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Old 01-12-2011, 01:21 PM   #155
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Thanks Andy:

Is there any simple formula or chart that a goofball like me could use to determine the correct lash-up combination for any given truck/trailer combination?

All my best,
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Old 01-12-2011, 01:34 PM   #156
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Originally Posted by CrawfordGene View Post
But, wouldn't is be nice if the information was "complete, verifiable, supportable, repeatable".

I appreciate Andy's effort to bring information forth a little more light to a topic that is usually characterized by endarkenment.
So, like newro' said, take it for what it is. It more than we had before.

Questions from my unscientific mind—wouldn't a stiffer bar provide more sway control? Which is worse—an accident caused by poor sway control or a trailer beat up by stiff bars? The last question does not mean I agree that stiffer bars beat up trailers—I don't know. My experience is that the obvious answer is not always the correct answer and that the obvious answer is often the correct answer. This is not a paradox.

Gene
Gene.

I already went further than any hitch manufacture, or RV manufacturer, or dealer, with those tests, AND without any support from anyone, except encouragement from nice people.

It's not and "END", but a beginning if someone else wishes to take it to the next level, with their time, money and talents. Then of course they also must accept the criticism from non believers as well, that more than likely would follow.

Please be advised, that load equalizing hitch torsion bars, DO NOT in any way, provide sway control. There are 2 types of sway controls, if you wish. There is the friction type, that has no idea if the rig is straight or in a turn. Then there is the torsion type sway control, that provides extra, unequal torsion, on the bars when in a turn. They of course seek minimum torsion, therefore they help the rig straighten out, as well as keep it that way.

In my opinion, Equalizier hitches "do not" offer "ANY" sway control, except in their ads.

Andy
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Old 01-12-2011, 02:00 PM   #157
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Originally Posted by CrawfordGene View Post
But, wouldn't is be nice if the information was "complete, verifiable, supportable, repeatable".
We'll know if they're repeatable as soon as someone else starts spending their own time & money on testing!

Personally I don't see the data as all that revealing. The percentages of deflection in 800 vs 1000 bars, round vs tapered vs EAZLift vs Equalizer, is interesting. I doubt the work Andy has done will actually sell more hitches for him (and he knows that), but it might help him and others make a better decision given a vehicle/trailer combo.

So guess what folks, you're still going to have to use your own head and do some measuring, weighing and thinking when tuning your hitch setup.

I'm keeping my subscription to this thread awaiting others tests though.
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Old 01-12-2011, 02:17 PM   #158
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Originally Posted by Secguru View Post
Is there any simple formula or chart that a goofball like me could use to determine the correct lash-up combination for any given truck/trailer combination?
Sec, find out how much your trailer weighs by measuring it at the scales or with a scale. Buy the bars that match that weight. You probably won't find bars that match your exact weight. Andy's answer, 3 posts above your question, is to go for the lighter bars rather than the heaver bars if you have a heavy duty vehicle, when that happens.

I'm not sure I agree with that, and others will flat out disagree, but that's his position in dozens of responses to your same question.
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Old 01-12-2011, 03:44 PM   #159
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Quote:
Originally Posted by Inland RV Center, In View Post

There are 2 types of sway controls, if you wish. There is the friction type, that has no idea if the rig is straight or in a turn. Then there is the torsion type sway control, that provides extra, unequal torsion, on the bars when in a turn.
Andy
Andy,

Again, you are partially correct. Those are two types of sway control, but you keep overlooking, or avoiding the type of sway elimination used by ProPride and Hensley.

But then again, you don't sell those hitches, do you?
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Old 01-12-2011, 04:21 PM   #160
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Andy is right in his conclusions, the heavy duty trucks with too heavy rating bars do cause more problems for their trailers, even if his method of not loading the bars the way it used when you are towing, does cause some concern. If the bars take a permanent set after use, then the bars you are using are not heavy duty enough for your type of usage. The rating of the bars does not have any effect on the amount of sway control they give you. Only the amount of load you put on the bars has any affect on the self centering force for a twin cam Reese. The amount of frictional sway control for a Equalizer hitch is dependent on how much you torque down the restraining ells as well as the frictional force developed by the bar force due to the amount of weight you are transferred. Draw a free body diagram, like mechanical engineers use, and it is easy to see and calculate.
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Old 01-12-2011, 05:13 PM   #161
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Old 01-12-2011, 06:36 PM   #162
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I am not trying to court controversy. I am attempting to confirm your findings.

Due to the lack of information on how the tests were conducted, I or anyone else are unable to repeat your tests and produce comparison data, even if we were inclined to.

That makes your data unverifiable and unsupportable.

That's why I asked the questions - to clarify the method used and to rule out any potential problems with your protocol. Without those answers, you can't even say, "controlled tests" because no-one beside you knows what the controls were.

Answering everyone's questions simply removes uncertainty about your 'data' and allows ALL of us to have more confidence in it.
Hey Dave, could you please call some tire manufactures and unload this thinking on them about their ST tires and do us ALL a favoure?
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Old 01-12-2011, 06:45 PM   #163
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Hi All, Please keep a cool head while posting...

