Ron Gratz
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Stressor wrote:Why yes Ron, when it was presented to you, with pictures, you posted about one and a half printed pages to the effect that it couldn't happen. And, yet, it did. Don't let empirical proofs get in the way of your expounding on your ill-informed theory though.
If anyone is wondering what Milt is referring to, you can read about his "demonstration" back on page 15 of this thread.
In the interest of civility which Will has requested, I will only refer to my response back on page 18.
Milt believes that a person who has never owned or towed with a HA cannot possibly have any valid understanding of how one works. Therefore, I will just point out that one HA owner who also is keenly interested in how the hitch works has concluded that the theory supposedly proven by Milt's demonstration was "shot down" and has characterized Milt's demonstration as "somewhat flawed".
Of course, any who wants to can digress 15 pages and form his own opinion.
Ron
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willald
NC
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Ron Gratz wrote:Milt believes that a person who has never owned or towed with a HA cannot possibly have any valid understanding of how one works. Therefore, I will just point out that one HA owner who also is keenly interested in how the hitch works has concluded that the theory supposedly proven by Milt's demonstration was "shot down" and has characterized Milt's demonstration as "somewhat flawed".
Welllllll, out of respect for Milt (and my firm belief that he is right, although his demonstration didn't prove such completely), I am going to retract that claim about him being 'shot down', and will say that the only thing that might be considered flawed, would be the way he went about proving such.
His principle about the Hensley being 'locked' from the trailer's perspective, is right on. The problem is, its very tough to show this to someone that has not seen/experienced a Hensley and what it does. Milt did come up with a very unique (and funny) way to try to prove such, although the reality is, it did not prove the point it was intended to prove. That does NOT mean the point he was trying to prove is false, it just means the proof of such was not quite complete.
Milt does make some really good points, Ron. You have never seen or experienced a Hensley, you are only using theory and Mathematics/Physics to try and predict how/why it works. Thats all great and interesting to read and talk about, but remember, practical experience goes a long way, too. All the scientists that use theory, Math, Physics, etc. still cannot explain why a bumble bee flies. But it d-mn sure flies. ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/smile.gif "smile")
Anyway, instead of trying to dis-credit each other by harping on things like lack of practical experience, etc., lets get back to the important things. Lets get back to what Don and I were illustrating, about the REAL reason why the Hensley essentially 'locks' things from the trailer's perspective. I think thats the only way we're all going to eventually agree, on how/why it does what it does.
Will
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willald
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Shoot, enough is enough! Tonight, I'm going to go rent a big crane. Then, I'll hitch up the trailer to the Excursion, and gently lift up the Excursion and trailer by the Ex's front bumper, with the crane. I'll then have to find a way with cables, ropes, etc. to tie the Excursion in place (suspended), so it cannot move around (I know, starting to sound like that F150 commercial..LOL!)
Then, y'all (Ron, Milt, and Don) can fly on over here, drink a few beers, and we can see how much force it takes to make the trailer swing back and forth. We can tie a rope to its back bumper, and try to pull it to the side with another vehicle! I know, I know - drink too many beers, and WE'LL be the ones swinging back and forth! LOL!
If we do that, Ron, and you find that the tension basically locks the connection so it will not swing, and we cannot get the trailer to swing/pivot), THEN, will you accept that what we've said is true?! ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/biggrin.gif "biggrin")
We can even take pictures, and post it on this thread! Then, everyone can see how we finally came up with an experiment, that proves once and for all how the Hensley REALLY works. Hahahahahaha!!
Will
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BurbMan
Indianapolis, IN
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Ya know Will, you got me thinking.....I know you won't really lift your X with a crane, BUT what about a model? All we'd need is a scale model of the HA. Use a Tonka truck, a model of a TT, and a HA replica, and we could prove this...
How 'bout it??
Anyway, I couldn't do this with the Sub, the hitch receiver would rip off the truck once it got off the ground.....
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willald
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BurbMan wrote:Ya know Will, you got me thinking.....I know you won't really lift your X with a crane, BUT what about a model? All we'd need is a scale model of the HA. Use a Tonka truck, a model of a TT, and a HA replica, and we could prove this...
How 'bout it??
Anyway, I couldn't do this with the Sub, the hitch receiver would rip off the truck once it got off the ground.....
