Another question on WDH's

iana · Guru

Another question on WDH's

Bevandy2 · Senior Member

er..yair, something like that, it's logical. and you make a good point.
The weight of the hitch and levelling bars would be a part of the weight on the ball. So you get the ball weight of the van, (by weighing it fully loaded) then add the hardware to that, and make sure it all comes in under the allowable rating. (350kg)

Compliance plate for tow bar would be correct, it just includes the weight of the towing gear.

Complicated by the fact that the levelling bars transfer some of the weight to the front wheels, probably best to not be too pedantic, just make sure the van, when loaded has a ball weight less than 350kg.

eg our tow bar has a load rating of 2300kg, and ball load rating of 230kg's, ball weight of the van when fully loaded is usually about 180kg, so the weight of the towing gear is of no concern. Yours may well prove to be of the same situation.

Bevan

rockylizard · Guru

Gday...

I am sure others will join in and quite probably correct me ........ BUT ......

I would actually say that the weight of the VEHICLE will include the weight of ANY towbar and tongue and/or attachment - therefore the vehicle's weight would include the WDH when it is attached to the vehicle.

The tow ball weight is that which is what the VAN puts on the towball ... it is that simple. The weight of the WDH is part of the vehicle's weight.

I will now wait to be howled down by the more knowledgeable on the forum. hmm

cheers - John

iana · Guru

A can of worms, nobody has thought about?

greyhoundtom · Senior Member

Well considering that the same pressure/weight on a longer lever increases the force exerted, I would be more concerned about what increased effect the ball weight of the van has on the vehicle with the longer lever created by the WDH. biggrin biggrin

Jaahn · Guru

rockylizard wrote:
Gday...
I am sure others will join in and quite probably correct me ........ BUT ......
I would actually say that the weight of the VEHICLE will include the weight of ANY towbar and tongue and/or attachment - therefore the vehicle's weight would include the WDH when it is attached to the vehicle.
The tow ball weight is that which is what the VAN puts on the towball ... it is that simple. The weight of the WDH is part of the vehicle's weight.
I will now wait to be howled down by the more knowledgeable on the forum.
cheers - John

Hi smile

IMHO John is correct here. The vehicle when weighed without the van will include the towbar and any attachments. The tow ball weight is just the weight the coupling puts on the ball.

GreyhoundTom also has a good point too.

The problem really is that people load UP TO a figure given and not allow any margin for anything. Common sense would seem to me that is 'PUSHING IT' and I would not do that. If you start out at the limit then there is nowhere to go but downhill IMHO biggrin

Jaahn

-- Edited by Jaahn on Tuesday 1st of March 2016 08:07:14 AM

rockylizard · Guru

Gday...

hmm I am probably going Off Topic 01.jpg here but I think these issues that so many are agonising about come from a simple problem.

It is becoming more and more common for people to -

believe manufacturer's comments/advice/specifications on the towing/carrying abilities of vehicles;
expect to have a van that has everything included to allow living as if in a home - hence vans are getting bigger and heavier with each new model;
buy a vehicle that is either just about on, or right on, the limit of its abilities to tow such vans;
have a budget that limits their ability to purchase a vehicle that does have the abilities to tow such vans;
perpetuate to others the myth of the capabilities of the current utes - and some smaller 4X4s;
struggle to juggle weight between, in and around the vehicle and van in almost futile attempts to be "compliant".

I am quite probably "out of step" with many (if not all) vanners but I believe that if you want to tow a van with an ATM upto and around 2,500Kg than any of the utes, and other large 4X4s with a 'rated' towing capacity of 3,000Kg and above, will cope.

If the van ATM is getting closer to, or exceeds, 3,000Kg then something like a small truck or F250, Silverado, etc should be used.

It should be considered that the towing weight abilities, of utes in particular, are more marketing than engineering - and because of the difficulty of how little REAL payload they can carry and tow - are over-stated by the manufacturer/marketing department.

Add to this that the often inability of modern utes to carry weights close to their GVM (full payload) without suspension upgrades clearly shows their 'rated' abilities are more marketing than engineering.

