WDH again

Gundog · Guru

WDH again

Brenda and Alan · Guru

yobarr wrote:
Please refer to my post of 3.40pm yesterday. Conduct the tests as described and then even you should be able to see that what I say is correct.
Introducing complicated formulae in an effort to cloud a simple procedure is an exercise in stupidity. Cheers

You post is predicated on your belief that towball download does not change. This leads you to your erroneous conclusion that the van as a unit must increase in weight. this is a physical impossability.

All that aside, you still fail to address the questions I have raised. All you do is run round in circles ,post irrelevant pictures and ignore facts.

Alan

Brenda and Alan · Guru

Let look at this a different way.

The tug is sitting on its own on a weighing plate.

Say its mass is 3000Kg. Its downforce on the scales is 3000Kg Wt.

Now couple a van to the tow ball. Say this van is 2000Kg with a tow ball download of 200 Kg Wt

The scales will now show 3200 Kg Wt.

Now tension a WDH on the setup such that the scales read 3120 Kg Wt.

The car alone is still only responsible for 3000Kg Wt.

Hence the load applied by the van is now only 120 Kg Wt

The WDH has reduced the tow ball download.

This is in fact is what should be expected as the WDH applies a lifting force at the hitch which opposes the towball download thereby reducing it.

Alan

-- Edited by Brenda and Alan on Friday 12th of May 2023 07:25:23 AM

BarneyBDB · Senior Member

Where has the other 80 kg gone???

yobarr · Guru

BarneyBDB wrote:
Where has the other 80 kg gone???

Barney, please don't confuse Alan.Many times the figures have been provided, and many times I have explained how to use a weighbridge to show the effects of using a WDH, but he steadfastedly refuses to accept facts.

Doesn't bother me too much, but I despair that newbies and others who are simply trying to learn will take on board his convoluted ideas, to their detriment. Cheers

Are We Lost · Guru

BarneyBDB wrote:
Where has the other 80 kg gone???

To the van wheels.

The weighbridge would have previously shown 1800kg for the van wheels. After tensioning the WDH it reads 1880kg. 80kg of the tug's weight has been redistributed to the van.

We know the mass of the van can't change. So if Yobarr is right that towball weight does not change (a huge IF), that would mean ....

200kg on towball plus 1880kg on the van wheels = 2080kg. Clearly that is impossible because the van can't gain weight. Yet many times including this thread, Yobarr has pointed to the additional weight on the van wheels.

Yobarr, you have been asked numerous times in the past to explain this.

Brenda and Alan I agree with your rationale although transfer of 80kg to the van is a larger amount than I would expect.

In reality, this is not an important issue. There is no easy way to measure towball weight when connected. and the difference when tensioned with WDH. In use it does not matter anyway. What is important it reducing weight on the tug rear axle and transferring it to the front. A side effect is a small increase on the van axles and if it is currently close to GTM (weight on the wheels) this needs to be considered.

-- Edited by Are We Lost on Friday 12th of May 2023 11:34:50 AM

KJB · Guru

Are We Lost wrote:
BarneyBDB wrote:
Where has the other 80 kg gone???
To the van wheels.
The weighbridge would have previously shown 1800kg for the van wheels. After tensioning the WDH it reads 1880kg. 80kg of the tug's weight has been redistributed to the van.
We know the mass of the van can't change. So if Yobarr is right that towball weight does not change (a huge IF), that would mean ..200kg on towball plus 1880kg on the van wheels = 2080kg. Clearly that is impossible because the van can't gain weight. Yet many times including this thread, Yobarr has pointed to the additional weight on the van wheels.
Yobarr, you have been asked numerous times in the past to explain this.
Brenda and Alan I agree with your rationale although transfer of 80kg to the van is a larger amount than I would expect.

The WDH converts the Ball Hitch (a flexible point) to an adjustable (by manual tensioning),semi flexible (spring steel arms), bottom Chord of a Beam between the front axle of the Tow vehicle and the Caravan axle group .....this then lets (by tensioning the WHD) these two axles to carry/share some of the weight that had been carried on the rear axle of the Tow vehicle.

The top Chord of the Beam is the Tow Vehicles Body/Tow bar and the Caravans Tow Bar /Chassis

The amount OF Weight Distribution can vary according to the vehicle/trailer involved and also by the amount of tension applied to the WDH.(bottom Chord of the Beam)

It has been shown that the rear Axle of the Tow vehicle can be lifted clear of the ground (not recommended...!) by a WDH thus sharing the total Tow vehicle /Caravan weight between the front axle and caravan axle group.

