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12-07-2010, 09:33 PM
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#1
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Load Equalizing hitches
Today, we started a research program on load equalizing hitches.
We are measuring the bend in the load equalizing bars, at 100 pound increments, with different brands as well as square and round bars.
The range of the tests start at a low level and up to and including a 20 to 25 percent overload.
We will publish the results as soon as the tests are completed, hopefully by the end of this year.
Andy
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12-08-2010, 03:31 AM
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#2
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Rivet Master
1970 27' Overlander
Espanola
, Full Timer
Join Date: Jun 2007
Posts: 1,753
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Is an equalizing hitch the same as a straight hitch?
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12-08-2010, 07:41 AM
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#3
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by redhawkerII
Is an equalizing hitch the same as a straight hitch?
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No.
Andy
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12-08-2010, 08:41 AM
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#4
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Maniacal Engineer
1971 25' Tradewind
Lopez Island
, Washington
Join Date: Jan 2010
Posts: 1,244
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Great idea... one of my favorite sayings is that one test is worth a thousand expert opinions.
I take it that this will be used to find what engineers call the stiffness of the bar - lbs/inch of flex. Beam theory tells us that this will be a linear relationship.
One of the interesting things we can find out is how much the preload (which is what does the WD function) is affected by a change in pitch angle between the TV and the trailer - which is what happens when the TV encounters a steep driveway or goes over a hill first.
It is my contention that the loads on our AS reduced if a more constant force spring could be used.
- Bart
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12-08-2010, 09:01 AM
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#5
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by barts
Great idea... one of my favorite sayings is that one test is worth a thousand expert opinions.
I take it that this will be used to find what engineers call the stiffness of the bar - lbs/inch of flex. Beam theory tells us that this will be a linear relationship.
One of the interesting things we can find out is how much the preload (which is what does the WD function) is affected by a change in pitch angle between the TV and the trailer - which is what happens when the TV encounters a steep driveway or goes over a hill first.
It is my contention that the loads on our AS reduced if a more constant force spring could be used.
- Bart
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This will be interesting. Bart, I don't think it will reflect a linear relationship, necessarily. I suspect that some of the tapered bars MAY BE a progressive rate setup. We'll see, because this is information that the MFRs have kept close to the vest. I suspect the round bars and square bars which do not taper or change shape along their length out to the tip will be linear in their deflection until the force nears the max. rating of the bar.
So much is going to be dependant upon the various alloys used in the spring bars also. I think, in previous discussions we all have a tendency to think all materials used by various MFRs are created equally. Not necessarily so.
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12-08-2010, 09:06 AM
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#6
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Be Calm, Have a Cupcake
Vintage Kin Owner
Houston
, Texas
Join Date: Nov 2007
Posts: 223
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Quick Question about WD Hitches and 3/4 Ton Trucks
Andy,
This may be the world's most stupid question but here goes... (See end quote for hilarity regarding me.)
It is my understanding that as Airstreams require a soft suspension to maintain their body integrity, and a 3/4 to 1 Ton truck needs a payload to achieve that, then are WD Hitches even needed on those trucks if their beds are otherwise empty?
If a 34' exerts 1000 lbs of tongue weight, and the payload on a 3/4 ton truck is 1500 lbs, would the combination work well without a WD hitch as the tongue weight of the Airstream would put the rear suspension of the truck right where it should be for a soft ride?
__________________
Secguru
Would you rather have a mansion full of money or a trailer full of love?
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12-08-2010, 09:28 AM
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#7
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Andy,
Will you be using various trucks and repeat the tests? I suspect the delfection of the bars at a given weight will be very different between a half, 3/4, and 1 ton rear suspension.
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12-08-2010, 09:57 AM
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#8
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by Secguru
Andy,
This may be the world's most stupid question but here goes... (See end quote for hilarity regarding me.)
It is my understanding that as Airstreams require a soft suspension to maintain their body integrity, and a 3/4 to 1 Ton truck needs a payload to achieve that, then are WD Hitches even needed on those trucks if their beds are otherwise empty?
