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Old 09-07-2012, 01:36 PM   #435
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Originally Posted by idroba View Post
I thought I might try to explain and analyze how the Andersen hitch provides the weight distribution to a tow vehicle. This is not easy, and I may not succeed, but here is my attempt. I will compare it with a conventional round bar system (RB), which uses bent bars which go into the hitch head, and are supported on the trailer side by snap up brackets and chains.

First, visualize the conventional RB from the side, lets say the road side. Sit on the ground (in your mind) and look at a hooked up TV and trailer. TV will be on the left, trailer on the right.

When hooked up, the RB system tries to twist the hitch head upward, or counter clock wise (CCW) by the lever arm provided by the length of the bar. The twist is provided over a few inches of metal which is inserted in the socket of the hitch head. The long end of the bar is supported by the chains from maybe 28 inches back on the bar. Those in turn are held up by the snap up bracket and apply additional force on the tongue, from about 28 inches back from the ball. The ball thus has the tongue weight on it, plus part of the forces from the chain from the spring bar . The CCW twist, is provided by the bent spring bar in the socket. We all know from years of experience that the conventional RB system works and re distributes forces forward, putting more downward force on the front tires.

Now look at the Andersen system from the same view, that is sitting on the ground on the road side of the hitch, TV on your left, trailer on the right. Assume that it is hooked up and properly adjusted.

The ball on the Andersen is a long tapers shaft from the top of the ball to the bottom where the triangular plate attaches. That ball shaft rides in a metal tapered socket which also has friction material in it (which we will ignore for now). The tapered socket is attached to the TV rigidly, via the hitch shank/stinger setup. Now pull rearward on the triangular bottom attachment with the chains which attach to the frame through some plastic bushings (ignore for now) and attach to the frame via the frame brackets. That rearward pull is resisted by the rigid trailer frame and the force is put forward on the frame of the trailer, and into the coupler and then to the ball, pushing on the rear side of the ball. We now have a triangle, with one short side (the ball and shaft) and two long sides, one the chains of the hitch, the other the frame of the trailer. With the ball and shaft being pulled from the bottom and pushed from the top there is a CCW twist applied to the ball/shaft side of the triangle. Since that short leg of the triangle can only move by twisting the metal tapered socket in which it rides, which twists the shank/stinger which goes into the TV we have the same result we had in the RB distribution system. Actually the short end of the triangle we are visualizing is about the same length in either the Andersen or the RB system. The twist on the TV hitch then transfers forces forward through the TV frame to put downward pressure on the front tires. Both the Andersen and the RB system accomplish the same thing, a CCW twist on the TV hitch box.

In the Andersen, the chains on the bottom, via the triangular plate, essentially do the pulling of the trailer, not the ball. The tongue downward force is still carried on the ball, and provides the pressure needed to make the friction material work for the anti sway feature of the hitch. The plastic bushings on the ends of the chains provide some flexibility in the system and the "anti-chug" feature that can help the ride quality.

The essential difference is that on the Andersen the ball/shaft carries the CCW twisting force needed for weight distribution, where in the RB system the bent spring bars do the CCW twisting. The twisting lever arm (short side of the triangle) is approximately equal in either system.

I am hopeful that this "sit on the ground on the road side of either hitch and look at them" approach will help people understand how both the RB and the Andersen work.

There are many good hitches on the market, and for 34 years I have used Reese and Draw Tight conventional WD hitches which were always satisfactory. I happened to need a new hitch, and found the Andersen. It works well and has some advantages in low weight, and smooth ride, as well as a very good built in sway control. However, every hitch out there is a bit different, and I don't think any are "bad" and should be excluded from your consideration. Each is somewhat different in weight, hookup operation, sway control, grease and lube needed and other factors. It is great to live in an economic climate where we have many choices. Depending on our perceptions and needs, we can decide the merits of each system and purchase accordingly.
Quote:
Originally Posted by Wazbro View Post
I made a drawing that shows my understanding of how the weight distribution works, it is a ruff drawing and I am sure many people will disagree with it.

This makes perfect since to you and I, BUT some engineers amongst us want the cold hard numbers. And since we are not the engineers with these numbers I don't think this will satisfy them.. IMO

Which is fine. I don't have a problem with them wanting them, or asking for them. But it is never asked for plainly.

Like; " does anyone have the physics calculations for this hitch" Plain a simple and I know what someone is looking for.. But it has not been asked for like this till after several posts, like the above ones.

IF someone wants them, the best place to get them is Andersen. Get them from the horses mouth. Not try to figure them out on their own like Andrew T did, and then say it won't work by their calculations, when we know it does work!

And I know someone will say "well their numbers work because it comes from them" Same can be said for any company if that game wants to be played. And it has been earlier in this thread with the videos from Andersen.

So we all know it works without seeing these numbers. I don't have a problem with someone wanting them, it would in fact be good to have them here.. So those looking for them, why not call Andersen and get them.

