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Old 05-03-2013, 09:43 AM   #1751
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Originally Posted by Kosm1o View Post
At least one has come uncoupled.
I thought I had followed the tread closely and have not noted this. Please advise who, when, and how this happened.
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Old 05-03-2013, 11:18 AM   #1752
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Communication with Andersen Regarding Atwood Issues

For the record, here's the transcript of response from Andersen when I asked them about the Atwood coupler compatibility issue. I got this response within a couple of hours just a couple days ago.

Myself, I'm not that concerned about the problem. It seems pretty clear it develops over time, not all at once, though I will eventually need to replace the coupler. Several stores sell the Atwood 81911 for about $35, and welding another $150 or so. While I suspect the Propride/Hensley are better overall, at almost ten times the cost and almost four times the weight, I'm willing to suffer a while with the simpler Andersen.
___________________________________
Dear Andersen:
I purchased the weight distribution hitch new a couple months ago in anticipation of using it on a brand new Airstream trailer I plan to pick up and tow home next week. I've since read of some possible compatibility issues with the Atwood coupler that is probably welded onto the front of the trailer.

Can you confirm or clarify any known incompatibility issues with this hitch? If so, do you have any suggested remedies?

********
Response:
Great question Kurt. Only the Atwood 88xxx series couplers are incompatible with our Weight Distribution Hitch. ALL OTHER Atwood couplers are fine (80xxx, 81xxx, 82xxx, etc). We are still doing testing, but our initial findings are that the best solution for the 88xxx series is to change out the coupler. Luckily it is not a common coupler, but is popular on Airstream trailers. Below is our official announcement which we are putting out tomorrow.

With thousands of units on the road over the last 2 years, we have had tremendous success and customer satisfaction with the Andersen “No Sway” Weight Distribution Hitch.

In the last 7 or 8 weeks we heard a few reports of an issue that was specific to the Atwood 88000 series coupler. Although there were only about 10-12 reported cases, it was enough to concern us, and we are currently performing in-house testing of the coupler.

The issue: A few customers reported the potential of the Atwood 88000 series coupler to come unlatched over time due to wear.

NOTE: The Atwood 88000 series (stamped on the coupler as "Atwood model 88xxx" - xxx being any digits) is the ONLY coupler design in the RV market we have found that has this potential issue is the . All other Atwood couplers work fine. The similarly designed Marvel coupler also works just fine with the Andersen WD Hitch.

What we have found so far:
We have been performing in-house testing of the Atwood 88000 series coupler, as well as consulting with engineers and RV Technicians. At this point we have not experienced the unit unlatching, but we can see there is the potential for the possibility of this happening over time with the Atwood 88000 series so we are taking the issue very seriously. From the reports given we were told that it is something that happens over time, not immediately.

What can happen:
Because of the particular design of the Atwood 88000 series coupler, there is a lot of extra movement inside the coupler as compared to other couplers on the market. When combined with the reverse pressure that our Weight Distribution system places on it, over time, the slack in the internal mechanism of the some of these couplers slowly works its way backwards trying to unlatch from the top 'fin' - and eventually it can wear the fin down enough that it does not fully latch any more.

The solution:
At this point our official position is that the Atwood 88000 series coupler is incompatible with our Weight Distribution Hitch, so the ONLY current solution we endorse is to replace the coupler. A good quality and sturdy replacement is the Atwood MPD 81911 coupler (seen below). However any coupler other than the Atwood 88000 series will work just fine. We have checked with several welding shops who told us that it would take about 1 hour of shop time to change out the coupler, averaging about $60–$100 in shop fees.

Atwood MPD 81911 Trailer Coupler, A-Frame Tongue (10,000 lbs tongue)

Other solutions:
Although we have heard of a few Airstream owners who have had some success with modifying the latch mechanism and greasing the paw and ball, Andersen Mfg. does not officially endorse any solution other than replacing the coupler itself.

In the interest of convenience Andersen Mfg. has the Atwood MPD 81911 coupler available for $49 retail, which includes shipping to most states in the continental USA.

Please feel free to contact us if you have further concerns or questions.
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Old 05-03-2013, 02:03 PM   #1753
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Quote:
Originally Posted by TG Twinkie View Post
---No one here could talk long enough to convince me the the force applied by the Andersen hitch could even come close to the forces applied to the coupler when the TV has brakes and the trailer doesn't. Any coupler design should be able and expected to handle these forces.
This post is not to convince but, hopefully, to inform.

To make an educated estimate of how much force is exerted between ball and coupler when TV is braking and TT is not, we need to know 1) the weight of the TV, 2) the weight of the TT, and 3) how much stopping force can be produced by the TV's brakes/tires.

For simplicity, we can choose the TV and TT to weigh 6000# each.

To estimate how much stopping force can be produced by a typical TV, we can use braking test data reported by http://special-reports.pickuptrucks.com/2008/11/braking.html.
The data show that, on average, the six trucks were able to stop within 163' under maximum braking from 60 mph.
This corresponds to an average deceleration of 23.7 ft/sec/sec ofr about 0.74G.
To decelerate a 6000# truck at 0.74G requires an average stopping force of 4440#.

