Dangerous outfit

[Lutz]

There's an easy explanation why you experienced improved stability with a big box on the roof of the car, Steve. The big boxes take the headwind that would otherwise hit the front of the caravan. The reduced wind drag on the van lessens the effect of decreasing the noseweight. As everyone knows, a low noseweight is one of the major contributors to instability, so if the noseweight is not reduced by air drag, the outfit will remain more stable.

 

[cris_408518]

I think you are having a problem and getting excited that the Germans are selling caravans that are not as safe as the British twin axles Lutz.

You are not reading straight, the comment was not re weight! But re Articulated style trailers that carried bulk not weight and had no need for multi axle trailers.

Having had a love affair with German cars and bikes for many years it has always amazed me that despite the quality of body building in German Caravans they opt for the more dangerous single axles. I guess its a money thing difference between the Brits and the Germans.

But then again may be the fact that most car manufacturers from Germany, Italy, France, Japan and America rely on British

Dynamics engineers to fine tune their cars handling is something the German and other Continental caravan manufacters should follow.

I'm not the average tow person as for many years I've towed for many more miles than the average car drivers total annual mileage. We changed from single axle to twin axle works trailers carrying the same weights and bulk for safety and stability when towing. It was not an idle whim, but a move made from experience and avery one that's towed the old singles noted the improvements with the twin axles.

Apart from safety towing long distances, the twin axle platform gave us a better spread of weight enabling us to reduce framework bulk and make a long collapsible trailer that would fit inside our vehicles when empty.

Our first T/A van was towed by the same car as our old single.

On the same holiday route to France apart from the noticable improvement I noticed even my wife and kids were aware how much better a drive it was. And the old single was a popular Swift with a good reputation.

Believe what you like Lutz, but from towing like loads with single axle trailers, race car trailers and caravans and camparing to the same loads with twin axles if you or any one else can kid yourselves that all things being equal the single axle offers you as much safety as a twin you are living in fantasy land dream world.

 

[cris_408518]

ps. One should also be aware that tests tend to be carried out by test drivers who spend their working day living on the edge and knowing what to expect and how to react and having the ability to take natural courses of actions to aid correcting test data in a relatively safe test track environment with bends and curves formed by markers with huge expanses of run off area to the side and no other traffic.

Many caravanners do not get those options when things get nasty. They have other traffic, side of road cliff faces or huge road side drops or kerbs or armco to avoid when they get it wrong or are forced to take evasive action.

Extra tyre grip, braking or straight line forces that a twin axle gives are not something you'll want to be without if all hell breaks loose with the wife and kids sat with you.

 

[Lutz]

Surely you aren't suggesting that German caravan manufacturers have less concern for the safety of their customers than others? That is really an abhorrent accusation. From your statements one would think that the whole of the Continent would be littered with the remains of whopping great single axle caravans. I can assure you that this is not the case. I cannot confirm that the accident rate involving caravans on the Continent is any higher than in the UK.

Furthermore, you still have not provided any real concrete or verifiable evidence that twin axled caravans are any safer than single axled ones other than your own personal conviction.

 

[cris_408518]

Any accidents rates would have to take into account a wide variety of other road issues Lutz as the roads differ so much between UK and much of Europe.

And I do believe that safety is compromised by towing large single axle caravans.

And whats wrong with personal experience, all things being equal carrying a child around on a motorbike should be as safe as using a car. Personal experience would suggest thats far from the case.

You have come up with nothing to suggest that single axles caravans are as safe as twins. All the guff about manoeuvereing on sites or loading issues are just smoke screens.

A twin can be easier to roll and move than than a single axle when unhitched.

When you tow a caravan if you have any sense you comply with all loading advice and nose weights etc so be it a twin or single axle it should hit the road in optimum trim.

People jump on the unhitched manoeuvrability of twin axle caravans but then discard the affects of the extra tyres when towing the van.

You also fail to address the trailer market and points made. Lets be fair, a caravan is a glorified trailer. Surely any business wants to save on expenditure when purchasing trailers.

If a single axle is so good and equal in performance to a twin axle why are there so many more costly twin axle trailers that could carry more weight by discarding the second set of wheels.

