Tuesday, Jun 24, 2014 at 19:40
Petra
My understanding of loading is this. GCM cannot ever be exceeded
What does this mean?
well its not straightforward.
There are many acronyms involved, and its confusing as people will advise that if you are overloaded,, then just get the heavy duty springs, and all is fixed.
Well I beg to differ.
Ok, some acronyms, GVM, ATM, GCM.
GVM is gross vehicle mass, the maximum weight that you vehicle can weigh when it is loaded . A combination of the weight (as supplied, maybe cab/chassis) and what you put in it, the tray, the dual batteries, the fuel the passengers, the stuff in the back, the lot. And 10% of the ATM if you intend towing something. You CAN upgrade the GVM by installing better springs, and often they come pre- engineered with the approval for a GVM increase. More on this later.
ATM is Aggregate Trailerable Mass. Or the maximum weight that your caravan, plus what you put in it, water, food, bits and pieces. Note this is not what your caravan weighs, its is the MAXIMUM it can weigh legally.
GCM, now here is where it gets messy. In Queensland, GCM can NEVER alter, even with an increase in GVM. I will try to explain this a bit better
In assessment of your GVM (when you are towing), you have to include 10% of your ATM, in my case with the Bushtracker, 10 % of the 3500kg ATM (empty it is 2700 kg) has to be included in the GVM calculation. So, 350 kg had to be added to my GVM assessment, not 10% of my actual caravan weight.
Getting back to GVM, the manufacturer gets the vehicles rated in Australia for the GVM, (and GCM)its actual approved weight is on the website etc,
well documented. And yes, you can upgrade this figure with an engineered package of springs etc.
But you can never alter the GCM, Gross Combined Mass. Ouch
At least in Queensland. SO, in effect, increasing the GVM with better springs etc, means that the towing capacity is funding it, If the GCM cannot ever be altered, then adding GVM capacity to the tow vehicle must subtract it from the item you tow. Why?
Because GCM is the addition of the GVM and the ATM... Add to the front, subtract from the rear.
So will you be able to tow your new van? I suggest packing your tow vehicle as if you were on the road. Go out to the recycle site and get it weighed. Look up the new vans ATM, and add it to your vehicle weight (assuming it does not already exceed its GVM(see ATM inclusion above)). Make very sure that the sum of the weight of the tow rig, loaded, and the ATM, does not exceed the vehicles GCM (look on site)
Now, this has been long winded, and I apologise, I am no expert on this and will doubtlessly attract a lot of differing opinions. But I speak thru experience.
If the caravan is single axel, it will probably work out ok. Dual axel,, do your maths.
regards
Jim
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