An interesting thaught about towing capacities and ATM.

Submitted: Wednesday, Mar 05, 2014 at 19:35
ThreadID: 106557 Views:2262 Replies:5 FollowUps:16
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Here is an interesting thaught...it might be "instresting" for some.

Now we all know that there is a declared towing capacity and coupling down force, published and declared for pretty well all modern vehicles.

We also know that pretty well all modern trailers of all types have a declared trailer mass and many have a declared ball weight.

HMMMM.....now if we get into semantics and pedantics..and the real meaings of the words used in the specifications and legeslation.....things get interesting...instresting.

In the past, it was considered fair game as log as the trailer..at the time of towing...did not exceed the capacity of the tow vehicle.

SO.....If I had a trailer that was good for 2 tonnes, but weighed under 750Kg empty.....it ised to be considered fair game to tow that arround with no brakes as it was under 750kg...and certainly it was not considered a problem that the vehicle did not have a 2 tonne towing capacity.


NOW....if we start throwing arround the real terms that could be used.

If the towing capacity is specified in terms for the trailer of either GVM( gross vehicle mass) or ATM ( agrigate trailer mass)...those terms apply to the trailer loaded or empty and do not change.

SO...if I have a trailer of 2 tonnes ATM,...and the towing capacity is prescribed in terms of ATM...do O need a vehicle with a towing capacity of 2 tonnes to tow it empty...evn though it s mass is 749Kg empty.



HMMM serioulsy think about tjis.

NOW bear in mind, all the heavy vehicle licences are clasified in terms of GVM......." drive a vehicle oc ###GVM and tow a trailer of ###GVM.

The licencing system cares not if the vehicle or trailer is loaded or not.

I'd be interested to see what A, the legeslation states ( semantics) and what the actual enforcement polocy is for light trailers...that is trailers under 4.5 tonnes.

Now the hevy vehicle industry is interesting because to my knoweledge the ratings rule, and what vehicles can legally be connected together is one thing and how they must be loaded is another and both can be a little more complicated.

Just some thaughts for discussion.

cheers
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Reply By: Member - Toyocrusa (NSW) - Wednesday, Mar 05, 2014 at 20:03

Wednesday, Mar 05, 2014 at 20:03
Sorry Cheers, It's been done to death on the Caravaners Forum, to the point of being "distresting". Bob.
AnswerID: 527722

Follow Up By: Member - Toyocrusa (NSW) - Wednesday, Mar 05, 2014 at 20:22

Follow Up By: KevinE - Wednesday, Mar 05, 2014 at 20:24

Wednesday, Mar 05, 2014 at 20:24
Yes,

But.................. after lurking on that caravanners forum for quite some time now, it's clear to me that most of the old men towing caravans around on highways know less about this subject than I do about neurosurgery!

At least most of the one's who post on that forum do anyhow!

I for one think this is a worthwhile subject to discuss ;)

My 2 cents, for what it's worth, is that with light trailers, regardless of ATM, you only need to worry about the weight you are actually towing.

Under 750kg & within vehicle specs = no need for brakes.

Over 750kg = brakes required.

Then there is the issue of breakaway brakes lol!
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Follow Up By: Member - David M (SA) - Wednesday, Mar 05, 2014 at 20:51

Wednesday, Mar 05, 2014 at 20:51
It might also be that these old men know more about Neurosurgery than you do about towing.
Dave.
PS. For what it's worth I don't think your 2 cents is worth much.
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Follow Up By: Ross M - Wednesday, Mar 05, 2014 at 20:54

Wednesday, Mar 05, 2014 at 20:54
Caravan towing, vehicle towing and neurosurgery are all connected with a brain, aren't they?

Kevin, haven't you been reading the Lancet recently?

A trailer under 750kg = no need for brakes, Hmm maybe not a legal requirement but in many situations having the Picks would be handy.
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Reply By: tonysmc - Wednesday, Mar 05, 2014 at 20:22

Wednesday, Mar 05, 2014 at 20:22
“SO.....If I had a trailer that was good for 2 tonnes, but weighed under 750Kg empty.....it ised to be considered fair game to tow that around with no brakes as it was under 750kg”
The answer is NO. Trailers must be fitted with brakes if the “GTM” exceeds 750 kg, regardless of what it weighs empty. End of story.
As far as the vehicle doing the towing. If the actual weight at the time when towing the trailer is under the allowable weight for the vehicle it is ok. In other words you may be able to tow a car trailer legally when it is empty but not able to legally tow it with a car aboard.
Where it is easy to get caught out is loading up the trailer close to the limit (which is below the cars towing limit) and loading up the car to near limit and then when you hook them together exceeding the Gross Combination Mass (GCM) which is often less than the GVM + Maximum tow capacity.

Cheers

Tony
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Follow Up By: KevinE - Wednesday, Mar 05, 2014 at 20:29

Wednesday, Mar 05, 2014 at 20:29
Have to agree with Tony,

Most forget about GCM!

But, my trailer is fitted with over-ride brakes. I don't legally have to engage them until I go over 750kg. They have to be there, but they don't have to be engaged until 750kg+

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Follow Up By: The Bantam - Wednesday, Mar 05, 2014 at 20:59

Wednesday, Mar 05, 2014 at 20:59
Yeh I know that what you are saying is the generally accepted situation.

Excpet that....as kev posts.....there is a generally accepted principle that if a heavier trailer is unladen and under 750Kg...while the brakes have to be fitted they do not have to be operative.

There are people who have specifically had trailers built with the intention of towing them from place to place with a vehicle that is not legally capable of towing them loaded..so that they can deliver them to where they will be used with another vehicle.

