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Old 03-28-2006, 07:20 AM   #57
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Thumbs up Good find Roger!

This is a good example of how every state is different.
Roger posted part of the state regulations for Iowa that I was unaware of, and I have towed thru Iowa before. Now, if I tow again, I know that I need a weight equalizing hitch and sway control for the travel trailer I am towing....

So, if I was towing across several states & Iowa was one of them, I would have to have the equalizer hitch & sway control in place at least in Iowa.

Thanks to Roger, I will use a sway control device & my weight equalizing hitch on all travel trailers I tow from now on. It seems the State of Iowa recognizes sway control and weight equalization as being as important as electric trailer brakes...

I might add, every trailer has different electric brakes. Before you begin a trip, be sure to "test drive" a section of road (with no one behind you) and trim the brake control to suit the trailer you are towing.....

Thanks Roger
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Old 03-28-2006, 09:33 AM   #58
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Originally Posted by nickcrowhurst
AZ, yes indeed, but with the proviso that after 2., the front jack must be fully raised so that it does not touch the ground thereafter. Good luck with the experiment. You have my admiration for being open to experiment, rather than taking a dogmatic position.
Nick.
well, I'm not taking a "dogmatic" position...I'm just reporting the results of my um..."experiment".

I think I can explain the "why" much easier than has already been attempted.

just picture a truck and a trailer, parked end to end, all nice and straight and level. now hook up the heavy trailer to the truck. what happens? truck's tail goes down, trailer's nose goes down. the point at which the straight lines of the vehicles meet is now bent at a hinge point. how do you straighten it back out? push UP. in order to get the weight "distributed"...actually moved back to the trailer's wheels, and forward to the truck's front axle, you have to push UP with a force in excess of the weight of the tounge, and twist it. (accomplished by the lever-action of the angled ball mount and wd bars). that force is re-directed fore and aft, because the locked coupler can't move. but if that latch is released when the bars are still attached, the coupler will go up, because the upward force exceeds the tounge weight. a force equal and opposite to the tounge weight would only level the load; not re-distribute it. (i.e. airbags on a tow vehicle's rear axle...).
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Old 03-28-2006, 10:12 AM   #59
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how do you straighten it back out? push UP.
Oh, no! Its getting more complicated than it needs be. Take gander at Occam's razor to find out why this can be a problem.

And yes, experiment is great. Been there done that, am using my own experience. You are more than welcome to repeat the experiments. Good exercise. Be sure to keep a good lab notebook. Share with us, too!

But we are talking about a beam and not a pilar system. There is no pillar of support at the ball (unless you are using a truck like in the Long Long Trailer movie). Instread, the hitch between the trailer axle and the tow vehicle axle is a beam held up in the same way a board stays up when placed on a couple of supports a distance apart.

The beam is straightened by increasing tension on the underside and/or reducing compression on the upper side. It is not pushed up in the middle.

Take two rulers and join them at one end and tie a string between them at the other end. Set them up as an A frame. How do you raise the point where the two are joined? By shortening the string between them at the other end, pulling the ends together, not by pushing the junction up.

One of the interesting things about a trailer hitch is that nearly all of the torque is managed by the ball mount assembly (that is why it is so heavy and stout). The trailer doesn't push forward on the ball as a simple beam model would suggest because the torque transfer mechanism (chains holding up the sping bars) is very careful to apply only vertical loads on the trailer A frame (this is also why the chain mounts on the A frame are usually able to slide back and forth). This is why the ball angle adjustment is often just a set screw pushing out the bottom of the ball mount and not a trapped adjustment.
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Old 03-28-2006, 11:16 AM   #60
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Originally Posted by Leipper
The beam is straightened by increasing tension on the underside and/or reducing compression on the upper side. It is not pushed up in the middle.
the resultant force at that spot is UP, otherwise, it wouldn't go UP.
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Old 03-28-2006, 01:36 PM   #61
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"""because the upward force exceeds the tounge weight. a force equal and opposite to the tounge weight would only level the load; not re-distribute it. i.e. airbags on a tow vehicle's rear axle...""

hi chuck and others.....

it's good to see the exchange about how w/d systems work.....and with enough examples, forumula, and trials we might have a good thread on w/d dynamics.....for all to learn from.

maybe we could move this info/exchange out of the bambi/sway control thread....

