STABILISERS

[GeorgeB]

Having now been towing since the late 60's, I've never ever used a stabiliser in all that time.

I firmly believe that the caravan being matched to the car, being loaded correctly, both total & nose weights, and towing within your limits are all thats required to be safe.

However................I'm just about to upgrade to a new van, a Bailey Senator Indiana, to replace my trusty old Castleton. The Bailey comes with an Alko stabiliser.

Am I the only one who thinks that a stabiliser contributes to caravan accidents? inso much as they "mask" the unstable nature of some outfits and the inexperience of some of the drivers, by the time they realise whats happening its to late, caravan flips over, blocks the road & hey presto caravaners get even more bad press.

GeorgeB

 

[Lutz]

I think you are taking a rather negative attitude to stabilisers, rather like that there were claims that people would drive more recklessly when seat belts (later air bags)were first fitted to cars, because they would think that they could always rely on the added protection that they provide and therefore would not have to take as much are. The same also applied when ABS was first introduced (and, for that matter, some years later when ESP appeared, too). However, I don't think that there are any statistics to support such an opinion.

 

[MikeP]

Here's my simple opinion on stabilisers - they make stable outfits more stable. So yes - get the match, weights and loading right, and maybe go for a test drive to see how it feels. If all is well, then fit a stabiliser.

I used to tow my 850kg pop-top with a 1,750kg (ish) Espace. That's around 50% weight ratio, and the caravan was barely wider or taller than the car. Going down the M5 one year I had forgotten to "wind up" the AKS1300 to apply the friction pads. I could feel the effect of lorries and a brisk cross-wind. I stopped at services to apply the pressure, and the whole outfit was definitely more stable during the remainder of the journey.

I wouldn't tow without one.

 

[GeorgeB]

Lutz,

As I work within the motor trade, I can assure you that accident rates did go up when each of the mentioned safety items were introduced, especially ABS & ESP.

When I learnt to drive (& its a continuing learning curve!)if you made an error you learnt from your mistake & didnt do it again, but with ABS & ESP in operation, the car corrects the minor errors & the driver does not learn by the mistakes, no matter how effective these systems are, they simply cannot defy the laws of physics, so when the driver "cocks up" its usually big time!

I have no doubt that safety measures, such as stabilisers, have their place, but too much reliance is now placed on them, hence what should have been a minor, but none the less heart stopping incident, escalates out of all proportion, because of the reliance of the "safety feature" to extract the inexperienced/unwary driver from the brown smelly stuff!

Thats my theory & I'm sticking to it! although it's refreshing to hear an alternative point of view.

GeorgeB

 

[PC_5119929]

Likewise, I've always had well matched van and cars and had correct nose weight et, but have always used a stabiliser! On two or three short moves between camp sites I've not bothered, partly through laziness and partly through curiosity!

Result BAD BAD BAD move, I've noticed a marked difference straight away and having towed in all weathers and conditions going without the added security would have been crazy.

Anything that aids keeping van in a straight line has to be a positive move for that one tiny second that it saves your life.

Lutz makes a good point about abs and esp. A near neighbours wife did a U turn infront of me without looking at the weekend. My ABS and traction control almost certainly saved us from a big accident. I did nothing wrong, without the aids I would have hit the car for sure.

 

[mike_5041102]

Perhaps George is taking a negative view, nevertheless a correct one in my opinion. Stabilizers delay the onset of sway by increasing the critical speed of the combination. People will naturally take advantage of this and therefore risk being involved in an accident simply because braking distances increase with speed.

Further, there is the difference between static and kinetic friction. Once static friction has been overcome by the force of a caravan starting to sway, the remaining, reduced, resistance due to kinetic friction means the caravan will initially sway with more force than in the non stabilized case. This means less time for a driver to react to a snaking caravan

Stabilizers provide safer towing at a higher speed but there is still a critical speed for every combination beyond which the combination is unstable.