It seems that in Lutz world the difference I and others note re the improved safety and handling are to be ignored as there is no bit of paper to say it has been proven on a test track by men in white coats.

Those nice big BMW's and Audi's gain bigger tyre footprints and more braking the bigger they get and the faster they go and are able to corner yet a twin axle caravans tyre footprint and brakes are to be ignored and supposely offer nothing over a two tyre set up.

I take it that you are saying Lutz, is that given the same two cars towing two correctly loaded equal sized caravans one being a twin axle and the other being single axle at 60 mph your first choice would be to tow the single axle when one tyre is blown out in the same way on each caravan.

If you honestly believe that you stand as even a chance of stopping as well as the twin axle will I and no doubt many others will be staggered.

In Lutz world it seems 25% loss is equals 50% loss.

 

[ProfAlGoogle]

It's the maximum legally permissible axle load of 10.5 tonnes per axle (in the UK) that governs the number of axles HGV trailers have. A 40-odd tonner is therefore going to need a miinimum of four axles (probably five due if the load on each axle isn't evenly distibuted). It has absolutely nothing to do with stability.

It also concerns road tax, more axles= less road tax,Hgv's running on 6 axles normally carry a pay load of around 28 tons, if the unladen weight allows, with a mgvw of 44 tons.

 

[Lutz]

If single axled caravans were significantly less safe, then the experts would have come up with verifiable evidence that this is the case by now and the fact would be general knowledge throughout the industry and the public. I make a point of reading as many research reports from the manufacturers, organisations and institutes on the subject of towing as I can lay my hands on and yet I have not seen one shred of evidence from any source of authority that there is any difference.

Most people cite examples of motorway accidents involving caravans (probably because they are the most spectacular) but I just cannot imagine that the conditions on the motorways of mainland Europe are, on the whole, that much different to the UK. (I'm in the UK at the moment so I am able to judge). OK, traffic density in France is probably on average less but that on German motorways compares closely (besides there is a bigger speed differential which, if anything, would aggravate the situation to the disadvantage of the towing community).

The justification for twin axled trailers, as opposed to caravans, is twofold:

The twin allows smaller wheels and hence a wider lower load height, a definite advantage for car transporters and horse boxes, for example.

The twin is less sensitive to unequal or varying payload distribution between left and right, such as twin horse boxes transporting only one horse or heaps of bulk material on one side of the flatbed. A caravan is not subjected to such large variations (the payload is usually only in the order of 200kg whereas a transporter can easily have a payload of over 1000kg).

The fat tyres on BMW's and Audi's that you mention are provided for driving conditions that are totally incomparable with towing a caravan. Few people have sporting ambitions when towing.

I cannot speak for relative stopping distances between a single axle and a twin and until I see actual data I cannot comment further and would ask to leave this issue open.

 

[ProfJohnL]

Hello cris & Lutz,

In the context of your argument, can each of you define 'safe' please

 

[Lutz]

In the context of my argument, 'safe' refers to absence of accidents attributable to the number of axles. It does not refer to any perceived feeling of additional security because an outfit may appear to be less 'twitchy', for example.

 

[ProfJohnL]

In the context of my argument, 'safe' refers to absence of accidents attributable to the number of axles. It does not refer to any perceived feeling of additional security because an outfit may appear to be less 'twitchy', for example.

Thank you Lutz,

I hope that cris also responds.

 

[cris_408518]

This is like the race driver who thinks that the theory book will make him a winner.

Time to get real Lutz you now acknowlege some of the benefits of a twin axle trailer but exclude them from a twin axle trailer ( that's what a caravan is )! There are plenty od bix trailers he size of caravans! You also ignore pitching in your summary re trailers.

You take the car case and equate it to a performance sittuation when any one with basic knowlege knows that improved traction has benefits at low as well as high speed, but for your argument you ignore the additional traction and improved sidways lateral movement abilities re twisting motions of a 4 wheel caravan compared to a 2 wheel single axle.

You can drive without a seat belt on or without abs, when things go wrong you realise that you might need them. It's the same with the extra traction and braking and low down weight of a twin axle caravan or when a tow blows out.

