, pushes fuel economy of the traditionally thirsty SUVs into the low 20-mpg range, making them viable in these days of high-priced gasoline. The 2-Mode Hybrid is scheduled for installation in Silverado and Sierra pickups later this summer, which could be useful in light commercial service. (We will report on our drive of a Tahoe hybrid in an upcoming issue.)

Manufacturers are progressing on plans for production of hybrids, and report orders for them and alternative-fueled trucks. Among the recent announcements:

UPS places "largest order ever" for hybrids and CNG vans from FCCC - Freightliner Custom Chassis Corp. said the order from United Parcel Service consists of 200 hybrid electric and 300 compressed natural gas vehicles, and will be manufactured on FCCC's MT45 and MT55 walk-in van chassis. UPS will use the "green" vehicles for daily delivery operations across the United States, supplementing its current fleet of conventional diesel-powered package cars.

Each of the MT45 and MT55 vans with Eaton 44-kW hybrid electric systems may realize a $4,500 tax credit, FCCC said. Fleet experience with more than 160 previously built vans, including 25 with UPS, shows that they save 40 percent in fuel and cut exhaust emissions by 90 percent. FCCC said it produced its first diesel-electric hybrid chassis in 2004. The 200 newly ordered chassis will use 6.7-liter 200-horsepower Cummins ISB engines, along with the Eaton hybrid systems that include 6-speed UltraShift automated mechanical transmissions.

Each CNG-fueled chassis with Cummins 5.9-liter 195-horsepower B Gas Plus natural gas engine may qualify for up to $25,000 in tax credits. CNG usually costs far less per equivalent gallon than diesel fuel and also drastically cuts emissions. FCCC said it built its first CNG-fueled chassis in 2000. Some of the 300 new vehicles will be rated at 29,000 pounds GVW, and all will have Allison 1000/2000 automatic transmissions with parking pawls.

AEP orders 18 hybrid utility trucks from International - American Electric Power, a large public utility company, has ordered 18 more International DuraStar hybrid trucks following positive experiences with four prototype units. The trucks use MaxxForce DT diesels with Eaton Corp.'s hybrid electric drive system, whose charging system and batteries enable the truck and its crew to work with the engine shut down much of the time. Engine-off operation saves as much as 60 percent in fuel, a test of 24 prototypes showed. In addition to operating savings, the Class 7 hybrids qualify for federal tax credits of $12,000 each.

AEP will place 13 of the hybrids with its Indiana Michigan (I&M) Power subsidiary and the rest with other operations in the Midwest. I&M tested two of the prototypes and found them reliable and economical, according to its president, Helen Murray. "It's a good business decision and the right thing to do for the environment," she said during a ceremony marking the purchase at Navistar International's plant near Springfield, Ohio, on Earth Day, April 22. Workers at the plant are building the hybrids on the regular assembly line, and Altec utility bodies with man-buckets are installed nearby.

Peterbilt readies Model 320 hydraulic hybrid for production - Peterbilt Motors said it will begin building its 320 low-cab-forward trash-collection truck with Eaton's Hydraulic Launch Assist, or HLA, late this year. It has some orders in hand, and while it declined to name the customer and the number, it's known that Waste Management is acquiring some of the Class 8 straight trucks for testing. HLA captures braking energy by pressurizing hydraulic fluid and sending it to accumulators, which store it at up to 5,000 psi; upon startup, the fluid is released back to the driveline pump, which becomes a motor and helps launch the truck from a standstill.

Tests show that retarding cuts brake wear by 50 percent, while hydraulically assisted launching saves up to 30 percent in fuel and cuts exhaust emissions by 40 percent. The system puts as much as 2,550 pounds-feet into the driveline, which, when combined with torque from a Cummins ISM diesel, makes for quick acceleration with the heavy truck. To gain more attention, Peterbilt displayed the 320 hybrid at the recent Waste Expo in Atlanta. The 320 is not yet on the Internal Revenue Service's list of vehicles certified for tax rebates, so it's not yet known how much it might be qualified for.

DRIVING THE FORD-AZURE WALK-IN VAN

Up until now, most hybrid truck development has involved diesels, so the Ford E-450 chassis with its Azure Dynamics electric drive system is different. Its engine is a Ford gasoline V-8, the 5.4-liter unit found in most F-150 pickups. It's being used because it's easier to meet the especially tough emissions limits in California. FedEx Express has ordered 20 of these trucks for use there.

Azure installs its hybrid components after the chassis leave Ford's assembly line. That, Ford executives had explained earlier, allows the builder to continue regular volume production while still participating in any trend toward hybrids, if one truly develops. Utilimaster mounts the aluminum bodies when work on the chassis is complete. The final product looks like any FedEx package van, but drivers will certainly notice that it sounds and feels different.

My driving experience with this van was very limited, as it was among about 10 hybrid and other vehicles available for very short test drives during the National Truck Equipment Association's Work Truck Show in Atlanta early this year. But a spin through parking lots and streets was enough to form some impressions.

The gasoline engine is somewhat quieter and smoother than the 4- and 6-cylinder diesels usually found in these vans. And the gas V-8 has less low-end grunt, so it needs some revving to develop propulsion power. With more cylinders and pistons - twice as many as in the Mercedes inline-4s that FedEx has been buying for its diesel-electric vans - the gas V-8 sounds busier, but works well with Ford's 5-speed TorqShift automatic.

Like other electric hybrids, the system generates electricity during braking and sends it to a bank of batteries. Its engine does not shut down but continues to idle to turn the power steering pump and other accessories, and it begins revving when "juice" from the batteries is exhausted and/or driving conditions demand more power, as at street or freeway speeds. How well will it work in everyday use? FedEx Express will report on its experiences after the trucks go into service this year. 

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