thomas malenich
sound beach, new york 11789
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Quote:Hi Tom,
I had always simply taken a trailer's "tongue weight" to be the difference between the total weight and the weight borne by the axle(s). That's certainly the way RV manufacturers use it. However, your question made me think about it a little more and I'm not so sure if that's the best definition in the context of our discussions. As soon as we mention "borne by the axle(s)", we're talking about the ground's reaction through the axles, which, as we've clearly illustrated in this thread, is changed by a WD system.
I think instead that the unchanging "tongue weight" that we've discussed would have to be described in terms of gravitational mass, but I'm not sure that there's a simple way to characterize the remaining mass that's not centered over the axle(s).
Care to take a stab at it?
Thanks for the brain ponder. ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/eek.gif "eek")
Tim,
My latest line of thinking is this: We have all been trying to define the WD system, when it is "tongue weight" that is giving us the trouble. Since page 1, I have had a problem with saying "tongue weight does not get distributed".
We all know what "tongue weight" means when the TT is sitting alone and the tongue is supported by the tongue jack. Now the problem: We drop the tongue on the ball and crank up on the jack and what happens? The manufacturers suggest by their wording that tongue weight is distributed to and borne mostly on the rear axle. This is the root of the confusion.
From Equal-i-zer: With ordinary ball-type hitches, most of the trailer tongue-weight gets carried on the back axle of the tow vehicle, often this raises the front end of the vehicle. The Equal-i-zer transfers the trailer's tongue-weight evenly to all the axles of the tow vehicle. This keeps the steering wheels in firm contact with the road surface -- giving you greater control and safety.
This way of thinking about tongue weight is what led to my initial problem with Ron's explanation of the WD system and tongue weight. My line of thinking was that some of the weight from the tongue was transferred through the hitch ball and receiver and was now borne mostly on the rear axle.
Ron said this in another thread:
Tongue Weight: That portion of the TT weight which is carried on the ball coupler as opposed to that carried on the axles.
Tongue weight, as a percentage of total TT weight, is a measure of the relative location of the TT's center of gravity. When WD bars are tensioned, the tongue weight does not change. WD hitch users should not be concerned that their TT's stability will be diminished due to the load transfer created by the hitch.
When WD bars are tensioned, the hitch load does change because some of the downward force exerted by the tensioners on the TT's A-frame is transferred to the TT's axles. The hitch load is reduced by the same amount.
Here is the decision we need to make. If we are to use Ron's definition of tongue weight, then as soon as the TT is connected to a TV, thats when we need to STOP talking about tongue weight, period. We should use terms like hitch load and axle load to describe weight changes.
Unfortunately the manufacturers suggest that tongue weight is transferred to the rear axle of the TV upon ordinary hookup. They are saying that tongue weight has already been distributed and that by using a WD system, tongue weight/load gets redistributed.
Ron has proved that a WD system can transfer load from the rear axle of the TV to the front axle and the TTs axles, regardless of and no matter what the tongue weight is, but we are left with a dilemma as to how to define tongue weight AFTER a WD system is engaged.
Thomas and Laura Malenich
1988 Suburban 1500, 4WD
Scotty 16 1/2' , smaller and loving it
2 kids and 3 dogs
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4runnerguy
Glenwood Springs, CO
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Quote:The manufacturers suggest by their wording that tongue weight is distributed to and borne mostly on the rear axle.
A common thread among this discussion is that it seems that we are getting hung up on the words "distribute" and "transferred". The first definition for distribute in our dated Websters is "to divide among several or many: apportion" while the third definition is "deliver". So when the tongue weight is distributed, it is being apportioned to the various axles, but not necessarily delivered, as in to hand over. The tongue weight is supported by the rear axle, and the ground beneath the rear axle. But the tongue weight is still there at the tongue/ball interface. If the tongue weight were not supported by the rear TV axle, the rear of the TV would not sink as the jack support is removed.
Quote:Unfortunately the manufacturers suggest that tongue weight is transferred to the rear axle of the TV upon ordinary hookup. Perhaps a less confusing way of putting it is that tongue weight is transmitted through the rear axle of the TV to the ground upon ordinary hookup. Again, looking at it from the ground's point of view, the weight that was originally supported by the tongue jack or whatever now seems to be supported by the rear axle (plus some weight transferred from the front axle to the rear axle by the lever effect). The tongue weight itself is not transferred as in given to the TV. The TV hasn't gotten heavier, but pull it (not the trailer) onto a scale with the trailer hooked up and it would weigh more.
