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Old 02-04-2014, 09:19 PM   #113
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Originally Posted by Ron Gratz View Post
The moment-arm fulcrum for both hitches is the hitch ball. The correct comparison is:
1) the product of the effective WD bar length (approximately 30") multiplied by the total WD lift chain tension (perhaps 2000#), versus
2) the product of the vertical distance from Andersen chain plate to ball center (reported to be 6.25") multiplied by the total Andersen chain tension (perhaps 2000#).
The first example torque would be 60,000 lb-inch versus the second torque of 12,500 lb-inch.

Ron
Ron

I find it interesting that you offer an mathematical explanation that offers 4 amounts, 2 of which are directly measurable and one that has been documented by actual measurement. The distance between the trunnion sockets on a Reese hitch, approx 4.1/5 in. and the plate to ball distance, approx 6in., of the Andersen can be measure by anyone. The tension in at least one Andersen system was recorded with a strain gauge, 2,000 lbs. and offered in this thread.

http://www.airforums.com/forums/f464...ead-92131.html

My question is what is the bases for the assumption that the lift applied by chains to a set of bars is 2,000 lbs.
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Old 02-05-2014, 01:43 PM   #114
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Originally Posted by HowieE View Post
My question is what is the bases for the assumption that the lift applied by chains to a set of bars is 2,000 lbs.
Howie, the basis for my use of "perhaps 2000#" of combined lift chain tension is both empirical and theoretical.

An example of empirical data is found in "The Hitch Torsion Bar Story" in the form of the WD bar load-deflection plots at the end of the article.
Andy's testing involved testing five different WD bars at loads up to 1600# to 1800#.
A middle-of-the-range load of 1000# per bar produced deflections of 1-1.6" which seemed to be fairly representative of a "typical" WD bar loading.
These data show that four of the five bars could be loaded to 1600-1800# per bar without showing signs of yielding.

The theoretical approach is based on calculating how much WD bar load might be required to restore a load of 500# to the front axle of a truck with 157" WB, towing a trailer which is 240" from ball to mid-point between axles, and using WD bars with effective length of 30".
Physics of levers says the amount of required load transfer to the TT's axles would be about 500*157/(65+240) = 257#.
And, a load transfer of 257# to the TT's axles requires a combined WD bar load of about 257*240/30 = 2056# -- approximately 1000# per bar.

Ron
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Old 02-05-2014, 02:52 PM   #115
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I accept you explanation of the 2,000lbs. used in your post.

Now if you accept my comment that the Andersen is not appropriate for a lightly sprung TV and that there is a difference between the 6 in. separation between the ball center and the chain plate of the Andersen and the 4 in. separation of the trunnion cups on a Reese. If so most readers will be able to see the limit of the Andersen to transfer weight and decide for themselves if they need that amount of transfer and thus be willing to sacrifice the advantages of the Andersen.

A bar system will overcome the shortcomings of a lightly sprung TV. The Andersen will provide a superior ride quality for those who are towing with the majority of the current TVs.
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Old 02-05-2014, 06:00 PM   #116
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Quote:
Originally Posted by Ron Gratz View Post
The theoretical approach is based on calculating how much WD bar load might be required to restore a load of 500# to the front axle of a truck with 157" WB, towing a trailer which is 240" from ball to mid-point between axles, and using WD bars with effective length of 30".
Physics of levers says the amount of required load transfer to the TT's axles would be about 500*157/(65+240) = 257#.
And, a load transfer of 257# to the TT's axles requires a combined WD bar load of about 257*240/30 = 2056# -- approximately 1000# per bar.

Ron
RIVETING!!! (pun intended)

(sorry, i couldn't resist)

(thanks for working thru this issue w/ "level heads", and edgumicating us common folk)
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Old 02-05-2014, 07:54 PM   #117
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Now if you accept my comment that the Andersen is not appropriate for a lightly sprung TV and that there is a difference between the 6 in. separation between the ball center and the chain plate of the Andersen and the 4 in. separation of the trunnion cups on a Reese.---
Howie, you asked for the basis of my assumptions, and I provided same.
Now I ask you -- what is the basis for your assumption that the Andersen is not appropriate for a lightly sprung TV?

I've seen only two reports of people being able to achieve close to 100% front axle load restoration when using the Andersen WDH.
One TV was a Honda Pilot, and the other was a Toyota FJ Cruiser.

It seems both of these TVs would be considered to be "lightly sprung", and they both achieved close to 100% FALR.
Why do you say the Andersen WDH is not appropriate for such vehicles?

Quote:
A bar system will overcome the shortcomings of a lightly sprung TV.---
Exactly what are the "shortcomings" of a lightly sprung TV,
and how does a bar system overcome them?

Ron
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Old 02-05-2014, 09:06 PM   #118
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Originally Posted by Ron Gratz View Post
I've seen only two reports of people being able to achieve close to 100% front axle load restoration when using the Andersen WDH.
One TV was a Honda Pilot, and the other was a Toyota FJ Cruiser.

