Hauling Capacity question

I looked at a tandem today and I'm trying to figure out the hauling capacity of the truck. The truck is rated at GVWR 51200LB with FGAWR 13220 and RGAWR 38000. The guy said he can legally haul 15 tons but that seems hard to believe unless I missunderstand how it works. I asked if it came from the factory as a dump truck but it doesn't have a double frame and and with a 13k front axle, this would have to be a road tractor conversion, right?

That would be a light duty tandem ........ as compared to one with big rubber (425x22.5) fronts & an #18,000/#20,000 F/A + at least a #44,000/#46,000 R/A ....depending on the Tare GVW of the truck would determine what you will be able to haul ...... we use a round and dirty calculation of #3200/yd for clean damp gravel (not dry & dusty ...lol)

Here we are allowed 9100kg over the front + 17,000kg on the rears axles GCVWR...or... ~#20,000 F/A + ~#37,500 GCVWR ...... you will want the big rear diff's to be able to pull a decent trailer loaded ........ if you are given any ID number for rear diff's .... the older diff's from Rockwell were called SSHD 44,000/ or a 46,000 lbs ...... Eaton used numbers like DS 440 /or DS 460 .... just to give you an idea of what you are looking at ..... hope this helps you a bit.

Thanks for the info Craft. So it could be a factory dump, just not a heavy duty version? I don't plan to have a full load plus pull a loaded trailer, my main concern is to be able to haul a full 15 tons so i can compete with the local tandem business. If I understand correctly, the vehicle can't weight more than 51200lb. So if 15 tons is 30k lbs, the truck would have to weight no more than 21200lb? That would have to be a light tandem.

How big of a deal is it for a tandem to not have a double frame. I originally set a double frame as a requirement but due to the good condition of the truck it makes me ask myself really how important is a double frame?

That does look light duty. Keep in mind that regardless of what axles you have you are limited by the states weight laws. Here, 34,000 is allowed for a tandem, and up to 20,000 or the axle rating, whichever is less, on steer axles. This would limit you to 47,220 gross. I do not know the rules where you live, so maybe someone else can help there. If you were told correct that it can haul 15 ton, then the truck lightweight must be around 17,000, or the weight rules different.

One thing that helps here is running with a 20,000 front, so you can get 54,000 gross if the front axle is loaded properly.

I know, clear as mud, right?

If the truck is light 20000lbs tare 7.8/8.3l motor, a thin box, I can see it handling 15 tons, it's getting the weight right on the axels. With a 13,000lb front & 38k rears it's better than most 12/36 ten wheelers running around.

My Truck started out back in '86 as a 248" wb Logger w/60" spread Hendrickson walking beam suspension .... it had a partial double frame to strenghten the rear suspension ......Logging went for a crap in '90 ....I had to shorten up the truck to amax 240" to be able to pull Super-B-Trains and to be no more than 82'-OAL ....

When I shortened up the frame I had the oportunity to install a 54" spread New Peterbilt Air Trac suspension under it ....I had to pull out the frame inserts and have longer inserts made to accommodate the Air-ride hangers ect ...ect. When we spec'd out the length it came with in 4' of the back of the cab ... we did that job for a couple of years .... logging picked back up, went back at that but it was only winter work ......Spring '92 I installed a 16'-6 out-side hoist high/lift tail gate dump box on ... we used as long a saddle support as we could, which really was only 4' long 4"x6"x1/2" angle iron .... as a logger for 3 mths/dump truck 9 mths a year that lasted 2 yrs ... it has since been a full time dumper ...... NO Frame issues have ever come up, due to a sagging or springing action (at the back of the cab) when lifting the box.

But as a tractor first off the assembly line it WAS spec'd with heavy hi-tensile frame rails .... if you go and look at some hi-way tractors you'll probably come across some frames that are shallow in depth and only 1/4" or 3/8" thick or worse yet Aluminum frame rails .... if you find a truck spec'd with bigger diff's, large F/A and bigger power chances are it'll have heavier rails as well ....... having a full length double frame isn't really that important ..... I don't know what the market holds down south, but it should be a buyers market .... as I mentioned just make sure the specs are there to begin with ....cheers

the engine is a cat 3306 with a 10 speed eaton fuller. i know the 3306 is lighter than the high hp engines but don't think it is considered a light engine.

I know a 18/44 tandem with 8ll, 3306, and double frame was around 24.5k empty. Would single frame, lighter axles, and different transmission make up 3k of weight?

Mine with the Cat 3406B 425hp with Retarder, RTLO Super 13spd, Dual 13'-6"high Stacks, 2- 100 gal alum fuel tanks full, #20,000 F/A 425Rx 22.5 rubber, front brakes ..... DT461 Eaton 2spd rears-w/lockers and 11Rx24.5 Deep lug Grippers .....wet-kit to rear, 30gal oil tank ....... 16'-6 light steel (wood supported T-1 floor) high-lift gate Box ... weighs in at 22,700 lbs.