LOL, actually, ANY receiver would rip off, under that much weight! AAMOF, I doubt the Hensley, A frame, or any other parts of the frame involved, would take too well to being hung vertically by a crane! Hahahahahahaha! I only posted that, to try to lighten everyone up some.
Yeah, would be easy actually, to find the appropriate model of a truck, and a trailer. Biggest challenge would be, getting/making a perfect scale model of a Hensley, that would act/pivot just like a real one, and would attach correctly to the model truck and trailer. Perhaps for the publicity of it, we can convince our friends at Hensley to provide us with such a model? Naaaaahh! They'd think we were a bunch of nut cases, for trying such (and we might be...)
Will
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Ron Gratz
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BurbMan wrote:Picture a pendulum with a rubber band connected to its bottom and the other end fastened to the ground surface below the pendulum. Any attempt to start the pendulum swaying along its arc will be resisted and eventually stopped by the force the rubber band exerts. The rubber band will effectively dampen the movement until the pendulum is once again hanging in a static position.
Don,
I'm glad that you did not contend that the rubber band would "lock" the pendulum at the center position and that no amount of force would be able to move it to the side. The tension in the rubber band would cause an increase in the amount of force required to move the pendulum. For example, if the tension were 1000#, it require an additional 17.5# of force to pivot the pendulum 1 degree.
However, the tension in the rubber band does not dampen the motion of the pendulum. The motion is damped only if there is an energy dissipating device, such as a shock absorber, in the system. That's why cars have shocks. A coil spring (or a rubber band) does not have enough internal friction to provide any significant damping.
Once the displaced pendulum is released, the rubber band tension will add a restoring force which will make the pendulum accelerate faster toward the center position. Energy will be conserved and the pendulum will swing to 1 degree in the opposite direction. Eventually, friction at the pivot point plus the small amount of internal friction in the rubber band will still the motion; but it is not due to the tension in the rubber band. Your use of the term, "eventually stopped", is correct; but not for the reason you postulate.
Quote:What Will and I are saying is that the drag and wind resistance created by the trailer act just like the rubber band in my example. Traveling at hiway speed, these forces amount to the equivalent of a very thick rubber band on the bottom of that pendulum, so any attempt to swing the pendulum is quickly dampened by the rubber band.
First - a rubber band (or a steel spring) would not add any appreciable damping.
Second - the tension in a rubber band will increase as the rubber band elongates. In your HA theory, are you claiming that the drag and wind resistance increase appreciably as the TT moves a fraction of an inch closer to the TV? If not, how does the rubber band analogy enter in?
Quote:Yes, the math says that movement is allowed, but you are ignoring the fact that the HA relies on tension bewteen the TV and TT to resist any movement introduced into the 4-bar linkage by the TT.
You have used the phrase, "resist any movement". If by this you mean, "absolutely lock out any movement", then I do not agree. If you mean resist in the sense that the mass of a pendulum resists its being displaced from its center position, then I do agree.
Quote:AND, it's not a question of whether the TT is allowed to pivot...as an example, if I am driving on the interstate at 70 mph with the HA connected to my 34' TT, and a 50 mph gust of wind comes up perpendicular to the trailer, I will feel the TT move. HOWEVER, the HA effectively dampens this movement to a single push, and this tension that Will and I are trying to explain prevents that intial movement from repeating itself into a sway condition, as a pendulum would when dropped from a point along its arc.
It is not the HA which is damping the movement. It primarily is the lateral resistance provided by the TT' tires which does the damping. Energy frequency content of a gust of wind is not sufficient to cause sustained oscillation in the presence of normal tire damping.
The reason that conventionally-coupled trailers tend to sway under these conditions is that some of the lateral wind load on the TT gets applied to the rear of the TV via the ball coupler. The TT tends to steer the TV and the driver might over compensate which can contribute to sustained oscillation of the TT. With the HA, the tendency for the TT to steer the TV is significantly reduced primarily due to the forward relocation of the pivot point.
I fail to comprehend why some HA owners cannot accept that the HA works for two fairly simple reasons:
1. the HA reduces the magnitude of the lateral loads, and
2. the HA reduces the length of the "steering lever arm".
These two effects combine to significantly reduce the "steering torque" imposed on the TV. This, in itself, is sufficient to explain why HA owners do not experience sway. That's all there is to it. There's no reason to make it more complicated with "lock up" theories, etc.
