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Post Info TOPIC: Rear Axle Load


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RE: Rear Axle Load
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I will try to keep this using the KISS method.

Step 1 (before anything else this is the most Important)

Place the caravan on a level surface level off the caravan using the jockey wheel.

Now measure the ball coupling height .EG 450mm.

Step 2.

Set the hitch height so the top of the ball equals the coupling height.

The rest is done using the measurement method, as this is the only way unless you have a weigbridge in your back yard.

Step 3.

With the tug and caravan located on a level surface but not connected.

Mark 2 points on the front and rear of the tug, generally the wheel arches are the best points ( I use masking tape with a line as the reference point)

A.Measure the tugs F&R reference points. Lower the coupling on to the ball, with the jockey wheel off the ground.

B.Measure the tugs F&R reference points again.

Step 4.

Engage the lift bars to transfer some of the weight on the ball back to the front axle adjust the number of loose links until the tug looks level.

Measure your reference points again, I like to have my front axle height to be 5-10mm heigher than what was recorded in 3A.

Step 5.

View you caravan if it appears low or high at the front of the caravan, this can be adjusted by moving the hitch head angle, tilting it forward or back. ( I prefer my caravan to be ever so slightly nose down)

 

These instructions are basically from my hitch, READ THE INSTRUCTIONS THAT CAME WITH YOU WDH.

I do not have a choice of wether to use a WDH or not, the use of a WDH is mandatory for my model Ford towing a caravan over 1800kgs.



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Ivan 01 wrote:

Yobarr,

I have little time for Cadogan and I dont agree with your views on WDH use.

I will just leave it at that if that is OK with you.


That's fine Ivan, and thankyou for your post. However, there is only so much that I can do to help people understand how a WDH works. Previously I have posted advice direct from Hayman Reese that confirms everything I've said, and I also have posted figures from my own exercises on a licenced weighbridge where I weighed every axle on both my car and my van without the WDH, both hitched and unhitched, and again with the WDH in place. The result was that I determined that a WDH is not the universally "cure it all" that many believe it to be, but is in fact a vastly over rated piece of gear that does next to nothing, so it was promptly thrown into the back of my shed until a 'newbie' caravanner spotted it when he was drinking beer with us, and asked could he 'borrow' it. Away he went, but I haven't seen the WDH since, nor has he mentioned it! Boo Hoo!  People waffle on about restoring front axle weight for steering and braking etc, but conveniently forget that bullbars, spotlights, 2nd batteries and a host of other 'extras' have already added weight to that axle well above what it was at the factory. Very few, if any, caravan accidents are caused by a car understeering but a WDH is likely to promote oversteer that few can manage. Braking is also misunderstood, with the axle that carries the most weight doing the most braking (Yes, I do know about weight transfer) so that too is a furphy. Indeed, in many countries, like Canada, semis (Tractor trailers!) do not have front brakes. How do they stop? WEIGHT on the rear axles.                                                                                                                                

        As an aside, I have heard through the grapevine (phone conversations with members) that one of the most vocal critics of my factual representations on our forum, about WDHs and weights issues in general, has recently posted a link, on another caravan forum, to the exact same John Cadogan educational video that I have posted here several times. Seems he has given up on simply posting copies of charts that have been available on the internet for eons. Cheers

P.S Just noticed Graham's suggested method for determining weight transfer caused by WDH, and while I have little doubt that he is sincere in his advice, such a system was rejected years ago with too many and variables and inaccuracies.                                                                              Think spring rates, shocks, wheelbase and TBO for starters.

 





-- Edited by yobarr on Monday 18th of July 2022 04:16:23 PM

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Yobarr I am one of people who think you are wrong in your assertion that a WDH does not change tow ball download. Also they do not and can not increase a vans ATM as you have asserted before.

If you had bothered to do the simple arithmetic on the hayman reece example I posted some time ago, you would find that they in fact do.

In the whole exercise of fitting and tensioning a WDH the masses of both van and car remain unchanged, (nothing taken from one and put in the other.

This being the case means that the contribution of cars mass to the weight read from the scales remains constant. When the van is coupled to the car the reading of the scales increases to reflect the contribution of the tow ball download. How ever as we tension the WDH the reading of the scale reduces somewhat as the tension increases. Quite clearly the towball download has been reduced by the tensioning process.

If this doesn't convince you try another approach.

Change the loading of the van so that the axle loading is same as in the tensioned example and the tow bar download will be reduced accordingly. Now do your calculations assuming the same ratio of wheel base to TBH and you will see the same weights as the haymen reece example.

Alan



-- Edited by Brenda and Alan on Monday 18th of July 2022 06:17:01 PM

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yobarr wrote:
Ivan 01 wrote:

Yobarr,

I have little time for Cadogan and I dont agree with your views on WDH use.

I will just leave it at that if that is OK with you.