The 3306 is lighter ..... a 10spd & 8LL should be the same but lighter than mine, and a 44 rear is deffinately lighter than my 46,000 lb 2-spds w/lockers ......

Don't know where they have all that hidden weight ?? .... are the sides really high maybe a doubled-up steel floor ??............. those are both Fords ? .............. wow sounds like a heavy tare weight .....

Thanks for the input everyone. I want to make sure I understand correctly. If the GVWR is 51200, if 15 tons put more than 51200 then I am technically illegal? Does the DMV check your registered weight rating or the GVWR on the door jam of the truck? The truck I am looking at has had a new bed put in over the old and it is 3/8s thick. Even if the truck could haul 15 ton before I am wondering how much hauling capacity that will take away.

IMHO 51200 minus the actual empty weight of your truck as weighed on a scale is the maximum weight you can legally haul unless your local regulations are different. And that's assuming that you get your loaded axle weights within the certified 13220/38000 max certification for each axle. I would start by putting the truck over a scale to find out how much it weighs empty with a full tank of fuel, or ask the seller if he has that data.

If this is the truck you mentioned that has a Tare weight of 24,500 lbs and it has the stickers on the door that claims your axle weights to add up to only 51,200 lbs ..... and you claim that they are telling you that you can haul 30,000 lbs (15T) ... hmmmm ..... lets do the Math :

.................. 51,200
.................. -24,500
..................=26,700 lbs payload is all that is left over for you to haul ......... NOT 30,000 lbs

so either that trucks Tare weight is wrong ...... OR SOMEONE is BS'ing you really bad ....all you gotta do is the Math pending what your State DVM laws are ....Good-luck

Nige said:

IMHO 51200 minus the actual empty weight of your truck as weighed on a scale is the maximum weight you can legally haul unless your local regulations are different. And that's assuming that you get your loaded axle weights within the certified 13220/38000 max certification for each axle. I would start by putting the truck over a scale to find out how much it weighs empty with a full tank of fuel, or ask the seller if he has that data.

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Thanks Nige, thats what I was thinking but just wanted to make sure I understood.

1toomanyhobbies said:

Does the DMV check your registered weight rating or the GVWR on the door jam of the truck?

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In my area the DMV will allow you to register the truck for as much as you want, however the DOT DOES check the weight rating on the door jam. They won't allow you to haul more than the factory rating even if you add air axles to the truck.

1toomanyhobbies said:

Thanks Nige, thats what I was thinking but just wanted to make sure I understood.

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Your problem as I see it is that your maximum permitted axle weights add up to EXACTLY your Max Certified GVW. Therefore although in theory you can haul the Max Certified GVW in all probability if you load the truck up to that GVW one end or the other will be overweight, and the other end will be underweight by the same amount. Unless you get the Centre of Gravity of the load absolutely spot on I see no way you can avoid this.

Let me give you a typical example from UK for a 3-axle tipper truck. Rear bogie - 19 tonnes, front axle 10 tonnes. total for 3 axles - 29 tonnes. Total Certified Max GVW for the truck - 26 tonnes, 3 tonnes less. Under that rating method you have plenty of what I call "wiggle room" on your axle weights while still staying inside the Max Certified GVW of the truck.

Here in NC they go by the bridge law, they measure the distance between the steer axle and to the center of the "group" of axles, a triaxle and quad are considered as a group of rear axles.

Everytime Im weighed which is very frequently around westinghouse and the stateline, they always go by the bridge law.

Honestly its confusing as hell, and even harder to explain it for me. I suggest going into the scalehouse at one of the local rock quarrys and have them explain it...they will also measure the wheelbase and amount of axles you have and they can tell you what you can legally haul.

Bridge law isn't that hard to understand as long as you know the allowed axle group weights, tire per inch weights, and have a bridge wheelbase chart.

In the OP's case I am going to assume the law will allow that truck 46,000 if the wheelbase is long enough, 34,000 for the tandems and 12,000 on the front axle. this is assuming that the tires are limiting the weight to 12,000 on the front.

So if the truck does weigh 24,000 that leaves 22,000 only 11 tons of carrying capacity.

Here you go, North Carolina Bridge chart.

http://www.ncdot.org/doh/operations/dp_chief_eng/maintenance/permits/docs/NorthCarolinaLaws.pdf

I called the guy and asked if he could have the truck weighed at a local scale. He said he had called over to a place he had taken it before and that the truck weighed 8300 pounds....I told him that was impossible, my single weighed 16k and he said that's what he was told and he had no interest in getting it reweighed. Oh well, back to the drawing board. :Banghead

LOL ! ...... maybe they weighed it in Kgs ....then it would be #18,298 .... would that make sence ....... who knows ...huh ! ........... or maybe that was only the front axle ????

CRAFT said:

LOL ! ...... maybe they weighed it in Kgs ....then it would be #18,298 .... would that make sence ....... who knows ...huh ! ........... or maybe that was only the front axle ????

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I thought about the Kgs but that would be kinda unusual unit of measurement for around here. To me, the fact that I had a valid question and the guy had no interest in doing something simple to make a sale turned me off on the truck.