Insurance and the 85% rule

[ProfAlGoogle]

Hi Lutz, you actually stated that the stopping distance would be shorter "It is a proven fact that braking distance is actually shorter when towing a trailer than when the car is solo (on condition that both the car's brakes and those of the caravan are properly adjusted and maintained)." Now normally when we all go away with our caravans in tow for our jollys, loaded up to the maximum legal amount for each combination, the way I read your posting is that a rolling 3.5 ton mass will stop in a shorter distance at say 60mph than what the tow vehicle would if it was without trailer? You can now see why I stated in my original posting that driver training should be made compulsory, as they say a little knowledge can be a dangerous thing, especially at over 3 tons on our very often congested Motorways.

Allan.

 

[Lutz]

I think Brian has the same test report in mind that I was thinking about.

I don't know what lessons for a category B+E licence which would allow one to tow over 100% and a combined weight of over 3.5 tonnes involve but this sort of thing should be included.

 

[ProfAlGoogle]

As I Said in my earlier postings Lutz, driver training should be made compulsory for all who have never towed before. Just run through a lot of these posts and what do you read, "we have just retired and want to buy our first van and tow car, what do you advice" "we are newbie's to all this what's the best way to load our van" etc etc, the list is not exhaustive. And with respect these are most probably very capable drivers, but when we add a caravan to the back of our cars the whole characteristics of that vehicle changes, steering has a different feel, uneven road surfaces are a completely different experience, cornering, overtaking, overall stopping distance, they all change. And I for one really don't believe that a novice should undertake this whole new learning curve with a tip here, a good bit of advice there, and a chap on site said I should keep well over to the left when on a motorway, and so it goes on. If you turn up for work on Monday morning and they have changed your job, and ask you to operate some new machinery, not only would you quite rightly expect to have adequate training, your company is bound by law to ensure that you receive training for your safety and those who could be directly affected by your actions. So don't you think it makes sense to train new people who are coming along to join the caravanning world.

Allan.

 

[ProfAlGoogle]

As I Said in my earlier postings Lutz, driver training should be made compulsory for all who have never towed before. Just run through a lot of these posts and what do you read, "we have just retired and want to buy our first van and tow car, what do you advice" "we are newbie's to all this what's the best way to load our van" etc etc, the list is not exhaustive. And with respect these are most probably very capable drivers, but when we add a caravan to the back of our cars the whole characteristics of that vehicle changes, steering has a different feel, uneven road surfaces are a completely different experience, cornering, overtaking, overall stopping distance, they all change. And I for one really don't believe that a novice should undertake this whole new learning curve with a tip here, a good bit of advice there, and a chap on site said I should keep well over to the left when on a motorway, and so it goes on. If you turn up for work on Monday morning and they have changed your job, and ask you to operate some new machinery, not only would you quite rightly expect to have adequate training, your company is bound by law to ensure that you receive training for your safety and those who could be directly affected by your actions. So don't you think it makes sense to train new people who are coming along to join the caravanning world.

Allan.

 

[Lutz]

I couldn't agree more but wasn't that the whole purpose of introducing the B+E licence in the first place?

 

[ProfAlGoogle]

I couldn't agree more but wasn't that the whole purpose of introducing the B+E licence in the first place?

Yes Lutz, but don't forget there is one hell of a lot of potential caravaner's out there that passed there test before that date, and who are quite legally entitled to tow any combination up to ( correct me if I am wrong ) 7.5 ton's, and also they can drive what seems to be getting more popular the fifth wheeler's, who at one time of day in the uk had to hold a class 4 hgv licence to drive that particular group of vehicle.

Allan.

 

[ProfAlGoogle]

Yes Lutz, but don't forget there is one hell of a lot of potential caravaner's out there that passed there test before that date, and who are quite legally entitled to tow any combination up to ( correct me if I am wrong ) 7.5 ton's, and also they can drive what seems to be getting more popular the fifth wheeler's, who at one time of day in the uk had to hold a class 4 hgv licence to drive that particular group of vehicle.

Allan.

 

[xtrailman]

The reason that an 85% rule is advisable takes into consideration not just the factor of a safe weight ratio but other considerations.

A lighter caravan can be pulled up hill far easier than one weighing 200kg more. Keeping a good speed helps the reputation of all caravaners with other road users.

Easier hill starts, less mechanical stress to the tow vehicle.

I am not convinced by Lutz claims regarding improved braking with a caravan on the back.

Why is a longer stopping distance recommended by the caravan club for safe towing if braking is unaffected?

On a hill descent are you seriously saying a van weighing the same, as the car will stop quicker?

Tests have proved that 4x4 have longer stopping distances than normal cars broadly speaking.

The braking efficiency between my last van and my latest caravan, which is about 250kg heavier, is noticeable; I have to give greater distances to stop for example.

If you ever get into a snake as I have you will be dam great full that your tow car has a weight margin over the caravan.

