WDH again

KJB · Guru

RE: WDH again

BarneyBDB · Senior Member

That is the simplest definition of weight, it ignores any other forces acting on the mass, ever heard of vectors?

Sorry, I was replying to the previous post.

-- Edited by BarneyBDB on Tuesday 9th of May 2023 11:16:31 AM

Gundog · Guru

So yobarr please explain this one 70 series Troopy towing a large single axle pop top, the caravan is level however the Troopy has the front high.

watsea · Guru

Many seem to be forget the torque moment applied to the system by the tensioning of the WDH arms or chains of an Andersen WDH. Reactant forces are generated in the vehicle and the trailer to resist the applied torque.

KJB · Guru

watsea wrote:
Many seem to be forget the torque moment applied to the system by the tensioning of the WDH arms or chains of an Andersen WDH. Reactant forces are generated in the vehicle and the trailer to resist the applied torque.

An often overlooked "side effect" ... that can cause major structural damage to the Tow vehicle or Caravan.

watsea · Guru

KJB wrote:
watsea wrote:
Many seem to be forget the torque moment applied to the system by the tensioning of the WDH arms or chains of an Andersen WDH. Reactant forces are generated in the vehicle and the trailer to resist the applied torque.

An often overlooked "side effect" ... that can cause major structural damage to the Tow vehicle or Caravan.

Yes, but the applied torque imposes the forces which cause the change in the axle loads of the axles of the vehicle and the trailer ie distributes the vertical loads differently to the vehicle axles and caravan axles.

So far my vehicles and caravans have been able to bear the forces generated by the WDHs which I have used. I am happy to continue using my WDH on apppropriate road surfaces and driveway surfaces.

Brenda and Alan · Guru

KJB wrote:

In simple terms ....some of the weight on the rear axle of the Tow vehicle is transferred to the Tow vehicles front axle and some is transferred to the Caravans axle group. That is what a WEIGHT DISTRIBUTION (notice the wording) Hitch is all about .

But You still ignore the fact that the weight of the van if permanently fixed by its Mass and cannot change, so if the weight on axles increases the draw bar weight must decrease to maintain the status quo.

Alan

watsea · Guru

Brenda and Alan wrote:
KJB wrote:

In simple terms ....some of the weight on the rear axle of the Tow vehicle is transferred to the Tow vehicles front axle and some is transferred to the Caravans axle group. That is what a WEIGHT DISTRIBUTION (notice the wording) Hitch is all about .
But You still ignore the fact that the weight of the van if permanently fixed by its Mass and cannot change, so if the weight on axles increases the draw bar weight must decrease to maintain the status quo.
Alan

As per my earlier post, you forgot the applied torque has been applied with the WDH tensioning. The orginal towball weight (ie before the WDH tensioning) at the point of contact at the tow ball is still active. By the way, I am not going to do a force and torque moment diagram and calculation to show why.

Maybe some explanation:

. Perhaps imagine the vehcle and van disconnected and apply the torque at the towball on the van's A frame and also apply a torque to the hitch arrangement of the vehicle.

. Applied torque at the hitch is generated by the tensioning causing a higher downwards vertical load on the trailer axles, by pushing on the caravan A frame.

. The applied torque to the vehicle's hitch causes a higher downwards load on the vehicle's front axle and a lower downwards load on the vehicle's rear axle.

-- Edited by watsea on Tuesday 9th of May 2023 02:57:34 PM

-- Edited by watsea on Tuesday 9th of May 2023 03:17:56 PM

-- Edited by watsea on Tuesday 9th of May 2023 03:18:40 PM

BarneyBDB · Senior Member

Brenda and Alan wrote:
KJB wrote:

In simple terms ....some of the weight on the rear axle of the Tow vehicle is transferred to the Tow vehicles front axle and some is transferred to the Caravans axle group. That is what a WEIGHT DISTRIBUTION (notice the wording) Hitch is all about .
But You still ignore the fact that the weight of the van if permanently fixed by its Mass and cannot change, so if the weight on axles increases the draw bar weight must decrease to maintain the status quo.
Alan

Weight is not fixed, mass is. Weight is a function of mass and the sum of the forces acting on that mass, one of which is gravity.