That's fine Ivan, and thankyou for your post. However, there is only so much that I can do to help people understand how a WDH works. Previously I have posted advice direct from Hayman Reese that confirms everything I've said, and I also have posted figures from my own exercises on a licenced weighbridge where I weighed every axle on both my car and my van without the WDH, both hitched and unhitched, and again with the WDH in place. The result was that I determined that a WDH is not the universally "cure it all" that many believe it to be, but is in fact a vastly over rated piece of gear that does next to nothing, so it was promptly thrown into the back of my shed until a 'newbie' caravanner spotted it when he was drinking beer with us, and asked could he 'borrow' it. Away he went, but I haven't seen the WDH since, nor has he mentioned it! Boo Hoo!  People waffle on about restoring front axle weight for steering and braking etc, but conveniently forget that bullbars, spotlights, 2nd batteries and a host of other 'extras' have already added weight to that axle well above what it was at the factory. Very few, if any, caravan accidents are caused by a car understeering but a WDH is likely to promote oversteer that few can manage. Braking is also misunderstood, with the axle that carries the most weight doing the most braking (Yes, I do know about weight transfer) so that too is a furphy. Indeed, in many countries, like Canada, semis (Tractor trailers!) do not have front brakes. How do they stop? WEIGHT on the rear axles.                                                                                                                                

        As an aside, I have heard through the grapevine (phone conversations with members) that one of the most vocal critics of my factual representations on our forum, about WDHs and weights issues in general, has recently posted a link, on another caravan forum, to the exact same John Cadogan educational video that I have posted here several times. Seems he has given up on simply posting copies of charts that have been available on the internet for eons. Cheers

P.S Just noticed Graham's suggested method for determining weight transfer caused by WDH, and while I have little doubt that he is sincere in his advice, such a system was rejected years ago with too many and variables and inaccuracies.                                                                              Think spring rates, shocks, wheelbase and TBO for starters.

 





-- Edited by yobarr on Monday 18th of July 2022 04:16:23 PM


 Hi yobarr

This old topic will go around and around long after both of us have gone.

I have read and analysed as best I can all comments and by applying it to my past vehicle and van I have formed my opinion.

I think most of us have said what we thought and that is why I am leaving it at that,

My view is that Cadogan is a car salesman and not an engineer and if I may be more bold I would nearly make a bet that he hasnt done much towing at all.

There are other publications available that have been written by some who are using references back into the early 1900s which to me is way-way out of touch with modern vehicles and vans.

So as I said I will agree to disagree but will leave it there.

Just off topic that float combination in another topic was a beauty, wasnt it.?



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Brenda and Alan wrote:

Yobarr I am one of people who think you are wrong in your assertion that a WDH does not change tow ball download. Also they do not and can not increase a vans ATM as you have asserted before.

If you had bothered to do the simple arithmetic on the hayman reece example I posted some time ago, you would find that they in fact do.

In the whole exercise of fitting and tensioning a WDH the masses of both van and car remain unchanged, (nothing taken from one and put in the other.

This being the case means that the contribution of cars mass to the weight read from the scales remains constant. When the van is coupled to the car the reading of the scales increases to reflect the contribution of the tow ball download. How ever as we tension the WDH the reading of the scale reduces somewhat as the tension increases. Quite clearly the towball download has been reduced by the tensioning process.

If this doesn't convince you try another approach.

Change the loading of the van so that the axle loading is same as in the tensioned example and the tow bar download will be reduced accordingly. Now do your calculations assuming the same ratio of wheel base to TBH and you will see the same weights as the haymen reece example.

Alan


Not again! Alan, I have spent many hours documenting stuff for you, including copies of information from the Hayman Reese website, ALL of which showed that a WDH DOES NOT change towball weight, and because  I did all this for you more than 2 years ago I thought that finally you'd woken up. Apparently not, but I simply can't be bothered iterating it for you. If you haven't learnt by now, it's unlikely that you ever will. You can take a horse to water but you can't make it drink. To help you, without to much more effort, I have posted screenshots of both a PM to you and a post from the forum, along with another suggestion that you Google "Weight distribution and load levelling hitches for heavy towing" by John Cadogan. You might like to access books written by Collyn Rivers, a noted expert on weights and dynamics, with over 60 years experience in this field, and a world recognised expert. Should you STILL fail to understand I suggest that you write to both Collyn Rivers and Hayman Reese and point out to them the error of their ways. You woukd no doubt then be happy to post copies of their correspondence with you, acknowledging that after 50 years in the business of weight distribution, they still know little? Cheers

P.S The Hayman Reese chart to which you refer seems to have been created for  absolute beginners in an effort to help them get a bit of an idea how a WDH works, and I have spent much time in the past explaing the workings. Perhaps you have not read that but it still can all be found using the search facility on our forum.

P.P.S Are you sure that you're not being michievous as nothing you've said makes any sense? 

 

63D1401C-96D6-4208-9420-272BB943DD81.png

 

79AFDDA7-C602-48BE-B7BE-8FEC200FD54A.png

 

0785F906-9DF0-4243-8504-1B58715C8804.png






-- Edited by yobarr on Monday 18th of July 2022 07:10:38 PM

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I see a few posts here have raised the heat on the forum, but I had already written my followup on HOW a WDH functions. Not how to set it up or even if it's beneficial. But I will give Yobarr a challenge. See at the end of this.

In the previous post (early hours of this morning) I posed the question

"Why does this work? Surely if the bars are lifting the rear end up, but those very same bars are pulling the drawbar down, they will cancel each other out and you will achieve nothing."

There is more than one reason .... first the leverage effect of the bar. Refer back to the previous post when I said I would come back to this point.

Let's say you put a load of 100kg on the towball. The back of the car sinks a bit, but you are able to level it again by lifting with the end of the bar. Maybe you are then holding 80kg. The front wheels of the car are now bearing that missing 20kg. Then, when you then attach the bar to the bracket on the drawbar, it is only pulling the drawbar down with 80kg.

This is where the second component comes in for a cumulative effect. The drawbar bracket is part way between the coupling and the van axles. When the bar is pulling the bracket down, that effective weight is shared between coupling and van axles. So while it may be 80kg at the bracket, it less than that at the coupling. Maybe 70kg. The other 10kg is now being borne by the van axles.

The net effect is that the rear end sags less because part of the towball download weight has been redistributed. 20kg to the car front wheels and 10kg to the van wheels with effectively 70kg at the car rear end.