If a 34' exerts 1000 lbs of tongue weight, and the payload on a 3/4 ton truck is 1500 lbs, would the combination work well without a WD hitch as the tongue weight of the Airstream would put the rear suspension of the truck right where it should be for a soft ride?
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Secguru,
I know you addressed to Andy, but here goes. There are MANY posts relative to these questions. Some with fairly heated discussions. Search on key words like hitch, tongue weight, etc. for all the reding you can stand!
You question on payload is :loaded" for so many reasons. Among them is spring rates of various truck manufacturers, proper load distribution (not lod on the rear suspension alone....etc.)
Also, I am aware of no 1/2 ton which has a payload of 1000#s, nor a 3/4 ton at 1500#s, nor a one ton at 2000#s.
This nomenclature is decades old when the ratings and names were accurte. Today most 1/2 tons payload is over 3/4 ton....a 3/4 ton is over one ton....and a one ton is well over 3000# (dependant upon single rear wheel and dually).
Add to that various manufcturers view on progressive spring rates and auxillary springs and you have a never ending discussion.
Remember, WD hitches are meant to distribute weight to achieve proper handling of the trailer/TV combination. There are many fine points to this discussion/argument....but they are well covered elsewhere.
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12-08-2010, 09:59 AM
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#9
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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I gota get a new keyboard!!!!! My most commonly used vowels don't "wk s wll", sorry.
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12-08-2010, 10:16 AM
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#10
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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SEC,
Just looked it up for a Silverado, just as an example:
Max payload:
"1/2 ton" 1980#
"3/4 ton" 4192#
"1 ton" 6635#
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12-08-2010, 10:36 AM
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#11
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Rivet Master
2005 39' Land Yacht 390 XL 396
Common Sense
, Texas
Join Date: Sep 2007
Posts: 5,319
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Oh Boy! Wait, let me make some popcorn.
__________________
Regards,
Steve
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12-08-2010, 10:43 AM
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#12
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by SteveH
Oh Boy! Wait, let me make some popcorn.
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You will need it.
So far, up until now, interested owners have posted.
I had a very hard time waiting for more negativity.
Andy
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12-08-2010, 10:44 AM
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#13
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by SteveH
Oh Boy! Wait, let me make some popcorn.
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Don't need to go there....that's for another thread...an existing one.
More on topic....Andy, will you share you test perameters and accept input, for what it's worth? (that'll open a can, won't it?)
I am thrilled you're taking the initiative to take this on, so we all have some factual data. Kudos!
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12-08-2010, 10:45 AM
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#14
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4 Rivet Member
1973 31' Excella 500
Spring Green
, Wisconsin
Join Date: Aug 2010
Posts: 265
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Quote:
Originally Posted by Secguru
Andy,
This may be the world's most stupid question but here goes... (See end quote for hilarity regarding me.)
It is my understanding that as Airstreams require a soft suspension to maintain their body integrity, and a 3/4 to 1 Ton truck needs a payload to achieve that, then are WD Hitches even needed on those trucks if their beds are otherwise empty?
If a 34' exerts 1000 lbs of tongue weight, and the payload on a 3/4 ton truck is 1500 lbs, would the combination work well without a WD hitch as the tongue weight of the Airstream would put the rear suspension of the truck right where it should be for a soft ride?
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I have towed my 31' AS three times for a total distance of less than 200 miles with my Ram 1500. I can tell you that with a tongue weight of about 800#, the load on the hitch definitely lowers the rear of the TV and takes load off of the front wheels (of the TV) with nothing in the bed of the truck. There is an effect on the handling although I've not had any significant problems. But, when her first trip is made in the spring, she will be equipped with a WD hitch.
The rated loads for pickups assume the load will be distributed within the cargo area, above or between the axles, which is a lot different than hanging it all on a hitch that is between 2 and 3 feet behind the rear axle of the truck. There is a significant difference in the load capacity and the allowable hitch weight for any pickup. (and it may even be so stated in the owner's manual of the pickup)
__________________
Lew TAC #WI-6
Nobody can help everybody, but everybody can help somebody.