In very simple engineering terminology, there are a series of actions and reactions from the tongue to the ground. At the hitch/ball interface, the hitch is pushing down with a force of 650#, while the ball is pushing up with a force of 650#. Similar thinking goes all the way to the tire/ground interface.
Quote:So, have we distributed the 900# "tongue weight"?
Nope, it's still where it was to begin with. But we have re-distributed the 900# load which was transferred from the tongue jack to the TV's axles.
With all respect to Ron, when I took my engineering classes, the answer would have said "Yes" to the question. We didn't use the word distribute to mean as one distributes candy on Halloween (to give away), but rather as to apportion the load among the load bearing members. The load (tongue weight) is still where it was to begin with, but how and where it reaches the ground has changed with the WDH.
Quote:
What happened to the "tongue weight"?
Nothing. The coupler still is pressing on the ball with a force of 900#.
Well, the loads on the TV's axles INCREASED by 1350-450 = 900#. Where did that come from? Some trailer weight must have been transferred from somewhere.
Nope, the 900# on the axles simply results from a relocation of the 900# reaction which previously was provided by the tongue jack. The loads on the TV's axles have changed, but the "tongue weight" has not changed.
Here, the word "transferred" trips us all up. I would leave out that entire sentence and say:
What happened to the "tongue weight"?
Nothing. The coupler still is pressing on the ball with a force of 900#.
The loads on the TV's axles INCREASED by 1350-450 = 900#. Where did that come from? The 900# on the axles simply results from a relocation of the 900# reaction which previously was provided by the tongue jack. The loads on the TV's axles have changed, but the "tongue weight" has not changed.
So let me modify the Draw-Tite definition to get rid of those pesky transferred's and distributed's:
"Weight distributing hitches apply leverage between the towing vehicle and trailer causing the tongue weight to be carried by all axles of the tow vehicle and trailer. This allows trailers with greater tongue weights to be towed and results in a more level ride which reduces stress on the rear of the tow vehicle and provides greater steering and brake control."
This definition steers us away from the techical explanation of removing loads from the rear axle and distributing it to the TV front axle and trailer axles. But for someone trying to simply understand what a WDH does, this definition won't cloud the issue by talking about distributing tongue weight and the confusion the word "distributing" could cause. If they want to get into the technicalities of this issue, they can wade through all of this thread themselves. ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/smile.gif "smile")
Ken & Allison
2 Camping Cats (1 diabetic)
1996 4Runner, TRD Supercharger, Edelbrock headers
2007 Fleetwood Arcadia, Honda EU2000i
4 mountain bikes, 1 canoe, 4 tents, 8 sleeping bags, 2 backpacks
(You get the idea!)
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thomas malenich
sound beach, new york 11789
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4runnerguy,
Right on - we are seeing eye to eye on this.
"With all respect to Ron, when I took my engineering classes, the answer would have said "Yes" to the question. We didn't use the word distribute to mean as one distributes candy on Halloween (to give away), but rather as to apportion the load among the load bearing members. The load (tongue weight) is still where it was to begin with, but how and where it reaches the ground has changed with the WDH."
At one point in our discussion I said this:
I agree with Barney and most of what Ron is saying. Ron is the engineer - I am just trying to keep him honest . I am nitpicking with Ron and our disagreement is mostly in terminology, but his point is that you should not be concerned that a use of a WD system will make a light tongue weight more of a problem and I agree too.
Unfortunately whatever we end up with - when this thread has run its course, the manufacturer definitions will not change. Also the way forum members talk about WD systems will not change. I can bet you that most people will continue to say "tongue weight gets distributed.....". If we can manage to define tongue weight, tongue load, hitch load, and WD system and make it sticky at the top of the Towing Forum, then we will have provided a useful service to other members.
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thomas malenich
sound beach, new york 11789
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I would further improve on your definition by changing the first "tongue weight" to "tongue load" to read like this:
"Weight distributing hitches apply leverage between the towing vehicle and trailer causing the tongue load to be carried by all axles of the tow vehicle and trailer. This allows trailers with greater tongue weights to be towed and results in a more level ride which reduces stress on the rear of the tow vehicle and provides greater steering and brake control."
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4runnerguy
Glenwood Springs, CO
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Of course we are still fighting the very name of the device: Weight Distributing Hitch.
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thomas malenich
sound beach, new york 11789
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Yup!