Weight distribution threads seem to bring out all lot of emotion.

Please be nice!
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Old 01-12-2011, 08:17 PM   #164
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First class work Andy, that had to be a lot of work and expensive..........

thanks
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Old 01-12-2011, 08:44 PM   #165
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Its obvious he has a love for airstreams and has devoted a great part of his life to them. So when he tells you to balance the running gear, he isnt trying to sell you centramatics, he doesnt want you to hurt your airstream......
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Old 01-13-2011, 12:23 AM   #166
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Very interesting data, Andy - thank you for collecting this.

As predicted, all the bars displayed linear load-displacement curves... save one. I'm curious if there were any experimental issues with the Reese 1000# tapered bars, as they displayed more deflection at high loads than the Equalizer 1000# bar - a result not predicted by beam theory and practice. The Reese 800# bar, which (presumably) has a very similar profile to the Reese 1000# bars, displays linear results to within measurement precision.

Note for a moment the very high loads produced by 1.5" deflection of the Equalizer 1000# bar. When beginning to climb a hill, the relatively angle between the TV and the Airstream will produce many thousands of lbs of extra load on the A-frame and hitch assembly.

The stiff bars are a design compromise needed to secure sufficient weight transfer force available with the limited bar deflection distance between unloaded and properly tensioned positions.

Thanks again, Andy.

- Bart
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Old 01-13-2011, 10:13 AM   #167
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Ok, I'll take a stab at this and try and see if there are any real world take aways for us relative to approach angle hitch bar flexing.

DISCLAIMER: This is a simi-mathmatically based SWAG analysis FROUGHT with variables!!!! So, with that in mind, take your potshots with BETTER math. This is the best I could come up with while trying to recall a lot of advanced math I haven't used much in 30 years. My head started to explode, then I realized, with all the variables, reasonable approximations would suffice.

Since spring bar flexing is a direct function of the change in angle between AS frame and TV frame, some of these variables are:
1) WB of TV
2) Distance from ball coupler to center of AS axle(s)
3) Distance of overhang from rear axle to ball on TV
4) Compressability of TV and AS suspension
5) Tongue weight (component of base static bar flex)
6) Sprung load in TV (component of base static bar flex)

Using my AS and TV here are some numbers:
(This scenerio assumes NO front TV, no AS suspension compression and no rear TV suspension lifting, so should RESEMBLE a worst case scenerio)

TV WB = 135"
TV + hitch overhang = 59.7"
Coupler to center of AS axles = 223.4"
Spring bar effective length = 30"

Worst case, hitch drags ground with a 20" rise of front wheels over my TV WB with a 8.9" drop at hitch. Again this assumes NO suspension flexing! But still, it is an aggressive approach which would result in about 4.5" of spring bar flex.

HERE'S A BIG SWAG.

4.5" of flex is unrealistic, I believe, in the real world because of the effect of the bars to flatten out the change in angle between the TV and AS due to suspension extension and compression. (Here enters the discussion of 1/2 vs 3/4 vs 1 ton IMHO, as well as the tongue weight and load on rear axle of TV)

I SWAG that we would expect to see 3" - 3.5" of flex in our driving when approaching step entry angles.

ANOTHER SWAG!!!!

It is necessary to extrapolate (read, "guess", with some predictability) the extension of the chart lines to get to some of the anticipatd data!!!!! (scary in and of itself!)
Like Bart, I am not understanding the last few data points for the REESE 1000#er. (yes Bart, although I still can't reconcile in my noggin the linear function of the tapered bars.....the data don't lie, and I concede!)

Because of that odd trend on the REESE 1000#er, I really don't even trust my SWAG (and that's too bad, as that is the setup I would most like to be comfortable with, data wise)

SO!, at 3" - 3.5" of flex, I THINK this:

Hitch Force exerted on tongue (approx)

REESE 800# tapered 1900 - 2100#
REESE 1000# tapered 1900 - 2000# (?????? odd curve)
REESE 1000# round 1600 - 1800#
Equal-i-zer 1000# 2800 - 3200#
EAZ Lift 1700 - 2000#

Ok, a lot more to discuss and this is just a STARTING POINT for meaningful DISCUSSION, please.

How much is too much on various AS frames?

Andy, The REESE 100# tapered results seem odd. Is there a way to validate that set of data? Maybe with a couple of different sets of bars?

Ok, all you brainiacs out there, do I lose the Equalizer 100#er and go with a REESE 800# tapered, or 1000# tapered with sway control?

No, I'm not going to go with Hensley or Propride. I've got nothing against them and appreciate them, but FOR ME, I don't see the cost/benefit analysis working. I am very comfortable with a PROPERLY set up conventional hitch with sway control.
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Old 01-14-2011, 09:55 PM   #168
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Thanks

Your work is appreciated Andy.
Thank you,
Robert
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