I have described this with weights. You can use the same principles with measurements. Because of leverage, the end of the bar must move more than the car rear end. But it can't because it is fixed to the drawbar bracket, where the opposite applies. The coupling must move more than the drawbar bracket. So the bar bends and the car rear end rises.

The beauty of the system is that the more weight that is applied at the towball, and the more the rear end tends to sink, the stronger the effect of the WDH. So, when braking or on road undulations it works harder.

Hopefully this is not too difficult. I know it was hard to write it and keep it relatively simple.

 

Challenge to Yobarr. I know you have repeatedly said that the towball weight never changes with a WDH .... Never has, never will. If the towball weight never changes please explain what happens when the HR bars are pulling down on the drawbar brackets. In my example 80kg per bar is applied at the drawbar bracket. The load is adjustable depending on how much tension you apply. A small percentage is added to the van wheels but most is added to the .......... (Hint "T _ _ _ _ _ L").  Please don't paste where you have told us before.  Please EXPLAIN what happens with this 2 x 80kg additional load to the drawbar.



-- Edited by Are We Lost on Monday 18th of July 2022 07:50:51 PM

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yobarr 



P.S Just noticed Graham's suggested method for determining weight transfer caused by WDH, and while I have little doubt that he is sincere in his advice, such a system was rejected years ago with too many and variables and inaccuracies.      Think spring rates, shocks, wheelbase and TBO for starters.

 

I'm sorry you cannot accept a different point of view.

The method I explained is not an opinion, but is directly from the manufacturers instructions of the WDH I currently use all be it an abridged simplified version, that is why I stated each user should consult their WDH manufacturers instructions.

Approximately 3 years ago or so on another forum, a group of members were quoting from a document that used 50% front axle load return as a control in assessing a different outcome, they then applied this as a mandatory requirement, before I read the entire document I followed the advice and adjusted my WDH to return only 50% FALR, upon leaving to my next  destination the setup was quite dangerous, the first opportunity I had I retuned my setup to the manufactures instructions.

I then researched as many WDH manufactures setup instructions, what I found was almost every manufacturers instructions were consistent with what I have posted, there was small nuances of difference attributed to the type of lift bars and hitch head. Even HR USA had different instructions for the different styles of hitches, but still were slightly differences to the method I used.

The variables you highlighted are basically BS, in an attempt to muddy the facts that a correctly fitted and adjusted WDH is fit for purpose.

-- Edited by yobarr on Monday 18th of July 2022 04:16:23 PM


 Alan.

Once you establish your towball weight, if its within the desired range, because when connect it to your tug wether you use a WDH or not its part of the combination.

It's time to let go of your concerns, because it's irrelevant.



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Are We Lost wrote:

 

I see a few posts here have raised the heat on the forum, but I had already written my followup on HOW a WDH functions. Not how to set it up or even if it's beneficial. But I will give Yobarr a challenge. See at the end of this.

In the previous post (early hours of this morning) I posed the question

"Why does this work? Surely if the bars are lifting the rear end up, but those very same bars are pulling the drawbar down, they will cancel each other out and you will achieve nothing."

There is more than one reason .... first the leverage effect of the bar. Refer back to the previous post when I said I would come back to this point.

Let's say you put a load of 100kg on the towball. The back of the car sinks a bit, but you are able to level it again by lifting with the end of the bar. Maybe you are then holding 80kg. The front wheels of the car are now bearing that missing 20kg. Then, when you then attach the bar to the bracket on the drawbar, it is only pulling the drawbar down with 80kg.

This is where the second component comes in for a cumulative effect. The drawbar bracket is part way between the coupling and the van axles. When the bar is pulling the bracket down, that effective weight is shared between coupling and van axles. So while it may be 80kg at the bracket, it less than that at the coupling. Maybe 70kg. The other 10kg is now being borne by the van axles.

The net effect is that the rear end sags less because part of the towball download weight has been redistributed. 20kg to the car front wheels and 10kg to the van wheels with effectively 70kg at the car rear end.

I have described this with weights. You can use the same principles with measurements. Because of leverage, the end of the bar must move more than the car rear end. But it can't because it is fixed to the drawbar bracket, where the opposite applies. The coupling must move more than the drawbar bracket. So the bar bends and the car rear end rises.

The beauty of the system is that the more weight that is applied at the towball, and the more the rear end tends to sink, the stronger the effect of the WDH. So, when braking or on road undulations it works harder.

Hopefully this is not too difficult. I know it was hard to write it and keep it relatively simple.

 

Challenge to Yobarr. I know you have repeatedly said that the towball weight never changes with a WDH .... Never has, never will. If the towball weight never changes please explain what happens when the HR bars are pulling down on the drawbar brackets. In my example 80kg per bar is applied at the drawbar bracket. The load is adjustable depending on how much tension you apply. A small percentage is added to the van wheels but most is added to the .......... (Hint "T _ _ _ _ _ L").  Please don't paste where you have told us before.  Please EXPLAIN what happens with this 2 x 80kg additional load to the drawbar.

