The Andersen WD Hitch User Thread

[SteveH]

Originally Posted by Sean Woodruff

Is it the consensus of Anderson hitch users that the data reported by Ron Gratz contains a lot of improper hitch set up?

I thought simplicity of the design was one of the benefits.

Sean,

I interpret Ron's data to show that, like users of all manufacturer's weight distribution hitches, there are a lot that are satisfied with just getting close to perfection with respect to hitch adjustment.

[Sean Woodruff]

Originally Posted by SteveH

Sean,

I interpret Ron's data to show that, like users of all manufacturer's weight distribution hitches, there are a lot that are satisfied with just getting close to perfection with respect to hitch adjustment.

Thanks, Steve.

So you believe that the Anderson hitch could return the front axle weights to 100%, with tongue weights of 600# and up, with proper hitch set up?

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[gmw photos]

Let's assume for a minute that it's true that on average, the Anderson does not return the steer axle weight to unhitched values.

Let's further assume that the subjective driving experience of the users of this hitch is that the rig rides and handles well with their chosen adjustments.

Could this imply that it's not necessary to return all the weight to the steer axles in order to get a good driving rig ?

I'm just thinking out loud here, because if I am not mistaken, I believe there is at least one tow vehicle manufacturer ( late model GM light duty truck ? ) that state when using a weight distributing hitch, that you do not have to return to the front to it's original ride height ( it can remain higher than unhitched height ). Somebody jump in here and correct me if I'm wrong about whether it's GM that states this or not.

george

[Sean Woodruff]

That's a good point, George.

However, porpoising is a symptom of improper weight distribution. Without the front axle loaded enough there will be "bounce" in some combinations.

That said, some tow vehicles will not bounce with under 100% of the front axle load.

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P.S. - there are A LOT of 5th wheels being towed by tow vehicles without the front axle loaded to 100%. Take a look at their bobble head drivers when you pass.

[SteveH]

Originally Posted by Sean Woodruff

Thanks, Steve.

So you believe that the Anderson hitch could return the front axle weights to 100%, with tongue weights of 600# and up, with proper hitch set up?

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Sean,

Mine compensated for the 400 pound tongue weight so easily, that I think it will not be a problem.

Also, I don't like Andersen's instructions because they tell you to adjust the nuts for a certain amount of compression of the nylon "springs", which I think is wrong, and may be even contributing to the results shown in ron's chart. I adjusted the nuts on my hitch to return the tow vehicle front to the unhitched height, which is how I adjust the WD part of all WD hitches.

The thing that I think may be clouding the results is the fact that the Anderson, unlike most all the rest of the non projection hitches built, does not rely on the friction CAUSED BY the WD system to provide sway control.

With the Andersen, as long as the chains have no slack in them, the sway control works great, no matter the amount of weight distribution adjusted in. ALL OTHER conventional WD hitches, that I know of, must have a certain amount of weight on the bars for the anti-sway system to work.

[SteveH]

Originally Posted by Sean Woodruff

That's a good point, George.

However, porpoising is a symptom of improper weight distribution. Without the front axle loaded enough there will be "bounce" in some combinations.

Sean,

It is my opinion that the Andersen is so effective at reducing the porpoising because the nylon "springs" do not release their stored up energy near as fast as a steel spring does.

[Road Ruler]

The amount of weight (whatever that is), directed to the front axles should be an amount related to optimum handling and performance. I will continue to rely on the experience of seasoned towing professionals to advise.

[HowieE]

Ron

I am not sure I can take any validity from your graph when 3 of the components of the formula are assumed and one, chain tension, you are just placing an arbitrary value on.

The important thing in all this is can the hitch maintain reasonable steering geometry, vehicle control, and provide adequate sway control. To date all that have used the hitch are reporting that it does.

Given that we have pretty much excepted that a significant percentage of the WD hitches on the road are not set up correctly why are we nit picking one that has such a high degree of confidence from it's users?

