trailer loading

[Mtngoat]

This may have been covered before, but I couldnt find it.



My example:



A triple axle 48 foot wedge trailer weighs 7800 lbs. It has 3 axles rated at 7000 lbs. Now, if you deduct the 7800 lbs. from the 21000 lb axle ratings, does that mean you can load vehicles with a total weight of 13200 lbs? My dually weighs 7440 lbs, so I could only put one dually on that kind of trailer?? Can that be right or am I missing something? I would assume tongue weight comes into play somewhere. .



Robin

 

[knewman]

That is how it works for dot and trailer capiticy but it is over the limit of the owners manual but i have hauled 20000 on my trailer many times it has 2 12000lb axles though when I hauled for a living i tried to stay under 16000 for my setup because one of my trailers weights 8000lb empty the other 8800lb

 

[EB]

The most we will carry on a mini-float is 16,000 payload. Most of the trailers will weigh 7-8000 lbs and that will put right at gross wt. (24,000 lbs) Doesn't always work that way, sometimes picking up at rigs, you will get over-loaded, but we try to keep it at 16k or less.

 

[Mtngoat]

So, is gross weight determined by the capacity of the axle??

Three 7000 lb axles mean the trailers gross weight is 21000 lbs?



Robin

 

[RustyJC]

How does your pin weight factor in? For instance, my 5th wheel has a GVWR of 13,500 lbs, but a combined GAWR of 12,000 lbs (2 each Dexter 7,000 lb axles, but limited by the 3,042 lb rating of the LT235/85R-16E tires). Loaded and on the road, the 5ver weighs right at the 13,500 lbs but carries 10,800 lbs on the axles and 2,700 lbs as pin weight transferred to the truck's GVW and counting against the truck's GVWR.



It's common practice for 5th wheel RV's to have combined GAWR's significantly less than the trailer's GVWR since they know that 20% or so of the trailer's GVW will be carried by the truck as pin weight.



Rusty

 

[EB]

My truck weighs 8200+ - depending on fuel. My trailer weighs 7000. The last time I weighed on a Cat scale my total gross wt. was 28560. The payload was 13360. It balanced out like this, I had 4660 on my steers, 6920 on my drive axle, and 16980 on my trailer axles. Also went across DOT scales with that load and had no problems. My truck is licensed for 14500 and my trailer is licensed for 24000, giving a total gross wt of 38500. I'll never get that heavy combination, because of the 16000 limit on the trailer that my company places on mini-floats, but I have carried over 6000 lbs. on my truck, which is why it is licensed for 14500.

 

[Mtngoat]

I may not be catching on. I guess basically I am asking: If a trailer has 3 7000 lb axles, is the total allowable weight on that trailer 21000 lbs including the weight of the trailer? Sorry if I'm being dense.



Robin

 

[RustyJC]

Robin,



What is the tagged GVWR of the trailer? That's why I gave you the example of our 5th wheel RV. It has a GVWR of 13,500 lbs but a GAWR of 6,000 lbs x 2 axles, or 12,000 lbs. The difference is pin weight.



The most your trailer can put on the trailer axle scale platform is 21,000 lbs, but it can (and does) put weight on the hitch as well, so the trailer's GVWR could be higher than 21,000 lbs. It just depends how the manufacturer handles his ratings.



Rusty

 

[Mtngoat]

I dont have a big trailer like that, maybe someday, I was curious about these 3 and 4 car wedge trailers with 3 7000lb axles and whether or not they are legal... Not that is a big deal to me, I just heard a few days ago that some insurance companies are going to start weighing vehicles and trailers involved in accidents, and if your overweight, you may have a problem collecting from them. Maybe true or not, but it is what I heard.

Sounds like you can only put one dually on one of those and be legal. I don't know I was just curious.



Robin

 

[CFAR]

Generally the trailer would be tagged at 21k. Some of the weight on the trailer will be pin weight, if you were to put 14k on the trailer and the trailer weights 7k, then went and had it weighed, the trailer axles weight would be less that 21k.



So technically I'm confused.



