Confusion

Thetwoofus · Newbie

Confusion

dave06 · Guru

if you have a stated towing capacity of 3,000 kilos (braked) then that is your MAXIMUM towing ability, the old adage of 85% of vehicle mass went out with the long boat

kerbweight relates to gross maximum loading or just simply gross weight, it has very little to do with the towing ability of the vehicle, ask the "expert" how a 5 tonne gross truck can pull a 55 ton "b" double

a lot of misnomours out there spread by folks who know nothing about that which they are sprouting!

Thetwoofus · Newbie

Thanks,

we are newcomers and planning to buy our first caravan.

Rolly · Guru

Welcome 2 the forum U2.

Do have a look at the old posts when you have time.

You'll find quite a lot of useful info.

PeterD · Guru

Have never heard of the 85% rule. Before manufacturers started specifying maximum towing weights for their vehicles, the NSW rule was the loaded weight of the trailer must not exceed the unladen weight of the tug. For the other states the tule was 1.5 : 1.

-- Edited by PeterD on Friday 6th of November 2009 11:01:27 PM

jimricho · Guru

dave06 wrote:

if you have a stated towing capacity of 3,000 kilos (braked) then that is your MAXIMUM towing ability, the old adage of 85% of vehicle mass went out with the long boat

kerbweight relates to gross maximum loading or just simply gross weight, it has very little to do with the towing ability of the vehicle, ask the "expert" how a 5 tonne gross truck can pull a 55 ton "b" double

a lot of misnomours out there spread by folks who know nothing about that which they are sprouting!

Re the 5 ton prime mover towing the 55 ton B double I'm inclined to think that the prime mover was purpose built for this task. Two ton cars and 4wds are not built to pull 22 ton trailers.

I have read the 85% "rule" (?) being quoted by the "experts" in various caravan journals. Maybe this is just a safety margin to allow for the fact that we don't run down to our nearest weighbridge each time we load and hook up in order to keep within the legal limit. These same "experts" probably feed off each other for their information.

Here is the NSW rule (don't know about other states but best to comply with "the worst case")

2942 NSW rule: towing by vehicles under 4.5 tonnes

(cf RRR, cl 49)
(1) A driver must not drive a motor vehicle (the towing vehicle) that has a motor vehicle, trailer or other vehicle attached to it for the purpose of being towed (the towed vehicle), if the laden weight of the towed vehicle exceeds:
(a)  the capacity of the towing attachment fitted to the towing vehicle, or

(b)  the maximum laden weight for the towed vehicle.

Maximum penalty: 20 penalty units.
Note. Motor vehicle, towing attachment and trailer are defined in the Dictionary, and vehicle is defined in rule 15.
(2) For the purposes of subrule (1), the maximum laden weight for a towed vehicle is:
(a)  the maximum laden weight for a towed vehicle that the manufacturer of the towing vehicle has specified in respect of the towing vehicle, or

(b)  if the manufacturer of the towing vehicle has not specified such a maximum, the manufacturer cannot be identified or the towing vehicle has been modified to the extent that the manufacturers specification is no longer appropriate:
(i) one and a half times the unladen weight of the towing vehicle if the towed vehicle is fitted with a braking system that is working properly, or

(ii)  the unladen weight of the towing vehicle in any other case.
(3) A driver of a towing vehicle does not contravene subrule (1) if:
(a)  the towing vehicle is driven or used in accordance with the prior written permission of the Authority and any conditions set out in the document giving the permission, and

(b)  a copy of that document is carried by the driver of the towing vehicle when using the vehicle otherwise than in accordance with subrule (1).

Note. Authority is defined in the Act.
(4) This rule does not apply to any vehicle or combination of vehicles with a GVM or GCM over 4.5 tonnes.
Note 1. Combination is defined in the Dictionary, vehicle is defined in rule 15, and GCM and GVM are defined in the Act.
Note 2. This rule is an additional NSW road rule. There is no corresponding rule in the Australian Road Rules.

(clear as mud now..eh!)

-- Edited by jimricho on Saturday 7th of November 2009 06:48:45 AM

-- Edited by jimricho on Saturday 7th of November 2009 06:53:37 AM

Thetwoofus · Newbie

Thank you all for the info. My wife was will be very happy about this.
We were looking at the jayco 21" as a starting point.

Peter_n_Margaret · Guru

Thetwoofus wrote:

Thanks,

we are newcomers and planning to buy our first caravan.

I strongly suggest that you start with something quite a lot smaller until you have some significant towing experience.

