Rgn center of gravity

Yes, you can carry more weight on 3 axles vs 2, that's why there is a third axle. Otherwise, all trucks would be limited to 80k lbs and be 5 axle setups because why add to the wear maintenance costs with more tires and more brakes. The exact amount you can carry will vary by state and manufacturer ratings for the particular setup, but in general, it's about 20k per axle.

 

After careful thought you are stating this:

`81000 pound item. 29 feet long.

Your deck is essentially 30 feet.

Your item appears to be even in it's own weight mass across it's length.

Ok... I guess 7 axles is next up.

5 axles give you 80000 pounds.

You are 7 axles assuming three axle semi tractor and a 4 axle trailer behind a 30 ish (One or two inches less but rounding for converstation) foot deck you probably are about maybe 34 feet between your rear set of 4 trailer axles and your tractor's drive axles.

I think you can bridge about 77500 on that 30 foot or 80000 on 34 feet axle spacing. The Federal Bridge Weight Chart tops out at 80000 at 7 axles.

NY State used to give maybe 117000 gross for example for 7 axles.

In anything you will want to double check that 81000 pound load against what states and where you intend to go with it. You probably will need a overweight permit to handle the extra excess. 81000 plus a tare of around oh... 34000 for tractor and trailer probably gives you maybe 115000 gross. You are going to be over on both axle and gross.

This is the extent of my careful thinking. I don't know if these educated numbers will hold up to what you are fixing to do with that load. It's going to be a permitted run for sure for weight over.

 

You are welcome. No sarcasm at all. Just working with ABC blocks trying to see where you are going with a 81000 pound load going onto your truck.

Now if your whole load including tractor and trailer grosses 81000 on 7 axles and only needs 29 feet of your total deck space of 29.11 then you are golden.

I already said earlier that my knowledge is limited. So instead of taking cheap shots at my limitations, maybe you can explain or expand further on the problems you have with my logic or thinking. We might actually have a understanding. But I think we are too far apart tonight.

Good luck with your load.

 

No problem, I misread what you wrote. I thought you asked if you could carry more weight, not that you were asserting that you can. My fault, sorry

 

It has been years since I have pulled a low boy much at all, but I tend to think the center light is going to be about load weight center with your flip up, maybe just a bit forward to compensate for the weight of the flip.

 

There is a way to mathematically calculate placement of the center of a load that worked for me for years.
You need a minimum 25 foot tape measure,an empty scale ticket and a calculator.
Measure the distance from the center of your drive axle group to the center of your trailer axle group in inches. Then figure the amount of weight you want to carry on the drive set(loaded minus empty) as a percent of your total load weight. As an example: 32000# plus 9800# mt wgt equals 41800 ( on 3 axles). Then your load wgt of 81000# divided into 32000 is 39.5%
Now measure 39.5% of your distance of your axle set to axle set center from the rear center point and put the center of your load at that point and your axle weights will be very close to what you want.
If I where you I would chart your measurements closed and at each open point as a 5,6 and 7 axle unit. That chart will serve you well as you run that unit.
I got a lot of use out of my chart after scaling each configuration at a closed DOT scale one long night. It saved on loading time every load from that point on.

 

Put some psi gauges teed into your tractor and axle bags, and in time with enough scales youll start knowing what psi is the no no zone.

For me its 45psi drives and about 67 psi spread. I know its not an immediate help but thats all i got.

You'll have to excuse X1. Hes off his rocker some times but he means well.