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Peterbilt, Eaton and Wal-Mart Partner on Class 8 Hybrid Truck

The Peterbilt 386 Class 8 hybrid.

Hybrid technologies developed jointly by Peterbilt Motors Company and Eaton Corporation have been integrated into an aerodynamically styled Class-8 heavy-duty vehicle.

Wal-Mart Stores, Inc., which operates the nation’s second largest private fleet, is supporting development of the technologies by helping to validate the concept and refine the final design.

Eaton’s Heavy-Duty Hybrid System. Click to enlarge.

The Eaton heavy-duty hybrid system with idle reduction features an automated manual transmission with a parallel-type direct hybrid system, incorporating a 44 kW electric motor/generator located 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.

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.

During third-party testing, the Eaton Hybrid Power System has routinely achieved a 5-7% fuel savings versus comparable, non-hybrid models. It may result in a savings of one gallon of fuel per hour when idling.

Peterbilt and Eaton have previously partnered to develop hybrid electric Class 6-7 vehicle platforms and Class 8 hybrid hydraulic vehicles. With a successful test and evaluation program, the heavy-duty hybrid electric power system will be available in 2009.



While the increase in efficiency may seem small, these are especially effective at reducing urban pollution around harbors and breakbulks. Based on that alone the system is financially worthwhile imo.


The system’s batteries power the heating, air conditioning and vehicle electrical systems while the engine is off.

This is a big deal. Exerting energy to move goods around? That's OK. Exerting energy to stay still for 8 hours at a time? That stinks. Reducing the idling is low hanging fruit, and hats off to them for plucking it.


One would think that modern trucks would come with a small and efficient power generator to be used when the main engine is off. I know RVs have them, so why not trucks? I know it's still burning a lot of fuel, but it would probably be much more efficient than idling a transport.

David M. Rouse

Now they need to run the truck on biodiesel. That would reduce the emmissions even more and the use of crude oil for that vehicle to zero.


Delphi is developing an SOFC APU that runs on diesel. Last I saw, it put out about 5kw.



they already got them on all of their fleet.

Bill Young

With Wally's history, I assume they will force Peterbuilt to move production offshore if this comes to pass.

Rikiki Weisbrich


Last year at the time of peak diesel prices... $3.00 in Plainview, TX we stayed at a motel next to a truck stop. The temp outside at 2200 was 74 degrees. 13 of the 16 big rigs (two new rigs without trailers) were running all night long. A driver with whom I spoke, shutdown his rig and took a room at the motel for the night. He told me that even idling his (Kenworth) rig burns two gallons per hour. 13 rigs, six hours at 2 gallons per hour is 156 gallons. None of the rigs belonged to major carriers.. All independents. Two of the three rigs shut down for the night were Volvo. ?? This goes on at many thousands of truck stops and rest areas every night. Do these guys really want a fuel efficient vehicle?

Even diesel pickups here in Texas are let to run while someone hops into the market or fills up.. I have a diesel Mercedes... I shut it off and it always restarts. Someone have answers?

Round Rock, TX

In my city, diesel idleing for more than one half hour can get you a ticket.



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.

Unless I'm interpreting this wrong, this seems like a major incentive for drivers to want to use this system. It seems like idling trucks wouldn't be that quiet or comfortable, and anything that helps the driver sleep better is a bonus. Their incentive might not be saving gallons overnight, since they're only saving 1 gallon per hour, Although they may not save much $ per night on gallons saved individually, as Rikki mentioned, many trucks add up.

John Ard

My father is a trucker, so let me take a stab at this. Idling the truck all night is not only wasteful, it is a source of excessive wear and, as noted above, is illegal in some areas. Most drivers that don't have APU's don't because they either (1) drive a company truck that they are not allowed to work on, (2) lack the mechanical skills to service their own truck, much less an APU, or (3) have trouble coughing up the $8000 a good APU would cost. The last reason is the most common, but many drivers are finding that with the high price of fuel and recent incentives by state governments, not owning an APU is simply stupid. For the record, my father considers himself stupid for not owning one, but too busy to do anything about it right now. Go figure. :)

Nicholas Moran

I was wondering why Great Britian is so far ahead on truck technology. I was watching the History Channel and can some body get a copy to copy what Europe and Great Britian are doing so that 156 glllons of fuel would then be able to get you clear across the country. Has anybody heard of Rotoblock,I hear that the Navy is using there engines on small and mediam class boats and can generate 2000 hp, and with that transmission using the brakes as the electric braking force down hills and charging the battery systems my question is what is the delay... njm

Gerald Robinson

In the overall process of refining crude, isnn't diesel the least expension of all the products? Other realizing obscene profits, what is the justification for diesel fuels to be so expensive ($3.00/gallon) at the pump for the trucking industry?


The reason diesel is 3 bucks a gollan has to do with the fact they refine oil now to make more gas then diesel AND other then specialty gas diesel in the us is not cheap to make anymore as it requires alot more processing and even some h2 to get it to the ultra low sulfer type made now.



Wake me when Peterbuilt builds a series hybrid, running a smaller 250hp diesel continuosly at its most efficient power rating to drive a generator. Use that power to drive an electric motor -- which has very high torque just like a diesel and is a good match for transmission and remainder of the drivetrain.

Use a 50kwh battery pack to add to the generator output for acceleration, power the sleeper cab at night, recapture braking energy, and vastly improve the in-town mileage. It should be theoretically possible to double the overall fuel mileage of a rig.

A 250hp diesel engine running in that mode would use less than 5gph, compared to the 10gph the average rig uses while cruising at 70mph.

A typical mileage for a rig is between 5.5 and 6.5mpg and average miles is 125k per year. Meaning it uses 20,000 gallons per year and $75K per year in fuel costs. Cutting fuel usage by even 1/3 should be possible and result in $25K annual savings. So what if such a fully hybrid system adds $50K to the initial price of a rig ? Payback would be relatively quick.


As for low sulfur diesel, I believe that the oil companies fought it 10 years ago, but now you see commercials about how great they are for promoting it. If the public does not know the truth, I guess they figure that they can tell them anything.


Kirk... why would current diesels be running so inefficiently at cruising speed? Isn't that what the gears are for, so that the engine is running in it's most efficient range?

Living by one of the world's largest ports, I applaud any effort to reduce the pollution from the stop and go within the city, but once on the highway hybrid technology would seem to have little effect on efficiency.


At 70 mph most of the energy is used to move the truck through the air, which is why we run at 55-60 mph

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