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Open Roads Forum  >  Towing

 > Weight Distribution (WD) Hitch --- How it Works

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CamperAndy

Coeur d'Alene, ID

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Posted: 08/30/04 09:06am Link  |  Print  |  Notify Moderator

Some may think this is a long winded thread but I think it is great.

#20 Home Depot summed it up great this morning
Quote:

To sum it all up:
Weight distribution bars simply change where the tongue weight of the trailer gets applied to the ground. It does not change the tongue weight.

Another visual aid may be to look at a 40' long beam that weighs 4000 pounds. If it were laying on 40 scales all would read 100 pounds as the "Weight is distributed" evenly. Now bend that beam in the middle and you will see that only 2 scales touch and the and they both read 2000 pounds. The beam still weighs the same and each segment still weighs the same it is just measured in 2 places instead of 40.

Now look at as with a TV/TT combo. 3 scales with big springs on them and the same 40' beam. The 3 scales will read a total of 4000 pounds just as before but depending on where you space them you may or may not get an equal distribution of 1/3x/1/3x1/3. Now bend the beam as in the first example. The middle spring will expand and the 2 end springs will compress. The total weight is the same but where it is measure changes. Any piece of the beam in isolation still weighs the same before or after bending but where that weight meets the ground can change.

Ron - Thanks for all the examples.


2005 Keystone Outback 28rs-s
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Ron Gratz

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Posted: 08/30/04 09:07am Link  |  Print  |  Notify Moderator

Quote:

--- Am I right Ron?

#20 Home Depot,

I sure hope so. If not, I've got to go back and retake Statics 101.

The point is -- the WD hitch redistributes SOME of the load which is on the TV's rear axle and it does not know where that load came from. Whereas the load on the TV's rear axle depends on both the TV's weight and the hitch load, the amount of CHANGE (redistribution) in axle loads resulting from the WD hitch has NOTHING to do with tongue weight. Whether the tongue weight is zero or 1000#, the change in axle loads remains the same.

thomas malenich

sound beach, new york 11789

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Posted: 08/30/04 09:25am Link  |  Print  |  Notify Moderator

Quote:

Thomas,

Please consider this situation.

A toyhauler trailer is overloaded in the rear and ends up having a tongue weight (by your definition) of ZERO before the WD bars are tensioned. The WD hitch (from my example) then is hooked up and applies an upward force of 1000# at the end of each 30" spring bar.

What is the tongue weight before and after the WD bars are tensioned?

How much of the ZERO tongue weight is distributed to the TV and TT axles?

How much has the load on each axle changed as a result of tensioning the WD bars?

On edit: Please assume the toyhauler and TV have the dimensions shown in my orginal post.


OK Ron,

All WD systems need a minimum amount of tongue weight in order to work properly. Call a few companies like Lindon Hitch and they will tell you that. That is because you need that minimum weight at the ball in order for the bars to distribute it. If you have 0 tongue weight, what weight can you expect to distribute?

Furthermore, your original drawing shows: TV receiver load WD hitch REMOVES 300#'s.

1. Where is this load removed from ?

2. You are saying in your drawing: There is 300#s removed from the TV's receiver, but then you claim that the load on the TV's ball which is directly connected to the reciever and is directly under and connected to the tongue remains the same. How is this possible? It seems you are disagreeing with yourself.

* This post was last edited 08/30/04 10:20am by thomas malenich *   View edit history


Thomas and Laura Malenich
1988 Suburban 1500, 4WD
Scotty 16 1/2' , smaller and loving it
2 kids and 3 dogs

thomas malenich

sound beach, new york 11789

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Posted: 08/30/04 09:34am Link  |  Print  |  Notify Moderator

To sum it all up:
Weight distribution bars simply change where the tongue weight of the trailer gets applied to the ground. It does not change the tongue weight.

___________________________________________________________________

I agree with this too - I said before that there are only three things that change tongue weight. A WD system does not change it, it distributes it.

Ron Gratz

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Posted: 08/30/04 11:56am Link  |  Print  |  Notify Moderator

Quote:

All WD systems need a minimum amount of tongue weight in order to work properly. Call a few companies like Lindon Hitch and they will tell you that. That is because you need that minimum weight at the ball in order for the bars to distribute it. ---

And what would the magnitude of that "minimum weight" be? 500#? 50#? 5#? How is it determined? Can you provide the name of someone who told you this? I certainly would like to communicate with that person. Perhaps you are thinking of the Dual Cam's requirement for a certain amount of WD bar load in order to make the SWAY CONTROL work properly.

Quote:

--- If you have 0 tongue weight, what weight can you expect to distribute?

I can expect to distribute some of the load which is on the TV's rear axle. In this case, it would be load resulting solely from the weight of the TV. This would be similar to the way a liftable tag axle on a concrete hauler redistibutes the axle loads when it is lowered.

