WDH

yobarr · Guru

WDH

BarneyBDB · Senior Member

There are people on here who are on their way to an "incident", not an "accident", because of their mistaken belief of how things work.

If tow ball weight exceeds your limit there are only two ways to fix the problem, reduce the weight or get a tug / towbar with a higher limit.

One way of reducing tow ball load is to NOT fit a WDH, the one that came with my van probably weighs 40 kgs.

yobarr · Guru

BarneyBDB wrote:
There are people on here who are on their way to an "incident", not an "accident", because of their mistaken belief of how things work.

If tow ball weight exceeds your limit there are only two ways to fix the problem, reduce the weight or get a tug / towbar with a higher limit.

One way of reducing tow ball load is to NOT fit a WDH, the one that came with my van probably weighs 40kg.

Yes Brodie, I have covered this before, along with the increase in TBO which multiplies the weight of the WDH unit.

The vast majority of WDH users seem to have no understanding of how an incorrectly set-up WDH affects a cars handling, inducing oversteer which can be very dangerous in unskilled hands, and affecting a car's inbuilt understeer characteristics.

Not to mention the enormous stresses applied to both the chassis of the car, and that of the van.

A WDH creates what us effectively a stiff-arm from the front axle of the car, through the hitchpoint to the van's axle group.

Can you imagine the enormous stresses applied when the car drives through a drain or whatever, where ALL weight is carried on the car's front axle and the van's axle group?

Get a more suitable car, or a smaller van, rather than trying to make a car do things for which it never was designed. Cheers

P.S Did the WDH cause this, I wonder?

Brenda and Alan · Guru

yobarr wrote:

Although I don't doubt the sincerity of some contributors on this topic, these "Academics" are not necessarily "clear thinkers" in a practical sense.
Their understandings are often "clouded" by complex theories which are often irrelevant to the simple case in question.
No matter how clearly, concisely and frequently I explain the effects of using a WDH, as confirmed by the designers and manufacturers of these devices, always we seem to get contributions from no doubt well-meaning members, with their own convoluted theories.
Their thoughts don't bother me, as we all are entitled to an opinion, but I do despair for newbies, and indeed current members, who simply are trying to learn about the much over rated, and frequently misunderstood, WDH.
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Yobarr what a load of bollocks. You choose to ignore the truth of science and carry on in the mistaken belief you are right.
So tell me if the car get lighter what does the WDH change , the mass of the car or the force of gravity. You have still failed to give me an answer to this question.
You remind me of Donald Trump, never let the truth get in the way of your narrative.
Why do you think some car manufacturers stipulate the use of a WDH with their vehicles when towing. It is to reduce the loading on the rear of the vehicle. These companies employ far more engineers than H-R, are these engineers wrong too.
Alan

yobarr · Guru

Brenda and Alan wrote:
Why do you think some car manufacturers stipulate the use of a WDH with their vehicles when towing. It is to reduce the loading on the rear of the vehicle. These companies employ far more engineers than H-R, are these engineers wrong too.
Alan

Again, can I remind you that we have covered this previously?

Have you considered that the reason that some car manufacturers "stipulate the use of a WDH" is that they realise that the rear axle of their car is not up to the task of carrying 10% of ATM, which is the generally accepted towball weight? And that using a WDH is a "quick fix" to circumvent that deficiency.

By stipulating the use of a WDH to get weight OFF the car's REAR AXLE they then can justify their often pathetically low rear axle carrying capacity.

And they get away with this because motorists often have NO understanding of weights, as evidenced by the popularity of a Yank Tank that has a 4500kg tow capacity, but only a 1770kg rear axle capacity. LaLa Land stuff.

Please Alan, instead of boring me by asking the same questions over and over again, and getting the same civil responses, perhaps your time would be better spent communicating direct with HR and other WDH manufacturers, letting them know that after successfully designing and building WDH units for over 50 years, according to Alan, they still don't know what they're talking about?

I'm sure that Hayman Reece would be humbled, and most appreciative of "assistance" from Alan?