-

Hi Stephen. Despite me spending many, many hours on the forum explaining the workings of a WDH, along with relevant screenshots from the Hayman Reese website  and advice on how to access relevant videos, combined with results from my own weighings on a registered weighbridge, still it seems that some don't want to know.  It is an INDESPUTABLE fact that a WDH DOES NOT CHANGE TOWBALL WEIGHT.                           Never has. Never will. No matter how some may waffle-on, and come up with their own half-baked theories there is no disputing what Hayman Reese says, nor the findings by Collyn Rivers who has 60 years experience with weights and dynamics. It is very easy to access his books online, as it also is easy to access the HR website. Since I joined this forum many have come to understand that when it comes to weights I do know what I'm talking about, but still there seem to be some who learn slowly or who just don't want to know. C'est la vie. Again I will suggest that you Google John Cadogan "Weight distribution and load levelling hitches for heavy towing" and make an effort to actively LISTEN to the lesson. If you then still do not understand it appears that there is little that can be done to help you. Cheers



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Gundog wrote:

yobarr 

The variables you highlighted are basically BS, in an attempt to muddy the facts that a correctly fitted and adjusted WDH is fit for purpose.


Interesting. Surely you jest, or are you seriously trying to convince us that the effects that a WDH has are the same for EVERY vehicle? Wheelbase, TBO and forward length  are major influencers on how much weight is transferred between axles, while spring rates and, to a lesser extent, shock absorbers affect how much a vehicle's stance may change. Hope this helps. Cheers

 



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Yobarr, did you see Mike Harding's post at 4:56pm on 17th (addressed to someone else)?

So, could you answer my question about where the 2 x 70kg goes. Or explain where I am wrong in my explanation of how a WDH works. I based my explanation on the fact that an essential component of the design is that the WDH applies greater load on the towball the more it is tensioned. Of course, this certainly does not change overall weight on the wheels .... never has. Never will.

Instead of repasting the same things again are you able to explain it?



-- Edited by Are We Lost on Tuesday 19th of July 2022 01:39:29 AM

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Chris, I will pose this question to you for your solution.

A vehicle manufacture requires the use of a weight distribution hitch when the towed weight exceeds 1800kgs.

When the caravan is lowered on to the towball, the rear suspension sinks and the front of the suspension rises. In this situation the vehicle is not safe drive.

Whats your solution ?



-- Edited by Gundog on Tuesday 19th of July 2022 01:43:48 AM

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Yobarr I'll set this out as simply as I can so even you should be able to grasp the fact that you are wrong in your assumption on WDH effects

Firstly the chart was created at a caravan show in front of an audience to demonstrate the effects of a WDH

The chart shows that the car weighs 1690 Kg Wt therefore it has a mass of 1690 Kg.

It the shows a weight of 1920 Kg Wt with the caravan attached.

The last shows a weight of 1850 KG Wt after the WDH is tensioned.

The car can only contribute 1690 Kg Wt to the scales.

Now here is the simple arithmetic.

1910 - 1690 =220

1850 - 1690 =160

This clearly shows that the towball download has been reduced by 60 Kg Wt.

If you can't accept this fact so be it, go your own way in ignorance.

Alan



-- Edited by Brenda and Alan on Tuesday 19th of July 2022 06:42:43 AM

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Brenda and Alan wrote:

Yobarr I'll set this out as simply as I can so even you should be able to grasp the fact that you are wrong in your assumption on WDH effects

Firstly the chart was created at a caravan show in front of an audience to demonstrate the effects of a WDH

The chart shows that the car weighs 1690 Kg Wt therefore it has a mass of 1690 Kg.

It the shows a weight of 1920 Kg Wt with the caravan attached.

The last shows a weight of 1850 KG Wt after the WDH is tensioned.

The car can only contribute 1690 Kg Wt to the scales.

Now here is the simple arithmetic.

1910 - 1690 =220

1850 - 1690 =160

This clearly shows that the towball download has been reduced by 60 Kg Wt.

If you can't accept this fact so be it, go your own way in ignorance.

Alan

 

 

I cannot follow this.     Where did the 1910 come from?     

 A WDH changes "axle weights" - not TBW .   

The "axle weights" of the caravan need to be shown "before and after"  as well - pretty important part of demonstrating the effects of a WDH.       KB

-- Edited by Brenda and Alan on Tuesday 19th of July 2022 06:42:43 AM


 



-- Edited by KJB on Tuesday 19th of July 2022 09:19:43 AM



-- Edited by KJB on Tuesday 19th of July 2022 09:38:47 AM

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This argument has been beaten to death on here.

WDH does not alter ball weight.

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Brenda and Alan wrote:

Yobarr I'll set this out as simply as I can so even you should be able to grasp the fact that you are wrong in your assumption on WDH effects

Firstly the chart was created at a caravan show in front of an audience to demonstrate the effects of a WDH

The chart shows that the car weighs 1690 Kg Wt therefore it has a mass of 1690 Kg.

It the shows a weight of 1920 Kg Wt with the caravan attached.

The last shows a weight of 1850 KG Wt after the WDH is tensioned.

The car can only contribute 1690 Kg Wt to the scales.

Now here is the simple arithmetic.

1910 - 1690 =220

1850 - 1690 =160

This clearly shows that the towball download has been reduced by 60 Kg Wt.

If you can't accept this fact so be it, go your own way in ignorance.

Alan


Alan the data used is in complete, remember to get your correct towball weight the caravan must be level and on a level surface. As soon as you get your TBW and if its in the correct range then forget it as it no longer matters.

See Chart

 weights1024_1.jpg

I made an error in the calculations chart 1 is actually ATM includes t

The shaded areas mean no longer revelent, whilst Montie and others are basically correct tow ball weight should not change when the WDH is engaged, but in some situations a small amount of weight can be transferred to the caravan axle group, which potentially exceed your GTM. On most occasions this is caused by an incorrect fitting and application of the WDH. Adjustment of the hitch head angle so the front of the caravan is ever so slightly lower than the rear can transfer that weight gain back to the tow vehicle.



