Overweight Toad?

80+ postings! I'm going to need more popcorn and a refill of my beverage.

Trackrig wrote:
Well, so far I haven't seen any one say they're a structural steel engineer or something related to designing steel frames for trucks or MHs, or did I miss it someplace?

If one pops up, my question would be "how do they determine the weight capacity that they post"? My guess would be they assign a weight that is very, very safe/conservative because they have no idea what people are actually going to do with the hitch. It's the mfg or engineering firm that stands a lot more of a chance at being sued if one fails.
Bill

I saw a comic strip (Calvin and Hobbes, IIRC) where the kid asked his dad how they determined the weight capacity of a bridge. The dad answered that they build the bridge, then run heavier and heavier trucks across it until it breaks, then they rebuild it and assign the weight limit.
That makes as much sense as some of the stuff on here...

Trackrig wrote:
Well, so far I haven't seen any one say they're a structural steel engineer or something related to designing steel frames for trucks or MHs, or did I miss it someplace?

If one pops up, my question would be "how do they determine the weight capacity that they post"? My guess would be they assign a weight that is very, very safe/conservative because they have no idea what people are actually going to do with the hitch...

Bill, where did you get that extra dose of commonsense?

I watched a very NICE class A RV TURBO DIESEL PUSHER, accelerate into the right lane of I-75 that had 70mph traffic, up a normal steep I-state short on-ramp incline, with ALL FOUR TOAD TIRES LOCKED UP.

I never did find out if all four got flat, or if he stopped in time...

I was in the wrong place in traffic that trying to make a difference would have been unsafe.

Was the toad within the hitch rating? Well, I would say, probably. "Was the hitch exposed to forces outside of the engineers idea of what idiots might do?", probably not in the past, but the reality is that people do DUMB in today's world.

If nothing else, you guys sure are entertaining.

Tom

Its not a big deal, I say go for it and be careful.

My qualifications..I stayed in an RV Resort last night "NO" Holiday Inn Express for me.

Well, so far I haven't seen any one say they're a structural steel engineer or something related to designing steel frames for trucks or MHs, or did I miss it someplace?

If one pops up, my question would be "how do they determine the weight capacity that they post"? My guess would be they assign a weight that is very, very safe/conservative because they have no idea what people are actually going to do with the hitch. It's the mfg or engineering firm that stands a lot more of a chance at being sued if one fails.

I'll bet there are people out there that put put more excess strain on a hitch like pulling 4X4s out of the mud (it was only a 3,500# jeep and the hitch is rated for 3,500#) than excess strain that the OP might put on the hitch.

Be safe - remember that the next time you coast off of a hill 2 MPH over the speed limit, you're just as illegal as the OP could be. We'll maybe you're more illegal since 1 MPH over the speed limit is against the written law. I can't say I've seen a law that specifically says you can't tow a few pounds over a hitch rating. They might use a law on unsafe conditions, but that's for the legal people to interpret. Might be that if it wound up in court and they go back to the designing engineer, he might say that "Oh,for that purpose it was well within design limits".

Bill

You all having fun yet?-----figuring out ways to NOT do something as usual!!!!!!!

tropical36 wrote:
...I've always wondered how these ratings were calculated in relationship to gravity and if hanging the whole rig vertically from a crane or other would be substantial...

Well, I don't mind admitting that I don't know how "they" determine a rating (and I didn't even try to Google it).

However, there a few things that are commonsense. Tires and pavement are reasonably grippy to each other. On a grade, there is G ( Gravity), but there could also be significant acceleration forces, both positive and negative. Consider that the hitch must be able to withstand the forces of emergency stopping on a grade; the actual acceleration(negative during braking)force would be added to the force caused by effect of gravity on the angle of the slope. I'd wager that this could actually be well over 1G with some vehicles; so simply hanging vertically from a crane is not likely enough.

And, I've forgotten so much since college, so I am just trying to cover the very basics. The bottom line is that the mass of the vehicle is only a portion of things to consider in order to determine if what the OP wants to do is reasonably safe.

tropical36 wrote:
...I'll say again, that most overloading will, if anything, affect the transmission first.

And, here I completely agree. And, again, this is something the OP has control of by being the driver.

I'd also add that overloading will result in longer stopping distances and greater brake wear. Note, the OP states using supplemental braking so this issue should not apply to the OP.

I hope my real world comments and examples have added something positive to this discussion.

Executive wrote:
Sounds like a lot of folks on here know more about towing and laws of physics than any of them dumb old engineers anyway, so go for it. If you're stopped or have an accident, just tell 'em the guys on RV.net said it was ok....that should work......Dennis

Just tell the Police RV.Net said it was O.K.! Another Outstanding Effort Dennis!

Sprig wrote:

Daveinet wrote:
...And most importantly DO NOT REPORT BACK TO RV NET that you went ahead and did it.

^^^THAT is funny right there...

I'm still entertained by the people on here that do NOT understand that F=MA.

The mass, or WEIGHT, is ONLY HALF of the basic equation.

Simply put, there are other considerations that are more important. I'm confident that if a mechanical engineer were to calculate the loads in the OP's configuration that they would "give a thumbs up" to it being safe.

Then, in addition to the above, the OP as the driver, has significant control over the A portion of the basic equation. This is something the hitch engineer has to use a nominal value in his design.

So long as the OP is not tackling the steepest streets in San Francisco, I just don't see the problem. As I see it, none of the weight police on this forum take into consideration that the hitch has to be designed to handle the extra F from steep grades. Maybe someone who has not been out of college for long as I have will want to do the actual calculations on the extra force applied for the hitch rating on a steep grade (assuming that A=G only(for grins))???

It would be really nice to see an actual educated opinion in reply to to my comments. All the lemmings that are scared near death because a single number is higher then one on a sticker don't help anyone learn.

With some of what you've posted here, I've always wondered how these ratings were calculated in relationship to gravity and if hanging the whole rig vertically from a crane or other would be substantial. I can say that with overloads, certain transmissions don't like long 6% grades. Then again, if you limit your climb to 25mph in low gear, you get an automatic 25% increase. I'll say again, that most overloading will, if anything, affect the transmission first.