The Tow Ball weight does not vary as this is fixed by its pivot point at the Caravan Axle and the fixed distance between the Axle and the Tow Ball .

The WDH will increase the "clamping effect" between the Ball and Hood but do not forget that no matter how tight you clamp two items together with a G Clamp it will not increase or decrease the weight of the two items....!

-- Edited by KJB on Friday 12th of May 2023 12:09:52 PM

-- Edited by KJB on Friday 12th of May 2023 12:41:53 PM

BarneyBDB · Senior Member

This is just going to keep going round in circles until some people get over their mistaken belief that mass and weight are the same...

jegog · Senior Member

Firstly, I would point out that there is no mechanism to transfer weight from the vehicle to the caravan.
Secondly, common sense tells me that if when attaching the caravan to the vehicle, if it results in the town all being depressed say 75mm then to return the lowball to it's original height a vertical moment equal to the lowball has to be applied to the lowball. This moment results in zero lowball weight and the lowball weight is added to the caravan weight.
For those who wish to dispute this I would refer you to: www.youtube.com/watch
The presenter assumes certain prior knowledge as it is not a truely for dummies presentation, but it is hardtop argue against his presentation.

Long Weekend · Guru

BarneyBDB wrote:
This is just going to keep going round in circles until some people get over their mistaken belief that mass and weight are the same...

Actually, mass and weight are the same.

Mass is a SI (System Internationale) term that most countries use. When Australia converted to metric in the mid 1970s mass was supposed to be used but was never fully adopted, hence the term weight is still in use.

Therefore, the term combined mass also means combined weight.

Now I suppose this will set off a flurry of postings of "he's right, he's wrong."

Murray

BarneyBDB · Senior Member

You can have a "Weight distribution hitch" or you can have a "load distribution hitch" but you cannot get a "Mass distribution hitch".

As for mass and weight being the same consider something like a weather balloon sitting on a set of scales, they will indicate a weight, now inflate the balloon with Helium, what is the weight shown on the scales now?

The mass of the balloon is unchanged but the weight has changed....

KJB · Guru

Long Weekend wrote:
BarneyBDB wrote:
This is just going to keep going round in circles until some people get over their mistaken belief that mass and weight are the same...
Actually, mass and weight are the same.
Mass is a SI (System Internationale) term that most countries use. When Australia converted to metric in the mid 1970s mass was supposed to be used but was never fully adopted, hence the term weight is still in use.
Therefore, the term combined mass also means combined weight.
Now I suppose this will set off a flurry of postings of "he's right, he's wrong."
Murray

...a breath of fresh air in the effort to try and keep the explanation of a simple, proven system, SIMPLE.

Axle Weights are all that the "Scale Operators" are interested in and in some cases (OVERLOADED REAR AXLES....) a WDH can help to keep everything Legal ....by DISTRIBUTING some WEIGHT to other axles - they have been proven and in successful use for years in many countries but it must be noted that they are not the answer to all overload problems.

Gundog · Guru

BarneyBDB wrote:
You can have a "Weight distribution hitch" or you can have a "load distribution hitch" but you cannot get a "Mass distribution hitch".

As for mass and weight being the same consider something like a weather balloon sitting on a set of scales, they will indicate a weight, now inflate the balloon with Helium, what is the weight shown on the scales now?

The mass of the balloon is unchanged but the weight has changed....

GCM,GVM,ATM,GTM......the last letter in all of these Mass, how do we get the mass we weigh it there for Mass=Weight for the average layman.

Where the Americans use GCWR Gross Combined Weight Rating, so what is the difference.

Long Weekend · Guru

When the SI (metric) was introduced into Australia the term 'mass' was intended to replace the term 'weight.' As mentioned mass never took on so weight is almost always used today. Possibly mass is only used in technical and scientific circles. And for vehicle registrations - my Ranger registration has the weights given as MASS, specifically GVM (Gross Vehicle Mass) = 3200.

As for the balloon, mass and weight are a downward force on the scales. While the inflated balloon still has the same mass/weight, the helium offsets that. Hence, provided that the helium balloon could be persuaded to sit on the scales, the gas would provide a lifting force resulting in, of course, a lower weight being registered.

