Thread: Towing a caravan going offroad

Originally Posted by zulu Delta 534

Land Rovers were rated by the manufacturer in reality to tow 4.tonnes but the laws in Australia limit any tow vehicle to 3.5 unless it is fitted with air brakes. Sort of makes a mockery of those who spend a fortune to purchase some monster Yank truck with an advertised 6 ton tow capacity when, unless it is fitted with an air braking system, it can still only tow 3.5 legally.
Enjoy your travels
Glen

Hi Glen,

I would like to know where you have seen that weight as I am rebuilding a plant trailer into a car (read Land Rover) carrier at the moment. It will have vacuum over hydraulic four wheel brakes as well as a vacuum over mechanical and hydraulic 'emergency braking system'.

From my reading of the current Rules the compulsory change to air brakes is more likely to be at 4.5Tonnes. You can of course have air brakes on lesser weight trailers also:

Vehicle Standard (Australian Design Rule 38/03 – Trailer Brake Systems) 2007
4. DESIGN REQUIREMENTS FOR TRAILERS UP TO 4.5 TONNES ‘ATM’
4.1. Every trailer must be equipped with an efficient ‘Service Brake System’ which, with the exception of trailers equipped with an ‘Over-run Braking System’, must be designed so that the braking force can be progressively increased and decreased by means of the ‘Control Signal’ from the towing vehicle.
4.2. In the case of trailers with a ‘Gross Trailer Mass’ of greater than 2 tonne, the ‘Brake System’ must operate on all wheels.
4.3. The ‘Brake System’ on trailers with a ‘Gross Trailer Mass’ up to 2 tonnes may be actuated for both ‘Service Brake System’ and ‘Secondary Brake System’ by the over-run of the trailer.
4.4. Every trailer having a ‘Gross Trailer Mass’ over 2 tonnes must be equipped with an efficient ‘Emergency Brake System’ which will cause immediate automatic application of its ‘Brakes’ in the event of the trailer accidentally becoming disconnected from the drawing vehicle. ‘Brakes’ so applied must remain applied for at least 15 minutes.
4.5. Trailers up to 4.5 tonnes ‘ATM’ are not required to comply with other clauses of this rule.
http://www.comlaw.gov.au/ComLaw/Legislation/LegislativeInstrument1.nsf/0/393E9A3C95F34923CA25731700204B36/$file/F2007L022231.pdf

In general trailers with a GTM of 4500kg and over - Require fully ADR-approved axles with "S" Cam Brakes, require ADR-approved Suspension or Load Sharing Suspensions and Compressed Air Brake Operating and Breakaway Kits.

Bob

While most people with little or no experience with pulling heavy vans think that power is the main issue, it is not. From experience, I am comfortable with the fact that handling/stability is by far the biggest issue with a large, heavy dirt road van.

Your RRS will have no problem with power.

By law you must not exceed the van's ATM, and that ATM must not exceed the tug's max towing capacity. Similarly the van's actual towball weight must not exceed the maximum permitted for the vehicle. That much is easy.

Now for the hard bit which the inexperienced find hard to believe. For stability (read safety), the van's centre of gravity must be a specific distance forward of the points of contact with the road, ie, the wheels. If it is too close to the axles, or god help us, over or behind them, then the van will be a death trap and will be uncontrollable once anything upsets it, such as a sudden swerve or a road train's bow wave hitting the van. It is accepted by experienced vanners and by road transport authorities around the world, including Australia, that that CG position will be ideal when somewhere between 7% and 14% of the caravan's ATM is supported by the tow hitch of the towing vehicle. The Australian authorities specify 10% as the ideal. Thus for a 3000 kg ATM van such as the Kedron you are looking at, you should have 300 kg on the tow ball (I understand that the RRS has a max towball weight of 350 kg). With that, the van should be fine on or off the road.