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4runnerguy
Glenwood Springs, CO
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Perhaps we should really address the initial problem -- the interpretation that lightening the tongue load by use of the WDH causes sway. Lets ignore the WDH for the moment. The advice on tongue weight is somewhere around 15% of the total weight of the trailer. What does this number represent? It is the weight that results from how the trailer is loaded, i.e. what percentage of the weight is in front of and behind the axle(s). If there is an equal amount of weight in front and back of the axle, there will be no tongue weight. If you use the often quoted 60% front/40% rear loading, in most cases you probably end up with about 15% of the total trailer weight on the hitch. So people use hitch weight to indirectly (and probably unknowingly) achieve the 60%/40% weight distribution. It's not the light tongue weight, per se, that causes sway. It's the improperly loaded trailer with too much weight in the back that is the problem. So regardless of what the WDH does or doesn't do with the tongue weight (tranfer, distribute, transmit, or somehow eliminate it all together), it doesn't effect the load balance of the trailer and the subsequent effect on sway.
My guess is that except for a very small amount of additional friction from the bars, WDH's in general have little effect on causing or decreasing sway. That's why we have Dual-Cams, friction devices, etc. as add-ons (except in the case of those units, such as Equal-i-zer, where the anti-sway is built in to the design).
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thomas malenich
sound beach, new york 11789
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My guess is that except for a very small amount of additional friction from the bars, WDH's in general have little effect on causing or decreasing sway. That's why we have Dual-Cams, friction devices, etc. as add-ons (except in the case of those units, such as Equal-i-zer, where the anti-sway is built in to the design).
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Agreed. I wish we could stop using the term "tongue weight" once the TT is placed on the ball and the jack is cranked up.
I would propose something like: Tongue weight is the weight measured at the tongue determined by the total weight of the trailer, axle placement, and where loading is placed inside the trailer. 12% to 15% should be the desired tongue weight in order to minimize sway.
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thomas malenich
sound beach, new york 11789
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Here is what Ron had said:
_____________________________________________________________________
What happened to the "tongue weight"?
Nothing. The coupler still is pressing on the ball with a force of 900#.
Well, the loads on the TV's axles INCREASED by 1350-450 = 900#. Where did that come from? Some trailer weight must have been transferred from somewhere.
Nope, the 900# on the axles simply results from a relocation of the 900# reaction which previously was provided by the tongue jack. The loads on the TV's axles have changed, but the "tongue weight" has not changed.
_____________________________________________________________________
Those words in red "relocation of the 900# reaction" are the key to Ron's thinking. Notice how he totally avoids anything to do with the words tongue or weight or distribute. However Equal-i-zer says: the trailer tongue-weight gets carried on the back axle of the tow vehicle
This is the first thing we need to deal with in my opinion. The WD system has not even been engaged yet and there is a difference in what (or at least how) the manufactures say happens and what Ron is saying. I think we need Ron to expand on and clarify this point.
Ron is it wrong to say "tongue-weight gets carried on the back axle of the tow vehicle"?
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tluxon
Kirkland, WA
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You guys are making some very good headway. I think the key is somehow making a distinction between mass (why I've thrown in the term "gravitational mass") and load bearing (for all practical purposes, "weight"). We know that a WD hitch does nothing with the mass from which the load originates, but has a significant effect on how the load is borne.
I don't believe the manufacturers are wrong, since they are talking about weight, which as we know from Newton's gravitational law, is simply mass acted on by gravity. You can't really have a weight unless it is reacted to, so the two are uncompromisingly intertwined. If you equate weight to a load and not just a mass, then Ron is unintentionally contradicting himself, as he clearly illustrated how the loads are changed. I believe what he really meant to clarify was that the gravitational mass over the tongue is not changed by a WD system.
Ken, I really like your wordsmithing to get rid of the words "distributed" and/or "transferred".
"Weight distributing hitches apply leverage between the towing vehicle and trailer causing the tongue weight to be carried by all axles of the tow vehicle and trailer. This allows trailers with greater tongue weights to be towed and results in a more level ride which reduces stress on the rear of the tow vehicle and provides greater steering and brake control."
If we want to change tongue weight to tongue load as Tom suggests, we should do it in both places to stay consistent and prevent confusion.
Tim -
wife Beverly & 2 boys who love camping
2002 K2500 Suburban 8.1L 4.10 Prodigy
2005 Sunnybrook 30FKS HP Dual Cam
Replaced 2000 Sunnybrook 26FK on 8/6/04
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