US truck fuel economy and Obama's new rules 5

[JayMaechtlen]

In thread71-223596 it seems that fuel economy has taken a real hit in the last few years due to emissions requirements.
Now, we see "Obama Signs Order to Boost Trucks' Fuel Economy"
Obama said the government believes that "we can increase fuel economy by as much as 25% in tractor trailers using technologies that already exist today."

http://www.ttnews.com/articles/basetemplate.aspx?storyid=24442

(There was a discussion in Pat's Pub, but this is a better place to discuss this.)




Jay Maechtlen

http://www.laserpubs.com/techcomm

 

[JayMaechtlen]

My (truck owner/operator) sister's comments:
"Funny about the fuel mileage, California put new clean air standards in for the trucks and it reduces the fuel economy.... And the really sad part of all of this is they think we want 6 or 7 (excellent mileage!) and they get 4-5 on some of the new ones, and we'd love 10!! Of course then they would want to give us no money at all to haul the loads!!"


Jay Maechtlen

http://www.laserpubs.com/techcomm

 

[drwebb]

This will be an area of continuing focus. ExxonMobil forecasts through 2030 "The major projected growth in transportation sector energy demand comes from commercial transportation, including heavy-duty trucks, airplanes, ships and trains."

http://www.imakenews.com/lng/e_article001768040.cfm?x=b11,0,w

 

[EdDanzer]

There is a program called 21st Century Truck that is to address the fuel consumption issues in trucks. These links will provide some background.

http://www.osti.gov/bridge/purl.cov...36888FE8253B2A088?purl=/777307-BKSUFs/native/

will allow you to download an early document 21CT-001

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/program/2005_ace_merit_review.pdf

is a 2005 review that shows very little progress has been made.

When I was trying to obtain funding for hydraulic drive train R&D it became apparent there was no room for small companies with the possibility of disruptive technology to be funded. Until there is a technology change in direction there will only be minor incremental fuel economy improvements.


Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[rmw]

Or until someone takes the plunge and makes some major change. When Kenworth came out with their "anteater" cab design some years ago, they were nearly laughed out of the market place, but they stuck to their guns. Boxy fronts were the order of the day back then.

Now, look at the aerodynamic truck cab designs. It was a bold move for the time.

Same with Detroit Diesel when they introduced the Series 60 Engine. I still remember the derisive laughter at their booth at the USA's major truck show (at the time). My comment was that if I were a Cummins or Cat engine salesperson, I'd be quaking in my boots. I was laughed at too. But as they say, 'the rest is history'.

What will drive change is the ability to produce a product that will be profitable to the maker, not governmment platitudes and mandates.

rmw

 

[tbuelna]

Heavy truck diesel engine SFC made rapid improvements starting in the late '80s, mostly due to high pressure digitally controlled fuel systems. Later on, when the NOx emissions requirements got strict, SFC got slightly worse mostly due to use of increased EGR rates.

Increasing heavy truck fuel mileage by 25% over current rates is a bureaucrat's pipe dream. They've already grabbed the low-hanging fruit. Any improvements going forward will be incremental at best. Maybe 1% per year with lots of hard work and luck.

This legislation will be just as successful as the law California's legislature passed back in the '90s mandating that 10% of all cars sold in California as of 2003 must be emissions free. What a flop that was.

 

[JayMaechtlen]

Comments from my sister the truck owner-operator:
"We have tandem, dual tire drive axles. "Super Singles" are great in certain respects, and I would change except there are no "automatic chains" currently for them. I need the ease of auto chains!! Another item possibly required in CA is a skirt on the side of the trailers that streamlines the air around the trailer but they are in the way if you have to back down into a dock, as we do so often. There are a couple of other small things I am very much in favor of and just haven't done yet due to lousy economy and I'll probably have to replace the truck soon, and with the new engine requirements of course the trucks are now worth zero!!
What fun!"

Just one set of observations/opinions from the field.
Regards
Jay


Jay Maechtlen

http://www.laserpubs.com/techcomm

 

[dicer]

I can think of many things that can be done to decrease fuel consumption on large trucks. Since they have DEF to cancle the NOx now, we don't have to worry about that.
Ridding the trucks of manual transmissions is the first place to start. The constant power down and power up to shift, as well as having a driver determine shift points is all old school and a waste of fuel and power-fuel.
Anything that adds inefficiencys to the combustion process needs to cease. Dilution is not the solution. Heat recovery is very important.