Gundog · Guru

All talk about ball weight and where it is when a WDH is engaged is all theory.

Why well we establish the actual ball weight when its measured with the caravan level unattached what happens when the caravan not level generally if the back is higher than the front ball weight should be greater, or we can use a weighbridge and do the math but to be accurate the caravan must be level.

We keep being told that ball weight never changes, how can you prove that without a load cell incorparated in the tow ball.

Driving up or down a hill or driving over undulating road does that force change weight in different directions effecting the handling of the vehicles.

The only reasonable way to measure weight is in stationary.

When weight is distributed from the rear axle to the front axle and to the caravan axle group, where does it come from ??????????

Are We Lost · Guru

Edit: I wrote this while Gundog was writing his, so not directed at you Gundog. Your question has inspired much heated discussion in the past, most specifically what happens at the towball. I have my views but will leave them for now. Back to what I wrote ....

I'm all for getting the right terms and agree that a van's mass never changes, but when the discussion diverges into technicalities it detracts from the subject.

Can I suggest it would be better to focus on the issue rather than the correct definition. Whether it's mass, weight, vectors, tension, pressure, force or load (any more?), the result when using a WDH the effect and how much is redistributed is measured and reported as weight and many of us do not use the correct terms.

A few posts back, Yobarr was questioning my statement that only a small percentage is redistributed to the van wheels.

The amount redistributed can be easily calculated. I invite Yobarr to produce those calculations for his rig (not what weights he measured because we can't verify that). Linear measurements and calculations can be verified. I know that isn't going to happen but maybe once Yobarr will respond with facts.

-- Edited by Are We Lost on Tuesday 9th of May 2023 04:58:00 PM

KJB · Guru

Gundog wrote:
All talk about ball weight and where it is when a WDH is engaged is all theory.
Why well we establish the actual ball weight when its measured with the caravan level unattached what happens when the caravan not level generally if the back is higher than the front ball weight should be greater, or we can use a weighbridge and do the math but to be accurate the caravan must be level.
We keep being told that ball weight never changes, how can you prove that without a load cell incorparated in the tow ball.
Driving up or down a hill or driving over undulating road does that force change weight in different directions effecting the handling of the vehicles.
The only reasonable way to measure weight is in stationary.
When weight is distributed from the rear axle to the front axle and to the caravan axle group, where does it come from ??????????

You just answered your own question........off the rear axle - that is what a Weight Distribution Hitch does.....

yobarr · Guru

Gundog wrote:
So yobarr please explain this one 70 series Troopy towing a large single axle pop top, the caravan is level however the Troopy has the front high.

Hi Graham. When Alan was conspicuous by his absence I assumed that he'd finally seen the light.Seems that I was wrong as he still talks rubbish.

However, I am doing big hours on the Roadtrain so can't devote enough time to do justice to the replies I'd like to make. Unlike some, I tend to think about what I write, and how to make my posts as easy as possible to understand.

However, your query is so easy to answer that it's absurd. Obviously the rear of the Troopie has lots of "stuff" in it, and it may have escaped your attention that a single axle van can have a HUGE towball weight and still be level. Depends on what height the drawbar was before the van was connected to the car.

Can't be bothered providing further help at the moment, but your fixation on having a level van is of concern. Take care. Cheers

yobarr · Guru

KJB wrote:
Gundog wrote:
All talk about ball weight and where it is when a WDH is engaged is all theory.
Why well we establish the actual ball weight when its measured with the caravan level unattached what happens when the caravan not level generally if the back is higher than the front ball weight should be greater, or we can use a weighbridge and do the math but to be accurate the caravan must be level.
We keep being told that ball weight never changes, how can you prove that without a load cell incorparated in the tow ball.
Driving up or down a hill or driving over undulating road does that force change weight in different directions effecting the handling of the vehicles.
The only reasonable way to measure weight is in stationary.
When weight is distributed from the rear axle to the front axle and to the caravan axle group, where does it come from ??????????
You just answered your own question........off the rear axle - that is what a Weight Distribution Hitch does.....