Yes the scale tickets I presented show a 120 lbs removed from the front axle of my Excursion, a vehicle with a 4220 lbs front axle dry load. I could have the same results if I loaded the rear of the truck, without a trailer attached. Are you saying that would be unsafe? If not why make such a fuss over that weight reduction when the trailer is attached. If I removed several hundred lbs. when hitched I would agree more weight would have to be transferred to the front axle or the vehicle would have lost significant steering control and put the steering geometry in a condition to adversely effect tire ware. 120 lbs lose does neither.

[Sean Woodruff]

Originally Posted by SteveH

Sean,

It is my opinion that the Andersen is so effective at reducing the porpoising because the nylon "springs" do not release their stored up energy near as fast as a steel spring does.

That makes sense.

Porpoising can also contribute to decreasing the load required to create enough friction for sway damping.



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[SteveH]

Originally Posted by Sean Woodruff

Porpoising can also contribute to decreasing the load required to create enough friction for sway damping.
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With a conventional weight distribution/sway control hitch, that is correct, but not with a PPP hitch.

[HowieE]

Yes. As I have mentioned several times before the resonant frequency of spring bars, ALL SPRING BARS HITCHES, is just about equal to that set up while traveling over a concrete slab highway at 60 mph.

It is almost impossible to conceive that the resonant frequency of the bushings could ever be met while driving. The lack of porpoising in this case is a freebee that is going to be very hard to argue against

[CanoeStream]

Originally Posted by Sean Woodruff

However, porpoising is a symptom of improper weight distribution. Without the front axle loaded enough there will be "bounce" in some combinations.

That said, some tow vehicles will not bounce with under 100% of the front axle load.

This calls for a 'Porpoising Forum Rally/Workshop' somewhere near MN-23 between Ogilvie & Mora MN (or I-90 between Beloit & Madison, WI). It would be a great way to tune up a lot of rigs.

I've heard this attribution before. It certainly may be true to some degree. Regardless how I modify my WD I cannot go on some tired poured concrete roads without shaking up the propane so bad that my stove won't light for a month. Just kidding... More elaboration is gooder -- maybe even its own thread.

Bob with a GMC Sierra 3/4 ton and Reese DualCam

[Sean Woodruff]

Originally Posted by HowieE

Yes. As I have mentioned several times before the resonant frequency of spring bars, ALL SPRING BARS HITCHES, is just about equal to that set up while traveling over a concrete slab highway at 60 mph.

I can remove it with a couple cranks of a ratchet wrench at any speed.

Originally Posted by HowieE

It is almost impossible to conceive that the resonant frequency of the bushings could ever be met while driving. The lack of porpoising in this case is a freebee that is going to be very hard to argue against

The bounce is more a function of the weight distributed, or lack thereof, that the resonant frequency of bars or bushings.


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[SteveH]

Originally Posted by Road Ruler

The amount of weight (whatever that is), directed to the front axles should be an amount related to optimum handling and performance. I will continue to rely on the experience of seasoned towing professionals to advise.

Well, that depends on your definition of "seasoned". Is that a person who sells hitches and sets them up for other users, or would that be someone who has actually used several various types of hitches, with different trailers and tow vehicles over a period of some thirty+ years?

[dkottum]

Originally Posted by CanoeStream

This calls for a 'Porpoising Forum Rally/Workshop' somewhere near MN-23 between Ogilvie & Mora MN (or I-90 between Beloit & Madison, WI). It would be a great way to tune up a lot of rigs.

I've heard this attribution before. It certainly may be true to some degree. Regardless how I modify my WD I cannot go on some tired poured concrete roads without shaking up the propane so bad that my stove won't light for a month. Just kidding... More elaboration is gooder -- maybe even its own thread.

Bob with a GMC Sierra 3/4 ton and Reese DualCam

I'm good for that next season, live nearby, and have the Andersen installed. Seat-of-the pants comparison would be useful.

