Caravan sway

GaryKelly · Guru

Caravan sway

Santa · Guru

GaryKelly wrote:
I see that today's GN story is about two accidents over the long weekend involving caravans and sway. Such incidents occur far too often. By the same token, a lot of GNs on the forum have been towing a rig for many years and many thousands of kilometres without incident, so what's their secret?

Morning Gary,

I suspect a good understanding of weight distribution combined with smooth driving habits and awareness would have to be pretty high on the list.

Dougwe · Chief one feather

Howdy Gary,

IMO I would say drive according to conditions and don't drive too fast, use your mirrors and look ahead plus all around you, know what is going on around you at all times.

kiwijims · Guru

I would agree with all the suggestions already mentioned but, there is still the un-known factor to consider, that is wind.

This can trap any experienced driver, especially out on the Plains such as crossing the Nullarbor,

I had a Mate who was crossing the Plains some years back, driving his brand new 18 wheeler,

he was driving along and suddenly found himself and his Rig on it's side, He said that it happened so quickly, there was no time to do anything.

K.J.

cultana · Senior Member

With one of those reports I find this interesting:
"In a strange twist, the car involved in the accident later caught fire and was completely destroyed while at the premises of the towing firm that had removed it from the accident scene."
But I suppose it saves having to fix the vehicle, though not nice for the owners.

oldbobsbus · Guru

Like others I spend a fair bit of time on the road and I think the 2 biggest contributing factors with towing accidents is :-

1 Poor weight distribution...

AND

2. Inexperience at driving with a trailer attached and driving to the conditions...

We see it only too often where drivers with a van on the back have very little control of their rig and are all over the road..

neilnruth · Guru

Yes we followed one down the highway that was all over the place and had no mirrors. I was glad when we overtook.

Scariest time I've driven a caravan was when I relieved an older couple travelling with us. He obviously had not loaded his van correctly and it was certainly a lot harder to drive than ours was. Weight distribution in the caravan is so very important.

wendyv · Guru

The caravan that was destroyed near Townsville had a large domestic air conditioner mounted on the rear bumper. It illustrates the fact that some caravan drivers have no idea about weight distribution in what they are towing.

Kendo · Senior Member

I'm sure I know the answer but some may not.

"Where is the weight best distributed?" confuse confuse confuse

My single axle poptop doesn't show any inclination to sway but again others may miss some of the telltales of an issue beginning to occur.

Just to finish "What are the techniques to stop a swaying combo once it starts?"

I always shudder at the "put your boot into it, and it will stop swaying" because you still have to slow down at some time. "Modern" rigs have electric brakes where you can press the button and allow the "van" to brake and straighten up but not all have that luxury.

Jeff

deverall11 · Guru

Kendo wrote:
"Modern" rigs have electric brakes where you can press the button and allow the "van" to brake and straighten up but not all have that luxury.
Jeff

Jeff, it's NOT luxury, it's LAW. Vam over a certain weight MUST have electric brakes.

Larry

Kendo · Senior Member

Thanks Larry.

But methinks you missed the whole point of my post. ie. What to do when the world starts a swayin!!

Perhaps a poor choice of words, and I hope all are doing the right thing as per the law.

I had an incident years ago towing a 6x4 trailer with some railway sleepers hanging over the back. Not a smart thing to do (I know now) but I used the stick your boot into it method which worked fine until the instant I tried to slow down again. I knew I was in trouble and after the second or third tank slap I just said "F@#@%!! it" and stood on the picks. I jack knifed but fortunately stayed upright. Little damage done but a lesson learned.

Advice on how to detect that "telltale wiggle" that something might just not be right to what to do when each sway is becoming amplified and your running out of options real quick, is all I ask.

This is a serious question and any advise could just save a life.

Jeff

Legendts · Senior Member

My opinion is if it starts to sway you can do a couple of things, together. As stated previously activate your van brakes only and also slightly accelerate at the same time. DON'T hit your tug brakes. If you don't have van brakes, slight gentle acceleration should help pull the trailer back in line and when it does stop and try to put a bit more weight on the ball. Again my opinion only but it has worked for me many, many years ago. Have not had a serious sway event in the past twenty or so years.