-- Edited by Gundog on Tuesday 19th of July 2022 10:46:26 AM

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Gundog wrote:
Brenda and Alan wrote:

Yobarr I'll set this out as simply as I can so even you should be able to grasp the fact that you are wrong in your assumption on WDH effects

Firstly the chart was created at a caravan show in front of an audience to demonstrate the effects of a WDH

The chart shows that the car weighs 1690 Kg Wt therefore it has a mass of 1690 Kg.

It the shows a weight of 1920 Kg Wt with the caravan attached.

The last shows a weight of 1850 KG Wt after the WDH is tensioned.

The car can only contribute 1690 Kg Wt to the scales.

Now here is the simple arithmetic.

1910 - 1690 =220

1850 - 1690 =160

This clearly shows that the towball download has been reduced by 60 Kg Wt.

If you can't accept this fact so be it, go your own way in ignorance.

Alan


Alan the data used is in complete, remember to get your correct towball weight the caravan must be level and on a level surface. As soon as you get your TBW and if its in the correct range then forget it as it no longer matters.

See Chart

 weights1024_1.jpg

I made an error in the calculations chart 1 is actually ATM includes t

 

The shaded areas mean no longer revelent, whilst Montie and others are basically correct towball weight should not change when the WDH is engaged, but in some situations a small amount of weight can be transferred to the caravan axle group, which potentially exceed your GTM. On most occasions this is caused by an incorrect fitting and application of the WDH. Adjustment of the hitch head angle so the front of the caravan is ever so slightly lower than the rear can transfer that weight gain back to the tow vehicle


 Graham, it is pleasing to see that you are among those of us who understand that a WDH does NOT change towball weight, and that the weight transferred from your car's REAR AXLE to the van's axle group can cause your GTM rating or your axle group rating to to be exceeded. (Those 2 figures are not necessarily the same as I have explained before, in detail).                                                                                                                                                           However, while I have little doubt that you actually believe what I have highlighted in the final part of your text above, you are terribly mistaken. It doesn't matter how much you adjust the hitch head you will NEVER remove the transferred weight from the van's axle group. In fact, unless the van is fitted with a load-sharing suspension system, lowering the towball height will actually reduce towball weight. You no doubt will be interested to read my next post, where I will again address  Alan's total and absolute misunderstanding of how a WDH works, but it will take me quite a while to compose! Cheers

P.S As Montie suggests, this arguement has been "beaten to death" but occasionally someone initiates more "discussion" rather than read the simple and indesputable facts that are outlined in the topic "The effects of using a WDH" started on May 6, 2020 in the technical section of our forum.



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yobarr wrote:
Gundog wrote:

 

. In fact, unless the van is fitted with a load-sharing suspension system.

 

All my info pertains to load sharing axle groups.

 

How about answering this one.

 Chris, I will pose this question to you for your solution.

A vehicle manufacture requires the use of a weight distribution hitch when the towed weight exceeds 1800kgs.

When the caravan is lowered on to the towball, the rear suspension sinks and the front of the suspension rises. In this situation the vehicle is not safe drive.

Whats your solution ?

 



-- Edited by Gundog on Tuesday 19th of July 2022 12:20:27 PM

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Brenda and Alan wrote:

Yobarr I'll set this out as simply as I can so even you should be able to grasp the fact that you are wrong in your assumption on WDH effects

Firstly the chart was created at a caravan show in front of an audience to demonstrate the effects of a WDH

The chart shows that the car weighs 1690 Kg Wt therefore it has a mass of 1690 Kg.

It the shows a weight of 1920 Kg Wt with the caravan attached.

The last shows a weight of 1850 KG Wt after the WDH is tensioned.

The car can only contribute 1690 Kg Wt to the scales.

Now here is the simple arithmetic.

1910 - 1690 =220

1850 - 1690 =160

This clearly shows that the towball download has been reduced by 60 Kg Wt.

If you can't accept this fact so be it, go your own way in ignorance.

Alan


                 A WDH DOES NOT CHANGE TOWBALL WEIGHT.    NEVER HAS. NEVER WILL.

 Rather than AGAIN spend many hours explaining that a WDH does not EVER change towball weight could I ask interested members to instead use the "Search" facility to access a topic titled "The effects of using a WDH", which was started on MAY 6,2020, in the Technical section of our forum. After many pages of information and discussion I believed that finally the OP of that thread had come to understand that a WDH NEVER changes ball towball weight, but seems he has forgotten the facts that I provided then?  Most of his confusion centres around him not understanding that towball weight is vastly different from the weight applied to the rear axle when a van is connected to a car. The EXTRA weight applied to that axle is usually 45-50% more than the towball weight, dependent on wheelbase of car and TBO (towball overhang, or distance from rear axle to hitchpoint). This is why Alan's "calculations" are flawed. Let us have a look at HIS figures.                                                                        Without the WDH tensioned  weight on car wheels 1910kg plus weight on van wheels 1230kg gives total weight (We'll refer to it as GCM if you like) of 3140kg. With the WDH tensioned weight on car wheels 1850kg plus weight on van wheels of 1290kg gives GCM of 3140kg.  Perhaps unwittingly Alan has illustrated exactly what I have stated .. a WDH DOES NOT change towball weight. Ever. Alan's total misunderstanding of the workings of a WDH do not worry me in the least, but my fear is that "newbies", or indeed current members, may be mislead by by this misinformation, and make EXPENSIVE mistakes. Anybody who is interested to know the true facts about WDHs, and indeed anything to do with weights and dynamics would do well to access books by Collyn Rivers, a noted authority with over 60 years experience in this field.                                                                                                                                                  To assist members I have included a screen shot of part of a list of the most common towing myths, which clearly explains that a the use of a  WDH DOES NOT CHANGE TOWBALL WEIGHT. Also, for those who choose not to access the original thread from May 6, I have included a couple of screen shots from that thread, along with the chart that Alan refers to. Hopefully the information that I have supplied here should be enough to illustrate that a WDH NEVER changes towball weight. Period. Cheers..