This site has been bandied around for months now ... but it clearly shows the difficulties in trying to tow a large van with a ute - AND be compliant.

https://practicalmotoring.com.au/car-advice/why-a-3500kg-tow-rating-may-not-really-be-a-3500kg-tow-rating/

Having now raved on and taken up all your time - unfortunately, cry all this is of no help to anyone who has already bought their van and ute and is struggling to get their rig compliant (and safe?)

Cheers - John

Izabarack · Guru

Yes, iana, I agree with the thinking. There are two components to consider in discussing adding the weight of a WDH to the coupling complex. Ball weight limits start with the assumption that there is a standard tow bar with a standard ball mount in the receiver plus a ball. The limit is all to do with the weight at the end of the lever measured from the back axle to the ball itself. Adding the mass of a WDH changes the weight at the end of the standard towbar lever by that amount. To be properly accurate in checking ball weight, the difference in weight of the WDH ball mount, from standard, should come off the book limit for a standard tow bar, and the ball weight of the van needs to be measured with hooks and bars and chains attached on the A frame side. Limits are always stated with some arbitrary safety factor protecting the engineering but if someone is already on or close to the limit, the mass of a WDH should be considered.

Iza

-- Edited by Izabarack on Tuesday 1st of March 2016 11:37:55 AM

Woody n Sue · Guru

Ok I'll play the devil here just get a fifth wheeler and this whole discussion is immaterial .

HOWEVER as a point of interest has anyone ever put there tug on a weight bridge weighed it with the van unhitched and the van wheels not on the weigh bridge obviously , then hitched up the van with there WDH and checked the weight of the tug this would be the ONLY true way to know how much weight is being applied to the tow ball .

Ok ducking for cover now the devil made me do it honest he did

rockylizard · Guru

Gday...

Woody n Sue - I included this in a previous post on the discussion regarding the way weight is transferred by a WDH etc.

If you carefully look at the weights at various stages (with each axle of vehicle weighed separately) - ie without trailer; with trailer & without WDH; and, with trailer and with WDH- you can see the effect.

The chart also shows the van's ATM (from the plate); van without vehicle; and, van after connected to vehicle with WDH in play.

If you would like I can re-post (or email) the whole spreadsheet showing a variety of vehicles that were weighed - just PM me your email address.

WDH affect.jpg

Cheers - John

Radar · Guru

Well said John

Thats as clear as it gets.

PeterD · Guru

Woody n Sue wrote:
HOWEVER as a point of interest has anyone ever put there tug on a weight bridge weighed it with the van unhitched and the van wheels not on the weigh bridge obviously , then hitched up the van with there WDH and checked the weight of the tug this would be the ONLY true way to know how much weight is being applied to the tow ball .

Hayman Reese often spend all day doing this at caravan shows. The JPG below is the result from one of the shows. Do a little maths and you will note the weight on the vans wheels increases and the total load on the tugs wheels decreases when they hitch up.

Also calculate the change of weight on the tugs rear wheels. Most people don't realise how much weight is transferred to the driving wheels id WDH is not employed. I would suggest that a lot of vanners are overloading their rear axles when they don't use WDH but would be OK if they did use it.

HR WDH display.jpg

iana · Guru

Just trying to work out how those measurements above were taken, If we take the weight D and C, then the only way to measure them would be to raise the van off the ground, and take those 4 measurements, then how did they get the ball weight which would be the result of moments from the fulcrum point, i.e. the axle?, because the axle would be off the ground. Just cant get my head around how you could measure D and C with the wheels on the ground.

Further if you add up the CVM in the last row, they forgot to add the weight of the hitch, in this case 275kg hitch 30.5kg. Which would take the CVM from 3140 to 3170.5kg. This was my original comment at the start of the post.

I don't suppose Haymen Reece sell weight distribution hitches do they? smile

On the comment I made about the ball weight of the tow bar, I have come to the conclusion its all Ball or Bull-****. The towing capacity of the towbar is 3500, now what's 10% of that ,Oh! its 350 how silly of me.