If the pin weight of the trailer averaged 10% of total trailer weight you can put a total of 16100lbs on a trailer weighing 7k. Make more sense? If you ran this combo over the scales the trailer axles would weigh in at 21k.

 

[knewman]

there are so many ways to read the many laws for hotshot trucks that the dot officers and i happen to be running buddies with one and he says most officers specialize on different things in particular but they are catching up quick. I remember one guy in dot in Austin that gave me good info about hotshot trucks and weight formulas for tire width for axle limits can't remember how he put it though do remember gross limit of 35000 for trucks with hyd brakes i think.

Plus you can't be over capt icy for you axle rating

 

[Fireman]

Mtngoat,



You said it's a wedge trailer, so I must assume it is a gooseneck. If so, the hitch should carry 20-25% of the trailer weight and the axles would carry the remainder. Therefore, the trailer should be capable of 28,000# GVW. You should be able to carry a payload of 20,000#, of course that would exceed the GCVW of your CTD.



Anyhow, that is the way my feeble brain perceives it.



Does the trailer not have a tag stating the GVW? It should come from the mfg. with one.



Fireman

 

[Mtngoat]

Fireman-



I dont have a trailer, I was looking at them on the internet, and this question came to mind. .



Robin

 

[Loren]

Robin,



Fireman has it exactly correct. The legal and safe way to determine the capacity of a trailer is to look at the tag on the trailer.



A gooseneck trailer with three, 7000 pound rated axles will typically have a legal capacity of more than 21,000 pounds due to fact that some of the load is carried by the hitch.



The math is as follows:



Capacity of the three axles: 21,000 pounds

Loaded hitch weight (estimated): 3,000 pounds

Total capacity: 24,000 pounds



Minus trailer weight: 7,800 pounds

Payload capacity: 16,200 pounds



This is how the math works, but the bottom line is always the capacity as listed by the manufacturer on the trailer. You also need to stay within the capacity of your truck, regarding GCVWR.



I know that drivers tow over capacity every day, and I have done it myself, but that doesn't make it safe or legal.



Loren

 

[Eric_77]

Ah you don't add tandems unless they are spread axles. I don't rememebr the exact formula for three axles but two 7500 axles is only GVW at 13,500 so 90% of rated axles combined ratings.



Triple axle I think is less than 90%(75-80% I think) but unsure.

 

[EB]

I guess this is a subject about like oil and transmissions. If you want to know for sure, ask a DOT officer, or stop in at a weigh station and ask questions until you are satisfied and understand. Be aware though, that different officers interpret the law differently. You can't win in that case. I've had that happen.

 

[Mtngoat]

EB-



Sounds like your right. Well, if and when I get a big trailer and do some hauling, I'll just load it like the manufacturers say and be done with it!



Robin

 

[TND2]

Ive got some info relating to VA laws on axle weights, i dont know it how it applys to hotshots or CTD, but the axle weight, and gross cannot exceed the manf. specs.

Single axle-20,000#

Tandem Axle-34,000#

If you have a spread axle trailer(axles 9' or more apart) you can carry 20,000# per axle

Tripple or more axle groups are determined by distance in feet from axle to axle of the outside axle of that group(Class 8 rig, 9' total tripple=42,500# for that group

Max gross 80,000#

The catch is:650# per square inch of tire surface that is in contact with the road surface!

Also VA uses a bridge formula that is related to the distance from axle to axle over the entire rig to govern gross weight reguardless of the per axle.

Now to mix this up, some conditions allow for overweight permits, example we have a 7 axle 65' axle to axle rig that can gross 125,000# legal, instead of the 80,000# limit.

Sorrry for the length.

 

[RustyJC]

Originally posted by TND2

Ive got some info relating to VA laws on axle weights, i dont know it how it applys to hotshots or CTD, but the axle weight, and gross cannot exceed the manf. specs.

There's the kicker, isn't it?



Rusty

 

[Loren]

Eric,



An excellent point about the spread axles. I had forgotten all about that from my pavement design classes in civil engineering school, but even then (late 1960's) tandem axles were not allowed to carry the same weight as two separate axles.



Another good reason to use the data plate on the trailer as the final word on capacity.



Loren