The Andersen WD Hitch User Thread

[Ron Gratz]

Originally Posted by purman

Then I'm pretty sure the link holding the chains to the plate would fail at that point. something is amiss.

Chains and attaching hardware usually are identified by "Working Load Limit" which typically is 1/3 of "Breaking Strength".

Ron

[Uzzah]

So, I've been staying up on this thread since the first day it was posted, and I'm curious. Why are there no pics of this hitch set up? I see pics of broken "conventional" hitches, but non of the usual "look what I bought and look how I put it on" posts. I value the back and forth engineer speak too, but I'd like to also see how this fits with the tanks and all the other stuff that was talked about at the start of this thread. I was hoping for some visual aids for us less intellectual young guys.

[idroba]

Ok, here are three photos of mine the day it was first installed.

[3Ms75Argosy]

Hmmm... are your saddles on the trailer frame tilted too far forward? Looks like a pretty good angle between them and the chains?

I like your trailer / TV setup by the way! Nice rigs!
Marc

[idroba]

Originally Posted by 3Ms75Argosy

Hmmm... are your saddles on the trailer frame tilted too far forward? Looks like a pretty good angle between them and the chains?

I like your trailer / TV setup by the way! Nice rigs!
Marc

They are tilted a few degrees but there were reasons...LOL. They have not moved since I installed them BTW. Since the chain comes in already at a steeper angle, I don't think it is much worse the way I set it up. Even if the frame brackets were horizontal, the chain angle would not be much different.

I love that little 20' Argosy and it has been very well updated, including axle, 16" wheels and all the interior plumbing, electrical and appliances, countertops, sink etc. The Grand Cherokee is a super nice tow vehicle. I average about 13.5 mpg towing the Argosy. 20 to 21 solo, 5.7L hemi V8.

And the Andersen makes it a real pleasure combination. I am off tomorrow on another jaunt to Glacier National Park.

[Uzzah]

Wow I really like the simplicity of that hitch. Thanks for the pics, I think the wife is sold on the idea of a smaller hitch apparatus and no grease to get on her pants again.

[SteveH]

idroba, Have you measured the height of the trailer frame, front and rear? It looks to me that you have your hitch ball set too high.

[HowieE]

Originally Posted by SteveH

idroba, Have you measured the height of the trailer frame, front and rear? It looks to me that you have your hitch ball set too high.

While I have commented often over the years that an Airstream MUST ride parallel to the ground because of the type of axles used that is no an issue with a single trailer. Riding tongue high or low with a single axle trailer is more of an aesthetic consideration.

[SteveH]

Originally Posted by HowieE

While I have commented often over the years that an Airstream MUST ride parallel to the ground because of the type of axles used that is no an issue with a single trailer. Riding tongue high or low with a single axle trailer is more of an aesthetic consideration.

Yes, you are right, it is not mandatory with a single axle Airstream, but it looks goofy.

[HowieE]

Originally Posted by 3Ms75Argosy

Hmmm... are your saddles on the trailer frame tilted too far forward? Looks like a pretty good angle between them and the chains?

I like your trailer / TV setup by the way! Nice rigs!
Marc

The reason for the tilt of the brackets is to a fix them to the frame so the the rotational force generated by the force on the chains is countered by the bolts in the brackets resting against the frame.

[mstephens]

Sample Math Using the Anderson Hitch

Just as a simple means of making rough calculations, if you know a few of the distances and the tongue weight, it would look like this.

If the distance from TV front axle center to ball center is 160".
And, the distance from center of ball to center of chain plate is 8".
The lever ratio to develop torque around the ball center would be 160/8 = 20:1

If you have a 800 pound tongue.
And, you want to shift 400 pounds of that on the front TV axle, you will need to generate a 400 pound rotational force at the center of the ball in the counter-clockwise direction.

The simplest conceivable means of doing this would be by simply lifting straight up on the ball with 400 pounds of upward pull. Of course, that isn't how a hitch works.

So, using the Anderson, this 400 pound torque force must be generated by pulling back horizontally on the chains to create torque around the ball center. Since the lever ratio is 20:1, it takes 20 x 400 pounds, or 8,000 pounds of pull on those chains to get the 400 pound rotational force around the ball. There are two chains, so each chain must have 4,000 pounds of strain in the static mode to get 400 pounds shifted from the rear axle to the front axle of the TV.