OK bull dung bull dung bull dung, got it! smile smile smile

-- Edited by iana on Tuesday 1st of March 2016 06:42:12 PM

Baz421 · Guru

Jaahn wrote:
rockylizard wrote:
Gday...
I am sure others will join in and quite probably correct me ........ BUT ......
I would actually say that the weight of the VEHICLE will include the weight of ANY towbar and tongue and/or attachment - therefore the vehicle's weight would include the WDH when it is attached to the vehicle.
The tow ball weight is that which is what the VAN puts on the towball ... it is that simple. The weight of the WDH is part of the vehicle's weight.
I will now wait to be howled down by the more knowledgeable on the forum.
cheers - John
Hi
IMHO John is correct here. The vehicle when weighed without the van will include the towbar and any attachments. The tow ball weight is just the weight the coupling puts on the ball.
GreyhoundTom also has a good point too.
The problem really is that people load UP TO a figure given and not allow any margin for anything. Common sense would seem to me that is 'PUSHING IT' and I would not do that. If you start out at the limit then there is nowhere to go but downhill IMHO
Jaahn

-- Edited by Jaahn on Tuesday 1st of March 2016 08:07:14 AM

Agree with John here also.

iana · Guru

Well I've had two bits of good news, rang up the heart specialist, and apparently my appointment is not for another 12 months, this is a good sign. And No. two, Mazda confirmed I have extra CVM as that's worked out by the Gov't weigh station, weight is not quite the as critical anymore. So I can breathe easier on both cases, now where did I put the beer and chips?
I found an interesting article on the net about all this stuff, if I can find it again I will post it up.

iana · Guru

Here it is. Interesting, no mention of a WDH.

Woody n Sue · Guru

Ok guys n gals I have humbly put my tail between my legs and am going home on the WDH point hmmm humble pie tastyyyyyy.

However I stand by my fifth wheeler as the safest way to tow a trailer
Woody

Jaahn · Guru

Hi smile

Not sure about that pie ?

However I agree about fifth wheelers being the best towing rig. You know the trucking industry noticed this 'some years' ago biggrin That's why most big loads are carried on a semi trailer. Stable loaded or not, perhaps even overloaded ! No argument here about 5th wheelers. Just the cost and some other small difficulties.

Jaahn

PeterD · Guru

iana wrote:
Just trying to work out how those measurements above were taken, If we take the weight D and C, then the only way to measure them would be to raise the van off the ground, and take those 4 measurements, then how did they get the ball weight which would be the result of moments from the fulcrum point, i.e. the axle?, because the axle would be off the ground. Just cant get my head around how you could measure D and C with the wheels on the ground.

HR use 9 load cells, one under each wheel and one under the jockey wheel. I have seen this exercise demonstrated at the Sydney show. Yes they have their towing gear on the same display stand. There is no slight of hand, they are just demonstrating how their equipment works.

Don't attempt to make any conspiracy theory about this subject.

Izabarack · Guru

iana wrote:
.....no mention of a WDH.

The dynamic situation provides a better environment for the analysis of the difference between weight and mass.

Iza

iana · Guru

Talking about pies, I am wrong, I didn't read the "rear wheels" "front wheels" under the chart, but took the weights to be taken at "D" & "C". Load cells under each wheel would give these measurements.

Tones · Veteran Member

Hi all.

In all the various discussions concerning use and non-use of WDH, I have never seen any comment concerning tow vehicles that might be fitted with rear axle brake proportioning valves. I know that various major manufacturers of twin cab vehicles and other vehicles fit transverse brake proportioning mechanisms across the rear axle assembly so that the loading of the rear of the vehicle will alter the percentage of braking application to the rear of the tow vehicle when the body of the vehicle is lowered by weight at the rear end.

Has anyone ever make inquiries concerning the effect on tow vehicle braking systems when weight is added to the rear of a tow vehicle and no WDH is used to restore the height of the rear of the tow vehicle.