 

[354]

Stabilizers, like seat belts, airbags, ABS, etc dont cause accidents, its people who cause them, if someone thinks that by having a safety aid fitted they can then drive more reckless and to the limits of the outfit it is tjey who are the accident risk not the safety aid. I to have driven and towed for a great many years, but with the avent of all the above mentioned aids I still drive within my and my outfits capabilities. I aim for a well matched outfit and a well loaded outfit.

Personally i wouldnt tow without a stabiliser, like seatbelts and airbags I hope I dont need it, but i know it is there as security.

 

[PC_5119929]

Accident rates going up re ABS is another urban myth I believe. We go to a road research track near Bracknell for adavanced driving skills courses and skid pan training.

People not understanding what ABS does may have lead to a few accidents, but statistics re what ABS does shows that the accidents would probably still have happened I undersatand.

Many very experienced drivers when put into a skid will not be able to handle it no matter how many years experience they have had.

People with views on experience v technology turn up at every driver training course around the country and end up with egg on their faces George. The technology will beat you hands down in general, it will not stop accidents but it will prevent many more than those relying on X years of driving.

 

[Lutz]

Perhaps George is taking a negative view, nevertheless a correct one in my opinion. Stabilizers delay the onset of sway by increasing the critical speed of the combination. People will naturally take advantage of this and therefore risk being involved in an accident simply because braking distances increase with speed.

Further, there is the difference between static and kinetic friction. Once static friction has been overcome by the force of a caravan starting to sway, the remaining, reduced, resistance due to kinetic friction means the caravan will initially sway with more force than in the non stabilized case. This means less time for a driver to react to a snaking caravan

Stabilizers provide safer towing at a higher speed but there is still a critical speed for every combination beyond which the combination is unstable.

Your comments are only valid for frictional stabilisers, not active (electronic) systems. The latter do not have any threshold value over which they cease to be effective.

 

[David_5127637]

We all have our special views on stability. Personally I would not be without my Scott Stabiliser, not so much for sway but to dampen pitching on minor undulating roads. Certainly the well and regularly serviced caravan must be correctly loaded with no full water containers to induce "free surface effect" (slop). However, I limit my towing to twin axel caravans with a vehicle match of no more that 50%. Twin axel vans I have found to be so much more stable and less prone to sway (plus the added safety of four wheels). It does mean I would have a problem finding a replacement for our trusty aging Bessacarr Cameo 470 which fortunatly is still in excellent order.

 

[mike_5041102]

David,

quote 'towing to twin axel caravans with a vehicle match of no more that 50%'unquote. Must be towing with a HGV, with that combination I would think the stabilizer doesn't get to do much work.

 

[mike_5041102]

Lutz,

Lutz,

Not really familiar with the Active Electronic Systems and wonder how long it will be before such things are commonplace. I've yet to see a report or advert for one and suspect they will bear a heavy price tag. And will they be retrospectively available or only supplied with a new caravan? I think the reasonably priced friction damper will rule the roost for years to come.

 

[Justin_5121034]

test

 

[Justin_5121034]

test

 

[Lutz]

There are 2 types of active electronic trailer stabiliser systems:

a) Electronic systems in the car that sense yawing motion of impending instability of the trailer or caravan. These systems are further developments of vehicle ESP systems and are by far the most common. They are already standard fitment to some cars such as the Merc M-class, the BMW 5-series, VW Touareg and new Passat, Vauxhall Vectra, although in some cases only in conjunction with a factory fitted towbar.

b) Electronic systems fitted to the trailer or caravan. They basically work on the same principle as the above and are relatively easy to retrofit. To my knowledge, the LEAS system that I have fitted to my caravan is the only one currently on the market but AlKo have announced that they are planning to introduce a similar electronic stabiliser, too.

 

[Lol1]

Stabilisers increase the chance of an accident? Sorry to go all Spock like, but that is illogical!

