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Update on Eaton Medium-Duty Electric Hybrids

The core of the system: the Hybrid Drive Unit. Click to enlarge.

In a presentation at the 2008 SAE Hybrid Vehicle Technology Symposium, Kevin Beaty, Eaton’s Business Unit Manager for Hybrid Power Systems, provided an update on the status of the medium-duty hybrid-electric systems the company currently has in the field. After several years of testing and putting prototypes into field trials with customers, Eaton began commercializing its medium-duty hybrid system in August 2007.

Eaton’s hybrid system for city delivery applications uses a parallel, pre-transmission design with Eaton’s Fuller UltraShift automated transmission. Primary components are the Hybrid Drive Unit (HDU), which combines a clutch, a 44 kW/420 Nm motor/generator and automatically controlled manual transmission; the motor inverter/controller; the DC/DC converter; and a 2 kWh li-ion battery pack from Hitachi. (Earlier post.)

The hybrid systems for utility companies feature a slightly more involved architecture, due to the addition of the ability to allow the truck booms to operate in electric-only mode.

Fedex. FedEx has 93 Eaton hybrid trucks operating at 20 stations in the US and Canada, and has ordered another 45 production trucks for delivery in the second quarter of 2008. The Eaton hybrids have accumulated a total of 1.96 million miles. The baseline engine for the FedEx delivery van is a 5.9L, 6-cylinder, 175 hp Cummins ISB. The hybrid version downsizes to a 4.3L, 4-cylinder, 170 hp MBE-904.

Eaton’s modeling and simulation projected a average 52% gain in fuel economy. Lab testing at Southwest Research Institute yielded a minimum 42% and a maximum 57% increase in fuel economy. FedEx has reported a wide spring in field operation from 10-80%.

UPS. UPS has 50 Eaton hybrids at 4 stations in the US, with an accumulated 501K miles. There are two models in service here, the P100 and the P70. Baseline engine for the P100 is an ITEC VT365 200 hp V8; the P100 hybrid engine is an ITEC VT275 V6 180 hp engine. The P70 baseline engine is a Cummins ISB 165 hp unit; the P70 hybrid engine is a MB904 170 hp unit.

Eaton’s modeling and simulation projected average fuel economy gains of 26% for the P100 and 52% for the P70. SwRI lab testing found average fuel economy gains of 32% for the P70 and 48% for the P100. Results in the field show gains in fuel economy ranging from 10% to 43% for the P100, and from 10% to 18% for the P70. The National Renewable Energy Lab is planning a controlled test of the fuel economy of these hybrid delivery trucks.

Coca-Cola. Easton has four trucks in service with Coke. Both baseline and hybrid engines are the same, a MaxxForce DT, 7.6L I6 225 hp engine.

Eaton modeling and simulation projected an average 30% gain in fuel economy, SwRI testing indicated an average 27% gain; and Coke field data shows an average 37% gain.

Frito-Lay. Frito-Lay has one Eaton hybrid, with 5,733 miles on it. The baseline engine is a GM 6.5L V8 160hp unit, and the hybrid engine is an ITEC VT275 4.5L V6 DI Turbo 180 hp unit.

Eaton’s modeling and simulation found average fuel economy gains of 34%. SwRI lab testing found average gains of 26%. Field results showed an average gain of 23%, with 14% minimum and 32% maximum.

Hybrid Truck Users Forum (HTUF). Eaton has 24 vehicles in 14 fleets in the hybrid utility truck program organized by HTUF. The trucks have accumulated 480K in-service miles. The baseline and the hybrid engines are the same: a 7.6L, 6-cylinder, 225 hp DT466 engine.

Eaton’s modeling and simulation projected a minimum fuel savings (as opposed to gain in fuel economy) of 29% and a maximum savings of 40%. SwRI testing found that the savings ranged from 38% to 60%, and field results indicate a range of 14% to 54%.