Murray

BarneyBDB · Senior Member

Ever heard the term "weightless" or "zero gravity"? How about pulling high G maneuvers? In each case weight changes, mass does not. Weight is a result of forces acting on a mass. They are not the same.

Long Weekend · Guru

Well, I have said my piece, mass and weights are the same thing. Perhaps somebody from the Weights and Measures Department - or whatever it is called - can clarify which is correct.

My Ranger has a mass of 3,200 kilograms. It can also be said that it has a weight of 3,200 kilograms. Ie, they are both the same.

I'll leave it before the posts start to get personal and keep going over a couple of pages.

Murray

Brenda and Alan · Guru

Long Weekend wrote:
Actually, mass and weight are the same.
Mass is a SI (System Internationale) term that most countries use. When Australia converted to metric in the mid 1970s mass was supposed to be used but was never fully adopted, hence the term weight is still in use.
Therefore, the term combined mass also means combined weight.
Now I suppose this will set off a flurry of postings of "he's right, he's wrong."
Murray

Barney

Mass and weight are certainly not the same. Mass is the amount of substance that makes up an item, the total amount of atoms in that item if you like. Mass has units of Kg in the MKS system

Weigh on the other hand is force , is expressed in Newtons in the MKS system and has units of KgM/S2.

That is Kilogram metre divided by second squared.

It is routinely expressed as KgWt for convenience.

The force that a Mass of 1 Kg exerts downwards in dependent on the force of gravity.

1 KG on earth weighs 1Kg, but on the moon only weighs about 160 grams.

Alan

Long Weekend · Guru

BarneyBDB wrote:
Ever heard the term "weightless" or "zero gravity"? How about pulling high G maneuvers? In each case weight changes, mass does not. Weight is a result of forces acting on a mass. They are not the same.

On second throughts I'll respond to the points raised.

I think that Barney is getting mass confused with volume. While mass/weight does change in space due to the lack of gravity, a person standing on the moon does not change their shape/volume but their mass/weight would definitely decrease.

Notice how astronauts in the space station move very slowly. That is although they appear weightless, they still have mass while their shape/volume is the same as on earth. Should one of them propel themselves at full speed into a bulkhead they would certainly suffer injuries, ranging from broken bones to fractured skull. So much for bouncing weightless off the wall.

As for high 'G' maneuvers, again the shape/volume of the pilot does not change, although the centrifugal force of the 'G' does certainly increase the mass/weight of the pilot - indeed the mass/weight of the entire aircraft.

Now I'll shut up and leave it to others to comment as they wish!

Murray

BarneyBDB · Senior Member

It is not me that needs convincing that mass and weight are not the same.

BarneyBDB · Senior Member

I was going to ask when / where the next global meeting of the Flat Earth Society was going to be held but it appears to be here and now.

Long Weekend · Guru

Before anybody else comments, do a Google search for System International. Tbere are a number of sites defining the SI terms in use.

Murray

BarneyBDB · Senior Member

FAQ - What is the difference between the terms "mass" and "weight"?
The mass of a body is a measure of its inertial property or how much matter it contains. The weight of a body is a measure of the force exerted on it by gravity or the force needed to support it. Gravity on earth gives a body a downward acceleration of about 9.8 m/s2. In common parlance, weight is often used as a synonym for mass in weights and measures. For instance, the verb to weigh means to determine the mass of or to have a mass of. The incorrect use of weight in place of mass should be phased out, and the term mass used when mass is meant. The SI unit of mass is the kilogram (kg). In science and technology, the weight of a body in a particular reference frame is defined as the force that gives the body an acceleration equal to the local acceleration of free fall in that reference frame. Thus, the SI unit of the quantity weight defined in this way (force) is the newton (N).

yobarr · Guru

KJB wrote:
Are We Lost wrote:
BarneyBDB wrote:
Where has the other 80 kg gone???
To the van wheels.
The weighbridge would have previously shown 1800kg for the van wheels. After tensioning the WDH it reads 1880kg. 80kg of the tug's weight has been redistributed to the van.
We know the mass of the van can't change. So if Yobarr is right that towball weight does not change (a huge IF), that would mean ..200kg on towball plus 1880kg on the van wheels = 2080kg. Clearly that is impossible because the van can't gain weight. Yet many times including this thread, Yobarr has pointed to the additional weight on the van wheels.
Yobarr, you have been asked numerous times in the past to explain this.
Brenda and Alan I agree with your rationale although transfer of 80kg to the van is a larger amount than I would expect.