Since the TT is assumed to produce zero braking force, the TV must stop the combined 12,000#.
This means the combo will decelerate at 4440/12000 = about 0.37G.
To decelerate a the 6000# trailer at 0.37G would require the ball to push rearward against the coupler with a force of about 2200#.

For comparison, in the SEMA video, Ryan Andersen stated that 1/4" of bushing compression gives a chain force of about 2000# per chain and the two chains would be "pulling the trailer forward with 4000# of force".
However, I've not seen any data to indicate the 4000# can be achieved.
I think a more likely value would be around 3000#.

One also must consider the duration of the applied force.
On a typical towing day, the TV and TT might be coupled with WD applied for 8 hours.
This means the Andersen-induced static force of 3000# would have a duration of 480 minutes.
The duration of the "no trailer brakes" maximum TV braking force scenario is anybody's guess.
I'm guessing at a duration of less than 10 minutes -- if any.

So the comparison should be:
"no TT brakes" maximum force of 2200# acting for less than 10 minutes -- if any
versus
Andersen-induced force of 3000# acting for 480 minutes.

I'm sure we could debate endlessly about choice of "typical" values, but I think it's unrealistic to say that the force applied by the Andersen hitch could not even come close to the forces applied to the coupler when the TV has brakes and the trailer doesn't.

Ron
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Old 05-03-2013, 03:36 PM   #1754
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While not debating the numbers. It's the hammer force of the trailer slammed into the back of the coupler by the braking action of the TV that would cause the fin to shear.
If there is any slop between the ball and coupler the hammer force can do considerable damage when taking up the slop.
I don't think the standard torsion bar WD hitch would prevent the slamming action. Whereas the cushioning provided by the bushings on the Andersen may.
I still have not convinced myself that the Andersen is the way to go. But we are headed on a 4,000 mile journey in 3 weeks. This trip should give me an indication of how it will perform.
My coach has a Marvel coupler rated at 20,000# so the Andersen may not be a problem. However, I will be keeping a close eye on it. Especially the brackets on the tongue. Looking for any movement. I have scribed lines on each side of each bracket, making it easy to identify the slightest change.
I will report any problems here. During and after the journey.
Just in case, I have installed a safety chain over the coupler to prevent it from lifting off of the ball.
So, we will see how it goes.
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Old 05-03-2013, 03:42 PM   #1755
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My truck will decelerate much faster than it will accelerate. Doesn't this prove that more force is applied to the coupler in braking than in towing? How much force is required to maintain 60 mph? Certainly not as much as when hard braking. Your 480 minutes assumes maximum force being applied the whole time, doesn't it? It takes a lot less force to maintain 60 mph than going from 0-60 or 60-0.
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Old 05-03-2013, 04:24 PM   #1756
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Without getting into a bunch of calculations the problem with this analysis is that braking force available isn't the limiting factor to stop an unladen pickup. Weight transfer that unloads the already light rear end is. This results in rear wheel lockup or ABS activation long before max available brake force is reached. If you check this out 2010 HD Brake Tests - PickupTrucks.com Special Reports. You will see that some of the trucks tested, see the GMC 3500 actually stopped quicker with 2000# added to the bed of the truck.

By the way you will see these 3/4 and 1 ton trucks stopped shorter than the 1/2 tons of a few years ago.

Bottom line is that a truck brake system can generate much more force than it can use in an unladen condition so trying to predict max force available from those stopping distance's is not feasible.

I am going to use my Anderson with my AS and see what happens.


Quote:
Originally Posted by Ron Gratz View Post
This post is not to convince but, hopefully, to inform.

To make an educated estimate of how much force is exerted between ball and coupler when TV is braking and TT is not, we need to know 1) the weight of the TV, 2) the weight of the TT, and 3) how much stopping force can be produced by the TV's brakes/tires.

For simplicity, we can choose the TV and TT to weigh 6000# each.

To estimate how much stopping force can be produced by a typical TV, we can use braking test data reported by http://special-reports.pickuptrucks.com/2008/11/braking.html.
The data show that, on average, the six trucks were able to stop within 163' under maximum braking from 60 mph.
This corresponds to an average deceleration of 23.7 ft/sec/sec ofr about 0.74G.
To decelerate a 6000# truck at 0.74G requires an average stopping force of 4440#.

Since the TT is assumed to produce zero braking force, the TV must stop the combined 12,000#.
This means the combo will decelerate at 4440/12000 = about 0.37G.
To decelerate a the 6000# trailer at 0.37G would require the ball to push rearward against the coupler with a force of about 2200#.

For comparison, in the SEMA video, Ryan Andersen stated that 1/4" of bushing compression gives a chain force of about 2000# per chain and the two chains would be "pulling the trailer forward with 4000# of force".
However, I've not seen any data to indicate the 4000# can be achieved.
I think a more likely value would be around 3000#.

One also must consider the duration of the applied force.
On a typical towing day, the TV and TT might be coupled with WD applied for 8 hours.
This means the Andersen-induced static force of 3000# would have a duration of 480 minutes.
The duration of the "no trailer brakes" maximum TV braking force scenario is anybody's guess.
I'm guessing at a duration of less than 10 minutes -- if any.

