Aerodynamic Truck

Shepherd777

Rookie Expediter
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I gotta hit the hay. I already put in a full day-and-a-half, today. If there is further interest, I can contribute tomorrow or possibly the weekend.
 

Shepherd777

Rookie Expediter
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This might interest you of a straight truck with a trailer tail:

Fuel Mileage update with Trailer Tail

Hi Bob -

That's a beautiful rig as well and a great demo of the TrailerTail on a straight truck. I'm not going to comment too much more on your rig because you are affiliated with a large OEM, and I hate all of the large OEM's. Nothing personal.

Have you addressed the space between the rear of the Freightliner skirts and the front of the box skirts yet? I think that would be my next step.
 

layoutshooter

Veteran Expediter
Retired Expediter
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Hi Layoutshooter -

Yep, that helps, some. Do you have any pics of the rig that you can reply with?

3.58:1 is relatively low gear differential gearing.
What RPM's are you turning at your normal cruise of 65 MPH???

I personally don't like 10 speeds. The engine is out of its "sweet spot" a lot. I can elaborate if folks are interested.

Why two axle drive? Slippery conditions? If so, why not just computer controlled tag axle?

Why a top mount TCU? Please explain and add pics if possible.

Also, how many miles do Expediters average per week? Per year?

I will send some pictures this weekend.

The top mount for the TCU is better for the TCU. Less salt, road dirt, etc. They run cooler and last longer when top mounted.

My normal cruise range is between 57-62MPH. Tach reads 1300 at 62.

The axles set up would be more for load distribution than anything.

I am running, 22.5 tires, on everything but the lift axle.

An average mile per week is hard to do. We run about 100K per year.
 

Shepherd777

Rookie Expediter
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I will send some pictures this weekend.

The top mount for the TCU is better for the TCU. Less salt, road dirt, etc. They run cooler and last longer when top mounted.

My normal cruise range is between 57-62MPH. Tach reads 1300 at 62.

The axles set up would be more for load distribution than anything.

I am running, 22.5 tires, on everything but the lift axle.

An average mile per week is hard to do. We run about 100K per year.

Thanks for the update.

Do you have any idea what the RPM is at 57?

What motor, and do you know the Peak Torque RPM?

What is the bandwidth of that ten speed automated shifter? In other words, if the engine lugs down due to climbing a grade, what RPM does it downshift at, and how high do the RPM's climb when it downshifts?
 

layoutshooter

Veteran Expediter
Retired Expediter
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Thanks for the update.

Do you have any idea what the RPM is at 57?

What motor, and do you know the Peak Torque RPM?

What is the bandwidth of that ten speed automated shifter? In other words, if the engine lugs down due to climbing a grade, what RPM does it downshift at, and how high do the RPM's climb when it downshifts?

EatonFuller 10SP autoshift. The one WITH the clutch pedal.

It is an MBE4000 450HP. I am not sure of the peak torque RPM

RPM at 57 is around 1200

When it downshifts on hills it is around 1500

Attaching two pictures of truck, will take on of the entire rig when the rain stops
 

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moose

Veteran Expediter
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Joe, we did not know that your mansion have a 2 bay garage with room to park your rig inside!
 

layoutshooter

Veteran Expediter
Retired Expediter
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Joe, we did not know that your mansion have a 2 bay garage with room to park your rig inside!

I am White Glove you know! LOL!

That was right after I got the new box put on. It was inside where they put the signs on. When they still had nice looking signs.
 

zorry

Veteran Expediter
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Joe, I don't think you've ever mentioned that we didn't have RED signs until Obama got into office.,
 

Shepherd777

Rookie Expediter
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EatonFuller 10SP autoshift. The one WITH the clutch pedal.

It is an MBE4000 450HP. I am not sure of the peak torque RPM

RPM at 57 is around 1200

When it downshifts on hills it is around 1500

Attaching two pictures of truck, will take on of the entire rig when the rain stops

I just Googled it. Peak Torque RPM of all MBE4000 series engines is 1100 RPM.

The 300 RPM bandwidth spread of your 10 speed sounds about right. That is the only reason that I am not fond of 10 speeds or less.