The WDH converts the Ball Hitch (a flexible point) to an adjustable (by manual tensioning),semi flexible (spring steel arms), bottom Chord of a Beam between the front axle of the Tow vehicle and the Caravan axle group .....this then lets (by tensioning the WHD) these two axles to carry/share some of the weight that had been carried on the rear axle of the Tow vehicle.
The top Chord of the Beam is the Tow Vehicles Body/Tow bar and the Caravans Tow Bar /Chassis
The amount OF Weight Distribution can vary according to the vehicle/trailer involved and also by the amount of tension applied to the WDH.(bottom Chord of the Beam)
It has been shown that the rear axle of the tow vehicle can be lifted clear of the ground (not recommended...!) by a WDH thus sharing the total vehicle/Caravan weight between the front axle and the caravan axle group.
The Tow Ball weight does not vary as this is fixed by its pivot point at the Caravan Axle and the fixed distance between the Axle and the Tow Ball .
The WDH will increase the "clamping effect" between the Ball and Hood but do not forget that no matter how tight you clamp two items together with a G Clamp it will not increase or decrease the weight of the two items....!

Been a bit busy for a day or two and unable to devote time to respond to either the common sense thoughts of several members who clearly understand simple physics, or the repetetive rubbish from a couple of others who flatly refuse to learn.

As I have said before, everybody is entitled to their opinion, no matter how misguided they may be, but my major concern is that their thoughts may be accepted as fact by people who simply are trying to learn. This could be very dangerous.

Some clearly know little, understand less and show no interest in learning. Very sad.

1) As Kerry has succinctly stated, a WDH can be used to lift the car's rear axle clear of the ground.

Got that? Rear Axle of car is completely off the ground.

So we now have the entire weight of the car and the caravan supported by only 2 axles, the front axle of the car and the axle-group of the van. Now try and tell me that the weight on the van's wheels hasn't changed. LaLa Land stuff.

2) Towball weight does NOT change.

To put to rest all this pontification and convoluted reasoning I suggest that a simple procedure be followed.

Take your car and van, with WDH fitted but not tensioned, to a weigh bridge.

Weigh front axle of car. Note weight. Drive car only onto weighbridge. Note weight.

Weigh car. Subtract front axle weight from total to get rear axle weight. Note weight. Drive car and van onto weighbridge.

Weigh car and van. Subtract weight of car from total weight of car and van. Note weight. That is weight on caravan's axle(s).

This can be confirmed by driving foreward until only van's axle group is on weighbridge. Note weight.

Reverse off weighbridge and tension WDH.

Weigh front axle of car. Weight will have increased. Drive car forward so both axles are on weighbridge.

Weigh car.Total weight of car will have reduced.

Subtract front axle weight from total car weight to get rear axle weight of car. It too will have reduced.

So:- Front axle of car has gained weight.

Rear axle of car has lost weight.

Total weight of car has been reduced because some weight from rear axle has been distributed to van's axle group.

Drive car and van onto weighbridge.

Weigh car and van. Note weight. Subtract weight of car from total weight of car and van. Note weight. That is weight on caravan's axle.

This can be confirme by driving forward until only van's axle group is on weighbridge. Note weight.

1) Car's front axle has gained weight.

2) Car's rear axle has lost weight.

3) Van's axle group has gained weight.

4) Total weight on car's wheels has been reduced.

5) Total weight on van's wheels has increased.

6) Total of weight gained by car's front axle, plus weight gained by van's axle group equals weight removed from car's rear axle.

Simple stuff.

Total weight (GCM) remains constant but 1)Car has reduced weight. 2)Caravan has gained weight.

It is all so simple that it is ridiculous, and when I did my tests I posted the results on this forum, but I have no clue how to locate those results now. Somebody more computer savvy than I may be able to locate them????

Could I respectfully ask that before we get any more sprouting of mass v weight, balloons, Astronauts, the moon, Isaac Newton and any other convoluted theories, that posters carry out their own tests as I have suggested. Please note that because of big weighbridge increments you're likely to get confusing figures, but you'll get the general idea.

While you're out looking for a weighbridge please keep an eye out for one of our members, as he seems well lost. Cheers

P.S Because I've been working big hours I am tired, so mistakes are possible. Please excuse if so as tomorrow I will check it.

