It’s approaching two years since the EPA announced the UPS hydraulic hybrid truck(s) would be road tested but I haven’t seen any results. I’ve seen some articles since that time that seemed to iterate the pretest numbers but I haven’t seen any actual mileage and fuel usage for the hybrids and standard trucks in actual use. I remember some years ago when NYC was first deploying hybrid transit buses they claimed they would increase mileage by 60% but early results improved only about 12%. So I was wondering if any one knows of a website that lists the actual mileage driven and fuel used in the UPS hybrid truck trials.

From what I've observed, Eaton, Parker, and Bosch Rexroth all are working on hydraulic hybrid drives. True, all of these are an extension of technology that had been developed more than 30 years ago. But does that mean they are not innovative?

Charles Robertson, a hydraulics consultant I've know and respected for about 20 years, mentioned to me that he had worked on a hybrid hydraulic drive for the US Postal Service back in the 1970s, when the oil embargo caused gasoline prices to skyrocket past $1 per gallon. However, when the price of gas stabilized, funding for the project dried up.

Of the three companies mentioned above, I think substantial progress has been made. For example, hydraulic pump-motors designed and manufactured specifically for this application are more mechanically efficient than their catalog counterparts. Also, Parker can use accumulators made of high-strength composites, which produces a big reduction in system weight. And, finally, no one would deny that today's digital controls are much more capable than those of the 70s or 80s.

Innovation? I think Eaton's hydraulic launch assist (HLA) is pretty innovative. It's a parallel system that lets you use the hydraulic drive when you're in the stop-and-go traffic of city driving. But when you hit the highway, you command a control to remove HLA from the power train so you can use the vehicle's more-efficient geared transmission. In both cases, you get by with a smaller engine, so you save fuel.

Some stats from Bosch Rexroth indicate pretty impressive numbers for fuel consumption/carbon dioxide reduction. Their parallel hydraulic hybrid system, which works in conjunction with a traditional drive train to improve fuel efficiency and decrease emissions, will be tested in a New York City refuse truck, with potential to reduce fuel consumption and emission by 30 to 50%. The HRB is connected to the truck's driveline. Full production should begin by 2009 or 2010, Bosch Rexroth representatives say.

Bosch Rexroth is also working with a series hybrid system. This standalone hydraulic hybrid system, called the MXT Series system, completely mechanically decouples motor and drivetrain. It is being developed for smaller vehicles, such as delivery vehicles and school buses, and again, will allow drivers to operate the vehicle at optimum speed. It will use a radial piston, variable-displacement pump in which individual pistons can be selected to digitally change the displacement. It will also include up to four high-low pressure accumulators. It is currently being tested on a military cargo delivery vehicle, with testing complete by September and full production slated for 2012. Officials say the MXT could see a 50% increase in fuel economy without downsizing the engine.

Edinburgh-based technology company Artemis Intelligent Power recently tested this Digital Displacement technology on a prototype BMW 530i. Tests showed the hybrid transmission doubled the MPG in city driving compared to the same car with a manual transmission. Overall, including highway driving, the prototype had 30% lower CO2 emissions than it had before the company fitted its energy saving transmission.

I expect we'll see more results from Bosch Rexroth in the near future, as the HRB is well out of testing stages and close to production, while the MXT development and testing will be complete by the end of this year.

I just noticed there have been 5,547 views to this Thread and only 32 post's.

Must be a Hot-Button item to a bunch of persons. I wonder why there are so few Post's?

Take a look at a discussion on Hybrids at a non-hydraukic site.
http://cr4.globalspec.com/blogentry/5983/Pump-me-up-at-the-pump

Perhaps what is or isn’t innovative depends on how broadly or how narrowly innovation is defined, but I think it needs to be more than updating old designs with current technology. Many technologies are not implemented because the costs outweigh the expected benefits. Worthwhile innovation tends to change the underlying cost-benefit ratio so as to make the technology more economically viable. I’ve read that gasoline in today’s dollars was $3-$4/gallon in the late 70s when hydraulic drives were being proposed for use in everything from sedans to garbage trucks. I don’t know what was verifiable but I’ve read some very impressive performance claims from back then. So has there been any real innovation? Or are Parker, Eaton, and Bosch-Rexroth busy adapting current know-how to applications that have been made economically viable by the increasing price of oil. Such efforts may be worthwhile but they are not innovation.

The need for the US to develop an efficient, cost-effective vehicle has existed since the 70s. The government has spent billions of dollars on advanced vehicle research but has failed. The US trade deficits have grown uncontrollably, driven by oil and autos. The only notable result was to prod the Japanese manufacturers into marketing the hybrid, but the hybrid is more a result of the problem, not a solution to it. The hybrid has been marketed in the US for about ten years but made no noticeable impact on oil consumption. It remains debatable as to what fuel cost and usage is needed to make the hybrid economically viable, however, it seems likely that the price of oil needed to support the hybrid will more than offset any reduction in oil consumption. Therefore, oil imports, in dollars, will not be reduced. The price of oil will do more to reduce consumption than will the hybrid.

There has been some innovation in hydraulic power since the 70s, but more so in electric power. Hybra-Drive, Valentin and Artemis all have hydraulic pump/motors that seem innovative to me but I don’t see innovation in the EPA/Eaton design installed in the UPS truck. I would say the EPA/Eaton work is more of an effort to market something that Eaton can build rather than a genuine effort to innovate a solution. Innovation is needed to curb oil imports and stimulate domestic auto production. Innovation would have brought forward pump/motors that can operate efficiently at about 12,000psi and at less than 10% flow. I doubt that such performance can be achieved by machines that rely on sliding contact between heavily loaded parts. I believe both GM and Honda have vehicles on the road that would be classified as ‘launch assist’, so what is innovative about Eaton’s ‘launch assist’? Using hydraulic machines instead of electric machines shouldn’t be considered innovative. It should be asked if they have done anything to make the machines more packagable, less costly, or more efficient. Updating designs (with current materials and/or processes), building to higher standards and implementing tighter control of processes can lead to marginal performance gains. But it is not innovation and marketing technology that rising fuel costs have made economically viable will not solve the problem. They’ve had the time, they’ve spent the money but they have failed to produce a cost-effective, fuel efficient vehicle technology in the US.

How about this idea:

http://www.greencarcongress.com/2005/02/ldquoextremerdq.html

This is from a search on Google for "flywheel+drive+vehicle

Needless to say there were a lot more hits.