Edit. Re telltale signs. First indications would be a feeling of the rear of the car "feels not quite right" and you should have been looking in your mirrors where you would see the vans rear swaying. Hope that helps to answer it.

-- Edited by Legendts on Tuesday 10th of June 2014 09:49:47 PM

Graden · Veteran Member

Haveing towed many types of trailers/vans, both single and twin axle, my experience has shown that good weight distribution is essential. That means placing between 5% and 10% of the gross trailer weight on the towball. Do not exceed the tow vehicle's towball or towing weights. Do not have a heavy weight placed after the rear axle of the van to compensate for too much weight forward, the effect of heavy weight after the trailer axle will promote a "pendelum effect" whereby the rear of the trailer will start to swing and build up momentum, eventually causing an almost uncontrollable sway. This effect is most noticeable on a winding road.

To control excessive trailer sway, lift foot off accelerator pedal and allow the vehicle to slow down, do not brake or accelerate. When control has been gained, gently brake to a stop and redistribute load, if possible, else proceed slowly until you can reload the trailer.

Read and follow the trailer/van manufacturers weight specifications as printed on the compliance plate of the trailer/van.

The following is an extract from Etrailer.com:-

Do's - Good Towing Practice

Gradually reduce speed
Steady the steering wheel - sudden turns can cause more sway
Apply only the trailer brakes to help reduce trailer sway

Don'ts - NOT Good Towing Practice

Do Not slam on the brakes - jackknifing could occur
Do Not attempt to steer out of a sway situation
Do Not increase speed - Trailer sway increases in faster speeds
Do Not tow a trailer that continues to sway
- Look at reloading the trailer or perhaps adding a sway control or a weight distribution system with sway control

Kendo · Senior Member

Thanks guys,

Just the sort of advice I was trying to raise.

I am certainly no expert, but I had the advantage of "Been there, Done that, and Survived to tell the tale"

It was a scary and dangerous experience. To read and understand a bit of advice may prevent someone having to do the same with the potential of much more serious outcome.

Again Thanks

Jeff

Aus-Kiwi · Guru

I find looking forward and driving straight.. Looking back makes it much harder to keep it straight..
Yes just a little brake.. Depends on tow vehicle also.. The closer the rear wheel are to tow bar the less
it will tend to sway.. The old Valiants although powerful the overhang didn't help..
Most good 4WD have wheels close to rear for clearance..

NandK · Senior Member

Some good advice on here but one thing not said is tyre pressure .
Correct tyre pressure is as important as weight distribution, if one tyre or two on tandem have different
pressure then you will get a lot of van sway.This happened when I moved a van for a relly could not get over 70ks,
I checked the tyres all four had different pressures put correct pressure in and made all the difference..

The Phantom · Guru

One can bang on all they like about weight distribution, tyre pressures, wind, brakes or whatever takes your fancy, but Dougwe's comment about going too fast is the main cause of sway.

Cut the speed and maintain control. All the other factors contribute to the final effect but speed is the main cause.

The Phantom

Cupie · Guru

The only time that I had a problem with trailer sway was many years ago, in the 1970s, when I was driving a Valiant with a box trailer on behind.

The trailer was very overloaded with old railway sleepers that I was using for landscaping. They were overhanging both ends of the trailer & piled right up. No ropes or tie downs. Used to get them from an old abandoned railway line.

Zooming along the country road & the bloody thing got up a huge sway. I think that I just eased back on the accelerator & let the unit slow down on the slight upgrade.

Very slow drive home after that & much smaller loads followed.