Nice one Kerry! Someone answers his own question and then asks others for the answer. Weird.

Reminds me of "What's your name Bob". Cheers

Brenda and Alan · Guru

yobarr wrote:

Hi Graham. When Alan was conspicuous by his absence I assumed that he'd finally seen the light.Seems that I was wrong as he still talks rubbish.
However, I am doing big hours on the Roadtrain so can't devote enough time to do justice to the replies I'd like to make. Unlike some, I tend to think about what I write, and how to make my posts as easy as possible to understand.

yobarr. There is no thinking involved in parroting what you find on the internet.

You never ever get around to addressing the issues I raise you just obfuscate, bully and side track to avoid showing you can't counter them.

Lets start with your claim that a caravans weight increases when a WDH is tensioned. If so then the weight of the tug must decrease. However any tug sitting on a weighing platform will impose a weight to that platform equivalent to its mass regardless of any other forces acting on it ( tow ball weight)

Explain then how you think mass is transferred from tug to caravan in the process

-- Edited by Brenda and Alan on Wednesday 10th of May 2023 07:53:07 AM

yobarr · Guru

Brenda and Alan wrote:
yobarr wrote:

Hi Graham. When Alan was conspicuous by his absence I assumed that he'd finally seen the light.Seems that I was wrong as he still talks rubbish.
However, I am doing big hours on the Roadtrain so can't devote enough time to do justice to the replies I'd like to make. Unlike some, I tend to think about what I write, and how to make my posts as easy as possible to understand.

yobarr. There is no thinking involved in parroting what you find on the internet.
You never ever get around to addressing the issues I raise you just obfuscate, bully and side track to avoid showing you can't counter them.
Lets start with your claim that a caravans weight increases when a WDH is tensioned. If so then the weight of the tug must decrease. However any tug sitting on a weighing platform will impose a weight to that platform equivalent to its mass regardless of any other forces acting on it ( tow ball weight)
Explain then how you think mass is transferred from tug to caravan in the process

Alan, this is becoming tedious as, at least twice, I have given detailed asvice on the weighbridge procedure required to show that a van's weight increases and a car's weight decreases when a WDH is tensioned. For those who appear slow to learn, or gave poor memories I will again post this advice, but as I said in a post above I'm working long hours and I presently don't have time to devote to this thread.

However, in case you don't yet know, a WDH DOES NOT CHANGE TOWBALL WEIGHT.

If you disagree you might like to contact Hayman Reese to let them know that the advice on their website is incorrect. Previously I have posted screen shots of that advice. Do you remember? I doubt it. Cheers

Gundog · Guru

"When weight is distributed from the rear axle to the front axle and to the caravan axle group, where does it come from ??????????"

This was a rhetorical question

Because if you bothered to read the entire post unless you have a load cell incorporated into the ball there is no way you can prove the ball weight doesn't change.

Gundog · Guru

I aquired this from another website it graphical display of correct ball height.

Ball Height.jpg

yobarr · Guru

Gundog wrote:
"When weight is distributed from the rear axle to the front axle and to the caravan axle group, where does it come from ??????????"
This was a rhetorical question
Because if you bothered to read the entire post unless you have a load cell incorporated into the ball there is no way you can prove the ball weight doesn't change.

Gee Graham, you wouldn't happen to know a chap named Alan, would you? Easy to show ball weight doesn't change, but scales far more accurate than a weighbridge are needed.

First do all your individual axle weights and total them, which will give you your total weight. (GCM)

Now tension your beloved WDH and again take your individual axle weights and total them.

The total weight imposed on ground will be exactly the same as it was before WDH was tensioned.

The total will be the same, but front axle of car will have gained weight, rear axle of car will have lost weight, and axle group of van will have gained weight. Total weight will be the same as pre-WDH, and the transferred weight gained by the 2 axles that gained weight will be exactly the same as the weight removed from the car's rear axle. Towball weigh does NOT change.

There are many variables, but the more important are wheelbase of car, towball overhang of car and forward length of caravan.

