07/05/2024
BOXES ON THE REAR OF YOUR CARAVAN CAN BE VERY DANGEROUS AND OFTEN ILLEGAL….
WHO IS LEGALLY RESPONSIBLE?
WHAT CAN HAPPEN WHEN YOU DON’T FOLLOW THE CORRECT ADVICE?
We often see large storage boxes and other items, even motorbikes, mounted on the rear of caravans and motorhomes as we travel around Australia.
These boxes and items are often in breach of the Australian Design Rules overhang requirements for your caravan and will, in many cases badly affect the stability of your caravan. These laws are adopted by all state and territory governments.
Any pig trailer / caravan should have a rear load carrying area that is no longer than the front load carrying area. The maximum rear overhang from the centre of the axles is 3.7m.
The centre of the axle group or the single axle in the case of a single axle trailer is classed as the measuring centre point.
The caravan load carrying area does not include the caravan A frame unless it has a storage box etc mounted on it.
Rear overhang includes any boxes, spare tyres etc mounted on the rear.
These boxes can make your caravan or motorhome unroadworthy and therefore your insurance may be voided. You may only find out when you make a claim. There are some vans that have the axle groups set further rear of centre, and others set approximately at centre.
See diagram of maximum overhang rules dimentions
Also weigh your caravan fully loaded to see if it is within the caravans rated ATM and where any extra weight is.
Just because others do it, DOES NOT make it right, legal nor safe. The blind leading the blind scenario.
Truck Friendly would like to remind all those contemplating mounting a heavy box on the rear to think again and do your homework first.
I have a question for all those businesses advertising and mounting these boxes on the rear of caravans and motorhomes, others giving advice, and social media that posts the advice to do it.
WHO WILL THE LAWYERS FIND RESPONSIBLE WHEN, BY ADDING THESE BOXES TO THE VAN OR MOTORHOME IS FOUND TO BE A FACTOR IN A FATAL ACCIDENT OR THE VEHICLE WAS MADE UNROADWORTHY?
The ‘industry experts’ who installed it, ‘driver’ or the ‘social media admin’ or ‘people who gave the dangerous advice’?
Only time will tell, But we WILL see it one day.
Does your insurance cover it?
These heavy items on the rear will make the caravan much more prone to dangerous caravan sway.
"My van does not sway", I hear you say.
However, I have not yet heard of anyone who has had their caravan sway and roll over, say that it often does that, or it was doing it before the accident. It is always, "My van was stable until .........".
Maybe you just have not found the ‘perfect storm’ where a few factors come together and set off the sway when you are least expecting it.
When it happens, you may only have as little as 5 seconds to identify what is happening, and correct it before it is uncontrollable, and you are just there for the ride of your life.
In those 5 seconds, you will need to identify that you have a problem, remember what to do about it, stay calm, and find and press the trailer override brakes to reduce trailer speed.
What can be ‘the perfect storm” –
LET’S LOOK AT WHAT CAN BE MAJOR CAUSES OF CARAVAN SWAY.
1. BAD LOADING WITH TOO MUCH WEIGHT ON THE REAR OF THE CARAVAN.
In the case of my previous caravan, a 2019 New Age 20' Oz Classic, and two other vans I have had, the tow ball weight will vary by 2 kg depending on whether the door is closed or latched back open. This highlights the impact a small weight shift can have on the caravan’s balance. The door is still attached to the caravan, but weight shift makes a big difference. A fact that many may not realise when loading a van. The leverage effect can severely impact on stability.
If that little shift in weight has such a big effect on the tow ball weight, can you imagine how much a large storage box, generator or 80kgs of fuel or water further back on the rear bumper will lighten the tow ball. Each van varies but it can reduce tow ball weight by 150% of the box weight.
I have had many say that they compensate by putting more heavy items on the 'A' Frame.
Having heavy items at the extreme front, or extreme rear of any 'Pig Trailer' is never a good idea and will increase the effect of any swaying motion or pendulun effect.
