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Post Info TOPIC: Caravan "Ratings & Masses" & "Ball-Loading"
Colin1947


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Caravan "Ratings & Masses" & "Ball-Loading"
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It is most disappointing to still read of significant mis-understandings of the important technical terms relating to caravans especially when these terms form the basis of the majority of complaints - and subsequent litigation - that are badly hurting the caravan industry. 

Unfortunately, many people continue to use the incorrect "old husbands' tale" - or "equation" - that:  

   Empty Ball Loading  =  ATM Rating  -  GTM Rating         or        GTM Rating  =  ATM Rating  -  Empty Ball-Loading

This is completely wrong, as there is no logical relationship involved! 

The ATM & GTM are fixed "Ratings", allocated by the manufacturer, in relation to the maximum-permissible "All-up" & "Axle(s)" limits.

The Empty Ball-Loading is an "actual mass" - that must be measured - and is obviously applicable only to the empty (Tare Mass) condition. 

 

The correct formula is, at any time:  Actual Ball Loading  =  "All-up Mass"  -  "Axle(s)-Loading" 

 

When looking over caravans, check the Trailer Plate to see if this "formula" has seemingly been used.   You may well ask "why"???

 

The Legal Load-Carrying Capacity equals the ATM Rating minus the Tare Mass.   (Not the ATM Rating minus the GTM Rating)

 

Under "COMPLIANCING" on - www.caravancouncil.com.au - there is a clear explanation of the vital terms regarding the all-important - but often mis-understood - "Ratings & Masses".

 

Safe & Happy Travels!



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montie


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Colin1947 wrote:

It is most disappointing to still read of significant mis-understandings of the important technical terms relating to caravans especially when these terms form the basis of the majority of complaints - and subsequent litigation - that are badly hurting the caravan industry. 

Unfortunately, many people continue to use the incorrect "old husbands' tale" - or "equation" - that:  

   Empty Ball Loading  =  ATM Rating  -  GTM Rating         or        GTM Rating  =  ATM Rating  -  Empty Ball-Loading

This is completely wrong, as there is no logical relationship involved! 

The ATM & GTM are fixed "Ratings", allocated by the manufacturer, in relation to the maximum-permissible "All-up" & "Axle(s)" limits.

The Empty Ball-Loading is an "actual mass" - that must be measured - and is obviously applicable only to the empty (Tare Mass) condition. 

 

The correct formula is, at any time:  Actual Ball Loading  =  "All-up Mass"  -  "Axle(s)-Loading" 

 

When looking over caravans, check the Trailer Plate to see if this "formula" has seemingly been used.   You may well ask "why"???

 

The Legal Load-Carrying Capacity equals the ATM Rating minus the Tare Mass.   (Not the ATM Rating minus the GTM Rating)

 

Under "COMPLIANCING" on - www.caravancouncil.com.au - there is a clear explanation of the vital terms regarding the all-important - but often mis-understood - "Ratings & Masses".

 

Safe & Happy Travels!

 Colin,

We have discussed this at lenght elsewhere and I still disagree. GTM is calculated and not a rating.



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Possum3


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Colin is an Automotive Engineer and founder of Caravan Council of Australia - I believe he would be the correct person to advise a legal definition - He does so on a daily basis.

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Radar


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RE: Caravan "Ratings & Masses" & "Ball-Loading"
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After a life time of driving trucks, knowing weights and meassures to point that it plain and simple automatic. I do not have a problem practicing weights.

Now with the caravan we have just been though getting that all corrected. The car registration papers corrected, dealers error, 200kgs of load carrying, then enquired and the caravan manufacturer rewrote the VIN plate another 100kgs making our set up very use able and legal.

But with this article below at first it just a picture with meanless numbers, letters then at the end the writer has the full description.. to me confusing, why write it in full first.

It seems backward, maybe it should be written in full eg. gross vehicle weight, gross combined vehical weight, tare weight instead of confusing the average caravan with these shorten eg. gvw, gcvw or tw.