(SWMBO later totaled my beaut Valliant when she ran in to the back of a cement truck)

-- Edited by Cupie on Wednesday 11th of June 2014 09:15:24 AM

Baz421 · Guru

Legendts wrote:
My opinion is if it starts to sway you can do a couple of things, together. As stated previously activate your van brakes only and also slightly accelerate at the same time. DON'T hit your tug brakes. If you don't have van brakes, slight gentle acceleration should help pull the trailer back in line and when it does stop and try to put a bit more weight on the ball. Again my opinion only but it has worked for me many, many years ago. Have not had a serious sway event in the past twenty or so years.
Edit. Re telltale signs. First indications would be a feeling of the rear of the car "feels not quite right" and you should have been looking in your mirrors where you would see the vans rear swaying. Hope that helps to answer it.

-- Edited by Legendts on Tuesday 10th of June 2014 09:49:47 PM

I agree Jeff with the thrust of what you say,,, and as I stated many times I used to teach guys to get out of jacknifing semitrailers in the 70's,, we actually started the jacknife slowly on dirt road and then corrected.

ONE VERY IMPORTANT THING TO REMEMBER - if you have a REAL EMERGENCY??????? WILL YOU BE ABLE TO TAKE ONE HAND OFF THE STEERING WHEEL TO APPLY TRAILER BRAKES ONLY????

From my experience many people wouldn't be able to do this for 3 reasons:

panic

location of brake controller and probably unable to reach (this equals increased danger of total loss of control) ie they never tried it whilst driving

the need to hold onto the steering wheel and drive the vehicle to maintain control

Agree to look ahead and straighten the rig IS THE MAIN PRIORITY.

Sorry about the red it's stuck ON.

Baz421 · Guru

NandK wrote:
Some good advice on here but one thing not said is tyre pressure .
Correct tyre pressure is as important as weight distribution, if one tyre or two on tandem have different
pressure then you will get a lot of van sway.This happened when I moved a van for a relly could not get over 70ks,
I checked the tyres all four had different pressures put correct pressure in and made all the difference..

Also if tyres are flat you don't get lateral support that tyres are designed to give,,, flat + more sway or yaw.

sandsmere · Guru

Another thing not mentioned here is the WDH setting .

I've often seen them incorrectly set up.

Also , there is often far too much weight at the rear of the van. Modern vans are made to be correctly balanced .

Adding too much weight to the rear bar can be fatal.

deverall11 · Guru

Legendts wrote:
My opinion is if it starts to sway you can do a couple of things, together. As stated previously activate your van brakes only and also slightly accelerate at the same time.

-- Edited by Legendts on Tuesday 10th of June 2014 09:49:47 PM

Good idea Jeff, except some new vehicles especially the one that have RBW systems, do not allow you to accelerate and brake at the same time. Try doing that on a 200 series Landcruiser.

Larry

Aus-Kiwi · Guru

Speed is a factor ... BUT if you have to drive "well" under the speed limit to be SAFE ? The rig is NOT set up correctly !!! I'm also very surprised at the quality of some tyres fitted!! They can be half warn but some new tyres that you wouldn't fit to a car shouldn't be fitted to your van ! San Yang I wouldn't fit to my wheel barrow let alone my pride and joy doing 80+kph ..
Btw heavy things should be between axle and front of van..
One smashed van I saw a fresh water tank behind the axle
, this would cause sway big time ! ESP if there's no baffles and full of water ! !!

-- Edited by Aus-Kiwi on Wednesday 11th of June 2014 06:37:30 PM

Legendts · Senior Member

deverall11 wrote:
Legendts wrote:
My opinion is if it starts to sway you can do a couple of things, together. As stated previously activate your van brakes only and also slightly accelerate at the same time.

-- Edited by Legendts on Tuesday 10th of June 2014 09:49:47 PM
Good idea Jeff, except some new vehicles especially the one that have RBW systems, do not allow you to accelerate and brake at the same time. Try doing that on a 200 series Landcruiser.
Larry

Sorry Larry I didn't make myself clear enough, by applying the brakes I meant only the van brakes, not the tugs.

Legendts · Senior Member

Aus-Kiwi wrote:

One smashed van I saw a fresh water tank behind the axle
, this would cause sway big time ! ESP if there's no baffles and full of water ! !!

