Semi's and Ecomodding
 

A couple weeks ago I was surfing Ecomodder and read a post about potential ecomods to semi's and tractor trailers.

Then last week I was up in around the St. Louis area when across the divided hwy in the on coming lane I see this semi going north on 44 with what looked like a trailer skirt on the bottom of his trailer he was pulling.

It looked like a flat piece of material that stretched from the back of the tractor's wheels all the way back to the rear wheels of the trailer. The back of it was cut in a half circle against the rear wheels and it hung about 6" off the hwy. There was one on both sides of the trailer.

I thought it was kinda cool. Anyone else see any trucking companies doing this? This is similar to what I saw -

http://www.midwestspl.com/semi.jpg

I haven't seen it first hand, but I know others have reported seeing them.

FYI:
Wal-Mart Seeks to Double Truck Fuel Economy by 2015

http://www.greencarcongress.com/2005...t_seeks_t.html

Trailer skirts are just one of several aero fixes they're pursuing.

wal-marts going cheaper! :D That's cool though, makes my stuff cheaper too! :thumbup:

I have seen trailers fitted with these coming into my shop. Working on them is not an issue with the skirts either.

I bet truck skirts will get REALLY popular once people realize that it's a great place to slap on some more ADVERTISING!

Check out the pics in this link. They say the mod could save thousands a year.

The Why Files | Truck rear end: it's a big drag

Guys, semis were some of the very first eco-modders. See that deflector thingy above the cab? Companies were adding aero devices such as this going all the way back to the 80s. Becasue they run mostly on the highway, they understood the value of enhanced aerodynamics. :thumbup:

HEHE Ken Visser is my instructor for an Aircraft Design Class this coming semester. I believe he drives an EV but i may be wrong.

I saw a DHL truck a couple weeks ago with skirts. The leading edge of the skirt actually started a little in-board so the wake from the truck wheels was diverted to the outside. I wonder if it had a flat under-body....

More semi stuff:

http://www.solusinc.com/pdf/SOLUSL&MLicOpp.pdf

My company uses side skirts on their straight frame trailers. I pulled the same trailer loaded (17k-25klbs cargo weight) and empty. Loaded I managed 9.3 from NE Tennessee up I-81-I-78-I-95 (NJTPK) - I-278 (Tolls into Brooklyn, NY) - I-495 to mid-Long Island, NY. I'm not sure of the empty MPG, but from Long Island through all the start and stops for tolls and traffic, I still manage 10+ from Long Island to Cleavland, OH. The next time I pulled a trailer without skirts in moderate wind, I stuggled to get 8.

edit:
Our trucks have all this, plus a more aerodynamic tractor.

http://bioage.typepad.com/.shared/im...ed/walmart.png

Update:

I have been on vacation (at home being sick this week). My truck was left at the terminal 5 hours away in Nashville supposedly getting fixed/serviced. I hitched a ride back yesterday to pick it up, and low and behold, the first thing on the list, the A/C, wasn't fixed, so I stayed around till this morning when they came in. While they were working on my truck, I was talking to the mechanic questioning him about the suggestions of blocking the bumper openings on my truck which led to my reading up on ecomodding, etc. He said he just got back from the home terminal in S. TX and the guy that specs the trucks they buy, is a engineer wiz of some sort and has working test trucks and trailers with alot of the mods mentioned in these couple of truck threads. The boattailling mockup linked above, they supposedly have it where when the truck is at road speeds, it extends into a boattail kinda thing. When stopped, it automatically closes. It's attached to the doors, so it doesn't have to be removed to load/unload. I asked about over length laws. He said, it's not illegal if it closes when you're stopped. Not sure if that's true or not.

Other aero mods they're working on are placing wedges infront of the landing gear and in front of the trailer axles.

This is exciting news, BUT, if they're making it (almost) foolproof to for trucks to automatically get a minimum mpg, how long will they keep paying a bonus? We'll see.

On a final side note, the guy that I rode back with was driving my truck. He joked that he was going to watch me drive, because he cannot figure out how I have been getting 8.5-9mpg, and in the three days he drove the truck, the best he did was 7.7, and the worst was in the 5's. lol. But, when it came to it, he drove back. It took every thing in me to keep my mouth shut and not be a back seat driver. I thought, as long as the computer system is recording this mpg under his name, I don't care. We were empty and he would start in second and max out every gear -- hard. I was going nuts. I'm back to work now (well, sunday) and going to try to get back into the mpg groove...

Can you draft other trucks safely? I've seen convoys of 2-3-4 trucks driving together around 5 car lengths apart not sure if they do it for company or whether they are trying to draft, seems like it'd help all the trucks involved if they took turns trading spots but I don't know how safely you'd be able to do it if something happened with one of the trucks.