 

[rmw]

Dicer,

I think if you will check you will find that modern "manual" transmissions are almost as automatic as automatics are. All the driver has to do is get off in first and the rest is up to the computer which selects shift points abased on lots of stuff that drivers might not have considered. Gone are the days of having to do all the thinking.

JMac..,

I was in the industry when super singles were introduced. I am no longer associated with the industry (for which I am eternally grateful-ask your sister) but I am truly surprised by the numbers of super singles I see on the road today. It will come when market forces drive it. And market forces may include abusive taxes. European trailers commonly have 3 axles with single tires rather than the more common USA version of 2 axles, dual or super single tires.

When I refer to taxes, once the tire size 11:24.5 was the most popular on the road. Then the government imposed taxes on tires on a per pound basis and suddenly the 11:22.5 tire (which you couldn't give away before) became the most popular tire size out there. If the government imposes some kind of "dual tire" tax, watch super singles mystically magically become the 'king of the road.'

What the government goons can do the industry scares me.

rmw

 

[YvesLLewelyn]

RMW - Sorry to be a bit ignorant but what are these modern "almost automatic" manual gearboxes you refer to?

 

[ornerynorsk]

Trains. There is not a truck on the road that can match the fuel efficiency.

 

[globi5]

Btw, this commercial 40 ton truck got 12 mpg with a 25 ton load and 50 mph average speed:

http://www.daimler.com/dccom/0-5-1087728-1-1087768-1-0-0-0-0-0-8-7163-0-0-0-0-0-0-0.html

 

[ornerynorsk]

That is impressive for an OTR Truck.

 

[patprimmer]

Despite the widespread availability of trains, trucks still feature strongly in long distance freight haulage. There are reasons that have already been discussed ad nausium.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[rmw]

YvesL...,

Here is one that I had in mind when I made the statement.

http://www.roadranger.com/Roadranger/productssolutions/transmissions/autoshift18-speed/index.htm

There are several other options on this site that you can look at.

Note, these are not "automatics" in the sense of torque converter operated automatics - they are shift by wire manuals with electronic control of the clutch mechanism.

rmw

 

[dicer]

Semi auto's can not be power shifted, gear sets need to have speed matching. Clutch packs are much better, like in Allisons, ZF's etc.

Trains? Take for ever to load, unload and still the product ends up on a truck, too much handling the product.
For large items, and large bulk they are great.

 

[rmw]

Power shifted??? We are talking about trucking, not racing.

The transmission changes gears just like a purely manual transmission does-except for the shifter mechanism, the gear box is the same as a manual transmission. The computer merely controls the engine rpm to allow the mesh speeds to permit the gear change while a mechanism moves the sift forks and clutch (if required) accordingly.

I never drove one, only the types that I had to do for myself, but at that, I could shift my 13 speed about as fast as I could romp on the fuel pedal. And this was without touching the clutch pedal except to get off in first.

The difference is that the computer does a better job that I could have with respect to keeping the engine at the best shift point with respect to fuel economy.

ZF's and Allisions are pure automatics, a different discussion.

rmw

 

[dicer]

Caterpillar made and installed a powershift transmission in their dozers. The term powershift means it can be shifted at full load at governed speed. I'm not talking about invented drag racer terms.

And yes that was my point, the engine speed needs to be fluctuated to shift, where as in the torque covertered and clutch packed automatic slash powershift transmissions the engine power and load can be fairly constant. Everytime the engine is burbed in load and speed it takes more fuel to catch it up. Simple test done years ago by GM when they made the powermatic transmission proved the increase in fuel consumption for manual shifting. Yeah it was carbureted gasoline engines, but still the same principles apply.

 

[globi5]

Also, aerodynamics alone can improve fuel efficiency of an OTR truck up to 12%:

http://www.sciencedaily.com/releases/2008/06/080611154206.htm

http://www.sciencedaily.com/releases/2008/04/080417105446.htm

 

[patprimmer]

Also, on road, for a fully loaded truck going up a steep hill, considerable speed and inertia can be lost in the time it took to do a double de-clutch gear change with the big heavy truck gear sets.

With diesel engine typical narrow power bands, you could need the next lower gear again by the time you selected the gear you where going for. With really bad luck and a minor miss management you could end up in no gear at almost a standstill, trying to engage low gear and still retain the very slow rolling start and not have to hammer the clutch to do a standing start on a steep hill.

Very quick reliable changes that minimise lost inertia are a real advantage for fuel economy and time saved.


Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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