-- Edited by Aus-Kiwi on Wednesday 11th of June 2014 06:37:30 PM

Not necessarily, our Evernew at nearly 8m has two water tanks behind the axle and one in front. If the manufacturer does his job right it's all about balance. Had the van 11 years, never had any issues with sway whatever and use only a WDH. I need to mention that the wheels (Simplicity suspension) are behind the van centreline and I have 340kg on the ball. I generally tow at 100k/hr depending on weather/road conditions.

Cupie · Guru

I have saved an extensive article by that well respected guru Collyn Rivers (I think) titled Vehicle Dynamics. Unfortunately it is copyrited to Caravan & Motorhome Books , so I can't post it here. It's a very long & technical article so I just pasted the conclusion here.

Sorry about the way it is formatted ...

"Conclusion

A long end-heavy caravan commonly feels more stable than a short one with centralised mass (short twin-axled vans are

usually very stable but often feel twitchy due to their fast but minor movements), but such impressions are illusory.

Inertia is not the same thing at all as inherent stability: a giant container ships seems ultra-stable - until a rogue wave rolls

it too far - and its inertia keeps it rolling).My mega-van always seemed rock stable until the day it jack knived and rolled over

is a very common post-accident reflection. I suspect further research will result in long end-heavy caravans being relics

of the past, not least because, over a certain length (that I suspect to be about six metres) the fifth wheel configuration

dynamically makes so much more sense. There is also ncreasing evidence that the probable safe speed for big rigs is less than

the limit of 100 km/h.

Having researched this issue in depth for the past 10 or more years I would not personally tow any conventional caravan

longer than five metres at over 90 km/h, unless built in accord with the generality of this article.

And even then, not at over 100 km/h, even were laws to permit"

-- Edited by Cupie on Thursday 12th of June 2014 09:13:40 AM

Bevandy2 · Senior Member

Speed, as mentioned, is a vital factor, also van set up and design.
10 to 15% ball weight is recommended, most vans are designed for that, as someone has mentioned, wheels set back of centre, and water tanks located to provide maximum stability.

Our pop top has two 58 litre tanks, one is well forward of the single axle, the other is just behind the axle, we always travel with them full for ballast and stability, (low centre of gravity) and try to load heavy stuff over the axle or forward of it. (the van is designed to enable that, behind the axle is mostly only the kitchen and toilet)

I tow at 90 to 100, conditions permitting, a very stable rig, barring devastating cross winds one trip down the Coorong, but that is another story.

Agree with all of the above, a lot of experience and good advice. (we have towed well over 200k with our pop top since 2001, never had any incident)

Bevan

Baz421 · Guru

Legendts wrote:
Aus-Kiwi wrote:

One smashed van I saw a fresh water tank behind the axle
, this would cause sway big time ! ESP if there's no baffles and full of water ! !!

-- Edited by Aus-Kiwi on Wednesday 11th of June 2014 06:37:30 PM
Not necessarily, our Evernew at nearly 8m has two water tanks behind the axle and one in front. If the manufacturer does his job right it's all about balance. Had the van 11 years, never had any issues with sway whatever and use only a WDH. I need to mention that the wheels (Simplicity suspension) are behind the van centreline and I have 340kg on the ball. I generally tow at 100k/hr depending on weather/road conditions.

Agree with Jeff here in regard to balance and tank behind centre line of the axle group,,,,, ie a 60 litre water tank in a van of 3000kg ATM is only 2% of the weight,,, not likely to effect the balance and dynamic stability is it, especially if its close to the centre of the axle group ie say within 1-1.5 metre.

Driver input to steering wheel,,, ie turn left/right and sudden corrections will have a far greater effect.

-- Edited by Baz421 on Wednesday 11th of June 2014 09:17:57 PM

NandK · Senior Member

I have had Electronic Stability Control (ESC) fitted and have found it well worth the $1300 paid.
Works well in cross winds and when semis go flying past at great ks..

Bryan · Guru

NandK wrote:
I have had Electronic Stability Control (ESC) fitted and have found it well worth the $1300 paid.
Works well in cross winds and when semis go flying past at great ks..

The dealer is fitting them to my van too when it arrives at month end.