Foton Bus. There are 31 Foton buses in service in Guangzhou, China with the Eaton hybrid drive system. The baseline engines varied, but were typically a 6-cylinder, 220-260 hp, Euro 2-3 unit. The hybrid engines are ISB3 6-cylinder, 185-220 hp, Euro 3 units.

Eaton modeling and simulation projected average fuel economy gains of 28%. Track testing yielded a 27% gain with a manual transmission and a 59% gain with an automatic transmission. Field results showed a 37% gain in fuel economy, and a 110% gain compared to an LPG bus with a manual transmission.



Crikey, these numbers are all over the shop!
This supports my comment. Different combinations of gens, engines, trans , diffs etc nearly anything will affect the bottom line in a similar way to the article story.
Just reading between the lines. With some industry knowledge.

What is easier to comment on is the approach from this major supplier.
When a generic supplier takes the bit and does their part supplying what will surely be a well made fitment, I'm thinking more the casings and transmission components although it sounds as though they supply complete systems This enables smaller builders into the game.
Standardised equipment will allow a variety of engines and chassis options while allowing manufactures and research departments comparison units, or truck makers the choice of engines etc with the accompanying versatility at the the least cost, while maintaining access to spares inventory and upgrades as and if they become available.
Mistakes will be made and rectified, the corporate memory and lessons learned will flow more easily.
The alternative of many agents working in the dark is just too awful to contemplate.
Of course it will be good to see plausible ideas and choice of supplier developed, Hopefully without the pressure of deadlines.
I think that there is much scope for this generic component supply for hybrid vehicle construction as for sometime development and supply will constrain delivery and cost (due to small production runs and a rapid evolution.)
The benefits from a spirit of co-operation, while traditionally far fetched, nevertheless will enable the maximum possibilities.

What is sad is how the simulations cook the books consistently in favor of better mileage than achieved in the field. They are all over only one side of the map. What is up with that. You would have a spread on both sides if incompetence was a major player. Nope, they seem to be using what they should know are unrealistic assumptions. Sad indeed.

Stan Peterson

Progress is occurring before your very eyes.

This is the way that engineering progress happens in the real world. For those with little technical training it isn't some mysterious process; it just takes lots of work, skull sweat, and continued effort, to advance the real state-of-the-art.

Some seem to still find a basis to criticize everything. Why?

There is evidence that hybridization can be applied to medium duty trucks and produce a substantial benefit. One size does not fit all trucks, and operating environments. And this is proof that hybridization can be applied to more than tiny passenger cars, and perform well.

Furthermore while we all await the next Prius and Volt like deus-ex-machina, meanwhile it seems clear that hybridization has arrived in the medium trucking industry and rapidly advancing to just a standard way of doing the routine and regular development of truck fleets, using off-the-shelf standard components, of which this Eaton hybrid drive transmission is now such a standard item.


i wonder what this system costs for an OEM. it seems like it'd be a good start for making a small battery electric vehicle. 44kW would be plenty for a Honda Fit sized vehicle.

just put a nice big battery pack in parallel with the little 2kWh pack it comes with. i bet if you get rid of the spare tire there would be space for sufficient batteries in the trunk.


i wonder what this system costs for an OEM. it seems like it'd be a good start for making a small battery electric vehicle. 44kW would be plenty for a Honda Fit sized vehicle.

just put a nice big battery pack in parallel with the little 2kWh pack it comes with. i bet if you get rid of the spare tire there would be space for sufficient batteries in the trunk.