Ron
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Ron Gratz
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BurbMan wrote:Ya know Will, you got me thinking.....I know you won't really lift your X with a crane, BUT what about a model? All we'd need is a scale model of the HA. Use a Tonka truck, a model of a TT, and a HA replica, and we could prove this...
Don and Will,
I would love to see you guys do this. It would mean that the model tests which Tim Luxon and I have conducted could be confirmed by two actual Hensley owners. OTOH, maybe you wouldn't want to confirm what we have been saying.
If you would like to see what another obviously biased and ill-informed non-Hensley owner has to say about testing of Hensley models, you can read this.
Ron
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Ron Gratz
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;willald wrote:His principle about the Hensley being 'locked' from the trailer's perspective, is right on. The problem is, its very tough to show this to someone that has not seen/experienced a Hensley and what it does. Milt did come up with a very unique (and funny) way to try to prove such, although the reality is, it did not prove the point it was intended to prove. That does NOT mean the point he was trying to prove is false, it just means the proof of such was not quite complete.
Interpretation: If you're a Hensley owner, your theory is correct even if it has not been proven????
Quote:Milt does make some really good points, Ron. You have never seen or experienced a Hensley, you are only using theory and Mathematics/Physics to try and predict how/why it works. Thats all great and interesting to read and talk about, but remember, practical experience goes a long way, too.
Interpretation: If you're not a Hensley owner, your theory is not correct until proven even if it is based on sound Mathematics/Physics; and even if it were proven, it would not be valid because you are not a Hensley owner????
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willald
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Ron Gratz wrote:I would love to see you guys do this. It would mean that the model tests which Tim Luxon and I have conducted could be confirmed by two actual Hensley owners. OTOH, maybe you wouldn't want to confirm what we have been saying.
Actually, I think it is YOU that may not be happy with the results of this test, if it was done accurately (taking into account the pulling/tension on the Hensley). You'd have to take back most of what you've said in this thread (and others). And, you'd realize, that sometimes all the Math and Physics in the world, will not prevent you from overlooking a simple thing or two, which changes everything.
Quote:If you would like to see what another obviously biased and ill-informed non-Hensley owner has to say about testing of Hensley models, you can read this.
Interesting reading there. Nice try, Ron, but I agree with a lot of what he said.
"My only reason for pursuing this subject to some logical conclusion was to identify what I would call a myth. In other words, some factual operating characteristics of the hitch, as related to sway(fishtailing), can not be successfully extrapolated to cover any and all trailer events."
Absolutely! Nobody (except Hensley's marketing hype maybe) ever said this hitch was 'magic' or that it could cover any and all trailer events. He went on to make an example of a situation, where a truck/trailer are going down a hill, and encounter a curve on a slippery surface, and that in this situation, the Hensley would not help you any better than any other hitch.
Funny thing is, even though he did not intend to, he is proving the point Don and I have been making all along, that once the tension/pulling in the Hensley goes away, the trailer is free to pivot (through the projected pivot path/arc the Hensley allows). If you're going downhill like that (without braking) as he describes, then briefly, the trailer could be pushing the tow vehicle instead of vice-versa. We've said all along, that taking away the tension/pulling in the Hensley, allows the trailer to pivot through the axis/arc that the Hensley forces. He's right - NO hitch will lock up the trailer in that circumstance, except maybe a real tight friction device (and that creates more problems than it solves).
Quote:
Interpretation: If you're a Hensley owner, your theory is correct even if it has not been proven????........
Interpretation: If you're not a Hensley owner, your theory is not correct until proven even if it is based on sound Mathematics/Physics; and even if it were proven, it would not be valid because you are not a Hensley owner????
Noooo, its more a matter of, so many of us that own a Hensley know what we have experienced, and know what our hitch does. In my case (and many others as well), I have a hard time believing that just the simple pivot-point projection the Hensley does, is enough to explain how much better it tows. In my mind, there HAS to be more to it than that.
Similar to the bumble bee thing - when you know for a fact that the bee can fly, it doesn't matter how many of the world's smartest scientists prove with Math & Physics that it cannot, you know and have seen personally, that it CAN fly. Soooo, you know in your mind, that there must be something more to it than the Mathematics/Physics models that 'prove' the bee cannot fly. Same kind of thing here.
Will
* This post was
edited 08/24/05 06:20am by willald *
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willald
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On a separate note: Haven't we set any records yet with this thread, for the LONGEST thread yet on the Hensley topic, that has stayed civil and intelligent (for the most part) the whole way?
Will
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