Specs on various chains can be found here.Gr 40 Windlass Anchor Chain

Just on appearances - - I don't like the idea that in this system, the full load strain (4,000 pounds in the example) is being carried through the very smallest parts. Those small parts are the D-link bolt and the nut on the back of the chain pull. By way of comparison, the WD bar system puts all the load forces on the heaviest members of the system - the bars and L-bracket feet.

I am not saying it doesn't work. Obviously the users report good results. I am only saying that the price of getting the convenience seems to be this idea of putting huge strain on small parts. The D-link bolt seems to fit loosely in that chain plate.

[HowieE]

Originally Posted by mstephens

Sample Math Using the Anderson Hitch

Just as a simple means of making rough calculations, if you know a few of the distances and the tongue weight, it would look like this.

If the distance from TV front axle center to ball center is 160".
And, the distance from center of ball to center of chain plate is 8".
The lever ratio to develop torque around the ball center would be 160/8 = 20:1

If you have a 800 pound tongue.
And, you want to shift 400 pounds of that on the front TV axle, you will need to generate a 400 pound rotational force at the center of the ball in the counter-clockwise direction.

The simplest conceivable means of doing this would be by simply lifting straight up on the ball with 400 pounds of upward pull. Of course, that isn't how a hitch works.

So, using the Anderson, this 400 pound torque force must be generated by pulling back horizontally on the chains to create torque around the ball center. Since the lever ratio is 20:1, it takes 20 x 400 pounds, or 8,000 pounds of pull on those chains to get the 400 pound rotational force around the ball. There are two chains, so each chain must have 4,000 pounds of strain in the static mode to get 400 pounds shifted from the rear axle to the front axle of the TV.

Specs on various chains can be found here.Gr 40 Windlass Anchor Chain

Just on appearances - - I don't like the idea that in this system, the full load strain (4,000 pounds in the example) is being carried through the very smallest parts. Those small parts are the D-link bolt and the nut on the back of the chain pull. By way of comparison, the WD bar system puts all the load forces on the heaviest members of the system - the bars and L-bracket feet.

I am not saying it doesn't work. Obviously the users report good results. I am only saying that the price of getting the convenience seems to be this idea of putting huge strain on small parts. The D-link bolt seems to fit loosely in that chain plate.

You seam to be on a dedicated quest to discourage as many people as possible from considering the Andersen hitch. While I am not in a position to go toe to toe with you on the math I can at least question it by a factor of 2X. The idea of transferring 400 pounds, the starting point of you math, is completely off the mark. I have most likely the largest trailer and and largest TV that will be considered here. I add 175 lbs to my front axle when setting up my WD hitch. So even if the balance of your math is correct, which I doubt because you are leaving out the effect on the rear axle springs, you are off by a factor of more than 2X.

Theoretical investigation has merit when one can be sure that every possible consideration has been accounted for. However theoretical investigation that can nor stand up to actual results causes one to question the theoretical. Remember a Bumble BEE can not fly by theoretical investigation.

[mstephens]

Originally Posted by HowieE

You seam to be on a dedicated quest to discourage as many people as possible from considering the Andersen hitch.

No, not at all. I like science. I like figuring these things out. I thought it was a fascinating hitch to look at. I wanted to engage other technically inclined folks and see what they thought of the mechanics.

I have no financial interest in the hitch industry. None. Are some of the people posting here financially involved in hitches? I'm just a guy who likes engineering and science, and is very curious about new things.

I think you are reacting a bit too personally here. You act as though I am disparaging you for having this hitch? I am not. When you say things like "You seam to be on a dedicated quest to discourage as many people as possible from considering the Andersen hitch," it tells me you are having some trouble spotting a simple technical discussion. Why are you trying to make this personal? I don't get that at all.

Anyway, here's the thing. If you continue to say things to me like that, I'll just have to ignore your comments in order to prevent ill-feelings.

It's a HITCH - we're not talking about someone's mother here. It's just a hitch.

I have no axe to grind with you. I hope you can see that.

[sierrafun]

mstephens,

Just curious, do you intend on calling Andersen and asking them for a drawing/explanation of the physics of their hitch design to share with us or will you simply continue posting conjecture?

[idroba]

Originally Posted by SteveH

idroba, Have you measured the height of the trailer frame, front and rear? It looks to me that you have your hitch ball set too high.

