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Post Info TOPIC: The effects of using a WDH
Greg 1


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RE: The effects of using a WDH
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I agree with Gundog and Yobarr on this. A WDH does not alter towball weight. It just distributes some of the load to different axles. The claim that a WDH creates understeer is the exact opposite of what it does. It, in fact, decreases understeer by placing load back on the front wheels. In fact, caution must be exercised that too much tension is placed on the WDH bars as an oversteer condition can be the end result which is definitely undesirable. I am an advocate of WDH's having towed with them since the early 70's, but some vehicle manufacturers suggest not using them with their particular vehicle and some strongly recommend their use. As previously stated, I would first be guided by your vehicle manufacturers advice. Towball weight must always be considered just as importantly as the other weights when towing for two primary reasons. The first to ensure there is sufficient weight on the ball to have adequate stability in the rig and secondly to ensure that you are not exceeding the vehicle manufacturers requirements for towball load. For those of you that are considering a WDH I can only give you advice from my extensive use of one over decades of caravanning, and that is if your vehicle has no negative recommendations from the manufacturer on the use of one then go for it. I have tried both with and without over a multiple of vehicles, and can only say I would not leave home without one if for nothing else than the better steering feel and control it gives.

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Greg O'Brien
KJB


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And here is a WDH designed to transfere MORE WEIGHT  onto the rear axle of the tow vehicle .........Weight Distribution Hitch .jpg



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yobarr


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iana wrote:

No body has mentioned "Center of Gravity". If we were to take a single axle van with an ATM of 2500kg, and the center of gravity (which I will call C of G) was at a point vertically above the axle, the ball weight would be zero.

With the draw bar (hitch point) set at the horizontal, which I will call zero degrees, a set of scales at the hitch would read O kg. If some of the weight in the van was moved forward, the scales would begin to read, as the C of G moves forward. Now the hitch is sharing some of the load. By moving more of the internal cargo load forward, so that the ball weight now reads 250 kg, the C of G will have moved forward, by how much would depend on the van, and I would have no idea where the C of G point is.

We can now say the Ball weight is 250 kg with the hitch point at 0 degrees to the horizontal.

If you hitch the van up, and the weight of the draw bar causes the back of the vehicle to drop, the draw bar is no longer at 0 degrees, it is now maybe -2 degrees, the van has rotated about its axis (in this case the axles), and the C of G has moved forward. The hitch will now be sharing more of the van load. The ball weight has increased, it is now maybe 260kg.

If you now use some method to raise the tow ball using heavier rear springs, air bags, or WDH, so that the hitch is now back to zero degrees to the horizontal, the load sharing of the hitch will be back to 250 kg.

 Interesting theory,and one which I had considered,but my subsequent testing,using bathroom scales,showed no change in towball weight when the drawbar was lowered 100mm.The test was carried out using a caravan with 5 metres from rear axis to towball,and non-loadsharing suspension,so loadsharing may produce slightly different results,but so minimal that I doubt that,even then,the  scales would register the change.10kg? ...don't think so.Results obviously will vary, depending on the distance from the hitchpoint to the rear axis,but if a car is dropping 100mm when a van is connected,I would suggest that the owner is way out of his depth with his weights!Cheers



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iana


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Not a theory but a fact, any change in the center of gravity will effect the weights shared by the axles and the hitch. The center of gravity will move forward or backwards depending on any change of angle, i.e. traveling up or down an incline, just going over a bump, or the change of angle of the hitch relative to the horizontal. The numbers were just to show an example.

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yobarr


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 Good to see that more and more members are now understanding how a WDH works,but I note that the OP has not returned? Perhaps he now is pondering the suggestion that I respectfully made to him in my post at 7.59pm on May 6th,in the "Ford Everest 2 litre bi-turbo 4x4" thread? He had asserted that he would immediately start a thread on the effects of using a WDH,so I suggested that,before such a thread was started,he familiarise himself with the actual physics of using a WDH.Seems my advice was ignored,but it is pleasing to see that more and more people are now understanding. This  means that there is a reduced chance of them finding themselves overloaded,unsafe and uninsured.Cheers.  

 



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yobarr


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iana wrote:

Not a theory but a fact, any change in the center of gravity will effect the weights shared by the axles and the hitch. The center of gravity will move forward or backwards depending on any change of angle, i.e. traveling up or down an incline, just going over a bump, or the change of angle of the hitch relative to the horizontal. The numbers were just to show an example.

 Ian,there is no dispute with your assertion,but with a forward length of 5 metres,and a drop in the height of the drawbar of 50mm,the change in towball weight is so small that it is immeasurable with any normal scales...certainly not on a set of bathroom scales,and definitely not on a weighbridge. 10kg?.....tell them they're dreaming! Cheers



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DMaxer


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I wonder how long it will be before Alan regains consciousness. I think the poor bloke is going to need a fair bit of therapy.



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yobarr


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DMaxer wrote:

I wonder how long it will be before Alan regains consciousness. I think the poor bloke is going to need a fair bit of therapy.

 Like you,DMaxer (do you have a name?) I too have been wondering about Alan,as he has neither acknowledged nor replied to the PM I sent to him,and has not further contributed to this thread.I can only assume that since he now should have a far better understanding of the effects of a WDH,he is busy setting up his car correctly? Whatever it is,I am sure you would join me in wishing Alan (and Brenda) SAFE and happy travels? Cheers



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yobarr


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KJB wrote:

And here is a WDH designed to transfere MORE WEIGHT  onto the rear axle of the tow vehicle .........Weight Distribution Hitch .jpg

 Hi Kerry...do you have any information on how this piece of equipment works? Looks to be something that would be used on the 3 point linkage on a farm tractor,but I may well be wrong? Even any information from the plate that is on the  side of the arm would help.Cheers.



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Jaahn


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yobarr wrote:
KJB wrote: ---------picture of old implement frame !

 

 Hi Kerry...do you have any information on how this piece of equipment works? Looks to be something that would be used on the 3 point linkage on a farm tractor,but I may well be wrong? Even any information from the plate that is on the  side of the arm would help.Cheers.

 Hi yobarr smile

Let it go ! "He is 'aving a lend of ya"biggrin It is a frame for a three point linkage attachment, and all three point linkage machinery is designed to put the weight and the implement forces directly onto the rear tractor wheels for max traction in use. Nuttin' too technical 'ere. whisper.gif       imslow.gif

Jaahn



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yobarr


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Jaahn wrote:
yobarr wrote:
KJB wrote: ---------picture of old implement frame !

 

 Hi Kerry...do you have any information on how this piece of equipment works? Looks to be something that would be used on the 3 point linkage on a farm tractor,but I may well be wrong? Even any information from the plate that is on the  side of the arm would help.Cheers.

 Hi yobarr smile

Let it go ! "He is 'aving a lend of ya"biggrin It is a frame for a three point linkage attachment, and all three point linkage machinery is designed to put the weight and the implement forces directly onto the rear tractor wheels for max traction in use. Nuttin' too technical 'ere. whisper.gif       imslow.gif

Jaahn

 Thanks Jaahn.....I had decided that is what it is as the Category 1 and Category 2 interchangeable pins looked familiar! I believe that a chain hangs from the end of the swivel arm,and is attached to the drawbar of the towed implement,which has its own connection to the tractor.Raising the hydraulic 3 point linkage arms creates a lever effect,with the swivel arm trying to lift the towed implent off the ground,thus putting a lot more weight on the tractor's rear wheels,and often lifting the tractor's front wheels completely off the ground too! Thanks again.Cheers



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