Saying that because you feel safer or a safety feature masks underlying problems, it is more dangerous to use one, is simply bananas. Using that same thread of assumption you could say that instead of using a stabiliser, the manufacturers can simply construct their product so that if you load it incorrectly or drive too fast, the outfit becomes very unstable. Imagine that, travelling at 65mph on the motorway and the caravan is wriggling on the tow ball like a worm on a fisherman's hook.

That would certainly make you think twice and save some lives.

Hope this helps.

 

[ProfJohnL]

Hello all,

I thought it was just me that was having posting problems with the forum, hope its sorted now.

I can understand George's point of view, and I fully agree it makes sense to arrange your outfit to be as well matched as possible, but I don't think it should preclude the use of additional equipment to improve safety margins.

I am sure there is a significant psychological difference between the effect of a resistance stabiliser and ABS/traction control etc.

In simple terms, all outfits will have some speed at which the driver feels they cannot maintain full control. This by definition defines one of the limits of the Safe Operating Envelope (SOP) For any given outfit without a stabiliser it is likely that it occurs at a lower speed than with a stabiliser.

The effect of a resistance stabiliser is progressive and it effectively increases the size of the SOP. Unfortunately there is no obvious signal or feedback to the driver when they transgress from the original size of the SOP to the area that is only kept stable by the stabiliser. If they go beyond the expanded SOP, then the consequences will be more violent and likely to lead to a serious incident.

This is very different to the application of ABS and Traction Control, These features do nothing to change the characteristics of a car /outfit and the SOP remains the same But they only begin to operate when the envelope is exceeded, and they actually do something to bring matters back under control, and they let the driver know they are actually acting.

Lutz has mentioned an electronic stabiliser system, which seem to offer the benefit of ABS as it acts as a safety net, rather than expanding the SOP

 

[rob_jax]

Hi John,

Exactly as you stated, the University of Bath research report clearly shows that a resistance stabiliser increases the zero stability speed - the speed at which the car and caravan are tipped on the point between positive stabilaity and instability.

But it is also clear the stabiliser device continues to operate in a perfectly linear way above that speed, so your conjecture that the car and caravan would suddenly become unstable - like a spring that snaps - is wrong.

The beneficial effect of the stabiliser is to increase the zero stability speed to way above the UK maximum speed limit for caravans, and better yet, for people towing at acceptable and legal speeds - the car and caravan are better able to resist external effects - like side-winds or passing trucks.

Bath Uni quoted an improvement of 15% in these areas - which was much more than the improvement from correct nose-weight loading of the caravan - which they tested from the legal minimum to maximum nose-weight - and achieved a measured 5% increase in stability.

I certainly agree that optimising our use of safety devices, correct loading, and sensible driving are additive - every thing that we do to improve safety is beneficial.

Can't agree with George's comments that modern safety devices (like a stabiliser) contribute to caravan accidents. This has the logical conclusion that we'd all be safer if the car air bag was replaced by a 10" steel spike.

Robert

 

[Lutz]

I agree with the comments from John L and rob_jax altough I am a bit surprised that it needed a University of Bath research report to come to the conclusions stated. With a reasonable amount of technical understanding they seem pretty obvious to me. Just one comment I would like to add, though:

Because, as John states, frictional stabilisers increase the threshold value of when instability occurs but are of little help once this point is exceeded and because electronic stabilisers do not change the characteristics of the outfit, the two systems actually complement each other ideally. A resistance stabiliser coupled with an electronic one will offer just about the best protection against instability that there is available.

 

[VIP2006]

I have listened to this very important topic on stabilisers etc. and I would like to ask Lutz and other members whether they consider my outfit is ok.

I use as my towcar a Mercedes ML270CDi Auto (with ESP) and my van is a 2006 Coachman VIP 520/4 I have also read on another forum that using ESP can contribute to a "snake" and therefore should be switched off when towing.

I experienced a snake about 12 years ago and would not like to have another one.

