Making Caravans Stable

Submitted: Friday, Nov 07, 2014 at 14:29
ThreadID: 110066 Views:2674 Replies:6 FollowUps:7
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Just letting you know that Collyn Rivers has a new article Making caravans stable on his web site today. He has already been contacted by some outraged van makers.


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Reply By: bluefella - Friday, Nov 07, 2014 at 15:00

Friday, Nov 07, 2014 at 15:00
That's an interesting read Peter, what I've seen some dual cab utes of all makes towing, caravans that would surely be on their limit, some dual cabs have 3.5t towing capacity. The unwary could easily take as being safe, IMHO I don't think it is, so off they go, just retired buy new tow vehicle and big caravan. If the tail starts to wag the dog this is a recipe for disaster.
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Reply By: Notso - Friday, Nov 07, 2014 at 16:24

Friday, Nov 07, 2014 at 16:24
On this subject, I had a lengthy conversation with a road train driver whilst on our last Round Aus van trip.

Discussed a lot of things but his main point was that the stability of vans has improved by leaps and bounds over the past few years. Hopefully this trend will continue and if the advice in the subject article was followed by all in the caravanning fraternity we would all be better off.

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Reply By: Member - Barnray (NSW) - Friday, Nov 07, 2014 at 18:12

Friday, Nov 07, 2014 at 18:12
A lot of people give Collyn a lot of hard time over his view's but He gets the facts so right. As far as I think they need to have a good look at the Facts and wake up to themselves. Barnray
AnswerID: 541400

Reply By: Ron N - Saturday, Nov 08, 2014 at 00:04

Saturday, Nov 08, 2014 at 00:04
"How the caravan is loaded may have a profound effect on stability"

Never were truer words spoken. Of all the things you can do to improve caravan handling, loading it correctly with the heavy items placed above or in front of the axle/s, will do the most to prevent the dreaded "tailwag".

I'm not so sure about the need for an extra-heavy tow vehicle. It's beneficial, for sure - but a properly set up towing combination will perform admirably with a tow vehicle lighter than the 'van.

In the 1960's I used to own a 30' early model, Modern caravan. It was single axle! - and it weighed 2.8 tonnes! (it used Landrover hubs and wheels - 7.50x16).
I used to tow it with a LWB traytop petrol, 4 cyl, 2.25L Landrover! The Landrover weighed around 1600kgs.
It took a while to get the old Landrover up to warp speed, but she would handle the 'van comfortably at 85kmh, and even 90kmh on a good run with the wind behind us.

The van was front heavy, it probably had 150kgs on the drawbar. It never once showed any signs of nasty handling behaviour, it trailed the Landrover like a puppy on a leash.

I've owned 2 x triaxle 27' Viscounts and they were towed with a 60 series Landcruiser with no dramas. Once again, the 'vans weighed more than the 'Cruiser. The Viscounts were always carefully loaded before shifting them, with attention paid to ensuring no heavy items were in the rear.
Heavy weights at the rear of a 'van are merely a pendulum waiting to be swung.

I've seen dozens of 'vans wrecked and most were destroyed by the wind blast from passing Interstate semi-trailers travelling at high speed.
The amount of wind deflection from a semi hauling an enclosed trailer doing 100kmh is huge.
If you have a 'van set up with marginal handling, all it takes is a good wind blast from a passing truck, and you're history.

There's little reason for the caravan manufacturers to be outraged. Many 'vans are badly designed, and very few have the axle set back from the centre of the chassis, as a good van should have.
I've seen 'vans that were an accident looking for a place to happen from the day they left the factory - because of poor axle/s positioning and poor design where heavy or bulky items were positioned too far towards the rear, in the construction.

I have always preferred front kitchen vans - for convenience, and because most of the weight tends to gather around the kitchen area.
There are many 'vans built with too much weight up high - which aggravates already suspect weight positioning.

And finally, I don't believe drivers with basic licences should be entitled to tow big vans.
If I had any say, anyone who wanted to tow a big van would undergo additional driver training, that included learning reversing skills, towing skills, and loading skills.
When they completed the training successfully, they would be given a caravan towing endorsement on their licence.