Maybe there is a qualified person out there who can comment with expert knowledge on this subject. I understand that as a general rule, motor vehicle manufacturers aim to have a brake application ratio of something in the order of 60/40%, that is, 60% front and 40% rear. Now if you are going to load up the rear of a vehicle that is fitted with a rear brake proportioning valve system (to increase rear wheel brake application ratio) AND NOT FIT A WDH, one would assume that you are increasing the brake application to the rear wheels of the tow vehicle and at the same time reducing the braking ratio to the front wheels.

I have read various comments about the fact that (in a perfect world) the use of WDH devices should not be necessary but I have never seen any comment about the issue that I have raised here.

I would be interested to hear if anyone has any up to date knowledge on this subject because I suspect that it is a very relevant (but overlooked) part of the discussion on WDH use.

Tones

-- Edited by Tones on Friday 4th of March 2016 08:45:40 AM

-- Edited by Tones on Friday 4th of March 2016 08:53:35 AM

Jaahn · Guru

Hi Tones,

I am no expert here but will throw in my two cents worth confuse

Rear brake proportioning valves are not really named correctly. They just set a load at which the rear brakes are shut off so they do not lock up. They are a blunt instrument but were useful on commercials that may have a very varied load in the rear. Better than locking up and spinning the vehicle.

HOWEVER that is old technology and the widespread use of ABS has mostly superceded it as I understand it. This of course only works in extremes but it certainly works and is not dependent on knowing the weight on the suspension. It also can be used with ESC and ELSD etc.

Cheers jaahn

Cupie · Guru

Tones wrote:
Hi all.
In all the various discussions concerning use and non-use of WDH, I have never seen any comment concerning tow vehicles that might be fitted with rear axle brake proportioning valves. I know that various major manufacturers of twin cab vehicles and other vehicles fit transverse brake proportioning mechanisms across the rear axle assembly so that the loading of the rear of the vehicle will alter the percentage of braking application to the rear of the tow vehicle when the body of the vehicle is lowered by weight at the rear end.
Has anyone ever make inquiries concerning the effect on tow vehicle braking systems when weight is added to the rear of a tow vehicle and no WDH is used to restore the height of the rear of the tow vehicle.
Maybe there is a qualified person out there who can comment with expert knowledge on this subject. I understand that as a general rule, motor vehicle manufacturers aim to have a brake application ratio of something in the order of 60/40%, that is, 60% front and 40% rear. Now if you are going to load up the rear of a vehicle that is fitted with a rear brake proportioning valve system (to increase rear wheel brake application ratio) AND NOT FIT A WDH, one would assume that you are increasing the brake application to the rear wheels of the tow vehicle and at the same time reducing the braking ratio to the front wheels.
I have read various comments about the fact that (in a perfect world) the use of WDH devices should not be necessary but I have never seen any comment about the issue that I have raised here.
I would be interested to hear if anyone has any up to date knowledge on this subject because I suspect that it is a very relevant (but overlooked) part of the discussion on WDH use.

Tones

-- Edited by Tones on Friday 4th of March 2016 08:45:40 AM

-- Edited by Tones on Friday 4th of March 2016 08:53:35 AM

"Sh*t"

Never thought about that.

I think that my old Patrol has that fitted. Never knew what its purpose was, let alone the effect of heavy ball weight/WDH.

Even Collyn Rivers hasn't commented on this (I think).

Oh well something else to ponder. A bit of research too.

Try this describes the device but doesn't address the question .. I think .... http://stoptech.com/technical-support/technical-white-papers/proportioning-valves

-- Edited by Cupie on Saturday 5th of March 2016 10:45:45 PM

Tones · Veteran Member

Cupie,

Good to see someone else is thinking about this. I came across the following explanation of Brake Proportioning Valves and it shows what I was trying to explain.

http://stoptech.com/technical-support/technical-white-papers/proportioning-valves

I should point out that in the above article, the name given to the brake proportioning valve that I was describing is the "Height Sensing Proportioning Valve" and to be honest, it gives a far better explanation of the operation of the device than I did.

If you read the article, you will soon see what the reason for my curiosity is. Unless I am missing something, this device (where it is fitted) is going to have a significant effect on tow vehicles on which WDH's are not being used to tow vans.

I again stress that I am not an expert; I am merely posing the question.

Tones