 

[Steve L]

With all this technical talk, realy it is just down to how YOU load your van and how You drive.

I tow what could be called a ridiculasly large van behind an un suitable car. (20ft twin axle van with a 1998 2Ltr Laguna estate), but with careful attention to loading and sensible driving I've had 6 years of trouble free towing with this outfit.

Paying attention to getting the heavey stuff over the axle and getting a 75Kg hitch weight have paid dividends.

Driving cautiously, leaving plenty of room between me and the guy in front, not racing to climb the hill, decending hills in low gear, have all paid off for me.

My stabiliser is a snakemaster, which while I don't notice any positive affect to swaying, does help with yawing (up and down noding of the hitch). May be my attention to detail of hitch weight and loading had the affect desired, ie a stable outfit.

Being an "old school guy" I think all the electronic gizmo's of today make some of us a little complacent and too reliant on technical help. I'm sure a small minority thought ABS was the end of skidding in the wet, Air bags ment you could drive faster because you had more portection.

Bring back the thinking motorist I say. Believe me there are plenty out there of all creeds who haven't a clue and drive on regardless.

 

[Lutz]

Shiraz, you say you have a Merc ML270CDi. The Coachman VIP 520/4 should be well within its capabilities so long as load distribution, noseweight, etc. are set correctly.

Although your car is not the current model incorporating the latest generation electronic stabiliser feature, I cannot think of a condition under which ESP should actually be detrimental to the stability of an outfit when towing and should therefore be switched off. It certainly does not apply to the latest model because the system on that was designed specifically with towing in mind. All the road tests that I have read have always commented very positively about the ESP system on the Merc, even the previous model and also when towing.

 

[PC_5119929]

If the extra friction of a conventional stabiliser stops the van starting to swing in the first place, I can't see how you would ever be better off without one.

In heavy winds or with large fast vehicle passing we normaly know when things are starting to get risky before any sign of snaking about so we take the right actions.

A track instructor we went out with told us of some well known racing drivers who were put against electronic safety devices.

In straight line dry track conditions two racers using highly developed cadence braking skills managed to out brake ABS, in damp and wet conditions the electronics one hands down.

At the same time traction and stability controls beat the race drivers as well.

Average road drivers with many years of experience just do not face dangers often enough or have the reaction times or skills to beat mechanical and electronic aids. With the caravan behind us the whole driving equation changes

If some people think that they can race on regardless of conditions or load problems because they have a safety aid I would be brave enough to suggest that they are an accident waiting to happen with or without safety aids.

 

[David_5127637]

Hi Mike,

Interesting comment which I guess could be true for a post 2000 caravan.

OK, about 50%!. No, I do not tow with HGV. I tow with a 2005 Jeep Grand Cherokee Overland 2.7 ltr diesel with a gross vehicle weight of 2506 kg and kerb weight of 2235 kg. The caravan weight is 950 kg and the maximum laden weight is 1200 kg. It has a body length of 17ft 6 ins and an overall length of 20ft 6ins which by today's standards is probably short for a twin axel van. You are right in that the stabiliser has (fortunately) little to do horizontally but is useful to dampen pitching on minor roads.

The weight of the caravan is the reason for my comment regarding the difficulty in finding a replacement caravan as today's twin axel vans seem to be much heavier and longer.

Best wishes for happy caravaning and safe towing.

David

 

[trucker]

George, I think you are missing something with regards to safty fetures.

Every thing in life is a calculated risk from crossing the road to using a stabaliser.

If you cross the road and use a crossing point it will be safer however if you missuse the safty feture IE dont wait for traffic to stop or dont wait for the gerrn man to appear you are more likely to get run down!!

likewise if yo travel with a stabaliser and you dont worry about the weight or the distribution of the weight you will be at as much risk as if you dont use one, however if you abide by the rules and laws you WILL be LESS likely to snake of have an accident

Get real