With great anticipation, we look forward to hearing of their response to your representations. Have a great day. Cheers

-- Edited by yobarr on Monday 16th of October 2023 11:40:38 PM

Brenda and Alan · Guru

Yobarr.

You are still evading the question as to what a WDH changes if the tow ball download is not changed . The force of gravity or the masses of tug and van. Simple question ,but still no response.

yobarr · Guru

Brenda and Alan wrote:
Yobarr.
You are still evading the question as to what a WDH changes if the tow ball download is not changed . The force of gravity or the masses of tug and van. Simple question ,but still no response.

Alan, again I will suggest that you contact HR direct, as it appears that your vast and superior knowledge could be of great assistance to them. How they've survived for 50 years without your claimed superior knowledge of weights and dynamics is puzzling..

You might also consider the first 7 lines of my post made at 7.41pm yesterday, and how they relate to your position. Cheers

watsea · Guru

The forces and reactions on the vehicle and van are altered by the tensioning of a WDH.

I am satisfied with the logic and physics about how they are altered by my reckoning with the example loading shown in my calculation in my earlier posts. Again, you can refer to those posts done 13th and 14th May 2023, by the following links:

https://thegreynomads.activeboard.com/t69403250/wdh-again/?sort=oldestFirst&page=3#comment-69434647

https://thegreynomads.activeboard.com/t69403250/wdh-again/?sort=oldestFirst&page=4#comment-69437698

I think that matters are related to the definition of Tow Ball Mass. A WDH cannot alter the Tow Ball Mass if the Tow Ball Mass is defined as the full mass of the trailer minus the mass of the trailer supported by its wheels in the unhitched state.

Brenda and Alan · Guru

Watsea Your calculations in fact show that tow ball download is indeed changed by a WDH. The term towball is a misnomer and I don't think it should be used. Again is is confusion between mass and force (weight).

Tow ball weight is in fact laden weight of van minus weight on wheels, whether a WDH is used on not.

Alan

-- Edited by Brenda and Alan on Tuesday 17th of October 2023 09:12:38 PM

Eaglemax · Guru

yobarr wrote:
Brenda and Alan wrote:
Yobarr.
You are still evading the question as to what a WDH changes if the tow ball download is not changed . The force of gravity or the masses of tug and van. Simple question ,but still no response.
Alan, again I will suggest that you contact HR direct, as it appears that your vast and superior knowledge could be of great assistance to them. How they've survived for 50 years without your claimed superior knowledge of weights and dynamics is puzzling..
You might also consider the first 7 lines of my post made at 7.41pm yesterday, and how they relate to your position. Cheers

Email response from Hayman Reece. Question: message: I'm enquiring about a WDH. Regardless of towcar/caravan, does your WDH increase/decrease tow ball download at all once hitched?

Anthony Suhr (Autopacific)

Oct 17, 2023, 2:23PM GMT+11

Hi Tony , thanks for your enquiry. The wdh spreads weight through the axles of the vehicle and van towed but the ball weight remains the same.

Regards.

AutoPacific Australia Pty Ltd
(Hayman Reese/Rola/Kaymar/Thetford)

Phone: 1800 812 017

AutoPacific Group

PO Box 4397

Dandenong South VIC 3164
Australia

-- Edited by Eaglemax on Tuesday 17th of October 2023 06:32:04 PM

yobarr · Guru

Brenda and Alan wrote:
Watsea Your calculations in fact show that tow ball download is indeed changed by a WDH. The term towball is a misnomer and I don't think it should be used. Again is is confusion between mass and force (weight).
Tow ball weight is in fact laden weight of van minus weight in (on?) wheels , whether a WDH is used on not.
Alan

Not when leverage applies a downward pressure to the van's drawbar. Over, and out. Cheers

yobarr · Guru

Eaglemax wrote:
yobarr wrote:
Brenda and Alan wrote:
Yobarr.
You are still evading the question as to what a WDH changes if the tow ball download is not changed . The force of gravity or the masses of tug and van. Simple question ,but still no response.
Alan, again I will suggest that you contact HR direct, as it appears that your vast and superior knowledge could be of great assistance to them. How they've survived for 50 years without your claimed superior knowledge of weights and dynamics is puzzling..
You might also consider the first 7 lines of my post made at 7.41pm yesterday, and how they relate to your position. Cheers
Email response from Hayman Reece. Question: message: I'm enquiring about a WDH. Regardless of towcar/caravan, does your WDH increase/decrease tow ball download at all once hitched?