If you need a bit of paper to confirm that loosing 25% of what holds a caravan up compared to 50% is not a better option than you need help Lutz.

As for safe John. Safe is when nothing goes wrong ;-)

Safer is having any little positive edge re maintaining stability when things go wrong whan towing a caravan.

Lutz thinks less traction, less braking, less tracking ability, worse c of g, higher up weight, no resistance to pitching and single axle pivot points are no advantage!

 

[cris_408518]

Accident sittuations happen and have nothing to do with the number of axles you might be towing at the time.

Lutz even ignores the sheer prove fact that a t/a van is harder to push sideways. The only advantage in Lutz mind is that its something t/a tuggers imagine.

Unreal, just unreal!

 

[paul_5132583]

Hi Guys, I presently tow a twin axle Swift Conqueror, didn't go out my way to purchase a twin axle, just right caravan and right price, my previous caravan was an elderly Elddis Sirocco twin axle,whilst towing down through France on two separate summers, first year suffered a blowout , didn't realise until it was brought to my attention, vehicle following repeatively flashing his headlights!, second year actually saw the tyre explode through the mirror, once again no stabilty or handing issues, I am not aware of any ones professional qualifications presently conversing on this forum, to substaniate the present topic, but i can offer my personal experience, like most things in life you can't beat experience.

Regards Paul

 

[Lutz]

Less traction?? The towcar is responsible for traction and this has nothing to do with the caravan.

Less braking?? I asked to leave this issue open as no information is available (unless you wish to produce it). Another case of 'I think it must be better so it is'?

Less tracking ability?? I presume this means straight line running. I'll let that advantage count but it doesn't necessarily make the caravan any safer in terms of accident avoidance, only less 'twitchy'.

Worse C of G?? How potentially 1" to 2" lower C of G can make a more than a marginal contribution is beyond me.

Higher up weight?? I think it should have become clear by now that the second axle of a twin cannot be weightless so the MIRO of a twin must be higher than an equivalent single axle.

No resistance to pitching?? Although a twin theoretically provides some resistance to pitching, a good stabiliser will do the same for the single axle and besides, few accidents can be attributable to excessive pitching (or do you have data for that, too?).

'I had an accident with a single axle so a twin must be safer' seems to me to be a very strange logic.

 

[MikeP]

Gents, a quick observation. I'm not taking sides, just saying what I see.

Cris - you're starting to get personal. Comments like "you need help Lutz" and "Unreal, just unreal" won't help. Lutz is responding as a true gent.

This has been a good lively debate - which surely is what the forum is about. Please don't start mudslinging and get the thread deleted.

 

[cris_408518]

So are you saying that only drive wheels gain traction Lutz?

Traction to me means Grip ! If you have no traction or grip from trailer tyre they would start to slide sideways on some corners.

Cornering needs traction/grip and a caravan will slide sideways due to cornering speed or under severe braking.

Pitching can lead to instability of a tow vehicle and a twin does not pitch in the way a single does either, with or without a stabiliser and because you to a twin it does not mean that you have not got a stabiliser as well.

Towing with a single axle and not having a problemsdoes not make it as safe as a twin either.

Where Lutz's "I had and accident with single accident" comes into it is beyond reason quite frankly and his comment re he will allow a point count is quite rude.

You can take all the test data and bits of paper you want but its the person behind the wheel that gives the best final assessment thats whuy they use test drivers ibn cars.

Pitching in itself should not cause to much of a problem, combine it with a strong side wind, going into a bend or with a strong bow wave wind from a truck or coach and the whole dynamic changes but Lutz either disregards that or can't fore see the possible problems.

Lutz's disregard for the fact that a caravan is a trailer and not some special case is staggering.

Lutz is good at avoiding questions and going on about bits of paper and data.

 

[sparkes]

Cris

traction and grip are two seperate forces even in motor sport.

Traction is a term used for driving wheels as it is the ability to move the vechile and place power from the engine. Grip is the adhesion of the two surfaces.

Its starting to look as if you want an argument with lutz for no reason. Lutz has a great deal of experience in this area.

The way you are wording your replies is to third parties and not direct. this is starting to look like an attack and will be picked up by the mods.