Q. Why does a grandfather clock have a large weight on the end of the pendulum? Answer. To maintain sway.
Play a game with bottles of w**e at 4 o'clock drinks. Hold your arms out and spin around then stop.
Now, do the same thing with a full bottle of w**e in each hand and you will note how much harder it is to stop spinning with the weights at the extremities. It is the same for your caravan. (It is also the same when you have consumed the two bottles of w**e, but that is another matter entirely)
If loading a car trailer, for example, you drive the car onto the trailer, not reverse it on. That way the heavy motor will be forward of the trailer axles helping prevent trailer sway.
Two women were killed in north Qld when a ute towing a car backed onto on a car trailer got out of control with trailer sway, and the trailer sway pushed the light ute into the oncoming lane of 100kph traffic killing two ladies who were innocently just going for a drive.
2. SPEED.
Caravan sway is proportional to speed. the faster you drive the more chance of, and the faster and more dangerous the caravan sway will be, and harder it will be to stop.
You have less reaction time, and there are worse consequences and sway is more likely to happen over 100kph.
Please do not tow a caravan over 100kph, no matter how stable you believe the van is or the posted speed limit. It may just take a small cross wind, air from a passing truck, undulation in the road, incorrect tyre pressures or other factors to come together to bring on unexpected sway.
I call it - "the perfect storm."
It is also illegal to tow a caravan over 100kph in WA, and also in NSW if your tow vehicles plated GVM or GCM when towing is over 4.5t, which includes almost every caravan and tow vehicle on the roads. These laws were put in place for a reason.
The faster you are going the least reaction time you have and the bigger the severity and impact.
3. TYRE PRESSURES.
Please ensure you check and maintain correct tyre pressures to help maintain minimal understeer and reduce oversteer in your caravan and tow vehicle.
NO- the max pressure indicated on the side wall of the caravan tyre is NOT the pressure to inflate them to.
Yes, I did have to say that, as some foolishly recommend that on social media unfortunately.
Your vehicle should have a tyre placard with recommended tyres and tyre pressures for certain conditions.
When towing, you may need to increase the tyre pressure in the rear tyres to compansate for the extra load, however as the front tyres usually have far less weight on them with a van attached they should remain at normal pressures to help maintain traction, braking and steering. Do not over inflate them.
The Truck Friendly web site has a section on TYRES under CARAVAN SAFETY. It also shows how to tell the age of your tyres.
4. CORRECT TOWING PRACTICES.
Please ensure your caravan and tow vehicle are set up correctly and both vehicle and caravan are relatively level when towing the caravan on the road. This will help ensure good braking, steering and improve stability. Approximately 50mm down at the hitch is a good general guide.
5. MAKE SURE YOUR TOW VEHICLE IS HEAVIER THAN YOUR CARAVAN.
You don't see a skinny hammer thrower at the Olympics for a reason.
Sumo wrestlers at heavy for a reason.
If a heavy car hits a lighter motorcyclist, who keeps going straight and who is flung off the road?
It is basic physics. Read Sir Issac Newton’s laws of motion we were taught in school.
Just because your friend said that they haven’t had a problem towing a heavy van with a lighter car in 20 years, does not mean they won’t have a serious problem on day.
A HEAVY CARAVAN WILL ALWAYS PUSH A LIGHTER TOWING VEHICLE AROUND. THIS IS NOT DESIRABLE.
Just because your glossy brochure said that the 3,200 kg GVM car, even when unladen at 2,300kgs can legally tow a 3,500 kg ATM caravan does not mean it should for safe towing practices. This is no matter what after-market accessories you have installed to try and stop sway.
Towing companies still recover rollover tow vehicles and caravans with anti-sway technology fitted.
Go back to basic safe towing practices.
We do not want a heavy caravan throwing around a lighter tow vehicle at 100 kph in any emergency situation.
There are other factors that affect caravan stability and sway that are covered in an excellent “10 causes of caravan sway” video by Robert Pepper – Automotive Journalist published previously on this page.
Above all, a little common sense may help keep us all safe.
Ken Wilson
Truck Friendly caravan road safety program
