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Old 12-13-2010, 08:12 AM   #85
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All of that if fine and dandy, and I will not disagree with any of it, but keep in mind Andy is only testing bars amount of bend vs load in these tests:

"We are measuring the bend in the load equalizing bars, at 100 pound increments, with different brands as well as square and round bars.

The range of the tests start at a low level and up to and including a 20 to 25 percent overload."

Personally, I think he needs to measure the amount of weight needed to bend each bar 1", and in additional 1" increments, rather than measure the bend at each 100 pound of weight loading. I think he will end up with so much data the way he says he is going to test that it will simply be confusing.

As an example, if testing a 1000 pound bar, he will have no less than 12 measurements for each bar if he goes to 20% overload.
We can do the math either way. I like more data points. More data is good IMO.
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Old 12-13-2010, 09:44 AM   #86
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I'm not saying a lot of data is bad, just that it can be confusing. Many times in lab type tests, there is so much data that no one but an engineer can actually make a determination from it. It leads to arguments many times.

We all here know that arguments are possible.
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Old 12-13-2010, 11:25 AM   #87
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Originally Posted by SteveH View Post
All of that if fine and dandy, and I will not disagree with any of it, but keep in mind Andy is only testing bars amount of bend vs load in these tests:

"We are measuring the bend in the load equalizing bars, at 100 pound increments, with different brands as well as square and round bars.

The range of the tests start at a low level and up to and including a 20 to 25 percent overload."

Personally, I think he needs to measure the amount of weight needed to bend each bar 1", and in additional 1" increments, rather than measure the bend at each 100 pound of weight loading. I think he will end up with so much data the way he says he is going to test that it will simply be confusing.

As an example, if testing a 1000 pound bar, he will have no less than 12 measurements for each bar if he goes to 20% overload.
I see what you mean, but from his brief description, you could interpret his methodology either way. He may be doing what you suggest in your statement.
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Old 12-13-2010, 11:35 AM   #88
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If we assume bars have length L and spring constant k, and we
denote the truck beginning to climb a hill as a positive angle theta, we
can say (assuming small angles of deflection, blah blah):

force due to hill = L * sin(theta) * k

or for a 24" bar, 10% grade (5.7 degree slope) and 500 lb/inch spring constant:

24 * sin(5.7) * 500 = 1190 lbs....

So climbing a steep hill effectively bends the bars a bit more than 2" extra....

Those w/ 1000 lb bars can wince now...

This is why I feel a more constant force hitch would be a good thing for
one's trailer if one needs a WD hitch... and why those headed off road may wish to relax their WD bars somewhat...

- Bart
Hmmm, Bart, how would you do that? Some sort of spring on a saddled spring setup? Better get your patent application in now!
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Old 12-13-2010, 07:05 PM   #89
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Hmmm, Bart, how would you do that? Some sort of spring on a saddled spring setup? Better get your patent application in now!
I'm inclined to suggest a suspension air bag w/ an external reservoir to increase volume as a useful relatively constant force spring. You adjust the pressure to control the amount of weight transfer; three-way solenoid valves could be used to release the air pressure on each bag to permit unhitching w/o emptying the reservoir. Any flow restriction between bag and reservoir would act as a damper to decrease pitching.

- Bart
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Old 12-13-2010, 07:09 PM   #90
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There ya go! Git 'er done, and send me a free sample to test out.
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Old 12-30-2010, 12:10 PM   #91
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Andy,

Any update on this?

Chris
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Old 12-30-2010, 03:54 PM   #92
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Andy,

Any update on this?

Chris
The research has been completed.

The write up however, is taking some time, as I want it to be as simple as I can, so as to minimize negativity.

A few more days should do it, since I have been very busy with some other projects as well.

Andy
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Old 12-31-2010, 09:52 AM   #93
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All of that if fine and dandy, and I will not disagree with any of it, but keep in mind Andy is only testing bars amount of bend vs load in these tests:

"We are measuring the bend in the load equalizing bars, at 100 pound increments, with different brands as well as square and round bars.