Quote:

Furthermore, your original drawing shows: TV receiver load WD hitch REMOVES 300#'s.
1. Where is this load removed from ? ---

The WD hitch produces an UP force of 2000# on the hitch head and a DOWN force of 1700# on the ball coupler. The net result is an UP force (removal) of 300# on the receiver. If the tongue weight were zero to begin with, the hitch now would be pushing UP with a force of 300# on the receiver. Whether the receiver load goes from 300# DOWN to zero or goes from zero to 300# UP makes no difference to the TV.

Quote:

2. You are saying in your drawing: There is 300#s removed from the TV's receiver, but then you claim that the load on the TV's ball which is directly connected to the reciever and is directly under and connected to the tongue remains the same. How is this possible? It seems you are disagreeing with yourself.

I have never said that the "load on the TV's ball --- remains the same". I have said more than once that the load on the ball increases by 1700# using my example WD hitch application.

Let me try once more:
Begin with X load on the ball which produces X load on the receiver.
Use the WD bars to pull down on the A-frame with 2000# which causes a DOWN force of X+1700# on the ball coupler.
You now have X+1700# acting down on the ball and hitch head.
Simultaneously, the front end of the WD bars push UP with a force of 2000# on the hitch head.
The net result (receiver load after WD minus receiver load before WD) is (X+1700-2000)-X = -300#. The WD has removed 300# from the receiver and it does not make any difference what the value of X is.

Thomas, since I invited questions and comments, I feel obligated to continue this as long as you want to. I just ask you again to please compare your definition of "tongue weight" with my definition of "tongue weight". We seem to be trying to compare apples and oranges.

Ron

ffrnemtp

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Posted: 08/30/04 12:54pm Link  |  Print  |  Notify Moderator

I'm the one mentioned is the original post who stopped using the WD system because of sway. When I first got the '28, I was pulling it with an '03 F-150. I now have an '04 F-250. The 1/2 ton really needed the help the WD hitch provided--the F-250 doesn't. I get miminal drop on the rear from tongue weight, and no disernable rise in the front. I just don't see why I need the WD system with this combination.


Doug & Lorri
2004 F-250 XLT 6.0L PSD SC SB FX4 DiabloSport Predator
2004 30' Thor Chateau TT with Reese HP Dual Cam
2004 Seadoos GTX 4-TEC Supercharged & GTI LE RFI

Ron Gratz

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Posted: 08/30/04 01:17pm Link  |  Print  |  Notify Moderator

Doug,

It was not my intention to imply that you needed to use a WD hitch. I do not know enough about your TV/TT combo to make such a judgement. It is possible that the WD hitch does contribute to sway in your case. For example, removing too much load from the TV's rear axle can cause instability.

My reference to your post was aimed at the statement, "The WD bars must have further lightened an already light tongue." If your WD bars are contributing to sway, I doubt that it is due to the lightening of an already light tongue. I do not want other members to believe this is possible and use this as a reason for not towing with a WD hitch.

If anyone really believes that their WD hitch is contributing to sway, then I believe they should be looking for some reason other than lightening of the tongue.

Ron

ffrnemtp

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Posted: 08/30/04 02:44pm Link  |  Print  |  Notify Moderator

With an empty weight of 6,000 and a loaded weight of 7,000-7,500, do you think I need WD with a '04 F-250 PSD? I'm still new at this, and sometimes experimentation is the best I can do. I wasn't offended.

Ron Gratz

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Posted: 08/30/04 04:00pm Link  |  Print  |  Notify Moderator

Doug,

In your Swaying Issue Solved topic, you stated that, without WD bars, your rear sags about 2" and your truck sits level.

How does your truck sit WITHOUT the TT on the ball? Is the rear a couple inches high then? That's the only explanation I can think of that would result in a TV-level attitude when the TT is on the ball.

In your "Swaying Issue Solved" topic, I asked if your hitch rises up when the WD bars are tensioned. If you raise the nose of your TT by any significant amount, this could explain why you get more sway with the WD bars tensioned.

Have you had a chance to weigh your axles with and without the WD bars tensioned? Also have you measured the tongue weight with the TT unhooked from the TV?

Ron

BarneyS

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Posted: 08/30/04 06:23pm Link  |  Print  |  Notify Moderator

Doug,
As I and many others tried to explain in your other topic, YES, you should be using WD with that trailer with that truck. Even at empty weight, your tongue weight will probably be over the rating of your hitch if you do no use the WD capability. I am not going to go over again all the reasons why you should use it as many of us have already done so on your other thread - just make sure you have your WD hitch and your rig set up properly and you should be able to tow without sway and in safety. In your last post on the other topic, you said you were going to try towing with the WD hitched up this weekend. How did that go?
Barney


2004 Sunnybrook Titan 30FKS TT
Hensley "Arrow" 1400# hitch (Sold)
Not towing now.
Former tow vehicles were 2016 Ram 2500 CTD, 2002 Ford F250, 7.3 PSD


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