 

 

 

F9512696-028F-454C-B848-C03F0E985923.png

 

 

3100A615-22A6-45EA-8DC9-F183AF37F2A8.png

 

 

                                              MYTHS

 

A4B52FB9-8950-4FC8-B3AF-72498A510C3D.jpeg

 

 

253893E6-3014-4ADA-BE4D-D7A5F68D46E3.png

 

 




 



-- Edited by yobarr on Tuesday 19th of July 2022 05:55:43 PM

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Gundog wrote:

Chris, I will pose this question to you for your solution.

A vehicle manufacture requires the use of a weight distribution hitch when the towed weight exceeds 1800kgs.

When the caravan is lowered on to the towball, the rear suspension sinks and the front of the suspension rises. In this situation the vehicle is not safe drive.

Whats your solution ?


 Hi Graham. Normally I would ignore such a question, but you seem to be a reasonable chap so I will reply. If the manufacturer advises that a WDH  should be used when towed weight exceeds 1800kg there is something drastically wrong. Unfortunately, tow ratings seem to be given using a vehicle's ability to tow a Dog trailer, where there is negligible towball weight, maybe 15kg, and are related mainly to braking ability and engine power. Do they really believe that a WDH would be needed with a Dog trailer?  Some vehicle manufacturers recommend the use of a WDH above a certain weight simply because they know that if the generally accepted 10%/towball weight was used then the car's lightweight rear axle would be overloaded. This is a nice easy inexpensive "out" that enables them to manage higher towing ratings without building a car. that is truly "fit for purpose". Then you get other manufacturers, who will remain anonymous on a public forum, who build cars that can allegedly tow 3000kg but towball weight must not exceed 180kg. Spare me! Thus towball weight is 6% of ATM which is sheer stupidity if a PIG trailer (caravan)  is the towed vehicle. And we wonder why there are so many caravan accidents. With your car you're stuck between a rock and a hard place because, realistically, the car is too small for your van and this is a perfect example of being told to use a WDH in an effort to make a car do things for which it never was designed. The apparent easy "fix" for your "sinking suspension" problem is to have heavier springs fitted at the rear, but you still are likely to have an overloaded rear axle if you apply 10% towball weight. Cheers

 



-- Edited by yobarr on Tuesday 19th of July 2022 03:04:47 PM

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montie wrote:

This argument has been beaten to death on here.

WDH does not alter ball weight.


 Thanks Montie. Most members seem to understand that a WDH does NOT alter towball weight, EVER, but there still are a couple who either learn very slowly, or who simply refuse to learn at all. C'est la vie. Cheers



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yobarr wrote:
Gundog wrote:

Chris, I will pose this question to you for your solution.

A vehicle manufacture requires the use of a weight distribution hitch when the towed weight exceeds 1800kgs.

When the caravan is lowered on to the towball, the rear suspension sinks and the front of the suspension rises. In this situation the vehicle is not safe drive.

Whats your solution ?


 Hi Graham. Normally I would ignore such a question, but you seem to be a reasonable chap so I will reply.

If the manufacturer advises that a WDH  should be used when towed weight exceeds 1800kg there is something drastically wrong.

Unfortunately, tow ratings are given using a vehicle's ability to tow a Dog trailer, where there is negligible towball weight, maybe 15kg, and are related mainly to braking ability and engine power. Do they really believe that a WDH would be needed with a Dog trailer?  

Some vehicle manufacturers recommend the use of a WDH above a certain weight simply because they know that if the generally accepted 10%/towball weight was used then the car's lightweight rear axle would be overloaded.

This is a nice easy inexpensive "out" that enables them to manage higher towing ratings without building a car. that is truly "fit for purpose".

Then you get other manufacturers, who will remain anonymous on a public forum, who build cars that can allegedly tow 3000kg but towball weight must not exceed 180kg.

Spare me! Thus towball weight is 6% of ATM which is sheer stupidity if a PIG trailer (caravan)  is the towed vehicle.

And we wonder why there are so many caravan accidents. With your car you're stuck between a rock and a hard place because, realistically, the car is too small for your van and this is a perfect example of being told to use a WDH in an effort to make a car do things for which it never was designed.

The apparent easy "fix" for your "sinking suspension" problem is to have heavier springs fitted at the rear, but you still are likely to have an overloaded rear axle if you apply 10% towball weight.

Cheers



-- Edited by yobarr on Tuesday 19th of July 2022 02:55:53 PM


 Sorry Chris that is a whole lot  of garbage based on personal opinion, I my lifetime I have never seen a dog trailer caravan being towed any popular tow vehicle, you may find one being towed behind a Grader grading rural dirt roads. A Dog Trailer would never need a WDH.

 



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Gundog wrote:
yobarr wrote:
Gundog wrote:

Chris, I will pose this question to you for your solution.

A vehicle manufacture requires the use of a weight distribution hitch when the towed weight exceeds 1800kgs.

When the caravan is lowered on to the towball, the rear suspension sinks and the front of the suspension rises. In this situation the vehicle is not safe drive.

Whats your solution ?


 Hi Graham. Normally I would ignore such a question, but you seem to be a reasonable chap so I will reply.

If the manufacturer advises that a WDH  should be used when towed weight exceeds 1800kg there is something drastically wrong.

