The Andersen WD Hitch User Thread

[Ganaraska]

Early in the thread there were reports from users under severe weather and traffic conditions who found the Andersen equal to the Haha and PP and better than the spring bar hitches. There were one or two reports of the tow vehicle's sway control kicking in, under extreme conditions, for a spit second.

[dkottum]

I'm going launch the idea that the Andersen does not apply weight distribution in the same way as spring bars. But I'm an artist not a scientist.

The Andersen transfers weight by shortening the distance from the bottom of the hitch to the frame brackets, lifting the tongue of the trailer. The pivot point is primarily the hitch ball.

The spring bars transfer weight by lifting the bottom of the hitch ball, then fastening the bars in that position, thereby lifting the tongue of the trailer. The primary pivot point is not the hitch ball, but a point somewhere between the tow vehicle axles.

If this is true, we would have to compute weight transfer differently for each. What do you scientists think?

doug k

[SteveH]

Doug, a specific question for you...when you set up your Andersen hitch, did you measure the front fender height before, and after the hookup? Or, did you go to the scales to weigh the front axle of the TV before and after?

[dkottum]

I adjusted it exactly as the instructions described. Front and rear fender well measurements, then return it to this attitude with the hitch.

With all w.d. hitches it is not clear to me whether the front suspension geometry should be restored using fender measurements (mfg instructions), or whether the front axle weight should be restored (forum expert instructions).

doug k

[HowieE]

For those still with questions on how the Andersen applies force to the TV look at the picture in post 1138.

My first thought and I assume the first thought of most considering this question was that the tension on the chains applies force to the Front face of the ball, much like the trunnions do to the upper cup in a bar type hitch. That is not the case. The chains pulling back is countered by the Back face of the ball resting against the coupling. Viewed from the trailer side this is somewhat hard to envision. However if you look at it from the receiver side and mentally extent the shank as if it were attached to the front axle of the TV, through the frame of the TV, using the springs of the front axle as the force applied upward and you will see what is happening in the Andersen.

[Ron Gratz]

Originally Posted by dkottum

The spring bars transfer weight by lifting the bottom of the hitch ball, then fastening the bars in that position, thereby lifting the tongue of the trailer. The primary pivot point is not the hitch ball, but a point somewhere between the tow vehicle axles.

If this is true, we would have to compute weight transfer differently for each. What do you scientists think?

Doug,

What do you mean by "primary pivot point"?

Ron

[Inland RV Center, In]

Fender measurements, are exactly that.

They in no way can tell you how much weight has been transfered.

Using commercial scales is the only practical way to know "EXACTLY" what weight is being transfered and to where.

Andy

[dkottum]

Ron, I'm not sure, floating a thought trying to understand what's going on. My head is stuck in neutral right now. I'll have to sketch diagrams again.

doug k

[SteveH]

Originally Posted by dkottum

I adjusted it exactly as the instructions described. Front and rear fender well measurements, then return it to this attitude with the hitch.
doug k

So Doug, you DID return the front fender measurement with the hitch to the unhitched height? Is that correct?

[gmw photos]

Originally Posted by dkottum

I adjusted it exactly as the instructions described. Front and rear fender well measurements, then return it to this attitude with the hitch.

With all w.d. hitches it is not clear to me whether the front suspension geometry should be restored using fender measurements (mfg instructions), or whether the front axle weight should be restored (forum expert instructions).

doug k

On my rig, when I returned the front fender height to it's pre-hookup measurement, the weight on the steer axle was also exactly the same as pre-hookup, as verified by the CAT scale. This is with another brand of WD hitch ( BlueOx Swaypro ).

[dkottum]

Steve, with Andersen and without. Front same height, rear down 3/4", within Andersen instruction parameters. Trailer level. Best handling and ride I've had with weight distribution, compared to Equal-I-Zer.

[SteveH]

Originally Posted by dkottum

Steve, with Andersen and without. Front same height, rear down 3/4", within Andersen instruction parameters. Trailer level. Best handling and ride I've had with weight distribution, compared to Equal-I-Zer.

OK, Thanks Doug. So this proves the Andersen WILL distribute the tongue weight properly, beyond a shadow of doubt in my mine, and contrary to all the nay-sayers on here that insist on saying that it won't.

If the height is the same, the weight is the same.

[Ron Gratz]

Originally Posted by SteveH

If the height is the same, the weight is the same.

That might be true if there were no hysteresis in the suspension components --
but, in reality, the friction-related hysteresis in suspension components means that there is not an exact correlation between height and weight.

I think any reasonable person who looks at very much height/load data would conclude that if heights are the same, the weights are not necessarily the same.

Also, wheel well height is not always measured and reported accurately. For the case in point:

Doug reported in Post # 757, "Truck very close to original attitude using wheel well measurements, and trailer about an inch low in front."

In Post # 764, he reported, "Trailer perfect level, truck down 1" in back and up 1/2" in front.

And, today he reported, "Steve, with Andersen and without. Front same height, rear down 3/4".

So, I don't know whether the front end was returned exactly to the unhitched height.
But, I do know that even if it were, that does not prove that the front actually was returned to the unhitched load.

Depending on the spring rate, a height discrepancy of 1/2" might correspond to a load discrepancy of 300#.

If you really want to know how much load is being transferred, you should get some accurate axle load data and forget about using wheel well heights.

Ron

[Ron Gratz]

Originally Posted by dkottum

The Andersen transfers weight by shortening the distance from the bottom of the hitch to the frame brackets, lifting the tongue of the trailer. The pivot point is primarily the hitch ball.

The Andersen produces an upward force on the drawbar in response to the added downward force exerted on the pavement by the TT's tires.
The upward force on the drawbar, in addition to the pitch-axis torque resulting from the chains pulling rearward and the tongue pushing forward, lifts the rear of the TV and the front of the trailer.
I do agree that the ball is the pivot point between TV and TT.

