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Old 01-01-2013, 10:47 PM   #1191
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Originally Posted by ROBERTSUNRUS View Post
Hi, I also agree that if the ride height is the same, the weight on the axles will also be the same.---
Bob, you could try a simple experiment --

If your tow vehicle has some point at the front center under which to place a jack, you can do the following:

First, on both front sides, mark a reference point on the pavement and a reference point on the fender above the axle.
Bounce the front of the vehicle up and down a couple times to try to get the front at a "neutral", unloaded height.
Measure the fender heights on both sides.

Then, use the jack to lift the front of the TV until the fender heights have increased by about 1".
This will simulate the initial lifting of the front due to tongue weight without WD.

Then lower the jack until it no longer is carrying any load.
The load on the front axle now is the same as when the first height measurements were made.
Again measure the fender heights on both sides and see how the heights compare with the first measurements.

I performed this experiment on my Ford Explorer this afternoon.

I first placed a short piece of 2x4 on the pavement directly below each axle's centerline.
I placed a piece of masking tape on each fender directly above the axle's centerline.
I placed a mark on each piece of tape at a height of 33" above the 2x4.

I then jacked the front of the Explorer until each side was 1" higher than before.
When the jack was lowered and removed,
the passenger side tape mark was at 33-3/16" and
the driver side tape mark was at 33-1/4".

With exactly the same load on the front axle, the front wheel wells now were 3/16" and 1/4" higher.

Quote:
What I haven't read here is the fact that both of the tow vehicle's front and rear fenders must be at the same [original, unloaded] ride height for this to be true. So if the front fender is the same ride height and the rear is lower, the front would be a bit lighter.
I agree, but we need to quantify "a bit".

If the rear is lowered relative to the front, the TV's center of gravity will shift slightly rearward (assuming the CG is located higher than the axles).
This will cause a slight decrease of load on the front axle and increase on the rear axle.
The question is, how much.

If the TV weighs 5000# and is "level", the front axle load might be 2750# (55%) and the rear might be 2250#.
If the CG is 13" above the axles and the wheelbase is 130" and the rear drops 1" relative to the front, the CG would shift approximately 0.1" rearward.
The load on the front axle would decrease by about 4# and the load on the rear would increase by about 4#.

Ron
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Old 01-01-2013, 11:34 PM   #1192
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Quote:
Originally Posted by Ron Gratz View Post

When the jack was lowered and removed,
the passenger side tape mark was at 33-3/16" and
the driver side tape mark was at 33-1/4".

With exactly the same load on the front axle, the front wheel wells now were 3/16" and 1/4" higher.




Ron

Hi, this is partially because of the Camber on the wheel alignment. That's why alignment racks have ball bearing wheel pads. Jack up the rear of a VW bug [ old models] with the rear axles swinging inward on the bottom; Let it down and it will be several inches higher until you roll the car a few feet.
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Old 01-02-2013, 07:09 AM   #1193
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Quote:
Originally Posted by Ron Gratz View Post
I first placed a short piece of 2x4 on the pavement directly below each axle's centerline.
I placed a piece of masking tape on each fender directly above the axle's centerline.
I placed a mark on each piece of tape at a height of 33" above the 2x4.

I then jacked the front of the Explorer until each side was 1" higher than before.
When the jack was lowered and removed,
the passenger side tape mark was at 33-3/16" and
the driver side tape mark was at 33-1/4".

With exactly the same load on the front axle, the front wheel wells now were 3/16" and 1/4" higher.
A simple but effective deminstration of mechanical hysteresis and no one can deny it's presence.

However this measurement is not the one we have been discussing while setting up the hitch. We are talking about measuring the fender height TV empty and the fender height AFTER adjustment of the hitch. The point in time you are noting will be passed through during this adjustment have have no bearing on anything.

In fact if one assumes that the condition you note is present every time and the hitch returns the fender height to or past its original height it has had to exert even greater force to do so. That component is called weight transfer. You know that which all the nay sayers are claiming does not exist.

Now keep the home fires burning guys as I am taking my rig with my Andersen and going south for a while. Will be reading the tread but may not be in a position to post. I expect to convince several Ha Ha users to convert while on the road by showing that time hitching and effort are not required to have a good ride and sway control.