it would be nice to use nicks thread on 'calculations' or a new thread on w/d analysis, theory, and application....or some such name.

so folks can learn/understand regarding w/d's without debating the need for sway control on all size trailers......the point of the original post...even bambi needs sway control....

trulyvintage.....other states do have w/d requirements, like iowa....and those tow ratings you mention also usually require w/d systems for tongue loads greater than 500lbs...

it's correct only the driver may know what happened....and even he/she may not....really know.....and by the way this trailer pictured should be long rebuilt by now and resold....that was the plan.

but the bambi pictured did not have sway control attached. and the 'bacon' you mention being saved was likely the result of a suburban sized t.v. not being controlled by a small trailer flopping about...

chuck....
your analogy to rear airbags doesn't apply here, and it isn't how w/d systems work.....because there is not ground contact/support....under the connection.....like with an air bag setup.

the lifting noted at the hitch/ball assembly is a byproduct of how the w/d system applies force....to look at it as 'lifting' at the ball is misleading...in fact if the ground were soft enough under the front t.v tires and trailer tires....the w/d forces could 'level things' and redistribute without raising at the middle...but buy pushing down the front and rear support points..

cheers
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Old 03-28-2006, 01:39 PM   #62
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the resultant force at that spot is UP, otherwise, it wouldn't go UP.
It doesn't "go" up rather it 'stays' up. There is no net force or there would be movement. (Newton #2).

As with any beam, the load is transferred out to its ends (the axles in this case).

The force UP on the ball by the hitch is equal to the force DOWN by the ball (Newton #3) and is the resistance of the hitch to being deformed.

see Newton's laws of motion and Bending in wikipedia

For another model to consider: Think of a steel I beam that runs from the middle of your tow vehicle back to the trailer axle. The trailer ball sits on that. You couldn't steer very well but you'd certainly have very good load leveling.

Come to think of it, that model is pretty close to a Pull-Rite hitch.

Also, you should understand that these concepts are not an easy to understand. It sounds simple and it is simple but they are some of the more difficult conceptual ideas to teach in basic physics. It took centuries before Newton really laid them out and, in the centuries since, many in the general public still don't get it because it takes a bit of counter-intuitive thinking and work to figure it out.
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Old 03-28-2006, 01:55 PM   #63
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...other states do have w/d requirements, like iowa....and those tow ratings you mention also usually require w/d systems for tongue loads greater than 500lbs...
...
but the bambi pictured did not have sway control attached.
...
your analogy to rear airbags doesn't apply here
2Air, I haven't seen many states requiring weight distribution like I do for brakes. A lot of trucks don't need it and some even don't need it for mobile home transit.

I know that towing a Bambi with even a sedan doesn't necessarily need sway control and even a modest burb or IH Travelall might not need load leveling with it.

The rear airbags may well apply here as the intelligent suspension on some newer vehicles are designed to handle several hundred pounds of hitch weight without any load leveling requirements. It all depends upon the design of the tow vehicle.
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Old 03-28-2006, 02:05 PM   #64
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Originally Posted by Leipper
The rear airbags may well apply here as the intelligent suspension on some newer vehicles are designed to handle several hundred pounds of hitch weight without any load leveling requirements. It all depends upon the design of the tow vehicle.
i'm not suggesting airsuspensions don't improve load carrying and handling....on some newer vehicles...like the touareg, cayenne, rover and so on....or even on semis and mohos.

my point is lifting the t.v. at the rear axle (with air or springs or a jack) doesn't mimic how w/d systems apply stress/force via the frame to redistribute...

so i stand by the observation that 'air bags at the rear axle don't apply' to how spring bar/wd systems function.

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Old 04-02-2006, 09:01 PM   #65
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The test part 1

Earlier in this thread we had a discussion about the possibility of the trailer coupler jumping off of the ball if the coupler was released with the WD arm attached. The theory was that the WD arms are listing the rear of the TV by lifting on the coupler. Several laws of physics are involved here. Because of my teenage years in the sixties I sometimes ignore the laws that I donít like or understand. I said I would test this theory and I did.
The first thing I did was to adjust the hitch ball in accordance with the instructions I downloaded from this site. The result was that my ball is now angled back to the TT several degrees, it was straight up and down before this. This adjustment most likely had nothing to do with the results of the test, but it needed to be done.
I used my 1075 Trade Wind with a listed tongue weight of 630 pounds. I attached my Reese WD hitch with 750 pound arms to the rear of my 2004 Tundra. (continued)
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Old 04-02-2006, 09:02 PM   #66
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The test part 2