Unfortunately, tow ratings are given using a vehicle's ability to tow a Dog trailer, where there is negligible towball weight, maybe 15kg, and are related mainly to braking ability and engine power. Do they really believe that a WDH would be needed with a Dog trailer?  

Some vehicle manufacturers recommend the use of a WDH above a certain weight simply because they know that if the generally accepted 10%/towball weight was used then the car's lightweight rear axle would be overloaded.

This is a nice easy inexpensive "out" that enables them to manage higher towing ratings without building a car. that is truly "fit for purpose".

Then you get other manufacturers, who will remain anonymous on a public forum, who build cars that can allegedly tow 3000kg but towball weight must not exceed 180kg.

Spare me! Thus towball weight is 6% of ATM which is sheer stupidity if a PIG trailer (caravan)  is the towed vehicle.

And we wonder why there are so many caravan accidents. With your car you're stuck between a rock and a hard place because, realistically, the car is too small for your van and this is a perfect example of being told to use a WDH in an effort to make a car do things for which it never was designed.

The apparent easy "fix" for your "sinking suspension" problem is to have heavier springs fitted at the rear, but you still are likely to have an overloaded rear axle if you apply 10% towball weight.

Cheers


 Sorry Chris that is a whole lot  of garbage based on personal opinion, I my lifetime I have never seen a dog trailer caravan being towed any popular tow vehicle, you may find one being towed behind a Grader grading rural dirt roads. A Dog Trailer would never need a WDH.


Graham, you have either intentionally or inadvertently misunderstood the reason for my mention of Dog trailers. This is the "out" that manufacturers can use when challenged about their product's towing abilities, and gets around the indesputable fact that a twin-cab ute with a GCM of 6000kg can NEVER safely tow a 3500kg van. NEVER. Please again read my post to you, and you MAY understand my intentions? Cheers 

P.S NONE of what I have written is "garbage" if the reader has any interpretational skills at all.

P.P.S For your benefit, these both are Dog trailers, and they are indeed caravans!

 

8F26AEB2-A5CA-4A8D-A75E-78FE3308748C.png

FA3CB6E7-E697-46FC-BC2F-E2322101B965.png



-- Edited by yobarr on Tuesday 19th of July 2022 04:13:14 PM

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Brenda and Alan wrote:

Yobarr I'll set this out as simply as I can so even you should be able to grasp the fact that you are wrong in your assumption on WDH effects

Firstly the chart was created at a caravan show in front of an audience to demonstrate the effects of a WDH

The chart shows that the car weighs 1690 Kg Wt therefore it has a mass of 1690 Kg.

It the shows a weight of 1920 Kg Wt with the caravan attached.

The last shows a weight of 1850 KG Wt after the WDH is tensioned.

The car can only contribute 1690 Kg Wt to the scales.

Now here is the simple arithmetic.

1910 - 1690 =220

1850 - 1690 =160

This clearly shows that the towball download has been reduced by 60 Kg Wt.

If you can't accept this fact so be it, go your own way in ignorance.

Alan


        Not again!  This was my initial response to the misinformation posted above! Since then, I have recovered sufficiently to AGAIN show that a   WDH  DOES NOT change towball weight. Never has. Never will. Cheers

 

61C46F4D-53B8-4A5E-838A-9489BEEC2A2B.png



-- Edited by yobarr on Tuesday 19th of July 2022 06:49:50 PM

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Yobarr, I have asked for an explanation but it seems all you can tell us is what a WDH does. But I have never seen an explanation from you on how it works. You may be surprised that I agree with most of what you say, particularly on what the WDH does and the weights it transfers. We disagree on the benefits, but that is not the issue here. 

So let me focus my question to you on just a small area. Your previously said (I retyped the words here) ....

"A WDH removes weight from the rear axle of the car, with around 70% of that weight being returned to the front axle of the car, whilst the other 30% is transferred to the van's axle group."

Yes. We are in agreement. That is what it does. Where we disagree is how that happens and to narrow it down further how the weight on the towball is affected. Have a look at this image.

Van and WDH.jpg

 

It shows the Hayman Reese bars pulling the drawbar down. In my previous example I said the tension was 80kg per bar, so will continue with that. As per your above words, 30% of the weight is transferred to the van axles. The other 70% of that weight has to go somewhere. There is nowhere else but the towball. The van is supported in only 2 places .... the wheels and the coupling onto the towball. So 70% of that additional weight must go onto the towball.

The fact that it then gets distributed elsewhere (to the wheels) is not the point. I agree it does. And I also agree that the towball weight once connected is not measured. In fact it would be difficult to measure it without some special weighing device. But to say a WDH does not increase the towball load is incorrect. The weight may not be relevant but it's there.

If you still think that is wrong, please explain how the 70% gets transferred from the drawbar.

 



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Are We Lost wrote:

Yobarr, I have asked for an explanation but it seems all you can tell us is what a WDH does. But I have never seen an explanation from you on how it works. You may be surprised that I agree with most of what you say, particularly on what the WDH does and the weights it transfers. We disagree on the benefits, but that is not the issue here. 

So let me focus my question to you on just a small area. Your previously said (I retyped the words here) ....

"A WDH removes weight from the rear axle of the car, with around 70% of that weight being returned to the front axle of the car, whilst the other 30% is transferred to the van's axle group."

Yes. We are in agreement. That is what it does. Where we disagree is how that happens and to narrow it down further how the weight on the towball is affected. Have a look at this image.

Van and WDH.jpg

 

It shows the Hayman Reese bars pulling the drawbar down. In my previous example I said the tension was 80kg per bar, so will continue with that. As per your above words, 30% of the weight is transferred to the van axles. The other 70% of that weight has to go somewhere. There is nowhere else but the towball. The van is supported in only 2 places .... the wheels and the coupling onto the towball. So 70% of that additional weight must go onto the towball.

