curb weight

[ajk1]

We want to check whether existing granite pavers will crack when a given vehicle with a given payload drives over them. We have developed sophisticated software to do this which accounts for many factors such as but not limited to the foundation factor of the base, etc etc. What we need to know now is where we can find the "curb weight" of a GMC 2000 Topkick C8500 truck. We can find the gross weight on the GMC website, but not the net (i.e. curb) weight. Does anyone know where we might find that information?

Thanks

 

[MikeHalloran]

It should be on the registration of any exemplar.
... and your GMC dealer should be able to find the information, if you ask nice.



Mike Halloran
Pembroke Pines, FL, USA

 

[racookpe1978]

It appears to be 60,000 lbs - from a "typical" vehicle GMC manufacturer's tag
Look at the data from a google images search.

http://www.machineryzone.com/used/used-truck/2635930/gmc-topkick-c8500.html

Now, here's your problem.

This would be apparently be rated load, at rated or nominal maximum GVW. But the thing is being as a dump truck by all sorts of numb-nuts drivers filled by equally (or worse) numb-nut load "dumpers" driving front-end loaders with little (or lots) of qualifications and skills and training and oversite. It would be my bet that probably 1/5 of the trucks are overloaded by more than 20-30%.

 

[ajk1]

To clarify, I am asking the question as it relates to several trips across some specific granite pavers of a specific truck with a known cargo weight. The known cargo weight is 3500 pounds. The truck is a GMC "Topkick C8500" model year 2000 truck. The distribution of GVW is 13,000 to the 2 front tires and 12,000 pounds to the 4 rear tires, we are told by the transport company (seems strange that the front axle load is more than the rear axle load). The tire pressure is 105 psi. The only missing piece of information is the curb weight (i.e weight without the 3500 pound cargo). It must be somewhere on the internet but I don't know where. Maybe the transport company can get us that info too, or maybe we will have to speak to a GMC truck dealer as Mike Halloran suggests, but I was hoping someone on this forum could tell us how to find it on the internet...

 

[Ron]

Take your truck to a certified scale and weigh each axle set. Absent a local scale, call your transport governing agency and ask if you can get a weight on your truck. They usually have portable scales that are certified for accuracy. Some airports have them as well for aircraft.

 

[1gibson]

There is always graph paper, trace tire contact patch. With known tire inflation (psi), and known area (in^2) you get load (lbs) with reasonable degree of accuracy. Doesn't directly address your question (where to find the info) but file it under "backup plans."

 

[dhengr]

Ajk1:
“We have developed sophisticated software to do this which accounts for many factors such as...” Oh, really? However sophisticated, you have probably missed a few factors, such as corner loads and variations in the granite paver strength or grain and strata orientation, sufficient soil base variation, etc. etc. I’ve never quite understood how they claim weights on vehicles, but when the truck is empty the front axle will likely be the heaviest axle. However, this is not normally true when the truck is loaded. I’d weigh it if you want to really know. Then define very carefully how the load is placed in it for transport.

Why not take most of this guess work and potential variation or error out of the problem, loading error, driver error, etc. Put down a couple inches of sand, and screed it flat. Then put down crane mats, several layers of 2x planking secured together in some way, several layers of plywood, or some such, to truly protect the pavers and distribute the loads over any irregularities?

 

[racookpe1978]

I have no idea where you are getting your information about weights and axle loading - BUT I disagree strongly with your assumptions and information. Even your balance point 9center of gravity/load distribution comment about front axle and rear axle loads is incorrect.

Look again at the manufacturer's nameplate data shown above: Your information above (13,000 to the front two tires and 12,000 to the four rear tires, with an "assumed maximum" ????? load of only 3500 pounds is going to get you in trouble.



Rated load seems to be 60,000 - 53,220 = 6,780 lbs

GMC's tag clearly says
GVWR (total) = 53,220 lbs
GAWR FRT = 13,200 lbs
GAWR INT = 20,000 lbs
GAWR RR = 20,000 lbs
GCW = 60,000 lbs

Again - None of these include 'stupidity" or overloading (accidental or incidental) of the dump truck - Notorious for both problems unless you are weighing (and unloading when needed) every load by scale. Even wet ground or rain is going to increase dump truck bed loads substantially over nominal weights and measures using the same volume or number of front-end-loader scoops.

1) How are going to limit weight in these trucks to only 3500 lbs?
2) Minimum loads need to be:

The interior axle = 20,000
The rear axle = 20,000
The front axle = 13,200 (close to your assumed value at least)

Perhaps we here, on-line and not knowing your location nor identity nor purpose nor background, cannot change your mind. But .......

 

[IDS]

Given the uncertainties in the stiffness of the subgrade, the stiffness of the granite, the flexural strength of the granite, effect of dynamic loads, and the 3D distribution of stress, the effect of variation in the distribution 3500 pounds in a total of 60,000 is entirely negligible.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[ajk1]

Thanks for all the comments and advice.

To Racookpe: the axle loads were given to us by the transport company, for the GMC model "Topkick 8500". Where did you get your loads from? Are they for this model truck?

To dhengr: Yes we are fully aware of all the factors that you mentioned, and there are a lot more than what you mentioned! But good for you for understanding the limitations of engineering analysis and calculations. Your comments are well taken. Yes we are putting down overlay but we are dealing with 2.5" thick granite pavers so the overlay must be stiff enough to spread the load as comapred to the granite. But you are on the same track as we so this is useful.

To 1gibson: that is a really cool idea!! I wish I had thought of it. We'll see if we can pursue that if we cannot get a definitive answer on the axle loads. Very much appreciated.

 

[ajk1]

Sorry - I had something wrong in my originla post. The truck is a year 2000 GMC Topkick 8500 (not C8500). My apologies. The GVW weight however remains as given to me as 25300 pounds, with 12,000 pounds on the front axle. The cargo will consist of a single 3500 pound vehicle. This is the type of truck that you see on the highway transporting multiple cars from the factory to dealers.