Anthony Suhr (Autopacific)
Oct 17, 2023, 2:23PM GMT+11
Hi Tony , thanks for your enquiry. The wdh spreads weight through the axles of the vehicle and van towed but the ball weight remains the same.
Regards.
AutoPacific Australia Pty Ltd
(Hayman Reese/Rola/Kaymar/Thetford)
Phone: 1800 812 017
AutoPacific Group
PO Box 4397
Dandenong South VIC 3164
Australia

Thankyou Tony, for again getting the facts "Straight from the horse's mouth" as I had almost given up banging my head against the wall. "When will they ever learn".(Peter, Paul and Mary 1962)

Everybody is entitled to an opinion, and there is little doubt that the dissenters amongst us genuinely believe that their convoluted theories and erroneous calculations have merit, but my concern is that this erroneous "data" will negatively influence those who simply are trying to learn.

Perhaps now someone might like to show that the world is flat? Cheers

Brenda and Alan · Guru

For what its worth Yobarr I went through this exercise with H-R over the phone some two years ago and got the same response. No Idea what position he was n the company, but when pushed on points he got onto your track of the van gets heavier and the car gets lighter. At that point I laughed at him and told him that was physically impossible. He then back tracked and said the only way to ascertain towball weight was with the van unhitched. Again I disagreed And that was the end of a useless exchange.

Alan

-- Edited by Brenda and Alan on Tuesday 17th of October 2023 09:23:34 PM

yobarr · Guru

Brenda and Alan wrote:
For what its worth Yobarr I went through this exercise with H-R over the phone some two years ago and got the same response. No Idea what position he was n the company, but when pushed on points he got onto your track of the van gets heavier and the car gets lighter. At that point I laughed at him and told him that was physically impossible. He then back tracked and said the only way to ascertain towball weight was with the van unhitched. Again I disagreed And that was the end of a useless exchange.
Alan

Alan, unfortunately for you both the hypothetical example presented by Stephen, and my own tests at a weighbridge, show that when a WDH is tensioned the weight on the wheels of the car decreases while the weight on the wheels of the van increases.

Nothing else changes. Simple, indusputable inconvenient truth. Cheers

P.S If you still can't understand this could I suggest that you make a real name for yourself by convincing HR, one of the world's biggest WDH designers and manufacturers, that their assertions are false? Cheers

Eaglemax · Guru

There's tension on the wdh chains, therefore downforce on the caravan wheels. That total van downforce (x)would I presume produce downforce on the front wheels (Y) + up force on rear of vehicle (Z). X=Y+Z. If towball weight changed that formula would be incorrect. I've run out of popcorn Tony

Brenda and Alan · Guru

My problem with both Yobarr and H-R is that they believe that the weight contribution of the car to the scales is reduced. And for the van the reverse is true. This is just nonsense.

Newtons laws have stood firm for over 300 years. His law of universal gravitation have been used since the sixties for successful space flights to many planets. This law proves that the weight contribution of both car and van to scales are fixed by their mass and gravity. Their mass does not change, the force of gravity does not change, there fore their weight does not change.

Have H-R put a man on the moon. No.

Alan

yobarr · Guru

Brenda and Alan wrote:
My problem with both Yobarr and H-R is that they believe that the weight contribution of the car to the scales is reduced. And for the van the reverse is true. This is just nonsense.
Newtons laws have stood firm for over 300 years. His law of universal gravitation have been used since the sixties for successful space flights to many planets. This law proves that the weight contribution of both car and van to scales are fixed by their mass and gravity. Their mass does not change, the force of gravity does not change, there fore their weight does not change.
Have H-R put a man on the moon. No.
Alan

Sorry Alan, but this is becoming monotonous. You're now telling HR they're wrong, and that you "laughed" at them.