The fact that it then gets distributed elsewhere (to the wheels) is not the point. I agree it does. And I also agree that the towball weight once connected is not measured. In fact it would be difficult to measure it without some special weighing device. But to say a WDH does not increase the towball load is incorrect. The weight may not be relevant but it's there.

If you still think that is wrong, please explain how the 70% gets transferred from the drawbar.


Hi Stephen. Thanks for this post. There have been many theories offered by many people, including you, on how a WDH functions, but unfortunately they all are wrong!  If you care to Google John Cadogan  "Weight distribution and load levelling hitches for heavy towing" you will find a 27 minute video that explains the process clearly and concisely, in a way that I can only dream of emulating. The most important parts of the video can be seen in the 13th-14th minutes, and between the 17th and 19th minute. When I did my experiment with a WDH  I transferred 100kg off the rear axle of my car, with 66kg being returned to the car's front axle and 34kg being transferred to the van's axle group. Nett effect was that 34kg was removed from weight on the car's wheels, while the weight on the van's wheels increased by 34kg. Towball weight and TOTAL weight (GCM?) stayed exactly the same. These results will vary from car to car, depending mainly on wheelbase and TBO (Towball overhang) but also on the forward length of the van. Sorry I can't be more help but I feel that what I have suggested will give you the answers you seek. Cheers



-- Edited by yobarr on Tuesday 19th of July 2022 09:07:11 PM

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I don't know of this will help

towball 1.jpg



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Plain Truth, I'm not sure if that was intended to support my view or Yobarr's. It did raise the point that I was making about being vitally important to understand how they work, and that how they work is different from what they do. That is all Yobarr has ever referred to.

I agree 100% that a WDH does not reduce towball weight. It can't because it can only apply extra load, never less than the coupling would otherwise apply.

Technically, it may (not would) by a very small amount due to the van front end being lifted, thus changing the centre of gravity. But that amount is small enough to be ignored. And, let's not get into load sharing suspension differences.

Yobarr, if you can't focus your answer onto that small part of the system I asked for your explanation on, I must assume you don't know.

How does that 70% extra weight get transferred from the drawbar to the car if it does get loaded onto the towball?


Edit: I see Yobarr posted the same time as me .... pointing to what I just agreed with. But apart from whover says it does or doesn't, the explanation is what I am seeking. Yobarr, you do see what I mean? The sentence above your big red circle.



-- Edited by Are We Lost on Tuesday 19th of July 2022 09:44:36 PM

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Very good advice here Alan. Thankyou for posting this. As can be seen I have taken a screen shot in order to highlight a couple of salient points. The damage that these things can do to car's  chassis, drawbar, towbar structure, springs and mountings is beyond the comprehension abilities of many, unfortunately. Better to get a more suitable car or a smaller van. Cheers

 

CCA42554-0442-49E7-8CB7-BC3D225C4A64.jpeg

 

 



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Are We Lost wrote:

Plain Truth, I'm not sure if that was intended to support my view or Yobarr's. It did raise the point that I was making about being vitally important to understand how they work, and that how they work is different from what they do. I agree 100% that a WDH does not reduce towball weight. It can't because it can only apply extra load, never less than the coupling would otherwise apply.

Technically, it may (not would) by a very small amount due to the van front end being lifted, thus changing the centre of gravity. But that amount is small enough to be ignored. Let's not get into load sharing suspension differences.

Yobarr, if you can't focus your answer onto that small part of the system I asked for your explanation on, I must assume you don't know.

How does that 70% extra weight get transferred from the drawbar to the car if it does get loaded onto the towball?


 Stephen, I have responded to your question with appropriate advice to enable you to obtain the information you so desperately, but needlessly, seek. There is little more that I can do as it would take literally hours to document everything that you might want to know, and I am not prepared to do that when it is all clearly explained, by an Engineer, in the video that I have suggested that you watch. Experience tells me that the more facts I provide the more people will want to argue about. Watching the video will answer all of your questions, I'm sure. Cheers



-- Edited by yobarr on Tuesday 19th of July 2022 09:46:28 PM

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Are We Lost wrote:

Plain Truth, I'm not sure if that was intended to support my view or Yobarr's. It did raise the point that I was making about being vitally important to understand how they work, and that how they work is different from what they do. That is all Yobarr has ever referred to.

I agree 100% that a WDH does not reduce towball weight. It can't because it can only apply extra load, never less than the coupling would otherwise apply.

Technically, it may (not would) by a very small amount due to the van front end being lifted, thus changing the centre of gravity. But that amount is small enough to be ignored. And, let's not get into load sharing suspension differences.

Yobarr, if you can't focus your answer onto that small part of the system I asked for your explanation on, I must assume you don't know.

How does that 70% extra weight get transferred from the drawbar to the car if it does get loaded onto the towball?


Edit: I see Yobarr posted the same time as me .... pointing to what I just agreed with. But apart from whover says it does or doesn't, the explanation is what I am seeking. Yobarr, you do see what I mean? The sentence above your big red circle.


 What "70% extra weight"  are you talking about? The weight DOES NOT get transferred from the drawbar but is transferred by a leverage effect from the car's rear axle to the car's front axle, with the other 30% of the transferred weight going on to the van's axle group. These percentages will vary from car to car, dependent mainly on wheelbase and TBO, but also partly on the van's forward length. When I was playing around on my car with a WDH there was 66% transferred to the front axle and 34% to the van's axle group, but my car has a sensible 3180mm wheelbase and short TBO. Cheers



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