Here are the numbers: (208) 523-6460 (800) 635-6106
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Old 09-07-2012, 03:42 PM   #436
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Old 09-07-2012, 03:43 PM   #437
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One of the smartest men I ever knew, an electrical engineer from Harvard, when I asked him to enplane a florescent light to me he replied it can't be done. That did not stop me from replacing thousands of them in my career. I never did understand them just used them

At least with the Andersen hitch I understand how it works. So it is at least one step above a florescent in my book and at least 2 steps above the competition.

Now I am sure there are some that will never accept the fact that this hitch works even after they see one in action, try one for themselves, or have a complex engineering explanation presented to them. So be it.

I started this tread to inform interested individuals of the hitch and have input from users not to listen to the NA Sayers voicing their uninformed opinions.
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Old 09-07-2012, 03:43 PM   #438
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Quote:
Originally Posted by Wazbro View Post
I made a drawing that shows my understanding of how the weight distribution works, it is a ruff drawing and I am sure many people will disagree with it.
Off hand the only thing I see, is there needs to be an equal and opposite vertical force on the frame of the trailer of the conventional design. This vertical force is applied to the ball and the trailer axles, increasing the downward force on them. These forces would be proportional to the distance from axles to chains and chains to ball.
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Old 09-07-2012, 04:22 PM   #439
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Originally Posted by crisen View Post
Off hand the only thing I see, is there needs to be an equal and opposite vertical force on the frame of the trailer of the conventional design. This vertical force is applied to the ball and the trailer axles, increasing the downward force on them. These forces would be proportional to the distance from axles to chains and chains to ball.
You could be right, but I wanted to keep it simple since I don't understand all the details enough to make a more complicated comparison especially if it makes it too specific to apply to multiple TV/TT combinations.
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Old 09-07-2012, 04:58 PM   #440
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I would draw the classic WD system like this. Then I will use that to redraw the Anderson type.
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Old 09-07-2012, 05:15 PM   #441
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For some reason your attachment shows up as a black print when expanded and is unreadable.

The one comment I would suggest is you include the force direction on the trailer tires and the trailer frame at the chains. It is not up at the frame as shown.
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Old 09-07-2012, 05:28 PM   #442
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I think the Anderson then looks like this. The obvious difference is that the force which is responsible for torque around the ball is now lying horizontal compared to vertical for the bar system. Does this matter? Well yes, since torque = rF sin Angle. The sine value being 1 at 90 degrees and zero at 0 degrees. This means the distance (r) is the dominant factor. A WD bar is maybe 36" effective length. Compare to the distance (r) of the ball to the chain plate, which might be only 10" or so, and you see how much more force would have to be generated using a horizontal pull.

Once more, I am NOT saying "this doesn't work." I am saying it is an unusual way to generate torque. If I have something wrong here, I will be delighted to be corrected. This is a quickie sketch.
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Old 09-07-2012, 05:44 PM   #443
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Originally Posted by HowieE View Post
For some reason your attachment shows up as a black print when expanded and is unreadable.
Just double click it.
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Old 09-07-2012, 05:47 PM   #444
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Given that I hitch/unhitch a lot how long does it take to do either on the Anderson? Does it take longer than a Reese (which I find easier than an Equalizer)?
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Old 09-07-2012, 06:00 PM   #445
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To unhitch it takes me as long as it takes to raise and lower my jack and pull one clip and remove one pin. About a minute. Almost all jack time.

While I was always pretty quick with the Reese I would say that took me about two minutes.

To hitch if I come at the trailer at the same angle I unhitched the timing i the same. If the angle is different than I would have release tension on one of booth chains to get the plate to align with the ball shaft.

In any case the time is less than a spring bar system.
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Old 09-07-2012, 06:05 PM   #446
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Quote:
Originally Posted by Wayne&Sam
Given that I hitch/unhitch a lot how long does it take to do either on the Anderson? Does it take longer than a Reese (which I find easier than an Equalizer)?
I would say once the ball is on the hitch it takes me a minute or less. I don't use the jack I just tighten the nuts.
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Old 09-07-2012, 06:16 PM   #447
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Quote:
Originally Posted by mstephens
I think the Anderson then looks like this. The obvious difference is that the force which is responsible for torque around the ball is now lying horizontal compared to vertical for the bar system. Does this matter? Well yes, since torque = rF sin Angle. The sine value being 1 at 90 degrees and zero at 0 degrees. This means the distance (r) is the dominant factor. A WD bar is maybe 36" effective length. Compare to the distance (r) of the ball to the chain plate, which might be only 10" or so, and you see how much more force would have to be generated using a horizontal pull.

Once more, I am NOT saying "this doesn't work." I am saying it is an unusual way to generate torque. If I have something wrong here, I will be delighted to be corrected. This is a quickie sketch.
One problem is, everyone thinks it's completely vertical. It's not, there is probably a 10 degree angle + between the bolt and where it connects to the plate under the ball, so in reality you are pulling back and up.

You are still making assumptions as you don't have the exact measurements or angles, you want the facts call Andersen.
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Old 09-07-2012, 06:27 PM   #448
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I'll make the drawings a little bigger
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