No, you can't, especially not heavy trucks.

The drivers that do are usually doing it out of habit and have never been bitten by it. Alot do it because they're impatient. I guarantee O% of them are thinking fuel mileage. Years ago, I drafted another truck just using the NASCAR rule to see if while on cruise, the lack of resistance helped me gain on a truck that just passed me. It did for a second or two, but none of my other driving habits were geared toward saving fuel.

5 years ago I had a rear end collision. Luckily in the grand scheme of things, It was minor. It did take me several years to get where my a__h__ didn't draw up every time I saw brake lights 1/2 a mile ahead. lol.

Sorry for the downtime between posts. I've been really busy with no updates.

I have been keeping up with my mpg, but the computer system (sat com) went on the blink and quit sending mpg data to my company, so I missed out on my bonus. I know I got it, but I had to go to our main terminal to get it "fixed". Short story, they didn't get it fixed. I changed into a truck that was operating properly, but had a different motor. Anyway. I'm still fighting for my bonus money for my 8.65 mpg last quarter, but the dummies reprogrammed my ECM before downloading the mpg data. They said they would give me the bonus but we'll see.

The truck I got out of had a Cummins motor, with the company, historically got the best MPG. The truck I just got into has a Catapillar. Cats are known for their superior HP and Torque, but not fuel MPG. For the first few weeks I've been in it, it's definately been a challenge to get over 8 mpg on a consistent basis. I'll keep you updated on my progress there.

While at the main terminal, I noticed an older truck, one that they'd turned into their test model. The aero mods I understood. They're all things I've read and talked about here.

Grill Blocking
Masking Tape Grill blocking test.
Bridging the gap


Can you tell me what they're testing here? It looks like a fuel cell, but not sure.
Cell / Tank
Maybe some hydraulic tank/pump system. Notice the cooling fan mounted on the left of the tank.

Inside the truck in the floorboard between the seats, going to and from that tank via the gearshift boot. Sorry it's not clearer; it's taken with a blackberry cam.

floorboard

Finally, the instructions taped to the dash.


I couldn't make heads or tails of this.

I've been seeing skirts since last fall, but last Friday, for the first time I saw a trailer with a kammback on the road.

I've seen a good few of those side skirts on trailers. I've also seen the front top corners of the box tapered down to match the deflector on the roof of the cab. Nice! But i've seen no rear end work done on anything yet.

ollie

I wonder if they're trying a hydrogen on demand system.

I've always wondered if Truck drivers modded anymore. I know they used to, but I just figured people in the last century or so just stopped caring. Or has it always been like that? :S

trailer skirts
 

Seen a few.Mayflower Moving uses a rigid compartment under their trailers for dolly and blanket storage,etc.,and get the aero benefit to boot!Good business practice.

once a torque curve for a given fuel gets what it wants... a trailer skirt for a diesel turbo seems quite silly. The conventional front end designs do help the most, the rest of airstream is just going to get thrashed anyway.
Its like putting a little wing on the space shuttle as it takes off vertical. the fuel just simply overwhelms the function. Little gas engines notice it, especially inlines, as they have a knifes edge torque curve and constant fiddling for bad design reasons on all of them...in contrast (I have joked of this several times) a 2700 pound subaru with a little boxer could care less about a roof rack opr radiator cover making a wall of the front end. Concerns for aerodynamics is a concern for enough power to overrule it casually...and it really can be. I ahve been growing up with trucking for over 30 years, from the 1970s horrible cbovers with 290hp to the 550hp common now..and ya know what? they use the same, but the 550 is much more casual with a bigger load. I learned to target other things (like lube) for cars and trucks, and if not enough, it needs a bigger engine to be casual, and then start saving. Today is goofier than ever, after carb standard disappeared. injection could do anyhting at any moment, the soft bodies of new make change invisibly. It is the concern for today and aero mods, I am certain.

FedEx uses belly-type trailers... the "belly" is what acts like the skirt... they figured out that they could load another few cubic feet of stuff in the trailer that way, and slightly lower it's center of gravity.

I was told we have a test trailer too, with "flaps" that open up into a kinda' boattail -- as shown in pictures above. They said they have it rigged where it closes when stopped and opens in motion. In theory, the DOT cannot get companies for over length trailers because they close below a certain speed.

The guy that does all the testing also said that the side farrings are being looked into. They've found a rigid, yet flexible rubber material where they can bridge the side gap between cab and trailer, but also allowing it to turn up to a 90 degree angle, and it return to it's original placement afterward. We'll see.