Again I will suggest that instead of waffling on with your convoluted theories you would be far better to visit your local weighbridge and carry out the weighing procedure that I've outlined many times.

Simple way of showing yourself that you're wrong.

Previously I have posted all figures from my own weighing process in support of my stance on this simple issue.

You no doubt understand that a tensioned WDH can indeed lift a car's rear wheels completely off the ground?

Consider a car and van with 1350kg on its front axle, 2300kg on its rear axle, and 3150kg on the van's axle group. (My own car)

Now wind your WDH waaaaay up until the car's rear axle is off the ground.

According to your convoluted theories, weight on the car's wheels doesn't change, so the front axle now would be carrying 3650kg, while the van's axle group would stay at 3150kg, because that doesn't change either, according to you.

Yeah, right! LaLa Land stuff.

Sincerely, I hope that this helps you. Cheers

-- Edited by yobarr on Wednesday 18th of October 2023 11:31:49 AM

Are We Lost · Guru

Just like Brenda and Alan I tried to get an answer from HR on the specifics and they won't be drawn into it.

The closest I got was that a WDH does not entitle you to attach a van that would otherwise overload the rating. That I entirely agree with. My belief the reason they have it in their marketing material and would not be drawn to discuss it is that some people would use it as a justification to attach something that would exceed the ratings.

In fact the component of the van's weight on the towball does not change but the weight transferred from the car onto the towball does change. Eaglemax points to the three components that make up the weight on the towball. That is the right way to look at it but with a little modification. The downforce on the van wheels is a separate function from the downforce on the car wheels.

Eaglemax wrote:
There's tension on the wdh chains, therefore downforce on the caravan wheels. That total van downforce (x)would I presume produce downforce on the front wheels (Y) + up force on rear of vehicle (Z). X=Y+Z. If towball weight changed that formula would be incorrect. I've run out of popcorn Tony

The lifting of the bars is a second class lever (like a wheelbarrow with the front wheel being the fulcrum).

Class 2.jpg

So, relating that the terns used in the diagram ...

"Effort motion" of a 100kg lift at the handles (equivalent to the chains on the end of the bars) may enable you to lift 200kg "Load motion" in the wheelbarrow (the back wheels of the car). That 100kg is added to the wheelbarrow wheel "Fulcrum" (equivalent to the front wheels of the car).

The weight lifted off the back of the wheelbarrow body (equivalent to the towball) will be more than the 100kg you are lifting .... maybe 150kg. So the back end of the car rises. You can measure the changing weight on the wheels, but there is no way to measure the change at the towball ..... only calculate it.

The chains are then attached to the drawbar of the van, part way along. The van is essentially a rigid beam supported at one end by the wheels and at the other by the towball. So when that 150kg from the chains is attached part way along, some is distributed as extra weight on the wheels (say 30kg), but most onto the towball (say 120kg). So the rear of the car sags, but not as low as it was without the WDH. On the van, there are now two components of the weight on the van wheels. The weight from the van itself, plus 30kg transferred from the tow vehicle.

At the towball, the net difference between uplift of 150kg and download of 120kg is 30kg uplift. So the component of the van's weight on the towball does not change, but the net weight on the towball does.

If you have one of these systems you can prove this is the way it works at home. Lift a bar and measure how much it raises the rear. Attach that bar to the chain on the drawbar and measure again. The car rear end will sag but not back to where it was.

Again, I say what is the point of arguing about this issue on the internal workings of the WDH? I was going to stay out of it but thought more was needed after the posting of HR's comment. Nobody on here has disagreed on the resulting weights on wheels, and that is what matters.