Considering the cost of fuel the Government ought to get behind Andersen and offer subsidies for the reduced fuel cost and environmental consideration by not have to burn a ton of coal to make those monsters and haul them down the road.

Have Fun
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Old 01-02-2013, 05:47 PM   #1194
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Quote:
Originally Posted by HowieE View Post
A simple but effective deminstration of mechanical hysteresis and no one can deny it's presence.

However this measurement is not the one we have been discussing while setting up the hitch. We are talking about measuring the fender height TV empty and the fender height AFTER adjustment of the hitch. The point in time you are noting will be passed through during this adjustment have have no bearing on anything.
Howie, you're missing part of the picture -- and, probably, the more important part.
Suspension hysteresis (a.k.a. "stiction effect") works
both when the front is raised above the unloaded height followed by a reduction of lifting force
and when the front is forced below the unloaded height followed by a reduction of load.
IOW, what goes up doesn't necessarily come back down as far as you would expect,
and what goes down doesn't necessarily come back up as far as you would expect.

Quote:
In fact if one assumes that the condition you note is present every time and the hitch returns the fender height to or past its original height it has had to exert even greater force to do so. That component is called weight transfer.---
If you use the tongue jack to raise the rear of the TV, you are applying a "negative tongue weight" to the hitch.
Just as a positive tongue weight removes load from the TV's front axle,
a negative tongue weight will add load to the front axle.
When load is added to the front axle, the front end will drop below the unloaded height.

When the Andersen's chains are tensioned and the tongue jack is retracted, load will be removed from the front axle.
How much load will be removed depends on how much tension has been applied to the chains.
Regardless of how much load is removed, suspension hysteresis (stiction effect) will prevent the front from rising as high as the net load would otherwise dictate.

Application of WD might have restored the front axle to its unhitched load,
but the front end could remain below its unhitched height due to hysteresis/stiction.
This could cause one to conclude there was more load transfer than actually occurred.

OTOH, if you do not use the tongue jack to raise the rear prior to applying tension to the chains,
the front end would initially rise and then be lowered by application of load distribution.
In this case, the front end would "hang up" a bit and one might conclude that the load transfer was less than actual.

In summary, if you raise the rear of the TV with the tongue jack and use fender heights to infer load transfer, you probably are overestimating how much load is being transferred.
If you do not use the tongue jack, you probably are underestimating load transfer.

If you really want to know how much load is being transferred -- use a scales.

Ron
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Old 01-02-2013, 08:06 PM   #1195
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I'll probably regret saying anything on this fender height vs scale weight issue but I have spent a lot of time doing just this when setting up race car chassis. A couple points from my background -
1- The friction in the suspension bushings do effect how the suspensions settles out after making a change to ride height, rubber bushings are very bad for this but race cars use solid bushings in most cases so it isn't too bad to shake out the suspension before taking a reading.
2-To set corner weights accurately the shocks have a big effect and must be disconnected. Gas filled shocks are worst for this.
3- Having considered 1 and 2 above IF you can get the suspension to settle out correctly and repeat the ride height measurements on all 4 corners the scale weights will be the same.

It seems to me that one way to do this would be for you drive the vehicle/trailer combination and come back to the same spot then check it fender heights after making a change to the weight transfer bars you can minimize these problems.

In my mind the exact same thing would have to be done if you are using scale weights. If you disconnected the bars and reconnected them while on the scale and took new scale weights without driving the rig to get the suspension to settle out as it will after going down the road you haven't gained any accuracy over using the fender method.
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Old 01-03-2013, 12:34 AM   #1196
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Quote:
Originally Posted by crisen View Post
In my mind the exact same thing would have to be done if you are using scale weights. If you disconnected the bars and reconnected them while on the scale and took new scale weights without driving the rig to get the suspension to settle out as it will after going down the road you haven't gained any accuracy over using the fender method.
Rick, I think I understand your rationale as it applies to height/load for an individual wheel.

However, I believe the combined left + right wheel load on a given axle of a typical tow vehicle is not affected by a friction-related change in ride height.

Ron
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Old 01-03-2013, 01:01 AM   #1197
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Quote:
Originally Posted by Ron Gratz View Post
Rick, I think I understand your rationale as it applies to height/load for an individual wheel.