Another reason I advocate the 85% rule {I know its not a rule but it should be) is down to claimed weights and actual weights.

Do you actually know the true weight of your car or caravan? I don't and in truth both will be different on every trip,

Many factors make a safer tow car/van combination, an 85% or less is one of them.

Every week during the summer a road or motorway is closed due to an overturned caravan, I find that quite worrying

 

[ProfJohnL]

Hello Ray,

I agree with a lot of what you say, but the 85% figure is potentially very misleading. As you concede it is not a rule, it is only a suggested guideline. We are unique in the UK in having this low suggestion, and whilst I agree it is sensible target ratio, I have seen several outfits in trouble that I have little doubt were equal or better than 85%. There is a lot more to towing than just a simple weight ratio.

We must not forget that there are legal limits which relate to the tow vehicles specification produced by the manufacturer, and of course the permitted MGW for outfits on standard driving licences.

If a legal ratio limit were to be set why choose 85%? This figure was suggested by the caravan industry, for caravans, But there are many other types of trailers, some are far more stable than caravans and some less, so perhaps the limit should be different limits for each type, Then the problem is defining which group your trailer fits and overseeing it would be come another opportunity for Government to charge us even more tax to administer the process.

As for braking distances, there has been some evidence that suggests that a well set up car and caravan can stop in a shorter distance than the solo car. This is a rather academic test because it only applies in a straight line. As you rightly say, under turning conditions, the outfit does behave very differently, and making allowances for that does mean increasing stopping distances.

With regard to the number of caravan incidents, the travel reports we get are very very biased. You often hear of road closures because of some unfortunate event, but if a caravan is involved the reporters seem to make a meal out of it. Disproportionate weight is given to incidents involving caravans, but in reality it is probably less than 1% of all road closure incidents.

I have no problem if you wish to keep your outfit entirely within the 85% figure, but that does not make others wrong or less safe if they exceed it provided the vehicle manufacturers specification allows it, and they drive sensibly.

 

[Lutz]

Taking Ray's reply point for point:

Of course a lighter van is easier to pull uphill but that has nothing to do with weight ratio between kerbweight of towcar and the weight of the caravan. That is purely a power-to-weight issue.

The recommendation to allow a longer braking distance when towing probably originated in the days before cars had ABS.

Following Allan's recommendation that drivers should be better trained would help in reducing the disastrous effects that occur when the driver react incorrectly in the event of a snake. No matter how good the weight ratio there is still a risk, however small, of getting into unforeseen instability and one should be prepared to take the correct course of action by instinctively knowing what to do when it happens.

The weight ratio is normally calculated on the basis of comparing the published kerbweight of the towcar with the fully laden weight of the caravan. This is a condition which rarely occurs in practice and the actual weight ratio will always be more favourable. Besides, the actual kerbweight is invariably higher than the published data so this too will reduce the actual weight ratio even further.

The 85% figure is purely arbitrary. Nobody has produced any data showing that accident rates would be any higher if the recommendation were raised to, say, 90 or 95%. How do you know that the accidents that you have seen on the roads involved caravans with particularly unfavourable weight ratios?

 

[MikeP]

A point on Ray's comment about the well-reported caravan accidents on main roads in the summer.

I doubt that these statistics exist, but I would be interested to know the proportion who fall into the following categories:

1. People who tow their caravan regularly, have it serviced each year and are "weight-aware".

2. People who use their caravan at Whitsun for one week and in the summer for 2 weeks, never have it serviced, never check the tyres and don't know anything about weight.

I know it will never be as simple as that, but it is quite worrying that there are many people out there in caregory 2. Apologies for the gross generalisations!

 

[ProfAlGoogle]

I for one would like to think that I fall in to the first category, then if not I will cease my hobby forthwith, once again there are far too many grey areas that concern caravans and there operators, is it not about time we lifted the fog? I think by now you all know my feelings on towing a trailer without compulsory training. So now lets turn our thoughts to servicing, no you can't force people to have there van's serviced just like you cant with there cars, so what about an annual inspection? Or if you like"MOT" I for one have nothing to hide and would welcome an annual inspection, we all get a little complacent and I am sure from time to time there must be things that I have overlooked that an inspection would make me aware of. We keep being told about the life expectancy of caravan tyres, five years old perfect tread from little use, but a potential time bomb waiting to go off, but with annual testing this would be high lighted and a refusal of a road worthiness certificate. Just look around you in the height of summer at some of the caravans on the road, and a lot of them being used by young families, yes got it cheap out of the local rag, been in me uncles garden for the last ten years and he gave it to us, and of they go............. Enough said.

Allan.

 

[ColinA]

In order for a car pulling a trailer to stop quicker than when solo, the trailer would have to apply a force to the car through the tow hitch which would require to be opposite to the direction of travel. In other words pull back on the car. If this happened the trailers brakes would be released. Aslo to pull back on the car a caravan (which weighs only a little less than the car usually) would have to brake harder than the car. This seems to be unlikely through only two tyres and with drum brakes.