All these will affect what percentage of the weight transferred (distributed) from the car's rear axle is applied to the car's front axle and what percentage of the transferred weight is applied to the van's axle group.

From memory, by really winding up my WDH as a test, I transferred 180kg from my car's rear axle, with 120kg (+/-) going to the car's front axle and 60kg(+/-) going to the van's axle group.

At that point I decided that 120kg was a joke, as without the WDH I still had 1350kg on my car's front axle.

How much front axle weight is enough?

As I have said many times, a WDH is used or recommended only by those parties who are trying to make a car do things for which it was not designed, and by those with a vested interest. Limited rear axle carrying capacity is a major concern with many cars when a heavy PIG trailer is to be towed.

Get a bigger car or a smaller van. Possibly I have told of running at 6800kg GCM, legal on every axle and no WDH. Cheers

P.S Could I suggest that before anymore hare-brained theories are presented by no doubt well-intentioned members, that those members who disagree with my representations carry out their own actual tests, as I have done.

But you MUST use scales other than a weighbridge, which has waaaay too big increments to be of much use. Good luck!

-- Edited by yobarr on Wednesday 10th of May 2023 03:53:32 PM

Gundog · Guru

Just for your Information which shoots down some of you theories, from the Toyota Basic Towing Guide.

Yes Toyota supports the use of LDH aka WDH and I think it mentions level, trailer heavier than the vehicle is ok.

Trailer Loading

Always ensure heavy items are placed over the trailer axles and as low down as possible, whilst maintaining a tow ball download of between 9 - 11%.

Ensure that the trailer coupling is the same height as the vehicle coupling point. In the first instance, always distribute vehicle and trailer loads accordingly to achieve a relatively flat vehicle and trailer posture without the assistance of load levelling or load distribution devices.

Load Distribution Hitches (LDH)

LDHs should only be used on highway style roads as a dynamic supplementary support to a correctly loaded vehicle / trailer combination.

Genuine tow bar tow ball position must be maintained.

Do not use with a high articulation coupling if driving off-road.

Do not use on vehicles with auto height adjusting suspensions.

Trailer override brakes are not recommended with the use of LDHs.

LDHs should never be used to compensate for incorrectly loaded vehicle & trailer combinations

Sway Control Device

If the total trailer weight is greater than the vehicle weight, use a sway control device.

Bobdown · Guru

Can't see any WDH in those pics Yobarr, maybe the first pic needs one. Not sure there is enough room on the second one.

yobarr · Guru

Bobdown wrote:

Can't see any WDH in those pics Yobarr, maybe the first pic needs one. Not sure there is enough room on the second one.

Well observed Bob! The reason for the first picture was to illustrate that this van is too big for the car, as evidenced by the difference in clearance above the rear wheels and the front wheels.

The second picture was just to show an interesting towbar system, with a stupidly long shank and an illegal "safety" chain set up. Is that a tie-down strap supporting the stupidly long chains? At least they're crossed, I guess! Cheers

Brenda and Alan · Guru

yobarr wrote:

Alan, this is becoming tedious as, at least twice, I have given detailed asvice on the weighbridge procedure required to show that a van's weight increases and a car's weight decreases when a WDH is tensioned. For those who appear slow to learn, or gave poor memories I will again post this advice, but as I said in a post above I'm working long hours and I presently don't have time to devote to this thread.
However, in case you don't yet know, a WDH DOES NOT CHANGE TOWBALL WEIGHT.

Yobarr
Again your usual obfuscation and failure to address the issue. Just answer my question.
If the weight of the tow vehicle becomes less what changes, its mass or the force of gravity

As for quoting hayman reece again, who shall I believe. Hayman or Issacc Newton. Hmm. Have HRs' theories put a man on the moon. NO

I think I will stick by the tried and proven Newton.

Something else for you to ponder. It is the towbar download on the tug which results in the rear axle increasing in weight and the front lighter.

If the towbar load remains the same then there would be NO redistribution and they would be a waste of time and money.