Cheers,
Peter

dave06 · Guru

I'd agree with starting within your ability's as far as towing goes, but a 21 footer weighing in at roughly 1800 - 2300 kilos should be within you and your vehicles capabilitys and a good size van

the manufacturer of any vehicle has made sure that the vehicle has undergone stringent safety testing and many calculations and simulations to find out what the vehicle is capable of, then a safety allowance is given, usually around 20% of nominated values, this is required by law, an accurate description of those values must be supplied to the new owner, this is also law

if it state's in the manual that it can safely tow 3,000 kilos then that is what it can safely tow, end of story!!!!!!!!

a prime mover (of which I am very familiar, having spent many years behind the wheel of all types and various other "heavy vehicles") is setup as a high speed tractor, but the principal is exactly the same, ability to pull the load and to stop safely are the primary concerns

pulling ability is governed by horsepower, gearing and traction, stopping is taken care of by by "on board" brakes in the tow vehicle and slightly by the tug, normally setup to 80/20 depending on load!

a good example of a vehicle pulling well outside of its class is the little 6 ton tractors hauling around 150 ton aircraft at airports?????????

to answer your original question it is still "no it is not correct", go by your vehicles logbook as to tow capacity, also be sure and have a similarly rated tow bar and watch your ball weight, don't exceed 10% of total van weight on the drawbar, thats all you need to know!

too much information in the wrong hands leads to a lot of confusion, go to the source (your logbook) and leave the procrastination to the others, keep life simple!

supa252 · Member

A Kenworth B/D tri/ tri weighs 22 tonne it pulls 38 tonne payload 500 hp motor jake brake/retarders not 5 tonne 34 wheels 10 5 inch brake drums and after all that some times they cannot stop a ute plus van 6 wheels 2 in brakes 2.5 tonne find it hard to pull up if your tow weight is equal or greater than the tow unit it will jack/knife or bulldoze to a end good or bad thats why 85% is rule of thumb also traction has to be loaded on the drive to inprove engine braking through the drive line if the van is heavier than the prime mover it will steer you not you steering it i have been 30 years in the transport industry as a mech/ engineer

dave06 · Guru

when we bought the kenny for the farm and general freight haulage we were presented with basically three options, low power 18 speed "general purpose",

median range 18 or 21 speed heavy haulage

or 21 speed heavy haulage with road train capability

there were other choices but they were the basics

externally to the untrained eye they were indistinguishable, internally a whole different box of fish, it took a salesman or a truck load of documentation to sort out the differences

I used the 5/55 equation simply as an example of what goes on, not as an accurate description of a real life truck although our first inter S.A. came close, we regularly exceed the 85% load factor, I have done it for years hauling d8's and d9's and an 85A to and from gunsen, isa and leigh creek, and in out of various quarrys, with b model macks and r models as well as a couple of cabovers

to bring horsepower in to a discussion about weight loading on a caravanner simply confuses the issue even more

the 85% loading must of course be obeyed by the man on the street with a "standard" car, it is law and common sense, however to understand the loads involved then a weighbridge and calculater comes into play

there was a discussion recently on one of the caravan forums/websites stating the inaccuracy of a caravans compliance plate

apparently when a van constructor builds the first model of a van it is weighed and then all consequent vans of that size use the same weight measure given even though there are extreme variances in internal fitout and that alters the weight considerably thereby relegating the compliance plate almost invalid

I am not sure what would happen if a diligent copper pulled old fred over and escorted him to a weighbridge and found he was over loaded
we must trust our manufacturers to do the right thing

thats why I rely on the manufacturers documentation to tell me what can and cannot be towed on a civilian vehicle!

I also have in excess of thirty years in heavy plant/truck experience but in the jockeying side of it not repairs

-- Edited by dave06 on Sunday 8th of November 2009 09:42:06 AM

ibbo · Guru

Gee life was simple when Caravans were pulled by carthorses.Cheers.Ibbo.

percy · Veteran Member

i think i will forget the caravan and hook up maggies old trotter would be a lot more simple

percy

dave06 · Guru

dont get too wrapped up in the detail here folks, yes there is an 85% ruling and yes by law you should not drive at night without a footman walking in front of you holding a white or clear lantern and you should have a red lantern hanging at the rear of your carriage

did you also know it is ilegal for a public place to not have a hitching rail out the front for you to tie your horse up to, and a water trough to ease the suffering of your horsey,

there are many strange leftover laws that we dont follow, we rely on manufacturers to do it for us

take a look at your vehicles manual, it will tell you your maximum towing weight, have a look at the caravan of your choice, take a gander at its compliance plate, if your vehicles towing capacity is greater than your vans weight then hook up and go,

well you may have to pay for it first

if you go close to your maximum it will pay to check the weight capacity of your towbar! to make sure it can cope!

simple as that!

Rolly · Guru

Geez.

I think I'll go back to camping under canvas.

But then, with my low activity ways, I'd prolly get done for loitering within tent.

Disco Duck · Guru

Love it Rolly !! If you must loiter................no better place!!