Just my thoughts, nothing else

 

[sparkes]

sorry I read my reply and explained it badly so will try again

Traction: the mechanical force used to achieve motion.

Grip: Frictional hold between 2 surfaces

Traction cannot be gained or applied to a wheel that does not have drive as it is the transmission of that drive to the road surface that defines traction. Grip is a component of the calculation of traction or is a stand alone component of a non driving wheel / surface connection.

Geek signing off now....

 

[Lutz]

The discussion has become rather heated so let me just summarise my position regarding twin axles:

Twin axles have their rightful place for those people who value their inherently good straight line running ability, i.e. towing comfort, very highly (although in this respect a good single axle can be better than a bad twin axle, as Steve himself has noted).

Also, for those people who, like Cris, have a 'gut feeling' through personal conviction that a twin axle must be safer.

I'd even not argue with those that say a big caravan somehow looks better with a second axle, i.e. the proportions are better.

BUT, from a purely rational standpoint based on safety, there is nothing to support the need for a second axle other than for the very biggest caravans.

Cris's reaction that, quote "You can take all the test data and bits of paper you want ...." confirms that he has shut himself off from further objective discussion.

 

[cris_408518]

It's actually splitting hairs Steve, it is common in Racing for loss of grip on un driven wheels to be described as loss of front wheel traction say in a F1 car or on a race bike. Even Senna's death was decribed as being possibly caused by loss of front wheel traction due to suspension failure on a bumpy part of the track.

So calling it grip or traction does it matter that much.

Lutz may have certian experience but his points exclude any common sense it seems and what I see as his blinkered attitude re having a bit of paper compared to well proven vehicle knowlege and practices is an attack. His attitude that twin axle is just some one upmanship is a futile remark and and could be taken as an insult to British Caravan manuafcturers.

Twitchy in my humble experience means instability when using some form of transport be it boat, car, truck, bike, trailer or caravan.

Lutz attributes weight to the second axle, but gives that lower down weight no credit re stability and dismisses effect such as weight riding lower down. A lot of race car engineers who have to weigh their cars in at fixed weight go to any length to shed weight that is not very high up in the first place just so they can get it lower down and improve cornering stabilty and lessen forces on suspension steering and tyres for cornering.

One formula championship was won last year with a new engine that shed about 10 kilos that was then moved to the floor pan of the car. No more power but lower c of g said to have given the winning advantage.

In a caravan weight differences may be minimal, but that does not mean that can not play a vital roll especially when things go wrong.

Two tyres tracking one behind the other in the rain and the rear tyre rides in less water as the front clears a lot of it is given no thought or credit. This is more extreme but given bad conditions on a wet dark motorway I'll put my money down that you will get better handling and braking from a twin axle rather than a single and that's excluding my personal experience of both.

Apart from many personal towing experiences and many observations re towing being a very high mileage motorist for many years I would add the following.

Towing a twin axle caravan on route in Wales we encountered new motorway road works with bad road surfaces and steep cambers. The rear nearside tyre of the caravan was pierced by a damaged road sign laying in the road. Due to the road surface I slowed even more as something felt wrong and as I took a roundabout I was aware of a lean to one side on the caravan and stopped, as I exited the car I had a police patrol vehicle stop behind me and the driver called and said to follow him. We were lead to a near by Asda car park and as it was raining the two stopped and helped jack the caravan and change the wheel.

They had been behind us on the coned off temporary road and had seen the tyre punctured, and stopped to remove the debris before catching up with us as I turned off the roandabout.

The senior officer of the two was some sort of police accident investigator and made comment that it was lucky we had a twin axle caravan, the area was being patrolled due to problems caused by the tempory road surface and ramps that the contractor had been forced to alter due to accidents. Two other caravans had tyres puntured there and being single axles they had been damaged and blocked the road. The senior officer with 22 or 23 year service himself said, "we see enough caravans to know what I'll buy when I get old" ( a joke re caravanners), he was referring to twin axles.

Many automotive firsts come about through a gut reaction and experience from simple observations and very simple practical knowlege.

Lutz seems to believe that I only count my own caravanning experience re my choice, that is not the case.