The range of the tests start at a low level and up to and including a 20 to 25 percent overload."

Personally, I think he needs to measure the amount of weight needed to bend each bar 1", and in additional 1" increments, rather than measure the bend at each 100 pound of weight loading. I think he will end up with so much data the way he says he is going to test that it will simply be confusing.

As an example, if testing a 1000 pound bar, he will have no less than 12 measurements for each bar if he goes to 20% overload.
How I designed the tests, was my choice.

They were designed to help the "majority", and not the "minority" that have already expressed negativity, even before the results are published.

Since you already disagree with that, then I would suggest you invest your own money, and time, and test them to your satisfaction.

Then, others can disagree with your test results.

Because of the negativity, from a small source, we will publish the results on our web site, only, with a copyright.

Andy
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Old 12-31-2010, 11:01 AM   #94
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Dear Andy,

I appreciate your efforts over so many years.
Not saying you are old, but I retired yesterday and I have followed your work for quite a while now.
In the next two weeks or so I am buying a load leveling hitch for my Airstream and a utility trailer. IS any of the information you derived useful as a sort of buying guide or is it engineer speak for top capacity Airstreams?
I was thinking of something simple, like me.
Thanks for all the parts and info.,
Rob
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Old 12-31-2010, 11:49 AM   #95
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I appreciate your efforts over so many years.
Not saying you are old, but I retired yesterday and I have followed your work for quite a while now.
In the next two weeks or so I am buying a load leveling hitch for my Airstream and a utility trailer. IS any of the information you derived useful as a sort of buying guide or is it engineer speak for top capacity Airstreams?
I was thinking of something simple, like me.
Thanks for all the parts and info.,
Rob
Rob.

I assume you still have the "Jeep".

If so, it's an OK tow vehicle for maybe a 17 to 18 foot Airstream, because of it's short wheel base.

To me, towing a 24 footer, is way past the "safe" point.

But, since you asked, probably a 750 to 800 pound full sway control hitch would be OK.

But, make super sure you have a full sway control, since in your case, the tail will easily wag the dog. Meaning, that your Airstream will shove your Jeep around as it pleases.

If your Jeep has a rigid suspension, then drop the rating down 200 pounds, as your rig will need all the help it can get.

Above all, be safe.

Andy
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Old 12-31-2010, 01:57 PM   #96
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I agree with Andy. first started towing 27 ft. Excella with a 1987 Dodge shot bed PU. Not too much longer than a Jeep. Very stiff susp. Just did not feel safe. Upgraded to a F250 extended cab long bed. All the difference in the world. Sal.
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Old 12-31-2010, 10:25 PM   #97
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I appreciate your efforts over so many years.
Not saying you are old, but I retired yesterday and I have followed your work for quite a while now.
I was thinking of something simple, like me.
Thanks for all the parts and info.,
Rob
Rob.

"OLD" is a state of mind.

Thinking and working, like a young person, "as long as the meds hold out" is the way to go.

If I quit, what would I do?

Gotta stay busy doing something productive.

Some say I lie about my age, and I say, "no I don't", but I do lie about my looks.

Keeping at least somewhat busy, is what makes the wheels keep turning.

Andy
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Old 01-01-2011, 02:11 AM   #98
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The Majority Values Your Work

Andy,

Forget about the naysayers. From what I can see in the forums, the vast majority of members value all your posts and comments. When someone of your vast experience and expertise goes to the trouble to conduct testing that has not been conducted by the industry or manufacturers, and that entirely at their own expense, not subsidized by any manufacturer, I for one am interested in the results.

It certainly makes no sense to criticize before the results are published. The fact that the results are NOT subsidized by any manufacturer speaks volumes about your integrity.

I hope you will reconsider and publish the results here in the forum.
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