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Old 09-07-2005, 07:32 PM   #15
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I'll definitely let everyone know the outcome of this problem. I haven't contacted the Mothership yet but I will before we make the 1,000 mile safari. I just wish the East-West route from Maine to Jackson Center had a few decent Interstate Highways. We came East from Jackson Center this Spring and the roads were lousy. I've even considered going North and coming in via Ontario. How's the Interstate that runs immediately South of Lake Erie? We chose the more direct Easterly route further South since it looked like it was less congested with city traffic. That worked - but I would have traded a semi tractor-trailer for every bone-jarring rut and pothole I rode over! That's probably what caused the axle problem in the first place - since it wasn't obvious when we were in Florida. On the other hand, I can't believe our Airstream's suspension system is so fragile. I've tried to recall if there was any really unusual event that might have damaged the axle - but nothing comes to mind.
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Old 09-07-2005, 07:38 PM   #16
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Originally Posted by Cracker
I've tried to recall if there was any really unusual event that might have damaged the axle - but nothing comes to mind.
Did you have a flat repaired on that wheel? Maybe the tire shop jacked the trailer up by the axle tube? Look at the tube for marks that would indicate it has been jacked upon.
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Old 09-08-2005, 06:50 AM   #17
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Cracker,

I heard said that the axles are prone to alignment issues if you back the trailer into a curb. You say it's the right rear tire that is scrubbing. Think back, did you back the trailer into a parking place and possibly scrub or hit that tire with a high curb? You say the outside tread is wearing. It sure sounds like this may have happened.

Best of luck.

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Old 09-08-2005, 06:54 PM   #18
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Curb contact

Mark:

That could have happened - since the problem is with the least visible wheel - but I can't recall any event of that nature??? Generally speaking, I'm loaded rather lightly when we hit the road - by actual scale weights. However, and that said, I would think that a wheel and axle assembly should still be tough enough to climb a curb, or withstand a shallow-angle slow speed contact. If not, we need to let everyone know just how delicate these axle assemblies are! I would, without question, expect the axle and spindle to be tough enough to skid the trailer sideways at any contact angle that was too shallow to permit the tire to climb the curb - even on dry asphalt or concrete pavement. If anyone can chime in here with some sound engineering data I would sure appreciate it. Maybe Henschen has the answers???

Keep in mind that we're not dealing with the complexities of high speed collisions - but only those that occur during slow speed maneuvering.
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Old 09-08-2005, 08:05 PM   #19
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Cracker,

The bending force on the axle spindle will be (n-1)W, where n is the number of tires, is the coefficient of adhesion, and W is the weight applied to each tire.

To illustrate, as your right rear tire strikes the curb at an oblique angle, the force trying to bend the axle is equal to the sum of the adhesion of the remaining tires to the pavement.

Hook a chain around the axle and try to drag the trailer sideways. The tension in the chain just before the tires slide is equal to the force being applied through the curb-climbing tire to the axle spindle.

I don't have actual numbers, but you can perform the experiment and let us know to numbers.

Alhough I agree with the consensus that you have a camber problem, it is a slight possibility that the cause of your tire wear anomaly is a tire manufacturing defect.
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Old 09-09-2005, 02:09 PM   #20
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I had the same problem with my '94 Excella. Took it to the Mothership this past June, 1100 miles from South Louisiana, the trip was worth it. They use a string line jig from front to rear, determine the adjustment needed and bend the axels with a hydraulic apparatus that does the job. Recommend you take it to the Jackson Center.
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Old 09-09-2005, 06:21 PM   #21
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Engineering Analysis

Quote:
Originally Posted by markdoane
Cracker,

The bending force on the axle spindle will be (n-1)W, where n is the number of tires, is the coefficient of adhesion, and W is the weight applied to each tire.

To illustrate, as your right rear tire strikes the curb at an oblique angle, the force trying to bend the axle is equal to the sum of the adhesion of the remaining tires to the pavement.

Hook a chain around the axle and try to drag the trailer sideways. The tension in the chain just before the tires slide is equal to the force being applied through the curb-climbing tire to the axle spindle.

I don't have actual numbers, but you can perform the experiment and let us know to numbers.

Alhough I agree with the consensus that you have a camber problem, it is a slight possibility that the cause of your tire wear anomaly is a tire manufacturing defect.
Your setup for determining whether or not the spindle would bend if subjected to certain sideways loading would, no doubt, produce interesting results! Now if we can just get someone to volunteer their 30' Excella for the test we'll proceed. In the meantime, I'm hoping that this analysis has already been performed by Henschen and that they are willing to share the results with those of us cursed by the engineering mentality!
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Old 09-09-2005, 09:35 PM   #22
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Maybe we can buy a junker on ebay and sacrifice it, in the interest of engineering curiosity.

I doubt if Henschen will be forthcoming with any data. I honestly don't know if they will survive, if /\irstrm drops them as a supplier.
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Old 09-11-2005, 09:28 PM   #23
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Does anybody see a problem with reversing my worn tire on its rim to even out the wear for the +/- 1,000 mile trip to the Mothership? I hate wearing down a perfectly good spare that's only 2-years old! The worn tire still has tread showing on the worn shoulder.
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Old 09-11-2005, 10:29 PM   #24
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Does anybody see a problem with reversing my worn tire on its rim to even out the wear for the +/- 1,000 mile trip to the Mothership?
Yes.
One of the forum members had their tires rotated, they cross-rotated the tires (switched direction of rotation) and two of the tires suffered tread separation and catastrophic tire failure, with damage to their coach.
The current price of Marathons is low enough, comparatively, to purchase a replacement tire after the work has been completed.
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Old 09-15-2005, 11:24 AM   #25
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I'm scheduled to be at the factory this coming Thursday for realignment and tire replacement - plus checking out my A/C. I plan to put my new spare in place of the subject tire for the trip. Surprisingly, Airstream's "alignment" facility was extremely busy. This means that it was either a tough summer on the highways - or, worst, the current crop of Henschen axles are experiencing problems. Actually, one bent spindle does not a bad "crop" make - but it does make you wonder! As for the highways, the U.S. Interstate system is really suffering in some areas.
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