However, I believe the combined left + right wheel load on a given axle of a typical tow vehicle is not affected by a friction-related change in ride height.
Ron
I'm not sure if this helps or not but on a chassis setup if you change the ride height of one wheel only, two thing happen, that wheel gets heavier and the diagonally opposite wheel gets heavier and this weight comes from the two diagonal wheels but it doesn't come off those evenly.


I believe you have two things going with a WD hitch, the weight that is transfered by the loading on the reciever and the weight transfer that takes place by the change in ride height. Again by my experience only, the latter is always there so I believe it affects the scale readings as surely as the reciever induced weight transfer.

I guess that one could test the theory by doing it both ways on the scale. Weigh all three axles on the scale w/o weight transfer, don't move the rig, apply weight transfer and re-weigh without moving the rig and then drive the rig to settle it out and weight for the third time without changing the bars. I haven't done this so can't swear to it but if I had access to a scale to set up the trailer I'd make darn sure the suspension was neutral from any friction/shock effects.
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Old 01-03-2013, 05:08 AM   #1198
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Ron Gratz and Crisen.
Why don't you two start a "Theory of Weight Distribution Hitch" thread and un hijack this one. Maybe a mod could clean up your posts and move them over to the new one.
Regards,
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Old 01-03-2013, 08:49 AM   #1199
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I find it interesting the argument that front fender height measurements are not acceptable because of hysteresis, and all sorts of other "drawing at straws" arguments to po-po the Andersen hitch.

However these same front fender height measurements have been used for years with bar type weight distribution hitches, and somehow it was acceptable with them. I personally have always used fender height measurements to setup weight distribution hitches for 40 years with good success.

I suspect some folks may have an adjenda that is biased against ANY new developments in hitch design, or maybe worse, are employed by some other hitch manufacturer to talk down the Andersen.
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Old 01-03-2013, 08:56 AM   #1200
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Originally Posted by AirHeadsRus View Post
Ron Gratz and Crisen.
Why don't you two start a "Theory of Weight Distribution Hitch" thread and un hijack this one.---
Joe, I agree this sidetrack has gone far enough.

This line of discussion was precipitated by the assertion:

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

I think that claim now has been thoroughly debunked.

Ron
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Old 01-03-2013, 09:31 AM   #1201
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The Hitch

I am now an Andersen Hitch owner. The hitch, (Andersen), is a beauty and really impressively solid looking than the
pictures or videos out there. If you trust your vehicle disc brakes, yes a friction type, to stop your vehicle, this
Andersen brake is a feat of engineering marvel.

Set up as instructed, just followed the manual instructions. BTW no scales, weighing nor any of that was mentioned,
thank heavens, for they're unnecessary for the hitch, (Andersen).

Now the anti-bounce or porpoising feature is unlike any other one out in the market today. Those bumps dampened and
making for a smoother ride. For a vintage owner that is a must have feature. Imagine the wear and tear that these
vibrations do over time especially w/ those heavy rigid hitches today? I might just do that wine glass test in the
trailer using the hitch, (Andersen), over my old dirty, heavy monster of a hitch. Now which hitch would spill the
the most or more likely tip the glass.

I am going on a cross country trip this spring and will post more for sure.

There's still a bit of a free market left I think so perhaps the best product will still win out and in my opinion
that product is the hitch, you got it, the Andersen hitch.
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Old 01-03-2013, 10:01 AM   #1202
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Well I knew I'd regret it, 4 pages of this discussion over 3 days and I make one comment, with one reply, based on real experience measuring wheel weights and I am accused of hijacking the thread. Amazing.
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Old 01-03-2013, 11:08 AM   #1203
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Well I knew I'd regret it, 4 pages of this discussion over 3 days and I make one comment, with one reply, based on real experience measuring wheel weights and I am accused of hijacking the thread. Amazing.
Sorry Rick
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Old 01-03-2013, 12:22 PM   #1204
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Hmmm? Wine glass test? Now I am wondering how one hitch would prevent more wine from spilling than some other hitch over the same road? The ball+coupler is solid in all hitches I know of except the Air Safe hitch.

If the TV body go up, the TT nose must go up! If the TV body dip down, the TT nose must dip down! Whatever suspension exists to mitigate the rough road is contained between the wheels and the body of the TT, and the wheels and the body of the TV. How does the solid ball/coupler hitch mitigate rough ride in the TT?
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