Brand new caravan write off Bruce Hwy.

[BruceandBobbi]

Very interesting read.

The only comments I will make is a lot of the accidents as the one in this discussion happen on motorways that don't have bumps or pot holes.

Is speed, to heavy ball weight causing light steering and/or incorrect loading the problem?

[tomwithannl]

Very interesting read.

The only comments I will make is a lot of the accidents as the one in this discussion happen on motorways that don't have bumps or pot holes.

Is speed, to heavy ball weight causing light steering and/or incorrect loading the problem?

Yes to all. One of the areas I have always worried about is the vans with a rear double bed that lifts for underneath storage. Such a great spot for the annex and poles, canned goods, bbq plate, even an extra spare wheel. You know all those "things" you may need but want them out of the way.

Tom

[nj swb]

I'd like to shift the focus of this back to the trailer axle design.


From the images it appears to be a tandem torsion suspension.
So after a web search I found this article which I think is interesting in that irrespective of a drivers experience / skill at some time they could be challenged.

https://mechanicalelements.com/torsion-axles-in-tandem-or-triple/

Note: I own a very old (self reconstructed) single axle trailer, now mostly used for storage. But observed that my neighbors first and only Aussi circumnavigation attempt with a torsion suspension trailer ("Off Road style") resulted in failure of all wheel bearings twice and abandonment of trip.
I'm curious as to the failures, accidents etc that can be attributed to these "new" trailing arm torsion suspension systems that are being used extensively in RV trailers.
Again have a look at the article, link above.

How did you conclude it's a tandem torsion suspension. It looks to me like an equaliser bar of some kind between the wheels in the first image, and the second image is a single axle (and not torsion).

The article you link is essentially about the perils of a non-load sharing tandem or triple axle design using under-rated components. But I think the author nails it with this comment:

My hunch is there is not enough engineering that goes into many of these trailer designs.

You haven't mention if your neighbour's experience was single or tandem, but I'll guess it was tandem, and poorly engineered with components not properly rated for the application. This does happen, even with "professional" products.

My father and his second wife bought an off-road caravan to tow behind their 4wd. In the Northern Territory, the brakes on the van failed and pushed the entire combination off the road and into the scenery. Why? Because the cables for the electric brakes had been cable-tied along the front of the axle, and were peppered to pieces by stones thrown up by the 4wd. The manufacturer denied all responsibility for the accident (and is no longer in business under that name).

While looking into the incident, I also noticed that their "off road van" purchased with an "off road pack" had been fitted with passenger rated tyres that weren't rated to carry the ATM of the van. If the brakes hadn't failed it was probably only a matter of time before a tyre did.

Bad design is rife in the industry.

[Pushbike]

Hi NJ SWB,
The neighbors van was single torsion suspension. Why it failed- overloading, wrong bearings, poor design or the behaviour of this type of suspension, I dont know.

What we have learnt from you is that poor design, e.g. unprotected brake wiring, among others is a big issue with vans.


So that is why I have an interest in this accident, which seems to be one of many, "Mike Clayton of Clayton Towing, whose staff attended the Bruce Highway crash on Sunday, said his service was responding to caravan accidents every few days."
The first pic. shows the van was tandem suspension, the second pic. shows bright orange angled members, which I took to be the suspension arms.


So I believe the referenced web article, https://mechanicalelements.com/torsi...dem-or-triple/, is relevant and I hope all van owners have a look at it.


There are also references to single "axle" torsion design which emphasizes that the set out geometry (fixing) i.e. tow point and each wheel, must be near exact.

[Two Emms]

Bad design is rife in the industry.

And obviously, regulatory control is weak. Bad enough that a (potentially) dangerous product is manufactured but then it is allowed out on the road

[Paj11]

Ok, so for the lamens which manufactures get it right? and when buying a dual axel caravan what kind of descriptive wording should we be looking for or asking when buying one to make sure it has the correct setup of the under carriage?

[Dicko1]

Ok, so for the lamens which manufactures get it right? and when buying a dual axel caravan what kind of descriptive wording should we be looking for or asking when buying one to make sure it has the correct setup of the under carriage?

The manufacturers can make a van as big as a house or as small as a shoebox. Its the purchaser who makes the decision as to what he wants. In many cases this is an oversized monstrosity that it at the limits ( if not overweight) of what their tow vahicle can handle. I,ve said it before but people get sucked in by bullshit advertising and also amny want the wow factor to impress their mates and others.



Heres one article...https://www.club4x4.com.au/modern-ut...atings-bullst/


I was always under the impression that camping/touring Australia was about experiencing the great country we have. Not pulling a large box that stress,s bothe driver and the vehicle. Many have no idea on how to load their rigs for safety and many are fully aware that their rigs are too heavy but dont give a stuff anyways.


Until we have a caravan and vehicle industry that is held to account with real world figures and safety margins we will continue to see more accidents. The corona virus will also see a huge spike in van sales, putting more inexperienced drivers/towers on the road.