I have never had an accident with a Caravan as such but I have had puntured tyres and know enough to make what I and many others would consider a more than well qualified choice.

We made an insurance claim for a twin axle caravan that was written of on a French auto route when we lent it to family. The accident had nothing to do with the caravan and was due a failure on the tow car. The Autoroute was closed and French Police accident investigators took all evidence, data and witness statements including that of an English truck driver who was a caravanner. I had to deal with the caravan claim and the car driver with the cars insurers.

The witnesses to the accident credited the straight lining of the twin axle as preventing it being a more serious accident. The understanding was that the French police credited the stability of the twin axle as a major factor in minimising the accident damage. Both the car insurers engineers and the caravan insurers engineers remarked indepedently that it was lucky that it had been a twin axle caravan in tow. Normaly I doubt we would have been in contact with those people, but as the accident was outside this country it was not a straight forward claim and involved calls to France and having a report from an English engineer familar with UK caravans for us.

Quite a number of our family and friends have caravans and I'm pretty sure all have twin axles now as their towing experiences bring them to the same conclusions as me and many others.

Pauls comment re his tyre loss experiences is quite a common theme with twin axle caravanners. Try it with a single axle caravan !

 

[sparkes]

a car towing a caravan can actually have a shorter braking distance than when solo. Test reports prove the case.

what test reports Lutz? how and when did they prove it?

I'm really interested in a caravan that can stop it's own mass with two drum brakes without abs, but not only that can also assist the towing vehicles braking performance to bring it to a halt quicker, let's have the hard facts and the proof please, like when and where the test was conducted, by whom, and towing what combination, and last but not least the braking distances from what speed, solo & towing.

Allan.

Allen, I saw this report as well. Also, by accident I can asure you a car/van together stops a lot quicker than the same car on its own.

 

[cris_408518]

Cris,

Re motor movers and twin axles, I've actually seen only a few twins with motor movers. I've never needed one when parking on a pitch and as we could drive our caravans in and turn around in our driveway and garden where we used to live and where we live now I can't see the need for one apart from if you have mobility needs yourself or you have a vary tight space to store the van.

I have a TA and use the movers a lot, I find it better to use the mover than tear up the grass when trying to reverse into most CC pitches.

Val & Frank

Frank. In all the years we've towed t/a's we've never "ripped" up any grass. If we have found space tight to reverse in we put the caravan in then use jockey wheel to lift the leading wheels and just push the caravan into its final position and do the same when we leave. It's part of good caravanning manners surely.

 

[Lutz]

That a puncture which did not lead to an accident with a twin axle would, under the same conditions, result in a certain disaster for a single axle is pure surmise.

 

[cris_408518]

Well then Lutz, as a life long biker I assume that goes the same for a front bike tyre puncture compared to a front car tyre puncture in your book.

If the bike tyre goes it does not mean for certain that it will result in disaster.

But I and many others do not need a scientific report to work out which is the better choice to be in control of in all probability.

Surely it is not beyong reason for even the most inexperienced driver to work out that towing with the same vehicles two similar sized caravans and have one tyre deflate which one you stand the best chances with.

I'm not quite sure where you are coming from Lutz as you seem to remove probability factors from safety.

The way you put your points Lutz, it seems that you would be quite happy to be pushed in front of family runaround doing 100 miles an hour as you would a 911 Porsche doing the same speed.

I guess there is not guarantee that they both can't brake swerve and miss you. But which one would you prefer if forced to, they both have brakes and can turn!

No doubt the guys down at M Sport or AMG always go and get a report out before they add extra braking when they shoe horn in an extra 100 or so bhp. Well they could keep the same brakes and the car would stop. What more do you want ;-)

 

[Lutz]

Comparing apples with bananas again. I am not talking about doing 100mph, nor about motorbikes, 911 Porsches, M Sports or AMG's but towed trailers with relatively evenly distributed payloads (caravans) doing around 60mph. The conditions are totally incomaparable.

I repeat that there is absolutely no data to confirm that single axled caravans are involved in any more accidents than twin axles. You may have some inner voice that tells you that a twin should be safer but there is nothing to back this assumption up.