ANYway..all the above is the generally accepted truth.....but is it the letter of the law.

cheers
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Follow Up By: Shaker - Thursday, Mar 06, 2014 at 08:16

Thursday, Mar 06, 2014 at 08:16
Isn't it a bit like saying you only need operating tail lights if you are driving at night?
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Follow Up By: The Bantam - Friday, Mar 07, 2014 at 21:30

Friday, Mar 07, 2014 at 21:30
And yes...that was very much the case is the not so distant past.....things change.

It was at one time ( posibly in the living memory of some)perfectly legal to tow a trailer during daylight hours with no lights whatsoever..and only a single tail light at night.

At one time a little more recent it was permissable for a trailer to have only one tail light and one brake light as long as the indicators on the towing vehicle where not obstructed by the trailer.

It was also not uncommon for trailers to have wooden drawbars.....but times change.

cheers
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Follow Up By: Stu & "Bob" - Saturday, Mar 08, 2014 at 21:50

Saturday, Mar 08, 2014 at 21:50
Don't forget about your axle loading as well...
One can be under both GVM and GCM and still be overloaded by axle weights.

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Follow Up By: The Bantam - Saturday, Mar 08, 2014 at 22:02

Saturday, Mar 08, 2014 at 22:02
Oh yes indeed...towing capacities are far more complicated than some people would like to know.

There would be a large portion of people out there thinking that their rigs are fine but in fact they will be well overloaded on the rear axle.

But that is another story all together.

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Follow Up By: Nomadic Navara - Saturday, Mar 08, 2014 at 23:54

Saturday, Mar 08, 2014 at 23:54
Quote "Don't forget about your axle loading as well...
One can be under both GVM and GCM and still be overloaded by axle weights."

Only if an idiot set the load limits and stamped them on the compliance plate. A responsible person would not set limits on the trailer like that.
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Reply By: pop2jocem - Wednesday, Mar 05, 2014 at 22:03

Wednesday, Mar 05, 2014 at 22:03
Couple of other thoughts for you Bantam. Ever wondered what the "Spell Check" and "Preview" buttons are there for at the bottom of the post, follow up or reply sections?

Cheers
Pop
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Follow Up By: Dennis Ellery - Wednesday, Mar 05, 2014 at 22:46

Wednesday, Mar 05, 2014 at 22:46
Don’t be silly Pop – that would take all the guesswork out of deciphering his posts.
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Follow Up By: The Bantam - Wednesday, Mar 05, 2014 at 22:54

Wednesday, Mar 05, 2014 at 22:54
Ever wondered why people cant be bothered with comments like that on internet forums.

If you want to correct peoples spelling an grammar....go and teach school......not interested....particularly when this forum gives me no opportunity to edit my own posts after they are posted.

cheers
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Follow Up By: pop2jocem - Wednesday, Mar 05, 2014 at 23:12

Wednesday, Mar 05, 2014 at 23:12
You're right mate, this forum does not give you the opportunity to correct your "grammar" after you submit.
Just a polite suggestion, maybe that's why the "Preview" and "Spell Check" are so handy to correct before you do. Takes the guesswork out a bit.

Just saying.

Cheers
Pop
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Follow Up By: Dennis Ellery - Thursday, Mar 06, 2014 at 13:50

Thursday, Mar 06, 2014 at 13:50
Bantam,
You are just trying to be a cool dude.
That’s ok for the teens chatting about their latest trends and keeping up with who’s doing who.
But on a 4WD site where others try to give accurate information, not doing the same, is just being plain lazy.
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Reply By: Motherhen - Thursday, Mar 06, 2014 at 01:14

Thursday, Mar 06, 2014 at 01:14
Hi Bantam

1. You would not be legal. The requirements for the brakes are based on the GTM not the empty weight.

2. If the trailer actual weight is below the stated towing capacity of your car it is legal, but may not be wise. If an insurance company became picky following an accident because they believed overloading caused the accident (a very long shot) you could have a fight on your hands – hence the differing opinions of the many caravanners forum threads on the subject. Better safe than sorry.

3. Please clarify what you are saying – I cannot follow you on this point. If you are talking about driver's licence classifications, you can drive a vehicle that does not exceed 4.5 tonnes Gross Vehicle Mass (GVM) and can seat up to 12 adults including the driver. This does not include motor cycles and motor trikes. You may tow a single trailer (other than a semi trailer) up to 9 tonne GVM or to the manufactures specifications (whichever is less) on an A class (car) licence. I can drive our F250 and Bushtracker caravan, 7.5 tonne all up fully laden for a big trip, on an A class licence.

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Follow Up By: The Bantam - Friday, Mar 07, 2014 at 21:46

Friday, Mar 07, 2014 at 21:46
My point being that the licence conditions and the rules in general that apply to heavy vehicles are framed bassed on rated capacity, not the actual load carried.


BTW as a seperate issue , I believe it is rediculous that it is legal to drive a 9 tonne combination made up of a 4.5 tonne vehicle towing a 4.5 tonne trailer...where to drive a single rigid vehicle over 4.5 tonnes requires a specific licence to drive a rigid vehicle over 8 tonnes requires yet another higher class licence.

UM...I dont think you can tow a 9 tonne trailer on a passenger car licence.
as far as I know, The 9 tonne trailer does not come in till light rigid.

Even then is pretty pointless...Id be interested to hear of a Light rigid with a 9 tonneGVM towing capacity.


cheers
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Reply By: Rustynails59 - Thursday, Mar 06, 2014 at 16:09

Thursday, Mar 06, 2014 at 16:09
Hi there again

you might be interested in the following

http://www.vanguardcaravansales.com.au/Vehicle%20Mass%20Towing%20Guide%20-%20May%202012%20.pdf

I see where you are coming from- if towing less than 750kg but trailer can carry more

for my two bobs worth, its the gross mass of the the trailer and what it can legally carry -, not what it actually carry's

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