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12-08-2010, 10:59 AM
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#15
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by driftless
I have towed my 31' AS three times for a total distance of less than 200 miles with my Ram 1500. I can tell you that with a tongue weight of about 800#, the load on the hitch definitely lowers the rear of the TV and takes load off of the front wheels (of the TV) with nothing in the bed of the truck. There is an effect on the handling although I've not had any significant problems. But, when her first trip is made in the spring, she will be equipped with a WD hitch.
The rated loads for pickups assume the load will be distributed within the cargo area, above or between the axles, which is a lot different than hanging it all on a hitch that is between 2 and 3 feet behind the rear axle of the truck. There is a significant difference in the load capacity and the allowable hitch weight for any pickup. (and it may even be so stated in the owner's manual of the pickup)
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All correct, and well covered elsewhere.
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12-08-2010, 11:09 AM
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#16
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by dznf0g
Don't need to go there....that's for another thread...an existing one.
More on topic....Andy, will you share you test perameters and accept input, for what it's worth? (that'll open a can, won't it?)
I am thrilled you're taking the initiative to take this on, so we all have some factual data. Kudos!
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We are investing our time, and money, for the research.
Our intent is to answer some questions, and to present data to those that are interested as a matter of information, and not another grandstand for slamming or arguing.
However, we understand that no matter what the results will be, there are those that will continue to argue.
We wish to advise them, at this time, that we will not, under any circumstances, get involved with that behavior.
But, we would invite them to spend their time, and money, and do the research.
So far, we have made tests on 4 different setups. The results so far, are very interesting.
Andy
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12-08-2010, 11:23 AM
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#17
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Chief Chili Cook
2010 30' Flying Cloud
Bakersfield
, California
Join Date: Feb 2009
Posts: 738
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It appears that Andy is testing various brands & styles of bars, for their rated spring rate vs actual spring rate. I doubt his test procedure will even include a tow vehicle, which would only cloud the results. It would be up to us to take the actual brand/style WD hitch spring rate into account in tuning our towing setup.
Until now the notion that round bars are softer than square bars has been measured by the seat of pants method, which sometimes can be accurate "enough". I want to thank Andy up front for undertaking this work, and I'm looking forward to the results.
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12-08-2010, 11:23 AM
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#18
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Rivet Master
2005 39' Land Yacht 390 XL 396
Common Sense
, Texas
Join Date: Sep 2007
Posts: 5,319
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Quote:
Originally Posted by Inland RV Center, In
You will need it.
So far, up until now, interested owners have posted.
I had a very hard time waiting for more negativity.
Andy
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Andy,
I have not said anything negative on this thread. I just think this will be very interesting, will draw lots of comments about how and what parrameters are used in the testing, as well as what hitch manufacturers', or as I fear manufacturer's products are tested.
I'm very much looking foward to hearing the results of the tests, as well as seeing what products are tested.
__________________
Regards,
Steve
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12-08-2010, 12:07 PM
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#19
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4 Rivet Member
2000 27' Safari
Suwanee
, Georgia
Join Date: Sep 2007
Posts: 485
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Looking forward to the results.
__________________
John & Robin
99 27' Safari
AIR #34494
Living the Airstream Life:
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12-08-2010, 12:17 PM
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#20
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4 Rivet Member
1973 31' Excella 500
Spring Green
, Wisconsin
Join Date: Aug 2010
Posts: 265
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Because I will be purchasing a WD hitch in the next few months, I appreciate that InlandRV is investing the time and money to make this information available. It will be another piece of information that I can use to make a final selection.
Now, if this testing were being conducted here in Wisconsin, I'd have to believe the techs and mechanics would have more than a few 12 packs of brew bet on the outcome...
__________________
Lew TAC #WI-6
Nobody can help everybody, but everybody can help somebody.
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