The first test was t attach the trailer and leave the coupler unlocked. I then tried to lift the trailer off of the ball. 630 pounds, not a chance. (continued)
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Old 04-02-2006, 09:03 PM   #67
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The test part last

The next step was a little harder to do. I could not lift the trailer and TV with the trailerís jack to help attach the arm. This made it quite difficult. I did place blocks of wood under the tongue of the trailer (just in case) but they did not touch. I did use my 6 ton hydraulic jack to raise the rear of the TV (at the hitch) and the trailer to attach the bars. The jack was removed for the lifting part of the test. I started with a small amount of tension on the arms and continued until I had gone one link past the level point for my TV. At that setting the rear of the TV was noticeable higher then the front and I had gone too far.

The result: At no point was the weight on the ball small enough to budge the coupler off of the ball. I even tried to leverage it with a pry bay and it would not move. The theory that the front of the trailer would be lighter is incorrect. I was wrong and I proved it. Thank you to everyone for not beating me up too much on this issue. Now can anyone explain why chuck said that his coupler rose into the air when he uncoupled the ball, I canít.
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Old 04-02-2006, 09:22 PM   #68
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good post azflycaster

i just love show and tell!

as i understand, the forces around the ball should have actually increased, not decreased as the spring bars were progressively engaged....only a sensor between ball/cup could show this, but the complicated vector graphs and forumla i've seen indicate this...

seems we will need chuck to repeat his process.

again good job; thanks for sharing...

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Old 04-03-2006, 10:37 AM   #69
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Hmmm...I think we're all saying the same thing, but it sounds like we're saying something different. The concepts are difficult to describe with words.

2-air: on the airbags, that's what I meant. airbags are like a pillar; wd is like a beam. You can "level" the load with airbags, but not "redistribute" the load the same way.

Leipper: yes, "beam". I get that. a beam works by balancing tension and compression, right? its like a beam when its all hooked up and adjusted correctly. But its not really "a" beam; its 2 beams, overlapped, and strapped together ("sistered") at 2 points. the forces on those 2 connection points have to be balanced, too, yes? remove one without removing the other, and you've got a hinge.

the experiment: I'll have to try and mimic the same thing. It looks like very similar equipment...comparable trailer and tow vehicle (1/2 ton)...reese hitch, although, I don't know how strong the bars are (old, and not clearly labelled), and there is a dual-cam attached. but I don't think that should make a difference. perhaps I've just got it too tight. It was difficult to get what appears to me to be "acceptable" deflection with the wd system, according to the standard bits of advice. "tv should settle the same amount at both axles"..."vehicle should be level", (that is contrary to the first bit, because the vehicle wasn't level to begin with). You can't follow the Reese instructions to the letter, because the bars will touch the ground before they reach the recommended distances "x, y, z"...possibly just because of our lower-slung than usual trailers. (If the whole thing was 6" higher, you could do it...at least more easily.)

anyway, I'm thinking that one explanation is that my front axles are stiffer (in effect) than the rears...moreso than typical. And as a result of my trying to level the load by conventional advice, rather than using a scale as my only reference, has caused me to adjust my bars too tight. I can tell you that jumping up and down on the rear bumper of this truck, its like a spring-board. like a swiming pool diving board. jump on the front bumper, and it barely moves. I've seen discussions on my snow-plowing forum about why chrysler says you shouldn't plow with this truck (1/2-ton quad-cab; 1/2 ton regular cab is "approved"). The stretched cab and lack of a "b-pillar" puts proportionally more weight on the front axle than a "conventional" setup, and the added weight of a typical snow plow would exceed the axle rating. So there's so little slop in the front end, the results of adjustment to a wd hitch are deceptive. just a guess. I'll have to try and repeat the experiment in a couple of weeks, when we get hooked up.
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Old 04-03-2006, 11:42 AM   #70
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Chuck... please do. I think many of us were puzzled by your coupler "springing up". I've never observed that occur, and I've prematurely unlocked the coupler on mine a number of times on various tow vehicle/trailer combinations without experiencing what you described. It's always been my experience that without raising the tongue and tow vehicle with the jack, it's not coming unhitched... period.

Let us know what you figure out.

Thanks!

Roger
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