So many times people switch between weight and mass, yesterday I was with a couple who have been though the ringer with caravan weights, changed towing vehicle to get a higher towing allowance all because the salesman said you will be right with that caravan. The tare weight of the caravan was well and truly under stated.

They were saying how confusing it gets when people talk, gross, mass in one all without taking breath.

Caravan tare weight, guide only taken with a pinch of salt.

Gross vehicle weight, either car or caravan. Important

Combination gross vehicle weight-- car and caravan. Real important 

Most transport drivers practice weight, measure and work dairies every working day. By getting it right a caravaner needs to only do it once in general, maybe a check once a year to be sure.

Thats my rant for month.



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iana


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Why are you confusing people with weight and mass, for these calculations they would be the same. Maybe a slight variation in weight, per unit mass, if you drove from Tasmania to Darwin, but in the big picture negligible.
To me its maximum ball weight, stamped on the vehicles tow-bar, unless otherwise limited by the tow vehicle, and maximum weight is the combined weight of both vehicles as listed by the tow vehicle manufacturer.
Try and keep the tow vehicle 10% heavier than the towed vehicle.
Try to make the tow ball weight between 6-10% of the all up weight of the towed vehicle.

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KJB


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Caravan "Ratings & Masses" & "Ball-Loading"
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Thanks Radar. A clear ,simple and practical explanation for the average user........ at last. 



-- Edited by KJB on Saturday 10th of February 2018 10:36:05 AM

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VandC


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BEING A FIRST TIME CARAVANER FOR THE LAST YEAR, I TOO FELL INTO THE TRAP OF CARAVAN WEIGHTS AND THE UNDERSTATING OF WEIGHTS BY CARAVAN MANUFACTURERS, PLEASE WHAT EVER CARAVAN YOU BUY,  BEFORE YOU PAY FOR IT,  MAKE IT A CONDITION THAT THE CARAVAN THAT YOU HAVE ORDERED OR ARE LOOKING TO PURCHASE, THAT YOU TAKE IT  OVER A LICENSED WEIGH BRIDGE TO CONFIRM THE COMPLIANCE PLATE!!! 

 

BE aware that accessories you order on your van are not always included in your tare weight on the compliance plate and could get you into severe trouble

MANUFACTURES PLAY WITH WEIGHTS ITS A HORRIBLE MESS 

The weigh stations on our roads are now asking anyone over 4.5Tonne to pull over as directed, we have seen lots of caravans at weigh stations just sitting there,  just left waiting for a truck to take them home due to rigs being over weight,  either tow vehicle over legal weight, caravan being over weight,  or GCM combined vehicle and caravan  being over weight.  The tow ball weight needs to be taken into consideration especially on the vehicle GVM, a trap I also fell into and had to increase the GVM on my Landcruiser.  

I purchased a van from a so called reputable manufacturer - TOO HEAVY - please be aware !!!

The best litmus test I found was speaking to people in caravan parks with the same model caravan, something I should have done before I bought mine!

I see on a lot of reviews,  a need for national caravan regulations and a regulatory body - why isn't there one? 

It would clean up a whole lot lemons and or bad apples 

 

 



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Bill B


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VandC wrote:

The weigh stations on our roads are now asking anyone over 4.5Tonne to pull over as directed, we have seen lots of caravans at weigh stations just sitting there,  just left waiting for a truck to take them home due to rigs being over weight,  either tow vehicle over legal weight, caravan being over weight,  or GCM combined vehicle and caravan  being over weight.



Would you care to name the locations where you have personally seen this happen ?

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TheHeaths


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Colin1947,

understand your point regarding what equals what. I will suggest that manufacturers weigh the Tare, may weigh the ball weight, then add their load allowance which may or may not have some engineering basis, and set ATM. As the van has not been loaded, the GTM must then be based somehow on the only known tow ball weight they have, that is at Tare. Guess what that then shows GTM to equal!

I still defy anyone to find a van where the ATM on the VIN plate, minus the GTM on the VIN Plate does NOT equal the Tare Mass ball weight quoted on the VIN plate.

Perhaps someone could send us a photograph if it is differnet on their van.


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Regards Ian

 

Chaos, mayhem, confusion. Good my job here is done
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