-- Edited by Are We Lost on Wednesday 18th of October 2023 03:17:01 PM

Brenda and Alan · Guru

yobarr wrote:

Sorry Alan, but this is becoming monotonous. You're now telling HR they're wrong, and that you "laughed" at them.
Again I will suggest that instead of waffling on with your convoluted theories you would be far better to visit your local weighbridge and carry out the weighing procedure that I've outlined many times.
Simple way of showing yourself that you're wrong.
Previously I have posted all figures from my own weighing process in support of my stance on this simple issue.
You no doubt understand that a tensioned WDH can indeed lift a car's rear wheels completely off the ground?
Consider a car and van with 1350kg on its front axle, 2300kg on its rear axle, and 3150kg on the van's axle group. (My own car)
Now wind your WDH waaaaay up until the car's rear axle is off the ground.
According to your convoluted theories, weight on the car's wheels doesn't change, so the front axle now would be carrying 3650kg, while the van's axle group would stay at 3150kg, because that doesn't change either, according to you.
Yeah, right! LaLa Land stuff.
Sincerely, I hope that this helps you. Cheers
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Yobarr Where did you get this idea that I said any where that the weight on the cars wheel don't change. I have never claimed this. What I am trying to get through your head is that the cars contribution to the weight on the scales is fixed no matter what is loaded on the towball. And once again simple subtraction ( hitched weight minus unhitched weight) gives the towball loading
The la la land stuff is yours and H-Rs claim that the car gets lighter (impossible) and the caravan gets heavier (equally impossible) Both of you need this claim to justify your stance but it is demonstrably wrong.
Your weighing procedure will not prove me wrong because I don't hold that the car and vans weight is variable as you do to fit your erroneous theory.
Alan

-- Edited by Brenda and Alan on Thursday 19th of October 2023 09:32:03 AM

Gundog · Guru

Weighing a caravan to establish towball weight, its generally accepted that the caravan should be level and that reading is say 250kg.

What happens to the level towball weight when at the van is raised or lowered at the coupling ?

When at 50mm lower does the TBW increase, and if it is 50mm higher does it decrease, lets say if it's higher or lower the variation is 30kg, what is the net effect ?

watsea · Guru

Gundog wrote:
Weighing a caravan to establish towball weight, its generally accepted that the caravan should be level and that reading is say 250kg.
What happens to the level towball weight when at the van is raised or lowered at the coupling ?
When at 50mm lower does the TBW increase, and if it is 50mm higher does it decrease, lets say if it's higher or lower the variation is 30kg, what is the net effect ?

For a caravan, the actual Centre of Mass is higher than the plane that contain its chassis.

So when the tow ball is lowered and the front of the chassis tilts forward front the horizontal, the Centre of Mass also tips forward of its original position. Because the Centre of Mass is further forward, so the load or the mass supported by the tow ball is increased and the load on the axles decreases.

Similarly, if the tow ball is raised so the front is raised and the rear is tilted backwards, the Centre of Mass moves backwards to behind the original position. Thus the Centre of Mass is now nearer to the axles which increases the loads to those axles and the load on the tow ball decreases.

Of course the mass of the caravan remains constant.

Are We Lost · Guru

I think the correct answer is "it depends".

Normally raising the coupling would decrease the towball weight as Watsea said, because the centre of gravity would be shifted towards the rear, and vice versa. To calculate that would require to know some accurate measurements.

But dual axles and particularly non load sharing suspension changes things. When raising the coupling, the front axle would take less load, and the rear more, which would put more load on the towball. How to determine that net effect is in the too hard basket for me.

I believe for the amount of raising/lowering you suggest, the difference would be small, and less than that 30kg.

-- Edited by Are We Lost on Thursday 19th of October 2023 11:34:23 AM

Gundog · Guru

Generally when the coupling is lowered onto the towball, if the rear of the tow vehicle and the front of the caravan depress, in effect the actual TBW has increased all be it marginal, so when the WDH is engaged the ball weight should return to it theoretical weight if the combination level.

All of that means SFA, all that matters is GVM, GCM and ATM are within the limits.

Proponents and opponents of the subject are both right and wrong, without a load cell under the towball, you cannot prove your position.

But to say the TBW never changes is total BS because when climbing or decending a road like Cunninghams Gap or Macquirie Pass your weight moves because of the attitude of the combination, or what about when you travelling along a good old western Qld road you combination is pitching and rolling because of the wavy rd your COG is constantly moving.

Does it matter NAH its not even worth worrying about.