In a perfect world, your truck would have a CVT (Constantly Variable Transmission) that would keep the rpm at 1100 all day long. The 13 speed Eaton RoadRanger that we had in the BulletTruck has a 150 RPM bandwidth. I am working with the nice folks at Eaton about spec'ing an 18 speed AutoShift for our new truck. It will have less than a 150 RPM spread. They are having their electronic engineers Flashing the PROM (Programable Read Only Memory) Chip to the shift points we want. I'll prolly just run an Eaton 18 speed in the prototype of the new truck to finely determine those shift points.

If it was my truck, I would just run it at 55 MPH if the expediency of the current load permitted. But that's probably just me.

You could also gain with full skirts, wide base tires, and a rear of truck aero device.

You would have to be real cognizant of not hindering the cooling of the Carrier TCU if you go with full skirts, of course. As long as the TCU radiator and condenser are on the inside face, you should be good. It may not even matter as I'm about 99% sure the fan on that unit is not clutched. Which means it will stay cool and not use any more fuel than it already does, without much outside air. I would add a remote dashboard mounted digital coolant gage for the TCU coolant if I added full skirts to make sure I was not hurting it.
 

zorry

Veteran Expediter
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The air above the cab is 30 degrees cooler than the air near road level.
Thats important to a TCU trying to operate in hot climates.
Thats a very big reason to use a top mount unit.
 

zorry

Veteran Expediter
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As a truck hauler we fought a constant battle of being overlength. Too much hanging off the front and or rear of our lowboys.
95% of our loads were illegal in Mich. This was very difficult being based in Flint.

Something that really ruffled our feathers as we dodged certain scales, altered our schedule to run certain areas after sunset, is that Reliable, Pilot, and BMT and other enclosed haulers often used nose cones, front and/or rear to give them more cargo space.

We chuckled that they got away with it while grumbling it gave them an advantage us open haulers didn't have.
 

Shepherd777

Rookie Expediter
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Yes. A Trailer Tail can be legally added to a 40' straight truck.

So have any of you guys ever thought about going with skirts and a rear aerodynamic device?

What MPG are you getting now?


Here's a little math on the BulletTruck. On one coast-to coast trip last year, we saved over $2500 in fuel.

We loaded in Farmington, CT and first stop was Tracy, CA. All the way from origin in CT to Cheyenne, WY we averaged 14.3 mpg. Then we hit 35 mph 3/4 headwinds throughout WY, and 40 mph crosswinds in UT. By the time that we delivered the first stop in Tracy, we had averaged 13.4 mpg coast-to-coast. We then went up to Hillsboro, OR to deliver the second stop. Then, we deadheaded up to Seattle to load a 2 stopper. First stop was in Austin, TX, second stop was Memphis, TN. We grabbed a motel on the 4th. of July in Memphis, then loaded next morning 20 miles south in Southaven, MS. We delivered that load later on Friday in Stephensville, KY. We loaded in Louisville for Cromwell, CT and back home. Average GVW of all loads was right at 65,000 lbs. We did only 6% or 7% deadhead on the total 8003 miles, if I recall correctly.

The national average for Class 8 rigs is currently right at 6.5 mpg.

Price of fuel in 2012 was right at $4.00 per gallon. And it makes the math easier.

8003 miles divided by 6.5 mpg = 1231 gallons of diesel fuel burned. 1231 gal. x $4.00 = $4924.00

8003 miles divided by 13.4 mpg = 597 gallons of diesel fuel burned. 597 gal. x $4.00 = $2388.00

So on this ONE run, we saved $2536.00 in diesel fuel not burned.
 

LDB

Veteran Expediter
Retired Expediter
Online
And if you paid attention to IFTA along the way when choosing your fueling locations it may have been upward of $2600 savings.
 

zorry

Veteran Expediter
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That is an item many overlook.
I've work for a few carriers that figured and PAID fuel taxes.
We just bought the cheapest pump price.
Today at 10 mpg+ and carrying 225 gallons I can buy when I want more so then when I have to.
I carry an additional 100 gallons of untaxed fuel for the reefer and APU.
 
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