 

[Lutz]

No Colin, you've got it wrong. The caravan doesn't have to brake harder than the car in order for the outfit to be able to stop more quickly. As you rightly say, it couldn't because then its overrun brake would be released.

The reason why stopping distance is shorter is because the car is actually braking harder than when solo. This is because there's more weight on the back axle. More weight, more friction, better braking, it's as simple as that.

 

[ColinA]

So you are saying a fully laden car will stop quicker than an unladen one?

 

[ProfAlGoogle]

"This is due to the fact that when the caravan's overrun brake is deployed, the caravan will tend to tip forward and the increased noseload will push the back end of the car down. This, in turn, increases rear axle load of the car, thereby improving the braking efficiency of that axle."

So if we look a bit deeper at this, we will then find that if the rear of the car is depressed downwards it is only right to assume that the front of the car will rise = less weight over that axle and by your own admission reducing the braking effect of that axle, so now we are back at square one. Another thing that puzzles me if all things are equal, if it stops quicker surely it should take off quicker? Please any newbies out there reading this allow for a greater braking distance when towing. And finally to all on here that have the very best of intensions when giving out advice on these forums please let's stay on the side of caution and stay safe.

 

[Lutz]

No, I'm not saying that a heavily laden car (solo) can stop quicker than a light one (also solo). I'm saying that if one can prevent weight transfer from the rear axle to the front one can stop quicker, no matter what the weight. One of the ways one can offset the weight transfer is to apply additional noseweight at the back end of the car. Hence, a heavily laden car towing a caravan will stop quicker than one which is just as heavy but solo (assuming the caravan is able to brake more or less by itself, which it should if properly maintained).

 

[Lutz]

There is a limit to what the brakes at the front of the car are able to achieve. This is dictated by the coefficient of friction between the rubber and the road surface. Once the front tyres have reached the limit of their adhesion to the road, no brakes, no matter how good, are going to improve the performance of front axle braking.

 

[Lutz]

"This is due to the fact that when the caravan's overrun brake is deployed, the caravan will tend to tip forward and the increased noseload will push the back end of the car down. This, in turn, increases rear axle load of the car, thereby improving the braking efficiency of that axle."

So if we look a bit deeper at this, we will then find that if the rear of the car is depressed downwards it is only right to assume that the front of the car will rise = less weight over that axle and by your own admission reducing the braking effect of that axle, so now we are back at square one. Another thing that puzzles me if all things are equal, if it stops quicker surely it should take off quicker? Please any newbies out there reading this allow for a greater braking distance when towing. And finally to all on here that have the very best of intensions when giving out advice on these forums please let's stay on the side of caution and stay safe.

The additional noseweight increases the load on the rear axle much more than it decreases the load on the front axle, especially if the car has a short rear overhang.

 

[ProfAlGoogle]

Lutz, we can go on & on, who is right who is wrong, but please for safety's sake lets all assume that when we have a greater load especially when towed it will take a greater distance to bring it safely to a halt.

 

[Lutz]

I have no issue with your statement other than it applies just as much to people who drive their car fully laden but not towing.

 

[ProfAlGoogle]

But they are less likely to be reading this debate as it is primly aimed at people who tow caravans. Let's put it to bed Lutz.

 

[MikeP]

It does not matter whether or not people are following this debate, as ignorance should not put them at a disadvantage.

If they don't know what Lutz knows, then any responsible person will probably assume that their car/caravan combination will have a greater braking distance than when solo. No problem then.

 

[ProfAlGoogle]

Is that as in ignorance is bliss? Tell that one to your insurance company, or better still a court of law. Sorry if I may sound abrupt but there are too many Chinese whispers on here, and people with the very best intensions giving out what could probably be very dangerous information. So unless your qualified, can give concrete evidence with times and dates etc to back up your findings then please keep them to your selves. So proceed with caution, expect the worse and you will be very well prepared.

 

[xtrailman]

I no longer watch top gear or fifth gear for that matter, racing expensive powerful cars round a track has absolutely no interest for me. However the disagreement regarding a trailer car combination braking distance could be decided by an actual test on track.

Perhaps practical caravan could stage such a test. Please do.

Lutz.

Tests have proved that stopping distances for solo cars are increased when ABS is fitted.

Not reduced.

This argument has been debated on the honest john forum some years ago.

However ABS will allow you to steer round a hazard under heavy braking.

Regarding having a mot for caravans.

This would not be a bad idea if it weren't for the appalling level of servicing provided by some dealers.

For 20 years I have always carried out my own servicing giving most attention to the braking system. However over the last two years I have had the caravan serviced by the main dealer.

Needless to say I am not impressed. Don't assume it will be carried out competently.

In my experience, as with car servicing you pay a lot for a little.