Brenda and Alan · Guru

Gundog I think you have missed the point of this discussion entirely. We are not concerned with tiny changes and tiny changes in weights.

Are We Lost · Guru

After Gudogs comment, which I thought was interesting I doodled with some figures. I believe it is not tiny, but would be less than 10kg difference. I am happy to provide workings if needed.

However, Gundog, towball weight should be measured with the van level, and the van should also be level when connected and ready for travel. So it would not be correct to think of it sinking when connected or raised when the WDH is tensioned. When ready for travel it is at the same height as when weighed standalone.

Eaglemax · Guru

So the question of towball weight change if under 10kg is miniscule in the overall picture. If any professional organisation states that "there is no change to towball weight" what they could be saying is there is no measurable change or significant change thats relevant.

If thats the case everyone that has posted on this topic 3 pages now is vindicated due to being such little weight change (and would depend on the rig) from zero change to up to 10kg.

If this is the case this thread is a giant leap forward on the topic of towball weight change with a WDH.

Tony

Are We Lost · Guru

Eaglemax, that part of the discussion raised by Gundog has no bearing on how a WDH changes things. Raising or lowering the coupling has the same result of moving the centre of gravity whether WDH is fitted or not.

But Gundog's comment about complying with ratings being more important is right.

-- Edited by Are We Lost on Friday 20th of October 2023 09:05:19 AM

Gundog · Guru

From memory one diagram in a similar thread, when a WDH was engaged 30kg went back to the caravan axle group as well as distributing weight from the rear to the front axles.

At the inital weighing of the unhitched caravan had an TBW= X GTM= Y, therefore X+Y= ATM. Now the Van and tow vehicle are connected this has 2 parts to it.

If at connection the combination remains reasonably level then TBW becomes part of the GCM.

If at connection the front van and rear of the tow vehicle drops 50mm, in theory that 30kg came off the axle group to the TBW and rear axle, however when the WDH is engaged and returns the combination to level then that 30kg is returned back to the van axle group.

Because this is all based on theory, unless you want to spend a lot of time at weighbridge, measuring and weighing it still will be guestimate becauce of the inherent inaccuracy depending on weighing devices +/- variation.

But at the end of the day if your within your specs, I would suggest that no scalie would ping you for a 30kg over in you GTM if your GCM was under.

Are We Lost · Guru

Gundog wrote:
If at connection the front van and rear of the tow vehicle drops 50mm, in theory that 30kg came off the axle group to the TBW and rear axle, however when the WDH is engaged and returns the combination to level then that 30kg is returned back to the van axle group.

Not quite. First, that 50mm difference in coupling height results in less than 10kg change in weight at the coupling according to my calculations. But that is not the point.

When you check the weight while on the jockey wheel the van should be level. When you then go to connect, you need to raise the coupling but only temporarily. At that moment, the towball weight will be a little lower. When you lower the coupling onto the towball (and optionally tension the WDH) the van should be level again. As there is no change in coupling height, there is no change in centre of gravity. So the additional 30kg on the van wheels is unrelated to coupling height.

Gundog · Guru

Are We Lost wrote:
Gundog wrote:
If at connection the front van and rear of the tow vehicle drops 50mm, in theory that 30kg came off the axle group to the TBW and rear axle, however when the WDH is engaged and returns the combination to level then that 30kg is returned back to the van axle group.
Not quite. First, that 50mm difference in coupling height results in less than 10kg change in weight at the coupling according to my calculations. But that is not the point.
When you check the weight while on the jockey wheel the van should be level. When you then go to connect, you need to raise the coupling but only temporarily. At that moment, the towball weight will be a little lower. When you lower the coupling onto the towball (and optionally tension the WDH) the van should be level again. As there is no change in coupling height, there is no change in centre of gravity. So the additional 30kg on the van wheels is unrelated to coupling height.

Remember the 30kg is an example number only, my caravan when hitched to the tug, the coupling height changes from 16 inches to 14 inches and when the WDH is engaged it returns to level.

Just for a little bit of additional information, the distance from the center of my axle group to the center of the coupling on my van is 17 ft.