Andersen WDH on a CL21BHS how to install

[gerry]

I debated on whether or not to get a wd hitch......with my truck, I have air suspension.....so it automatically adjusts to the hitch weight. I felt that the Andersen is a compromise, but after reading all the reviews, with my set up, it would fit the bill......I will see soon!  

[djsamuel]

I've got about 6000 miles on it so far. The coupler looks fine, no obvious signs of wear. The ball looks fine as well. I've towed the 21BHS with no WDH and t tows fine in terms of truck stance. When I lower the trailer on the Ram 1500 the rear drops about two inches and the truck sits nice and level. When I tighten up the Andersen hitch, I only raise the rear about 1/2 inch, but sway control is great and it reduces bouncing a lot when driving over things like small bridges, etc. I don't tighten the hitch up too much. Wouldn't want to use any other WDH with the setup I have.

[kodabear]

[quote timestamp="1415209006" author="@david" source="/post/4802/thread"][p][span style="font-size:10pt;"]But a 6" lever arm just isn't going to transfer much force to the front wheels are 15 feet forward. 
[/span][span style="font-size:10pt;"]. . .

A trunion bar type WDH has a much longer lever arm which operates on the hitch- usually 24-32" from the ball to the frame attachment point as opposed to the 4-6" of the Andersen below the ball pivot point.

[/span][span style="font-size:10pt;"]. . .[/span][/p][p]
David[/p][/quote]David, I disagree strongly. I understand your explanation, but I think you are mis-labeling the elements of the lever. The lever that acts to transfer the weight to the front of the TV is NOT the long side of the trunion bar. It is the short leg of the el that connects to the weight distributing head. The length of the trunion bar multiplies the force applied at the trailer end to move the top of the trunion bar forward, tilting the receiver downward, which transfers the weight forward.  That lever arm is probably less than the six inches you refer to in the Andersen system. The screw threads at the trailer end of the Andersen system are, essentially, an inclined plane that serves the same purpose as the long arm of the trunion bar - to multiply the force applied at the trailer end of the system. The chains then transfer that force to the weight distributing head. So Anderson uses an inclined plane where Reese and most other systems use a long lever. Euclid would be thrilled!

I stand ready and willing to be corrected  8-|

[david]

icebear:

Thanks for your comments. You obviously understand physics and mechanics and you are absolutely correct. Both the Andersen and trunion bar WDHs create a couple (force times lever distance) at the hitch ball. As you point out, Andersen's is created by the chain acting on a point 6" below the ball as a result of the chain pull which is created by the inclined plane of the nuts. The trunnion lever arm creates a similar couple either measured 24" behind the ball (force upwards) or about 6" below the hitch ball where the trunion bars connect (force backwards).

But the problem is how these couples are created. When you lever up a trunion bar (or use your tongue jack to load it) you are probably putting 1,000 lbs of force at that point if you want to transfer several hundred pounds of hitch weight to the front wheels. That force creates about 2,000 ft lbs of torque for each side based on a 24" long trunion bar. That same force gets transferred at the hitch and can be considered to be 4,000 lbs at the trunion bar hitch attachment point 6" below the ball. That is why the trunnion to hitch connection is so beefy.

To achieve the same torque with the Andersen system, that same 4,000 lbs of force needs to be transferred at the chain to hitch attachment point. Neither that attachment point, the chain nor the chain to frame bracket look like they can take that kind of force. As a result the Andersen system is not designed to be tensioned to those forces and as a result the weight transfer capability is limited.

Can you imagine what that rubber insert at the chain attachment point would look like with 4,000 lbs on it? It would probably squash flat. So no one tightens the nuts up enough to do that.

djsamuel gives us some hard data on the Andersen's weight transfer capability in his post above. He loads his hitch with 525 lbs of tow weight, the rear sags 2" and when he tightens the nuts the rear end goes back up 1/2". That means he is transferring roughly 1/4 of the 525 lbs forward or about 130 lbs. I suspect that much weight transfer is typical of the Andersen hitch.

If that much weight transfer works for him, ok the Andersen is fine and also provides good sway control. But for the guy who has a 650 lbs tongue weight and only 400 lbs of available rear end load rating, the Andersen won't do the job. Or if his front end is high and his steering is light, he needs a trunion bar type WDH that can transfer more weight.

And FWIW the 6" dimension quoted above is appropriate for the 8" drop version of the Andersen hitch. The 4" drop version will transfer about half as much because the lever arm is shorter.

David

[djsamuel]

Absolutely. If you really need to distribute weight, i.e. towing with a bare hitch isn't practical, then you really need something other than an Andersen. In my case, the sway control and bounce attenuation is the benefit I gain.

[kodabear]

[quote source="/post/4826/thread" timestamp="1415286289" author="@david"]But the problem is how these couples are created. When you lever up a trunion bar (or use your tongue jack to load it) you are probably putting 1,000 lbs of force at that point if you want to transfer several hundred pounds of hitch weight to the front wheels. That force creates about 2,000 ft lbs of torque for each side based on a 24" long trunion bar. That same force gets transferred at the hitch and can be considered to be 4,000 lbs at the trunion bar hitch attachment point 6" below the ball. That is why the trunnion to hitch connection is so beefy.