It's not good enough that someone who got their licence in an automatic Barina and who has never driven outside urban areas, can be let loose with a heavy 'van at highway speeds on the open road.
It's simply a matter of ensuring that people have the necessary vehicle control skills to enable them to keep control, when they encounter adverse conditions with a towing combination.

Cheers, Ron.
AnswerID: 541410

Follow Up By: Zippo - Saturday, Nov 08, 2014 at 11:45

Saturday, Nov 08, 2014 at 11:45
Ron, I couldn't agree more regarding the driver's licence. Heck, from the meal many have made of reversing a simple box trailer, a mandatory test and endorsement for towing ANYTHING would be an improvement.
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Follow Up By: skulldug - Saturday, Nov 08, 2014 at 16:10

Saturday, Nov 08, 2014 at 16:10
Ron,

With respect, I assume the interstate semi-trailer drivers you refer to have received training. Is it also reasonable to assume they are aware of the destruction they cause to other road users, yet they blast on down the highway regardless?

Skull
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Follow Up By: Zippo - Saturday, Nov 08, 2014 at 16:25

Saturday, Nov 08, 2014 at 16:25
Skull, what else do you expect the semi drivers to do when they see an approaching caravan rig - pull off and wait for it to pass?
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Follow Up By: Ron N - Saturday, Nov 08, 2014 at 17:14

Saturday, Nov 08, 2014 at 17:14
Skulldug, I will agree that a few (the minority) of interstate truck drivers have a hatred of caravans.
However, the problem is simply one of too many narrow highways. The Coolgardie-Norseman Rd and the Eyre Hwy used to be notorious for caravan wrecks, and it was purely and simply because the road formation was too narrow.
Vehicles travelling in opposite directions had only 1.2 to 1.5 metres at best for passing clearance.
Since these highways and many others have been substantially widened, the problem is not as bad as it used to be.
However, there's too many arterial roads left, that are still too narrow, and used by trucks at highway speeds.

Trucks are entitled to do 100kmh on the highways, that's the speed limit.
I don't recall any truck being instructed to slow down just because they see a 'van coming.
It takes time to wind 40 or 60 tonnes up to speed and most truckies hate slowing down.
However, if 'van owners are aware that the displacement of air from an oncoming rig can be a pretty solid hit, then they can be alert to it.
The largest % of truck drivers I know are reasonably considerate for 'vans, as long as the 'van owner has some consideration for the hassles of driving a big rig.

Surprisingly, it's not the flat-front full cabover trucks that are worst for the wind displacement problem - I've found that the short bonnet trucks such as the SAR Kenworth and the T series Scanias and the N Series Volvos all displaced air more violently than the flat-front models.
I've been overtaking an SAR Kenworth and had the displaced air from the prime mover send me a metre sideways in my ute when I hit the displaced air blast, such was the force. And that was with travelling in the same direction!

Cheers, Ron.
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Follow Up By: disco driver - Saturday, Nov 08, 2014 at 20:44

Saturday, Nov 08, 2014 at 20:44
And there is a huge difference with those semi's/Bdoubles with an Air deflector thing on top of the cab and those without.
Those with the air reflector fitted definitely do not disturb passing
vehicles anywhere near as much as trucks without the air deflector.

Just my thoughts.

Disco.
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Follow Up By: skulldug - Saturday, Nov 08, 2014 at 21:25

Saturday, Nov 08, 2014 at 21:25
Zippo,

I understand what you are saying but perhaps not killing people because you are in a hurry is a good idea.

Skull
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Follow Up By: Zippo - Saturday, Nov 08, 2014 at 21:45

Saturday, Nov 08, 2014 at 21:45
Skull, I'm not disagreeing with you but they ARE going to "keep-on-trucking. On single lane black stuff I couldn't even guess at the number of times I have needed to get right off and leave it to the semi or B-double.