Steve H: The photo was taken on the very first day I had the Andersen on the rig. A combination of photo optics and how it was adjusted at that point make it look a bit off level. The air suspension on the Grand Cherokee also has a mind of it's own (honest) and has an automatic cosmetic correction which sometimes raises or lowers a wheel or an entire side of the car. It makes photos sometimes funny, and looks of the lash up somewhat variable, depending on what the TV is doing. All of that said, I am thinking of lowering the ball one adjustment level down, to see if I like it better that way. It may look less "goofy" that way...lol, at least at some times depending on what the TV is doing.

The frame brackets could be changed for cosmetics too, but are really stronger the way I have them set up. The slight angle wedges the connecting bolts against the top and bottom of the frame and less pressure is put on the set screw for location.

On the other discussion going on now about the forces in the chains and so on, I can only say that if anything does fail in the chain or plate or frame brackets the only thing that is lost is the WD characteristics of the hitch. The ball would simply pick up the towing load, and you would revert to a weight carrying hitch until repaired or corrected. There would be no uncoupling or danger associated.

I have a pretty heavy tongue weight of 700 pounds on my little 20' Argosy so there is a fair pull on the chains. I have towed around 4000 miles and the "made in China" shackles still can unscrew with my fingers. I have reported a creaking sound and have isolated that to the way the chains go into the frame brackets. On inspection I have found some wear on the chains there, and have put a small amount of lube on the tubes and chains at that point. I am off on another 800 to 1000 mile trip and will see how that works out.

I hope this thread can continue to be civil and productive, with experiences, ideas and theory all given their just due so everyone benefits. That was what HoweE intended in his very first post, and what I hope continues.

[Bill M.]

"The simplest conceivable means of doing this would be by simply lifting straight up on the ball with 400 pounds of upward pull. Of course, that isn't how a hitch works."

You sure about this? Looks to me like the conventional hitch bars do lift up on the ball and pull down on the axle. Is there a vertical component in the Anderson also?

[HowieE]

Originally Posted by idroba

I have reported a creaking sound and have isolated that to the way the chains go into the frame brackets. On inspection I have found some wear on the chains there, and have put a small amount of lube on the tubes and chains at that point.

A very interesting point. I just went out and looked. The ware is from the movement caused while the bushings are compressed and relaxed do to bumps in the road and "thank you mams" in the road, small hills and valleys.

I have to say that the picture show more ware than I would have expected for the time I have had my hitch, then again I live in New Jersey and travel a lot on Pa. 2 states that compete against I 10 in LA. for the worst roads in the nation.

From what I have seen to date this looks like the point of eventual failure. Not that it will be a catastrophic failure, the bottom of the bracket will just start to tear and produce a sharp edge. Other than lube I do not see a solution. If the tube on the bracket was changed to align with the chain that would put the nuts end of the screw too close to the frame for convenient access.

[crisen]

Originally Posted by HowieE

A very interesting point. I just went out and looked. The ware is from the movement caused while the bushings are compressed and relaxed do to bumps in the road and "thank you mams" in the road, small hills and valleys.

I have to say that the picture show more ware than I would have expected for the time I have had my hitch, then again I live in New Jersey and travel a lot on Pa. 2 states that compete against I 10 in LA. for the worst roads in the nation.

From what I have seen to date this looks like the point of eventual failure. Not that it will be a catastrophic failure, the bottom of the bracket will just start to tear and produce a sharp edge. Other than lube I do not see a solution. If the tube on the bracket was changed to align with the chain that would put the nuts end of the screw too close to the frame for convenient access.

This is interesting to me since I am seriously considering getting one of these hitches. I did notice in a previously posted photo(post #463) that these brackets were not in line with the chain pull and thought that it didn't look good. So my question is are these brackets adjustable for angle when they are mounted on the frame rails of the trailer?

Thanks,

[Mike91208]

Originally Posted by crisen

...I did notice in a previously posted photo(post #463) that these brackets were not in line with the chain pull and thought that it didn't look good. Thanks,

Exactly. I just had my Andersen hitch installed yesterday and the chains do not touch the brackets. I'm going on a trip next weekend and when I hitch it up, I'll take a picture and post it.

[HowieE]

Originally Posted by Mike91208

Exactly. I just had my Andersen hitch installed yesterday and the chains do not touch the brackets. They are straight and parallel to the frame. I'm going on a trip next weekend and when I hitch it up, I'll take a picture and post it.

Please take a picture of your brackets and post it now if possible.
I can't not envision any way the chains could ever run parallel to the frame. The distance from the top of the frame to the chains and from the top of the framel to the triangular plate are different thus precluding the chains to be parallel to the frame.