[/quote]I'm trying to understand where your 1000 lbs or 2000 lbs or 4000 lbs figures are coming from. Common sense has gotten me in trouble before, but I can transfer a couple hundred pounds of force to the front wheels of my vehicle just by sticking a long wrecking bar into my hitch receiver and deadlifting the distal end. Try it. I'll take some pix later. 

[david]

icebear:

One thousand pounds was just an example to compare the torque produced with a trunion bar vs the forces needed to produce the same torque with an Andersen hitch. It should be pretty obvious that it takes 4 times the force at a 6" lever arm to produce the same torque as with a 24" lever arm.

But 1,000 lbs per side on a 24" lever arm is in the ballpark of what it takes to transfer 300-400 lbs to the front wheels of a 5,000 lb TV. I can't easily send you the moment and force balance diagram that proves it, but like they say....trust me.

I think you will be surprised at how much force it takes with a long pry bar on the hitch to transfer 200 lbs. I can easily (well not for long!!) lift 100 lbs at the end of a 4" long wrecking bar. So I am putting 400 ft lbs of torque on the hitch. I'll bet it transfers much less than 100 lbs forward.

David

[kodabear]

[quote timestamp="1415286289" source="/post/4826/thread" author="@david"]
Can you imagine what that rubber insert at the chain attachment point would look like with 4,000 lbs on it? It would probably squash flat. So no one tightens the nuts up enough to do that.

David[/quote]Setting aside for the moment your figure of 4000 lbs, which I think is incorrect by an order of magnitude, I offer some data:
Urethane is not rubber. A 1.125" diameter,2" long, 90 durometer urethane bushing, with a 5/8" rod hole in it will compress lengthwise about 1/2" when loaded to 600 lbs. That kind of pressure is very easy to generate with a bolt and nut. I have no idea if this is the particular bushing Andersen uses. I just picked one out at random, but I suspect Anderson has engineered the hell out of this system.

I used to have a steel and wood 26" Outback that weighed maybe 7500 lbs. My Reese hitch used 1200 lb trunion bars. To load the system, one used a little steel tube to raise the over-center things that carried the chains the trunion bars rested on. I could do it with one hand, so no way does it take 1000lbs to raise it. Yeah, I was burlier then  . I'm not unfamiliar with weight distributing hitches, and I still have that ginormous Reese hitch. I use it to keep my shed from blowing away in the wind.

[kodabear]

[quote source="/post/4841/thread" timestamp="1415300852" author="@david"]
I think you will be surprised at how much force it takes with a long pry bar on the hitch to transfer 200 lbs. I can easily (well not for long!!) lift 100 lbs at the end of a 4" long wrecking bar. So I am putting 400 ft lbs of torque on the hitch. I'll bet it transfers much less than 100 lbs forward.

David[/quote]Yep. I'm not the man I never was. Instead of using the wrecking bar, I used one of the 1200 lb trunion bars from my old hitch. I think I need to go to the ER. I can't believe I used to do deadlift reps with 350 lbs.

[david]

[p]icebear:

I don't think I can convince you of my position without sitting down with a piece of paper and drawing a moment diagram. So let's put it aside and enjoy camping in our LLs, ok!!![/p][p]
[/p][p]My purpose in starting this discussion was to warn prospective WDH purchasers that the Andersen hitch would not be adequate to transfer several hundred pounds to the front wheels. All of the empirical evidence I have seen on this forum supports that view.

David[/p]

[kodabear]

Well, I'm taking the 14DBS on its maiden voyage to the Blue Ridge for a long weekend tomorrow morning! No weight distributing hitch or sway control yet. I'ma wait and see. And I hope you don't think I'm arguing with you. We're "discussing."  I'm pretty confident I know what diagram you'd draw and I expect I'd say that you had it right. What I think you're missing is that the inclined plane of the bolt and nut is every bit as effective a force multiplier as the lever action of the trunion arm. Don't forget, you're not finger tightening that nut. You're using a wrench with a 12-18" long lever to turn it up the very long inclined plane represented by the threads on the screw. Mechanical advantage is mechanical advantage, whether generated by a lever, an inclined plane, a set of gears or block & tackle system.  

[fasteddieb]

Where in the Blue Ridge?

[kodabear]

Northern end of SNP. Actually camping in Shenandoah River State Park. No cell or internet. Up on Skyline Drive right now with a three-bar 3G signal. 28F last night. Water hose froze. Camper lines OK. Whew.

[gerry]

I went for a short ride the other day....with my Andersen wd hitch hooked up......it made a big difference!  the ride was much smoother.....I had to look back to see if the trailer was still there.....and my bike is in the trailer......mpg is about the same...around 15mpg......very little bounce, no sway, steering much easier.....I'm a fan!  

[kodabear]

I'm sold.