Class A Towing capacity

lbligh wrote:

Daveinet wrote:
Except for one problem. Once I modify a vehicle, I have taken the responsibility for rating it because it is my modification.

Not really. You re not authorized to rate anything. The ratings are set by the manufacturer and certified on the Federal Weight Certification. Sorry... you simply are not qualified nor do you have enough liability insurance. I would love to watch you try that on a Scale Master or Inspection Officer. Try telling them you modified the vehicle and it is all good. That would get a good laugh after they put the red tag on the vehicle.

Safe travels.

I assume you have never heard of custom vehicles, or street rods. When they go for a title, they do not ask the builder's qualifications or certifications. It goes through an inspection, but the level of inspection does not cover details of load ratings and the like. Nothing prevents me from building a trailer either. Tons of DIY stuff out there. They are titled as home built. No one looks at the frame rating and engineering aspect.

nevadanick wrote:
In this state you can only be cited for exceeding registration, axle limit, not rating and tire rating, that yellow sticker means nothing. I was at a aggregate plant the other day and a truck came across the scales at 128,100 lbs. do you think the yellow sticker in the cab of that truck said gcwr of 128k ? He was within registration and tires rating and under on axle limits which is all that matters

And if indeed he was "under on all axle limits" my guess he was under his stated/registration weight. A "registration weight" is simply a means of buying weight fees that fit your needs, as long as the unit has the capacity to meet or exceed the "registration weight." Now, you said this was a "truck" (without a trailer)? If so, what does GCWR have to do with it? Maybe you should be talking about GVWR? I guess I don't understand your point?

The 2008 Newmar 3752 has a tow rating of 6,000 lbs.

In this state you can only be cited for exceeding registration, axle limit, not rating and tire rating, that yellow sticker means nothing. I was at a aggregate plant the other day and a truck came across the scales at 128,100 lbs. do you think the yellow sticker in the cab of that truck said gcwr of 128k ? He was within registration and tires rating and under on axle limits which is all that matters

Guess I better get someone from the US DOT in here to let me know if I should move this 1/2 million$$ worth of equipment to a race this weekend like I do every weekend......That guy above would fit perfect as a member of a suburban HOA.

Daveinet wrote:
Except for one problem. Once I modify a vehicle, I have taken the responsibility for rating it because it is my modification.

Not really. You re not authorized to rate anything. The ratings are set by the manufacturer and certified on the Federal Weight Certification. Sorry... you simply are not qualified nor do you have enough liability insurance. I would love to watch you try that on a Scale Master or Inspection Officer. Try telling them you modified the vehicle and it is all good. That would get a good laugh after they put the red tag on the vehicle.

Safe travels.

Except for one problem. Once I modify a vehicle, I have taken the responsibility for rating it because it is my modification.

Daveinet wrote:

lbligh wrote:

Dave,

As I have said, I have been in this business for 40 years. NOTHING you have said is related to the issue of gross capacities. Are these engineering specifications that are used in developing a gross capacity? Maybe. As I have said before... I do know that many things are taken into consideration by engineering (which I never claimed to be one) in the development of the gross capacities. Now, to use your term, lets don't be "silly," and ever think that one pound over any gross capacity is going to make a difference. However, I believe that we both know that taking any component to its maximum stress point constantly will shorten its life span....

I guess I'm not sure how the engineering basis for developing gross capacities has "nothing" to do with gross capacities.

Does 2 lbs over the limit matter? Does 5 lbs or 10 or 50, or 100, or 500? At what point do you hit the "wall"? The point is that it is not a wall. From a regulatory stand point it might be, but from an engineering standpoint, its not. It is as the stress factors rise, longevity goes down. Handling may or may not come into play. How bad is it?

Something else that is significant is that most motorhomes are not really using dedicated motorhome chassis parts. They pick and choose truck parts that fit the need. So where in a commercial vehicle, most design limitations all hit at once - meaning that everything is sized for a specific capacity. In an RV chassis, its a hodgepodge of parts, which means you have some parts that are way over sized for the job, and some that just barely meet the requirement. They just don't build enough motorhome chassis to warrant sizing all components to just make the minimum. A motorhome is a totally different animal than a commercial truck.

Dave,

See... people like you are the reason that gross maximum limits are set and required by Federal law to be posted. Guys like you who want to say well, one pound must be ok. Maybe 500 lbs is OK. Maybe 1000 lbs are OK. The fact is that the gross limit is the stated limit. They don't leave it up to you or anyone else to determine. End of story.