So the comparison should be:
"no TT brakes" maximum force of 2200# acting for less than 10 minutes -- if any
versus
Andersen-induced force of 3000# acting for 480 minutes.

I'm sure we could debate endlessly about choice of "typical" values, but I think it's unrealistic to say that the force applied by the Andersen hitch could not even come close to the forces applied to the coupler when the TV has brakes and the trailer doesn't.

Ron
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Old 05-03-2013, 04:31 PM   #1757
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Quote:
Originally Posted by TG Twinkie View Post
It's the hammer force of the trailer slammed into the back of the coupler by the braking action of the TV that would cause the fin to shear.
Hi, [my opinion] I don't believe this statement to be true; Otherwise we would hear of many more failed couplers. I believe the cause is a combination of a dry hitch ball, pulled tightly against the pawl, and the hinging effect at the ball forcing the pawl upward. This would in turn put undue pressure on the fin, as we call it. Therefore this is an Andersen only, concern.
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Old 05-03-2013, 05:57 PM   #1758
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Quote:
Originally Posted by ROBERTSUNRUS View Post
Hi, [my opinion] I don't believe this statement to be true; Otherwise we would hear of many more failed couplers. I believe the cause is a combination of a dry hitch ball, pulled tightly against the pawl, and the hinging effect at the ball forcing the pawl upward. This would in turn put undue pressure on the fin, as we call it. Therefore this is an Andersen only, concern.
I agree with that Bob.
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Old 05-03-2013, 06:25 PM   #1759
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Quote:
Originally Posted by ROBERTSUNRUS View Post
Hi, [my opinion] I don't believe this statement to be true; Otherwise we would hear of many more failed couplers. I believe the cause is a combination of a dry hitch ball, pulled tightly against the pawl, and the hinging effect at the ball forcing the pawl upward. This would in turn put undue pressure on the fin, as we call it. Therefore this is an Andersen only, concern.
Wouldn't the dry hitch ball be a problem for all couplers, not just the Andersen?
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Old 05-03-2013, 06:38 PM   #1760
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The trailer slamming into the hitch under braking can be eased by adjustments to the brake controller. If the trailer brakes come on earlier would that not tend to drag the tv back and cushion the blow to the hitch. I hope I am saying this correctly. I know from my experience setting the controller this way helos to eliminate the bump the trailer does to the tv and hence to the hitch. Jim
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Old 05-03-2013, 07:47 PM   #1761
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Wouldn't the dry hitch ball be a problem for all couplers, not just the Andersen?
Dry hitch ball is not a problem with Quickbite. IMHO.
Joe
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Old 05-03-2013, 08:00 PM   #1762
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It is not a braking issue. The static force applied to the pawl by the tension of the chains is amplified by the shocking forces of road conditions. This combination is only offset by the shark fin and over time the fin is sheared off.

The ball having grease or not would have little effect, however if there is grease between the back of the pawl and the incline of the coupler there would be little friction to reduce this hammering.

It is likely that many of the older Atwood coupler have grease at there and thus the conditions are ripe for a problem. New user may want to degrease that the coupling as grease can only promote a problem at this point.

In any case the fact remains that there is a constant force amplified by the hammering of road conditions applied to the pawl pushing it upwards against the fin and the fin is completely inadequate to carry this load.

This condition will not be eliminated by additional discussion. User of the Andersen have 2 choices. Replace the coupler or use another Wd system.
It is a simple chose if you want an effective system.

I changed mine and have not looked back. The quality of the ride was still worth the investment.

Oh yes there is NO GREASE anywhere now.
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Old 05-03-2013, 09:16 PM   #1763
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Quote:
Originally Posted by TG Twinkie View Post
---If there is any slop between the ball and coupler the hammer force can do considerable damage when taking up the slop.
For every coupler I've looked at, the function of the latch is to maintain contact between ball and "pawl" or similar part.

Quote:
I don't think the standard torsion bar WD hitch would prevent the slamming action.---
If you're now adding the unlikely occurrence of "slop" to the unlikely occurrence of no TT brakes, you're comparing a very unlikely condition for the bar-type hitch with the every-day operation of the Andersen.

Quote:
---Whereas the cushioning provided by the bushings on the Andersen may {"prevent the slamming action"}.
Due to the very high level of force pressing the rear of the coupler against the ball, I doubt there would be any "slamming action" with the Andersen.

Ron
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Old 05-03-2013, 09:27 PM   #1764
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Quote:
Originally Posted by Rendrag View Post
My truck will decelerate much faster than it will accelerate. Doesn't this prove that more force is applied to the coupler in braking than in towing?---
The issue being discussed is braking force with a bar-type hitch versus the chain-tension-induced force between ball and coupler for the Andersen hitch.

Quote:
---Your 480 minutes assumes maximum force being applied the whole time, doesn't it?---
Please re-read my post.
The 480 minutes assumes the TV and TT are coupled for 8 hours with the Andersen's chains tensioned and producing 3000# of force between ball and coupler for the full 8 hours.
It has nothing to do with braking force.

Ron
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