Ron
Ron, As you know, the FJ Cruiser is mine, and yes the Andersen hitch does distribute 100% axle load restoration , or more with my trailer. It is my opinion the Andersen works well for me because a:the Casita's tongue weight is only 400 pounds, +,-, and b:the FJ Cruiser is a rather short wheelbase vehicle with an even shorter rear overhang.

The FJ for it's size and type vehicle is actually not very "lightly sprung", and is rather stiff with parallel leaf springs. It is easily as stiff suspension as a mid sized pickup truck.
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Old 02-06-2014, 01:09 PM   #119
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The FJ for it's size and type vehicle is actually not very "lightly sprung", and is rather stiff with parallel leaf springs. It is easily as stiff suspension as a mid sized pickup truck.
Steve, I concluded your FJ would qualify as "lightly sprung" (as regards load transfer) because of how easy it was for you to get the front end to drop below its non-hitched height.

Ron

Quote:
This trailer is about 3,500 pounds, and 400 pounds tongue weight. The adjustment for the proper weight distribution went suprisingly easy, and I was rather taken by the light amount of tention required on the chains to return the front of the vehicle to it's non hitched height. As a matter of fact, I adjusted it too tight on initial attempt, and had to back off to raise the front back up a bit.
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Old 02-06-2014, 02:04 PM   #120
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A mid sized pickup would be a three quarter ton. Your FJ is that stiff? Jim
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Old 02-06-2014, 02:13 PM   #121
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A mid sized pickup would be a three quarter ton. Your FJ is that stiff? Jim
No, by "mid sized", I meant like a Tacoma, Colorado, etc. vs a full sized pickup like an F-150, Ram 1500, or Silverado 1500.

They used to be called small pickups, but in recent years they've become larger, but not as large as the full size.
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Old 02-06-2014, 02:15 PM   #122
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Ron

I have read your post
Woodalls Open Roads Forum: Towing: Weight Distribution (WD) Hitch --- How it Works

While it is a simple explanation of the net effects a WD hitch has on the measurable loads on the 3 axle sets involved in a towing configuration it completely ignores the dynamics within the head of the hitch. That is where the effects of a WD hitch are accomplished.

You state that there is a 300 lbs reduction in the load at the hitch and one would assume from the loads illustrated at the axles that that might in fact be the case. If one accepts that there was an original tongue weigh from the trailer and an additional downward load on the ball is generated by the tension on the bars. It is clear that even though the tongue may have been raised by the application of the WD hitch the net dynamics within the hitch head was not negative.

Neither of us, nor any of the other posters, has the capacity to to fully explain the overall dynamics that takes place within the hitch head. The best we can do is accept the fact that a static tongue load applied to the receiver is partially converted to a rotational force that tend to bend the center of the system upwards at that point. This point, the transfer of weight, can be clearly deminstrated by scale tickets but not demonstrated by a simple static beam analysis.

Given that limitation I suggest we confine our comments as to which TV/TT combination might best be addressed by different WD systems. There are limitation to every WD system and the end user should be advised of those rather than subjected to veiled advertisements.

I currently use the Andersen with my 34 ft trailer and Ford Excursion with great results. I had for years used both the Reese dual cam and straight line systems. During that period I posted quite often on how to set up and use those systems.
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Old 02-06-2014, 02:21 PM   #123
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It will be interesting who gets the last word on this. I can hardly wait! Jim
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Old 02-06-2014, 03:53 PM   #124
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While it is a simple explanation of the net effects a WD hitch has on the measurable loads on the 3 axle sets involved in a towing configuration it completely ignores the dynamics within the head of the hitch. That is where the effects of a WD hitch are accomplished.
Howie, is this your explanation of your basis for saying that "the Andersen is not appropriate for a lightly sprung TV"?
We need to play fairly. When I show you my "basis" -- you're supposed to show me your "basis"

Quote:
---I suggest we confine our comments as to which TV/TT combination might best be addressed by different WD systems. There are limitation to every WD system and the end user should. be advised of those rather than subjected to veiled advertisements.
I agree -- let's start by having you explain why the Andersen WDH is not appropriate for a lightly sprung TV.
Until I understand your thinking in that regard, there's not much point to trying to discuss the effects of different WD systems on various TV/TT combinations.

Ron
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Old 02-06-2014, 04:11 PM   #125
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Could we also know what vehicles are "lightly sprung". The Andersen weight transfer was not sufficient on our 2006 Tundra (140" WB) nor our 2012 Ram 1500 (120" WB), among the other problems we had with it.
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Old 02-06-2014, 04:15 PM   #126
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It seems to me that HowieE is saying if your vehicle is so lightly sprung that it won't carry the tongue weight of your trailer without a weight distribution hitch, the Andersen WD hitch won't work with your trailer/vehicle.
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