Many years ago I was involved with the organisers of the first Darwin-Adelaide solar car race. Because of their concern for the competitors' welfare out on the Stuart (given that most pilots were foreign uni students and not used to road trains OR driving on the left), we had an extensive testing day at Hidden Valley. The cockroaches had to travel at a predetermined speed (60k I recall) while passing a road train doing 100k, and the results were closely observed. They all eventually passed the tests but some cockie drivers had to change their kimbies. (The hardest bit was getting the road trains up to 100k on the straight after coming around the preceding corner, and synchronised with the cockie).
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Reply By: Member - Chooky and Wobble - Saturday, Nov 08, 2014 at 23:14

Saturday, Nov 08, 2014 at 23:14
I agree with the comments, especially about the rear overhang of towbars.
My first vehicle for towing a van was the old G60 Nissan Patrol the rear axle was almost at the rear of the vehicle and the tow bar was mounted directly to the rear chassis member. The van was an early Millard and was quite heavy but it sat behind the G60 like it was on rails and nothing made it move.

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Reply By: The Bantam - Sunday, Nov 09, 2014 at 16:46

Sunday, Nov 09, 2014 at 16:46
If certain caravan manufacturers ( or others) are offended by CR's written comments...good....them being offended is over due.

The fact is caravan technology has done very little in the last 50 years.

The fact is the majority of caravans are of a format that is fundamentally unstable.....and extending that format makes it more so........ and little can be done to improve that.....it is the problem of the format......

"fundametally unstable format"

There are people talking about speed reduction......well I don't believe there should be any vehicle permitted on australian roads that is not fundamentally stable and perfectly safe at 100KMH, unless it operates under a special permit and carries rotating beacons and a warning sign.


While the heavy transport industry actively discourages the use of fundamentally unstable pig trailers ( one with a single, centrally located axle group) in favour of far more stable fifth wheel and dog trailer formats, the vast majority of caravans remain pig trailers....they call em pig trailers for a good reason......thay handle like a pig.



There is another matter that CR does not mention..that is most vehicles towing caravans that are not designed to perform well when near their maximum load capacity yet are loaded as such.

Allmost all heavy vehicles such as trucks and busses are designed specifically to perform at their most efficient when fully loaded....and in a commercial situation they are daily loaded fully.

Most of our passenger cars are designed to perform at their best when lightly loaded.
Thus their suspensinon are inhenrantly soft...this is not compatable with stable towing.

There has also much been said about these rediculous towing capacities many of these modern vehicles have.




Back to the caravan manufacturers being offended.

We all have to face the fact that almost without exception caravans are rubbish in comparison to mainline vehicle manufacture.....rubbish in every way.

Right from the wheels and tyres up.

Mostly the wheel and tyre format is pushed right up to its maximum capacity.....and them manufactured in cheap components.

NO main line vehicle manufacturer would even try to bring a vehicle no matter the price bracket to market with out shock absorbers and bump stops.....yet tha vast majority of trailers and caravans manufactured have neither.

The simple addition of adequate shock absorbers would improve the stability of any caravan or trailer.

look at the springs...usually short stiff and mounted direct to a straight, flat chassis.....little or no design involved.
and we could go on.


If you find a caravan manufacturer that claims they have anything like equal design and testing input in to their trailer designs as the main line automotive industry....ask them how many full time engineers they employ and if they can show you the results of the last lot of lane change tests they conducted.

All the major vehicle manufacturers will have done their own lane change testing....and if you or I wish to do ant sort of serious suspension modifications to an existing motor car we lwill be required to do lane change testing and produce engineers reports.

But none of this is required...in fact the caravan industry remains pretty well unregulated.
There are no formal requirements to set up as a caravan manufacturer.
There are is mandatory testing of caravans
There is not even any formal requirement for caravans or trailers to be engineered under 4.5 tonnes.
HELL, you don't even need to have any qualifications to weld caravan chasis.

Then there is the rediculous situation that you can drive a 9 tonne combination on a pasenger car licence.

You cant drive a 6 tonne GVM coaster buss on a passenger car licence....and they are a hell of a lot easier to drive than a landcruider with maximum towing capacity hitched up.

I'm not sugesting that a bloke should not be allowed to weld up a simple box trialer or even something bigger at home or that there should be a licence to tow any trailer.



BUT there has to be some sort of legal oversight introduced at some level.

Power to ya Colin...testify brother.

cheers
AnswerID: 541456

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