Extra Storage - Tow Trailer?

[whemme]

Matt,

Since you have the E350 chassis, I will bet you a dollar and a donut that your rear axle is overloaded with the truck box on the rear.

[stevek]

Just out of curiosity...
I have a E350. And assuming the tanks are pretty full.
Ball Park Wise..Just to give me a general idea.
What would you say would overload the rear of my BF with weight on the hitch?
200 pounds?
300?
500?
Thanks

[shilohdad]

We have a different coach, but we also wondered how loaded our rear axle might be, given that we are pack rats. Born Free (either Kim Olsen or Ed Newman, can't remember which) was able to supply us with the spreadsheet they use when designing the coach. We added our estimates of our expected loads to see how we were doing. Actually, it came out real close to our actual weights when we went to a scale at a Flying J. Maybe you can get one for your coach.

Of course, you could take your coach with a typical load to a Flying J, Pilot or other truck stop with scales and get weighed. Then add whatever other loading you want to add on the rear. Remember, though, that you can't just add the simple weight of your load, as any weight you put on the bumper is cantilevered back from the axle, effectively adding more weight, perhaps much more, on that rear axle.

[Mel Wilbur]

When it comes to weighing a motorhome the only accurate way is wheel position weighing. This gives you the exact weight on each corner of your coach. The best place to check out this method is http://www.rvsafety.com We have used them in the past and they are a very professional group. The only problem is finding a place in their schedule (listed on their website) that would work for you.

[stevek]

Good link Mel. Thanks.
Here in Oregon, we have free roadside weight stations operated by the state of OR.
The trouble is they may not be long enough.
Someone told me that if you weigh the front wheels, then pull forward and weigh the back wheels:
and add the two weights together it will be pretty close to the total weight.
Do you think this is true or not?

[Ray]

There are a few truck/frame/alignment places that have the portable scales that can weigh each wheel. Not sure what they charge. I had my last BF weighted when it was in for a alignment. Have not done it on this one yet. I suppose once I get this scooter thing figured out I will.

I tried useing the cat scale at the local Flying J but with one wheel on the pad they said the scale would not register - it faulted saying there was not enough weight.

[Ray]

Also something I forgot about - A friend said I could take it to the local scrap yard and have them weigh one wheel/axle at a time, by postioning the RV - But I have not done that - just something wrong with pulling my BF into a scrape yard - LOL

[shilohdad]

Yes, getting a 4-wheel weight is ideal. We did do that using the web site Mel Wilbur referenced. Luckily, that organization is based in Merritt Island, FL, about 30 miles from my father, whom we were visiting. Walter Cannon, the president, is a very nice, knowlegeable fellow. Our coach was almost perfectly balanced left-to-right. Walter said that he has always been impressed by how well-balanced Born Free coaches are coming out of the factory.

However, seeing as Walter's organization rarely gets out west (I saw one scheduled in Pomona, CA, and 2 in Las Vegas), that may not meet Steve's desires. If he cannot find another place that does 4-wheel weighing, I would still think that getting each axle weighed is better than nothing. As I said in my previous post, most truck stops such as Flying J, Pilot, Travel Authority (TA) offer this for a nominal fee.

[whemme]

Good link Mel. Thanks.
Here in Oregon, we have free roadside weight stations operated by the state of OR.
The trouble is they may not be long enough.
Someone told me that if you weigh the front wheels, then pull forward and weigh the back wheels:
and add the two weights together it will be pretty close to the total weight.
Do you think this is true or not?

Steve,

Sure would. Why would you think they would not add up correctly?

[stevek]

Thanks Bill. Good to know. Guess I was making it too complicated.

Also the Escapees RV Club has "smart weight" to weigh the 4 corners.
http://www.xscapers.com/xscapers-knowledge/smartweigh

Not too bad. $45 for a MH.

[whemme]

Of course, you could take your coach with a typical load to a Flying J, Pilot or other truck stop with scales and get weighed. Then add whatever other loading you want to add on the rear. Remember, though, that you can't just add the simple weight of your load, as any weight you put on the bumper is cantilevered back from the axle, effectively adding more weight, perhaps much more, on that rear axle.

Joe is right about the multiplying effect of hanging weight on the rear of your motorhome some distance behind the rear axle. I have gone thru the calculations with the following results: The Ford E450 chassis used by Born Free for their 26' length motor coaches has a 178" wheel base. The truck box mounted on the rear of Matt's coach would be located approximately 11' (132") behind the rear axle. For every 100 lb in added weight in the truck box location, the rear axle would have an increased weight on it of 174 lbs and the load on the front axle would be reduced by 74 lbs.

[Dallas Baillio]

There is a component to Steve's question that could cause a scale to register zero for either the front or rear axle--a weigh in motion scale. If at the moment the weight is recorded the axle is airborne the axle is weightless. A raised area on a scale could cause such a result. It would not be accurate, but is still be possible.

So let's not assume a superior attitude. If we think it through keeping an open mind we may learn something.

Bill,
For the uninitiated, non-engineering mind.......this would seem like a brain-twister:
Which weighs more; the total weight of the vehicle weighed all at once, or, the same vehicle when weighed front axle weight, then rear axle weight? I got a chuckle when reading that one! [/quote]

[whemme]

Dallas,

All weigh in motion scales by regulation have a very flat platform and a low approach speed to prevent the very thing you mention. It would take a very large 'hump' in the scale's platform and a high crossing speed to unload an axle completely.

[Mary]

Here is a link to an interesting swivelwheel tow trailer configuration. Having it follow the direction of the tow vehicle while backing up seems a plus. Has anyone on the forum seen one in action?

Mary

http://www.cruiserlift.com/swivelwheel.html

[Ray]

Dallas,

All weigh in motion scales by regulation have a very flat platform and a low approach speed to prevent the very thing you mention. It would take a very large 'hump' in the scale's platform and a high crossing speed to unload an axle completely.

Bill

I have to agree with you on that one, I think it is probably unlikely that one would be going fast enough or hit a big enough hump/bump to get 100% of the weight off either axle when in motion weighing a vehicle. Although, I have hit a speed bump in the road (wasn't marked) that I didnt see which I am sure took at least 50% of the weight off my back axle, I know things were kinda at zero gravity inside the coach for a brief period of time

I am not all that familiar with in motion scales, I am a little familiar with the standard platform scales that use a strain gauge load cell set up and have heard about the newer piezoelectric ones a little. Years ago I did have a little experience with load testing mechanical ones but I doubt if any of the exist anymore except in maybe Fred Sanfords lot

Anyhow, How does a in motion scale compensate for things such as change in speed, momentary application of brakes, (or another momentary motion restrictive source) or for that matter even the sloshing of fluids, as in a tanker. Those fluids do slosh a bit even though they are baffled tanks. Our tanks are not baffled so I am not sure what effect that would have.

I do know that lateral forces will transfer through the chassis and suspension via tire contact with the weighing platform and effect the vertical force on the scale to some proportion. I am not sure what the proportion is, I am sure there is a formula somewhere in one of my old work books But I guess that is a mote point as long as we except the fact of lateral to vertical force transfer of momentum due to to surface friction/tension between the item being weight scaled and the weighing platform.

Do you think that a in motion scale is just as accurate as a static scale?