When I look at FedX, UPS, Coke and Frito I imagine lots of delivery trucks running around an urban and suburban setting. This seems like good territory for hybrids. Companies have the funding and financing to do this and they use lots of fuel and emit lots out of the tail pipes. More power to them! (pun intended:)


Enova Systems(ENA) is better. Enova Systems, Inc. engages in the development and production of digital power management systems for transportation vehicles and stationary power generation systems. The company develops and produces software, firmware, and hardware for applications in vehicle power generation and stationary power generation markets. It offers digital power conversion, power management, and system integration products. Enova Systems offers drive systems and related components for electric, hybrid-electric, fuel cell, and microturbine-powered vehicles; and power management and power conversion components for stationary distributed power generation systems. In addition, the company engages in research and development to augment and support others and its own related product development efforts. Its products are used in light, medium, and heavy duty trucks; train locomotives; transit buses; and industrial vehicles. The company has strategic relationship with Ford Motor Company to develop and manufacture high power and voltage conversion module for Ford's fuel cell vehicle; and International Truck and Engine Corp. Enova Systems was founded in 1976. It was formerly known as U.S. Electricar, Inc. and changed its name to Enova Systems, Inc. in 2000. The company is headquartered in Torrance, California.

Geoff Howat

Maybe individual drivers' driving standards affect fuel economy, thus creating the spread in fuel economy in field tests?


While different drivers techniques can have an enormous effect on economy figures, education will even that out.
Given the same operator say a robot that behaves exactly predictably then we are left with the operating environment. With heavy vehicles with large energy demands the matching of all engine drivetrain, chassis tyres streamlining etc is critical. The ability to specify the configuration is "where its all at" once these parameters are dialed in, the engine, body management software can be adjusted through adaptive learning or analysis of recorded telemetry to get that last bit.
The more things that can be tweaked the better the outcome. Conversely the less options, one is stuck with, from manufactures proprietary decisions, the bigger a dog we're stuck with when its found to be inappropriate.
Imagine if shoes only came in 3 sizes.
At the same time we don't want every manufacturer trying to be everywhere at once, but only offering their own option.
Loss of reputation and business and progress will stagnate.
Frustrate and annoy the tradespersons, who are in my experience across many trades 'past carin'


As most of you know, Eaton is the real thing, they aren't vapor merchants. They have chosen to move into new powertrains by extensive partnering with companies that operate a lot of commerical vehicles. IMO a very sensible approach.

I can't imagine being upset because simulations didn't match field testing. But I will give two hints. Simulators have perfect drivers. And simulators drive standard imaginary routes.

Actually field testing is just advanced simulation. It gets closer to actual use but the test drivers still tend to be better than average and the routes are by definition a subset of all real routes.

A little off the hybrid topic. Eaton is also partnering with Walmart to improve their corporate diesel fleet. When you operate as many trucks as Walmart even a small improvement in mileage is worth investigation.


Though the simulations may have had some bias, I thought they were reasonable. The design of the system would have optimized its performance in the simulation rather than in testing or field trials. This would introduce a bias into the simulation results. So I don't think it's cynical retention of assumptions but an inexcusably less than perfect model.


What is sad is how the simulations cook the books consistently in favor of better mileage than achieved in the field.

Not true.

Trial Sim vs Field
Fedex 52 vs 10-80
UPS P100 26 vs 10-43
UPS P70 52 vs 10-18
CocaCola 30 vs 37
Frito 34 vs 23
HTUF 29-40 vs 14-54
Foton 28 vs 37

In Fedex, UPS P100 and HTUF trials the sim and field were consistent although field had a wider spread. In CocaCola and Foton trials field results beat the sim. In UPS P70 and Frito trials field results fell short of the sim. Where's the optimistic bias? The field results will feed the next round of sim design such that the sim will become both more accurate and able to handle a broader variety of input conditions. Eaton will use the improved sim to tweak their design to best match real-world usage and customers will use the improved sim to estimate fuel burn for their own unique conditions. This is the whole point of the exercise.


I don't think you understand, doggydogworld. If one lacks the understanding to analyze and discuss the details and implications of an article, the only other way to make oneself appear and feel intellectually superior is to pour out non-detailed disdain and cynicism.


It seems like there will be a high demand for small, light, high power electric motors in the years to come. Whether, HEV, PHEV, EV or FC, they are going to need motors. This seems like a major growth opportunity for a company that can produce the most value in their products.

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