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US truck fuel economy and Obama's new rules
5

US truck fuel economy and Obama's new rules

US truck fuel economy and Obama's new rules

(OP)
In thread71-223596: Fuel Consumption Issues - TIER 3 ENGINES 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

RE: US truck fuel economy and Obama's new rules

(OP)
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

RE: US truck fuel economy and Obama's new rules

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

RE: US truck fuel economy and Obama's new rules

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.cover.jsp;jsessionid=ED86D43A3CAB0E136888FE8253B2A088?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
www.danzcoinc.com
www.dehyds.com

RE: US truck fuel economy and Obama's new rules

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

RE: US truck fuel economy and Obama's new rules

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.

 

RE: US truck fuel economy and Obama's new rules

(OP)
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

RE: US truck fuel economy and Obama's new rules

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.  

RE: US truck fuel economy and Obama's new rules

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

RE: US truck fuel economy and Obama's new rules

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

RE: US truck fuel economy and Obama's new rules

3
Trains.  There is not a truck on the road that can match the fuel efficiency.

RE: US truck fuel economy and Obama's new rules

That is impressive for an OTR Truck.

RE: US truck fuel economy and Obama's new rules

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: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
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RE: US truck fuel economy and Obama's new rules

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.  

RE: US truck fuel economy and Obama's new rules

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

RE: US truck fuel economy and Obama's new rules

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.

RE: US truck fuel economy and Obama's new rules

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: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
 

RE: US truck fuel economy and Obama's new rules

(OP)
Cost of blipping a carburated gasoline engine is probably far greater than with a  diesel engine.
In fact: if a diesel is under load in upper rpm and dragged to lower rpm by power shift, what is change in airflow versus fuel flow? Does that cause a brief overfuel condition?
Does dropping the load and picking it up again (during the non-power shift) result in worse or better net fuel combustion?

Jay Maechtlen
http://www.laserpubs.com/techcomm

RE: US truck fuel economy and Obama's new rules

Purely hand-waving...

If a diesel were subjected to a sudden decrease in engine speed at full load, I'd expect it to lean out until the turbo slowed down.  Fuel injection quantity (unless mapped to engine speed) shouldn't change.  Boost pressure would temporarily be higher than the steady-state condition.

- Steve

RE: US truck fuel economy and Obama's new rules

... I meant quantity per shot, not fuel flow rate.

Maybe quantity per shot is also mapped these days with common rail.  It never was with mechanical FIE.  Maybe modern truck engines have clever control systems to run the engine during rapid transients?  Some light-duty diesels have such systems.

- Steve

RE: US truck fuel economy and Obama's new rules

Dicer,

Every HD vehicle automatic transmission (torque converter type) I have ever encountered operated where the engine to change RPM as it shifted through the various gears.

The only difference between them and the manuals was that the transmissions shifted when they wanted to, not when the driver chose to make the shift and did it without clutch action - the torque converter took care of that.

Maybe someone can adapt the Cat powershift transmission to HD vehicles and Obama can get his fuel mileage increase out of it.

rmw

RE: US truck fuel economy and Obama's new rules

Maybe this is stating the obvious, but an immediate and cost-free approach to reducing the amount of diesel fuel used by trucks on US roads would be for Obama and Congress to quit over-regulating and over-taxing US businesses.  If more goods were produced within the US, they would not have to be trucked in from places like Mexico.

Encouraging production of goods domestically and closer to their point of sale would also have the added benefit of reducing prices.

RE: US truck fuel economy and Obama's new rules

You may find the CAT powershift a bit heavy, in reality it is VERY heavy, but the transmission weight really isn't an issue in a bulldozer is it?

CAT actually had an on road automatic transmission under test for a number of years, along with a turbine based on road truck driveline.  The tranny was a beast, nearly indestructable, but nearly twice the weight of a competitor at the time.  Can't remember the model number, but it was a commercial failure and got shelved.

In the early to mid 90's CAT spent a ton of money on owner and driver education, and getting the best possible fuel economy.  They made significant improvements and worked with truck builders to come up with some helpful changes. In earlier electronic engines they introduced "advance on steady state" timing strategy, which helped fuel economy with very little negative impact on emissions, but ended up costing them (and some of the other manufacturers who tried the same thing)millions of dollars in fines to the EPA.

I think in a nutshell in this country we don't have a well integrated energy and environmental policy, it seems the two get in conflict not only in trucking but in other areas, like marine and electric power as well.  I did some cogeneration projects in Denmark and Holland in the late 90's and was impressed by the emissions regulatory people I met, as they seemed to be more technically proficient in engine technology and their related emissions, and would actually try to help improve a system instead of just "whining and fining" like so many of the regulators I dealt with here at home.

RE: US truck fuel economy and Obama's new rules

today,the big deal is gear it to run fast and drive slow.this works good on flat land and no restrictive winds while under cruise control,which all truckers select.climbing hills,windy conditions,rain effect mpg as we all know.this doesn't cause it to go lean,it's removing the air from the equation and lowering volumetric efficientcy.you can't run a diesel in a high load demand under full t/position and expect it to get near same results as less load stress.under these conditions using c/control should be eliminated.the closest you can get to 100%of V/E is @peak torque.peak tq is above 1600rpm.egt and boost guages should be used extensively for mpg,higher manifold press and egt means less mpg.learning how to use the operation of the motor needs to be relearned . more mpg can be obtained just by letting air catch up to fueling under load in a 2 second delay manner while accel and will gain a 10%boost in mpg.

RE: US truck fuel economy and Obama's new rules

All modern diesel engines have fuel injection quantity per shot mapped to power demand, intake pressure and temperature, etc and modern control systems are capable of recalculating the required injection quantity and changing it for each individual shot. If engine rpm changes rapidly then the injection quantity will be recalculated before the next injection shot happens. Transient conditions with regards to the fuel delivery aren't an issue any more. Also, if the turbocharger comes off boost during a long manual gearchange, the new injection quantity will be automatically recalculated to compensate for this. No more puffs of black smoke on taking up the load like in the old days, and no more wasted fuel making that puff of smoke.

Having said that, I don't think manual vs automatic vs powershift or whatever you call it is the main culprit behind higher truck fuel consumption nowadays. Maybe in mountainous areas or in city driving there might be some effect, but most long haul trucking is done at more or less steady speed on main highways, and then the only thing that matters is how mechanically efficient the transmission is (and whether it's geared appropriately to the engine).

It's the emission controls. Injection timing has to be moved away from best-BSFC settings in order to cut engine-out emissions and/or regenerate the various catalytic converters.

I don't know if the heavy trucks are using active regeneration of their DPF catalysts but if they do (like the new VW diesels and pickup truck diesels do) that's costing some fuel consumption. The new VW diesels have higher fuel consumption during real world city driving than the previous pre-DPF models. On the highway, they're not too different, perhaps even a little better (but they've got the benefit of gear number 6 in the manual transmission).

Engines that are using in-cylinder NOx control are probably compromising fuel consumption relative to those that are using SCR and AdBlue. Even on those using AdBlue, if the compromise has been shifted towards cutting engine-out NOx in the interest of cutting AdBlue consumption, that could cost something.

The envirofreaks fail to realize that you cannot achieve perfection and you cannot have everything your way.

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