Alan

KJB · Guru

Brenda and Alan wrote:
yobarr wrote:

Alan, this is becoming tedious as, at least twice, I have given detailed asvice on the weighbridge procedure required to show that a van's weight increases and a car's weight decreases when a WDH is tensioned. For those who appear slow to learn, or gave poor memories I will again post this advice, but as I said in a post above I'm working long hours and I presently don't have time to devote to this thread.
However, in case you don't yet know, a WDH DOES NOT CHANGE TOWBALL WEIGHT.

Yobarr
Again your usual obfuscation and failure to address the issue. Just answer my question.
If the weight of the tow vehicle becomes less what changes, its mass or the force of gravity
As for quoting hayman reece again, who shall I believe. Hayman or Issacc Newton. Hmm. Have HRs' theories put a man on the moon. NO
I think I will stick by the tried and proven Newton.

I am sure that the "theories" used by Hayman (and many other manufacturers ) in the performance of their WDH products align with the applicable theories of Newton. Leave the moon out of it.......scales probably need to be recalibrated up there.....!

Something else for you to ponder. It is the towbar download on the tug which results in the rear axle increasing in weight and the front lighter.
If the towbar load remains the same then there would be NO redistribution and they would be a waste of time and money.
Alan

Brenda and Alan · Guru

KJB
The moons gravity is one sixth of earth so things on the moon weigh one sixth of what they do on earth, no recalibration of scales is required.
If as Yobarr says HR claim the tug becomes lighter and the van heavier they are most definitely at loggerheads with Newtons accepted laws of motion. Namely the second law.
Force = Mass x 9.8 m/s2
rewritten
weight=mass x 9.8m/s2

Alan

Gundog · Guru

For example the towball weight is 250kg when the caravan is level, assuming the caravan is loaded correctly.

What effect to the towball weight would be if the caravan was 50mm lower at the coupling.

What effect to the towball weight would be if the caravan was 50mm higher at the coupling.

yobarr · Guru

Gundog wrote:
For example the towball weight is 250kg when the caravan is level, assuming the caravan is loaded correctly.

What effect to the towball weight would be if the caravan was 50mm lower at the coupling.

What effect to the towball weight would be if the caravan was 50mm higher at the coupling.

Unless the van had non-load sharing suspension the effect would be hardly enough to be bothered with.

You appear to be clutching at straws. Cheers

yobarr · Guru

RE: WDH again(

Gundog · Guru

RE: WDH again

yobarr · Guru

Gundog wrote:
yobarr wrote:
Gundog wrote:
For example the towball weight is 250kg when the caravan is level, assuming the caravan is loaded correctly.
What effect to the towball weight would be if the caravan was 50mm lower at the coupling.
What effect to the towball weight would be if the caravan was 50mm higher at the coupling.

Unless the van had non-load sharing suspension the effect would be hardly enough to be bothered with.
You appear to be clutching at straws. Cheers
I will quantify my reason for the question, gennerally speaking we dont have access to weighbridge when we are setting up our caravans (Reich caravan scales to be accurate you need 1 for each wheel for the van and tug, otherwise it split weighing and that is inaccurate)
We know our ball weight, and we have decided to use a WDH, the hitch is installed according to the manufactures instructions. preparing to connect the van and tug together following the manufactures setup instructions using the measurement method, we have all the measurements when connected the front of the tug sinks 50mm, using the instructions we engage the lift bars and return the front of the tug back to as close as possible to the origional measurement.
We now have the combination in a reasonable safe condition to drive to the weighbridge to establish all weights and make any adjustments to meet GVM,GTM,GCM and Axle Limits, at this point ball weight irrelevant.

The only time ball weight is revelant is to ensure you do not exceed the ball weight rating of the towbar Id plate.
Ball weight do you measure it everytime/day before you hitch up I bet not.

Always I have had concerns about your methods of using a WDH, but never did I realise that you appear to have such supernatural powers that can make the front of your car sink 50mm when you connect your van to the car.

Even more intriguing is that you then can "engage the lift bars and return the front of the tug back to as close as possible to the original measurement.

So when you engage the lift bars the front of the car actually rises. Who would have thought? I'm impressed. Cheers

P.S The "measurement" method has many flaws, and went out when decimal currency was introduced.