The spring bars transfer weight by lifting the bottom of the hitch ball, then fastening the bars in that position, thereby lifting the tongue of the trailer. The primary pivot point is not the hitch ball, but a point somewhere between the tow vehicle axles.

The front ends of the spring bars push upward on the bottom of the hitch.
The rear ends of the spring bars pull downward on the tongue with a force of the same magnitude.
Most of the downward pull on the tongue acts as an added downward force on the ball. The remainder of the force is transferred to the TT's axles.
There is a net upward force acting on the hitch. Its magnitude is equal to the load transferred to the TT's axles.
The upward force acting on the rear ends of the spring bars also generates a pitch-axis torque on the hitch.
The ball is the pivot point between TV and TT.

If this is true, we would have to compute weight transfer differently for each. What do you scientists think?

IMO, your premise (as I understand it) is not true.
If I am not understanding your premise correctly -- perhaps the sketches would help.
IMO, weight transfer should not be computed differently.

Ron

[AWCHIEF]

Laughing to myself. This thread is like the Mayan Calendar - it just goes around and around in circles and keeps coming back to the same point.
Like someone previously said:
(Paraphrased) There are two views on the Andersen System. Those that have actually and honestly used the system and are generally happy with the performance and those that have not and no matter what anyone tells them just will not except that it works as advertised.

[afneill]

I am new to the forum and to Airstream ownership. The experience I had with a dealer installed WD hitch sent me in search of answers on the Air Forums. I first found a post by Andy on another thread that confirmed my experience-some if not many dealers do not know how to set up a hitch. Based on Andy's post I ordered lighter weight bars to replace the ones installed by the dealer. While waiting for those to arrive I found this discussion. The past four or five days I have read it in its entirety and have enjoyed it thoroughly. And learned more about hitches than I thought I wanted to know. I just wish I had read it prior to letting that dealer install a hitch. While I am not an engineer (biology is my field) I do know and understand numbers. Numbers are my friends! I appreciate all the input from those who not only know the theory behind these hitches, but how to explain it so others of us can understand it. I also appreciate those willing to try something new and report back on real world experiences to the rest of us. Having said all that, I am really close to being convinced to try the Andersen hitch. I like to think I am open to new ideas and concepts (I was an early concert to the Tempurpedic mattress). With new technology and the availability of new materials and applications it seems to me it should be time for a step forward in WD hitches and sway controls. Is this it? Time will tell but I think I am ready to take the plunge. Thanks again for all the input and the effort it required. I do appreciate it.

[SteveH]

Originally Posted by AWCHIEF

Laughing to myself. This thread is like the Mayan Calendar - it just goes around and around in circles and keeps coming back to the same point.

To me it is now beyond funny, it's ridiculous.

[Ganaraska]

Originally Posted by afneill

I am new to the forum and to Airstream ownership. The experience I had with a dealer installed WD hitch sent me in search of answers on the Air Forums. I first found a post by Andy on another thread that confirmed my experience-some if not many dealers do not know how to set up a hitch. Based on Andy's post I ordered lighter weight bars to replace the ones installed by the dealer. While waiting for those to arrive I found this discussion. The past four or five days I have read it in its entirety and have enjoyed it thoroughly. And learned more about hitches than I thought I wanted to know. I just wish I had read it prior to letting that dealer install a hitch. While I am not an engineer (biology is my field) I do know and understand numbers. Numbers are my friends! I appreciate all the input from those who not only know the theory behind these hitches, but how to explain it so others of us can understand it. I also appreciate those willing to try something new and report back on real world experiences to the rest of us. Having said all that, I am really close to being convinced to try the Andersen hitch. I like to think I am open to new ideas and concepts (I was an early concert to the Tempurpedic mattress). With new technology and the availability of new materials and applications it seems to me it should be time for a step forward in WD hitches and sway controls. Is this it? Time will tell but I think I am ready to take the plunge. Thanks again for all the input and the effort it required. I do appreciate it.

What kind of tow vehicle and what kind of trailer? The Andersen seems to work best with a truck or heavy duty SUV not so well with a car.

[AWCHIEF]

Originally Posted by SteveH

To me it is now beyond funny, it's ridiculous.

I agree, I was trying to be nice. You know how touchy some people are around here.

[idroba]

Originally Posted by afneill

I am new to the forum and to Airstream ownership.
(snip)
I appreciate all the input from those who not only know the theory behind these hitches, but how to explain it so others of us can understand it. I also appreciate those willing to try something new and report back on real world experiences to the rest of us. Having said all that, I am really close to being convinced to try the Andersen hitch. I like to think I am open to new ideas and concepts (I was an early concert to the Tempurpedic mattress). With new technology and the availability of new materials and applications it seems to me it should be time for a step forward in WD hitches and sway controls. Is this it? Time will tell but I think I am ready to take the plunge. Thanks again for all the input and the effort it required. I do appreciate it.

I do believe if you try it you will like it. I was a relatively early Andersen user and after having used Reese or Draw Tight hitches for 33 or so years, I find that the Andersen is simply a better hitch for my 20' 700# tongue weight Argosy. It tows better, and is a pleasure to use with my 2012 Grand Cherokee with air suspension. My first towing with the GC was with the old hitch system, so I had a good comparison.

I wish I had been able to take it to the scales so my numbers were available, but I did not do that, and now cannot until spring. I did my setup by turning off the Air Suspension, and using the old fender measurement system. The Argosy was always an easy trailer to tow, but now it is even better.

Nothing new in this comment that I have not posted in the past, but a lot of things have become lost in the 80 + pages of comments. Lets remember the goal: Good towing experiences. Andersen delivers.