Now you want to discuss how chassis parts are selected by the different manufacturers and how in your mind that also is a variable? One thing I forgot to mention about my background, I am also an ASE Master Technician. So I believe that I fully understand trucks and parts. OK?

Nothing you or anyone else can say will change the fact that the posted gross limits are just that... the maximum limits. As I have said, guys like you and your "silly" arguments really make the case for CDL certification requirements to operate a coach. I would really love to see a guy like you try your argument on a Scale Master or Inspection Officer. I have seen guys try and you know what happens? It is called a Red Tag.

Now, I have given you and everyone else the facts and clearly the link I provided show anyone who is interested (and who actually reads the information) in the subject just how things actually work in the rating process. You and others may not like it... but it is the law. I believe we are done here.

Safe travels.

lbligh wrote:

Dave,

As I have said, I have been in this business for 40 years. NOTHING you have said is related to the issue of gross capacities. Are these engineering specifications that are used in developing a gross capacity? Maybe. As I have said before... I do know that many things are taken into consideration by engineering (which I never claimed to be one) in the development of the gross capacities. Now, to use your term, lets don't be "silly," and ever think that one pound over any gross capacity is going to make a difference. However, I believe that we both know that taking any component to its maximum stress point constantly will shorten its life span....

I guess I'm not sure how the engineering basis for developing gross capacities has "nothing" to do with gross capacities.

Does 2 lbs over the limit matter? Does 5 lbs or 10 or 50, or 100, or 500? At what point do you hit the "wall"? The point is that it is not a wall. From a regulatory stand point it might be, but from an engineering standpoint, its not. It is as the stress factors rise, longevity goes down. Handling may or may not come into play. How bad is it?

Something else that is significant is that most motorhomes are not really using dedicated motorhome chassis parts. They pick and choose truck parts that fit the need. So where in a commercial vehicle, most design limitations all hit at once - meaning that everything is sized for a specific capacity. In an RV chassis, its a hodgepodge of parts, which means you have some parts that are way over sized for the job, and some that just barely meet the requirement. They just don't build enough motorhome chassis to warrant sizing all components to just make the minimum. A motorhome is a totally different animal than a commercial truck.

Daveinet wrote:
Lbligh, I am curious to know what the criteria is for any of the particular load limits? Is it a wear limit? Is it a stress limit, where if exceeded, it will immediately have catastrophic failure?

A perfect example would be my front differential. It is a Dana 70. If you look at the specs, it gives 2 numbers. One is a continuous operation and the other is a peak limit. Basically what those numbers mean is that the differential is expected to last X amount of miles if a continuous load of 2500 ft-lbs. It is rated for a peak torque load of 7000 ft-lbs. Basically if you exceed the peak torque, you will break teeth. That means you can exceed the continuous load rating and not break anything, but you will shorten the life. So if you use this axle in a towing situation, the tow rating will be based on the expected average torque load, because they want to get decent wear. So if you exceed the tow rating, what happens? NOTHING, except you will probably slightly shorten the life of the differential. So in this single example of one component, in this specific case, exceeding the tow rating is not catastrophic.

That is what tow rating are. If you have a 5000 lbs tow rating, and you tow 5001 lbs, does that mean you are taking a serious chance at causing a problem? Lets not be silly. Ratings are based on worse case scenario. IF you are more cautious about how you treat the vehicle, you can compensate for the limits of a rating up to a point.

Dave,

As I have said, I have been in this business for 40 years. NOTHING you have said is related to the issue of gross capacities. Are these engineering specifications that are used in developing a gross capacity? Maybe. As I have said before... I do know that many things are taken into consideration by engineering (which I never claimed to be one) in the development of the gross capacities. Now, to use your term, lets don't be "silly," and ever think that one pound over any gross capacity is going to make a difference. However, I believe that we both know that taking any component to its maximum stress point constantly will shorten its life span.

Now, my guess is that maybe you have never seen a Federal Weight Certification sticker? All items are shown in a standard format in gross capacity categories (GVWR, GCWR etc.) Now... do people overload vehicles and escape failures (obviously by more than one pound)? Absolutely. Would those same folks be cited and possibly not be allowed to move their vehicle until corrections were made to comply with the stated max ratings if they were a commercial vehicle? Absolutely. As I said, all of the arguments being made here to allow max ratings to be exceeded sure makes a good argument for CDL certification requirements for operating a coach.

Safe travels.