Bridge Weight Laws

[arky]

I need some help with something I've been kicking around a little. I have an '01 FL Columbia sitting in my driveway, but for now, I'm still driving for Maverick flatbed. My truck is actually a 24' straight truck (expediter).

I've been kicking around the idea of adding some lift axles and a flatbed to it and build a 24' flatbed straight truck. I would want to get as close to an 80,000 GVWR as possible.

My question:

If I add lift axles to the point that I have 4 rear axles (5 total counting the steer), how much weight could I legally gross? I would have approximately a 370" wheelbase from the front axle to the rear axle and 220" between the steer axle and the 1st rear lift axle. This is assuming a 50" spacing between the centerline of each of the rear axles (I think this is fairly accurate).

I would defintely make the two lift axles in front of the drive steerable. I would also have the option of adding some more space between the drive axle and the 2 steerable lift axles. How much space would be required to gain any GVWR?

The bridge laws are fairly confusing to me. Can anyone explain it?

I don't think i would gain anything with this set-up over a traditional t/t flatbed. The straight truck would be a breeze to get around in though. I know that a large percentage of the loads I pull at Maverick would fit on a 24' bed, but I'm not sure if I can get the GVWR up high enough to have a decent payload.

Thanks for help on the bridge laws.

Arky

[Uturn2001]

If you travel in an area that utilizes the bridge formula there is no way you can get 80,000 lbs, regardless of how many axles you put on it.

Basically the bridge formula boils down to, the more space between sets of axles the more weight you can carry, and while I do not recall the exact number for 80,000 it is over 40 feet.

There is a chart in the front section of the Rand McNally Motor Carrier atlas that tell you how many feet you need between axles you need.

[jorlee]

Take a look at this 79,000 gross. http://www.truckpaper.com/listings/d...3D9D20AE1182EC

The catch is it's a 26 ft bed, and is just full of axles, with a fat tire up front. I'd sure hate to buy tires for the darn thing.

[Orangetxguy]

Take a look at this 79,000 gross. http://www.truckpaper.com/listings/d...3D9D20AE1182EC
The catch is it's a 26 ft bed, and is just full of axles, with a fat tire up front. I'd sure hate to buy tires for the darn thing.

Arky...why would you want a straight truck expediter unit capable of handling 80,000 pounds? Has someone given you an indication that such a unit would be in demand? Most expedited loads do not fall into the 80K arena. Most of them don't even fall into the 25K arena.
Talk with the companies you plan on working with and find out what would be the best design for a straight truck. I can see one...even two lift axles on such a unit...but not so many as are on this unit in Jorlee's post...which is a function specific unit. It's designed for hauling grain.

[arky]

I do have some specific things in mind if the truck could be built. I would have no intention of doing expedite work with it in this configuration. I'm just looking at options mainly.

The thing that confuses me is that I see dump trucks all the time that are quad axle. They tell me they are legal to 73,280. That is most likely in AR and could be different in other states I'm assuming.

Thanks for the help.

Arky

[arky]

OK, I found what I was looking for. I had looked at the RMMCRA before but never fully understood the system. They show a link to a download on their website though. This is a PDF file with basicly the same chart, but a good explanation of the regulations. They also have a good example to go by.

http://www.randmcnally.com/pdf/tdm/Federal_Bridge.pdf

I can use this to determine if what I want to do is feasable. For what it's worth, it doesn't look to be at this time. With a lot of work and money, I could ramp the GVWR up, but the cost would be prohibitive when compared to just selling the straight truck and going to a t/t combo with more marketability.

Thanks, Arky

[Mack2]

With that setup you would gross 67,500 on the fedral bridge law and have 54,500 on your inner bridge.

Is that wheel base from the middle of the front axel to the middle of the back axel if not you would need to add 27" to it.

[marylandkw]

I know you have already made your decision arky, but for future thread searchers and readers...

Realistically in order to get 80K on a straight truck you are going to end up needing a 20k front axle. This means you have to use those big meaty 425 float tires on the front. Those things are just no fun, grab every grove in the road and bounce you all over the place. It might be one thing in a dump truck on a job site but bouncing down the road all day it get old quick.

[arky]

Mack2 and MarylandKW are both correct. Yes, the wheelbase quoted is from center of the axles.

I don't have my numbers with me, but from what I came up with, I could possibly get the gross up to around 73k-75k with ALOT of work.

That becomes a trade-off. The straight truck would be a dream to get around in. I know there are some coil loads near me that pay decent, so I was thinking why not just set the straight truck up for that. The trade-off would be that it wouldn't be nearly as versatile and marketable as t/t.

I believe the empty weight would come out about the same as a t/t by the time I added all the axles and I just wouldn't want to do it without having around a 45k payload available. Unless I could definitely come with a good dedicated run, I wouldn't want to put that much into the straight truck.

Thanks for the help guys. I'm always kicking stuff around. I like thinking crazy stuff through. LOL

Arky