We couldn't rid the proposing from our Equal-I-Zer (and they could be brutal) with two different-sized new Airstreams no matter how I adjusted it. Replaced that dog with the Andersen. In 3700 miles from MN to Wash DC to AZ, with plenty of side trips, we have not experienced it.

doug k

[HowieE]

Originally Posted by Sean Woodruff

The bounce is more a function of the weight distributed, or lack thereof, that the resonant frequency of bars or bushings.
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I am sorry but this is about as far off base as you can get on this one. While resonant frequency can be changed to some small degree by the weight applied to the system it is a function of the length and material used in the spring bars. The Andersen does not have spring bars. The resonant frequency of the Andersen hitch will be the load and material of the bushings. Urethane has long been used as a damping material against many forms of vibration because it's resonant frequency is so far off scale.

Just think with the Andersen you could travel route #10 in La. and not have to stop at the dentist afterwards or pick your refrigerator door off the floor.

And the ride would be so smooth you could see those Bees Flying by.

[Ron Gratz]

Originally Posted by HowieE

I am not sure I can take any validity from your graph when 3 of the components of the formula are assumed and one, chain tension, you are just placing an arbitrary value on.

The essence of the graph are the nine data points which are calculated from values reported by users. The three assumed components to which you refer have nothing to do with the placement of the data points.

The two theoretical curves were included for reference. They simply show what the FALR vs Tongue weight relationship would be for chain tensions of 1000# and 2000#.
One of the "assumed" parameters, the Lever Arm, actually is a measured value reported by Bruce H. I referred to it as "asssumed" because I do not have independent verification of the value.
Typical values of "BOH" might range from 4.5' to 5.5' versus the 5' which I used for producing the example curves.
The theoretical calculation is relatively insensitive to "TTL". A 100% variation in this value changes the result by about 8%.

As for the "correct" value for FALR, that's open to much discussion. People express strong opinions, and then they change their minds.
For example, in this post -- http://www.airforums.com/forums/f238...ml#post1154357 -- you stated:

"What you are attempting to accomplish is to at least return the weight to the front axle that the trailer reduced by the cantilevering effect of have applied the trailer weight behind the rear axle. This insures the steering system is in a normal configuration and improve sway control that would be reduced by the reduced weight on the front axle."

I take that to mean you previously believed the FALR should be at least 100%.
Now you seem to be saying that 40% is okay.

Ron

[Sean Woodruff]

Originally Posted by Sean Woodruff

I can remove it with a couple cranks of a ratchet wrench at any speed.

The bounce is more a function of the weight distributed, or lack thereof, that the resonant frequency of bars or bushings.

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Originally Posted by HowieE

I am sorry but this is about as far off base as you can get on this one. While resonant frequency can be changed to some small degree by the weight applied to the system it is a function of the length and material used in the spring bars. The Andersen does not have spring bars. The resonant frequency of the Andersen hitch will be the load and material of the bushings. Urethane has long been used as a damping material against many forms of vibration because it's resonant frequency is so far off scale.

So you're saying I can distribute very little weight and just replace spring bars with Urethane and I will not get any bounce? The bounce IS NOT a function of the weight distributed?

Interesting...

[HowieE]

Ron

Actually if you go back a bit further in my writings, several years worth, you will see that I have written on the Reese systems often. I wrote that one wanted the front axle to drop in the range of a 40/60 ratio to the rear axle, depending on the springs set of the TV. That was based on a need to get the rig in a drivable condition mostly attempting to reduce the Porpoising so characteristic with a Spring Bar system.

Have I changed my mind? No not with respect to a Reese or other spring bar systems. But YES having set up the Andersen originally as per above and now having used it enough to realized I do not have to go that far to get the functions I am looking for from the Andersen.

The slight reduction that I currently have on the front axle is well within the range of design load for the Ford Excursion. Again 120 lbs on a 4220 axle is lost in the second decimal place.

The published beat frequency for a Bee wings is from 190 to 200 beat per second. That is a 5% range. You will note that if he changes frequency from day to day he can still fly. There is room for deviation hear also.

[HowieE]

Originally Posted by Sean Woodruff

So you're saying I can distribute very little weight and just replace spring bars with Urethane and I will not get any bounce? The bounce IS NOT a function of the weight distributed?

Interesting...

No Sean. Spring Bars are loaded perpendicular to the center line and the bushings are loaded along the center line so a direct replacement is not possible. Design changes are required and they have been done.