Photo is over 40 years old! Truck was Big gear in its day. No WDH either!

-- Edited by yobarr on Saturday 13th of May 2023 11:19:55 AM

gold dandelion · Senior Member

There exist a direct relationship between the mass and weight, such that the greater the mass of something, the greater is its weight. Although, the main difference between the two terms lies in the fact that mass is constant, while the weight of an object changes as it depends on how far is the object from the centre of the earth.

Mass is a measure of the amount of matter an object is made out of. Mass is measured in kilograms (kg). Very small masses are sometimes measured in grams (g). There are 1000 g in one kg. Weight is the force that acts on mass due to gravity and is therefore measured in newtons (N).

en.wikipedia.org/wiki/Mass_versus_weight

Gundog · Guru

If you are a WDH user and want to see something new, the Weigh Safe WDH might be for you.

It will give you your ball weight and then after a number of measurements entered into an App it will tell you how much load the weight gauge up to distribute the weight correctly.

If you want to know more ther is a Vid is available on youtube,

-- Edited by Gundog on Saturday 13th of May 2023 02:35:22 PM

watsea · Guru

I made a post recently in this thread saying that I was not going to an analysis of the physics.

But after my reading of the posts that have followed, I did a few calculations with a set of vehicle and caravan dimensions and loads. Case without a WDH and a case with a WDH.

In the work, I assumed gravity was constant and thus did not write it into my calculations. Just multiple by gravitational acceleration, if anyone thinks that is useful.

In the work, I assumed that the WDH would be tensioned (torqued) to distribute an extra 50kg to the wheels of the van. My calculations, with WDH, determined that the torque or moment applied, would be 225kg.m or 0.225t.m (I know not a typical unit for torque, but good for these calculations).

As per previous posts and my own observations of my rig with a WDH, with the tensioned WDH, extra weight distributed to the van's wheels and weight distributed to vehicle's front wheelsand weight reduced on vehicle's rear wheels as compared to untensioned but hitched rig.

What was interesting, was that my calculations gave a value of vertical load at the ball coupling, if a load cell was inserted.

Of course, there was no reduction in overall vertical weight of the van and caravan whether they were on connected, hitched without the WDH being tensioned and hitched with the WDH being tensioned.

I assumed the weight of the WDH is already included in the vehicle's weight.

I have attached two pages with some analysis sketches showing dimensions, weights, the loads and the calculated reactant loads. I could show the calculations but more work to make them presentable for the forum and attach as well.

-- Edited by watsea on Saturday 13th of May 2023 03:28:11 PM

Are We Lost · Guru

Oh no! Bringing practical and detailed into a WDH discussion will be all too much.

I will be interested to see your workings on how you calculated the difference when tensioning the WDH. I would have thought you would need the measurement of where the WDH downward force is applied on the drawbar to derive the ratio with the van wheel distance.

Also, the usual guideline for a starting point is to return half the lost weight on the tow vehicle front axles. Your calculations show a restoration of almost 100% so your example is not a recommended situation. However I appreciate that your calculation starts with a given at the van wheels.

Possum3 · Guru

watsea, Analysis sketch is showing a weight reduction of 200 kg on single axle of trailer - Did the trailer go to Genny Craig?

Gundog · Guru

Interesting that yobarr has suggested the method of using measurement in the setup of a weight distribution hitchs, went out with decimal currency and that happened in 1966.

The Weight Safe Distribution Hitch is one of the most recent adaptions of the WDH system and yet it is strong on the use of measurement in it's setup and application.

The inital set starts with measuring the height of the caravan and tow vehicle at the front and rear of both, the caravans attituded is adjusted with the jockey wheel until the caravan is level. the coupling height is established, then the towball is setup at a height 12-24mm higher than coupling height.

The vehicles are connected together, this when the weight safe hitch dial gauge shows the actual towball weight.

There are other measurements and known weights that are input to a phone app for the application of the lift bars.

Another newer style of wdh with sway control

Recurve R3.jpg

-- Edited by Gundog on Sunday 14th of May 2023 01:11:53 PM

-- Edited by Gundog on Sunday 14th of May 2023 01:29:50 PM

BarneyBDB · Senior Member

You do not see a problem with moving the towball further away from the rear axle? That system is aimed at the US market for trucks like F350 and bigger.