Caravan training course, compulsary ticketed individual van weights and vehicle tow weights decreased will see a safer road system for all.

[nj swb]

Ok, so for the lamens which manufactures get it right? and when buying a dual axel caravan what kind of descriptive wording should we be looking for or asking when buying one to make sure it has the correct setup of the under carriage?

I'm not in the market for a caravan, I'm just an interested observer watching from the sidelines with some fear & trepidation, so I'm not too sure who's good and who's not.

Start by looking at how long the manufacturer has been manufacturing in Australia - if they've been around for decades they should be doing something right. This is not to say that newcomers can't build good vans, and old manufacturers could be bought out / taken over / new management with "new ideas".

Research online reviews. You'll find bad reviews for every company, because we Aussies are much more likely to write a bad review than a good one. Some bad reviews are simply unjustified (the people who bought a behemoth too large for their twin cab to tow safely) and some good reviews are just fluff (We just picked up our new van! OMG it's so awesome!) Look for reviews from owners who have had their van for months or years, and offer good points and bad (tows like a dream, but the cooker needs another burner).

In terms of twin axle designs, look for "load sharing" suspension designs, or a model where each individual axle is rated for close to the ATM i.e. if the design doesn't inherently share the weight between each axle, then any axle could end up (briefly) carrying more than its share, so make sure it is rated for that.

A LR licence endorsement allows you drive a combination up to 16t gross mass, or about double a car licence. 8t GVM tow vehicle plus trailer not weighing more than tow vehicle.

A MR licence allows you to drive any 2 axle rigid truck which means effectively up to 16.5t, and tow a trailer up to 9t ATM. So about 25.5t or about 75% higher than LR.

A HR licence allows you to drive any rigid truck with more than 2 axles, so a 3 axle rigid up to 23.5t, plus trailer up to 9t ATM. So about 32.5t gross mass.

LR the trailer must not weigh more than the towing vehicle. MR & HR have limits such that the trailer is highly unlikely to weigh more than the towing vehicle.

But our least educated / poorest trained drivers are allowed to tow a 3.5T trailer behind a 2.5T ute at highway speeds. And we wonder why Clayton's towing is seeing caravan roll-overs on a regular basis?

I don't want to see a new licence requirement for towing a 6x4 to the dump, but I think the current system is simply inadequate. Perhaps we need a license endorsement for towing any trailer that requires breakaway brakes?

[Pushbike]

Ditto nj swb, well stated.


Could try van owners forums for info on the different units.

[Having Fun]

Bringing the thread back to the original photo of the wrecked caravan; I've looked closely at photos of that wreck here & elsewhere.

How did the wreck happen? Who knows!

However, the shackles in the chains on the draw bar are still done up, with the pins in place.

Kinda hard to see how that could happen if they were correctly attached to the tow bar while the van was being towed?

But, the fact is that those chains still have shackles in place, with the pins done up, after the crash.

We'll never know if the hitch was done up, as it's missing from the draw bar on the caravan.

[old Jack]

Bringing the thread back to the original photo of the wrecked caravan; I've looked closely at photos of that wreck here & elsewhere.

How did the wreck happen? Who knows!

However, the shackles in the chains on the draw bar are still done up, with the pins in place.

Kinda hard to see how that could happen if they were correctly attached to the tow bar while the van was being towed?

But, the fact is that those chains still have shackles in place, with the pins done up, after the crash.

We'll never know if the hitch was done up, as it's missing from the draw bar on the caravan.

A good observation!

I have always wondered how strong the attachment of the shackles to the tow bar is after I had a coupling come off at low speed. HR replaced the tow bar because the shackle attachment was bent and the holes elongated.

https://www2.pajeroclub.com.au/forum/showthread.php?t=53354

I often see safety chains that are way too long and would not prevent the coupling from contacting the ground it the trailer becomes uncoupled. Easiest way to check is to measure the height of the shackle attachment on the towbar from the ground and subtract 50mm , and this should be the maximum chain length. I suspect 99% of trailer and vehicle combinations would fail this test!

OJ.

[nj swb]

How did the wreck happen?

I'll guess something like this: https://m.facebook.com/7NEWSCQ/video...2728036503981/

No failure of draw bar / hitch / chains required.

[old Jack]

Good question and agree.

In the linked video the trailer did not become disconnected from the vehicle when the vehicle lost control and rolled but is appears that in the photo in post #1 the vehicle is not connected and the safety chains appear intact. It would good to know more about this situation.

The video link just proves how quickly things can go wrong with a simple overtaking manoeuvre at speed and with a vehicle trailer combination that is inherently unstable or has become unstable due to the change in road conditions, mechanical failure or driver input.

OJ.

[Just Cruzin]

You know what they say about common sense.

[nj swb]

I've just been back to have another look at the news story, and the first pic has been cropped.

When I first read the story, the first pic looked like this:


Based on the "tourer" branding on the side I tried to find more information about the van, but came up empty.