Nice one Brian, I hope members of older vans know this, otherwise I will be giving them a wide berth on the motorway!
Captain, you are misinterpreting my statement concerning caravans being designed for 100kph (60mph) max. as though I am suggesting that anything above that is immediately unsafe. Things aren't as black and white as that. Think of it as the start of a grey area, much like the ominous 85% recommendation.
In order to cater for possible misuse, safety related designs necessarily have big margins of safety consequently with a very wide grey area. For example, a lift designed to carry 10 persons won't crash to the ground if an 11th or even a 12th person gets on but if they do, the manufacturer cannot be held liable if something does happen.
I was just trying to say that, if a design was meant to have a particular margin of safety, then I would not want to accept responsibility of reducing this factor to less than what was intended.
I certainly wouldn't want to try an emergency brake from 80mph with a fully loaded car and caravan just to see whether I this margin is still large enough.
Don't forget that, compared to modern cars, caravan chassis are relatively low-tech designs. For example, virtually no caravans have disc brakes. It's therefore quite a tribute to the manufacturers that they have optimised their simple constructions to suit current levels of speed but I would not want to push it further without technical improvements.
In order to cater for possible misuse, safety related designs necessarily have big margins of safety consequently with a very wide grey area. For example, a lift designed to carry 10 persons won't crash to the ground if an 11th or even a 12th person gets on but if they do, the manufacturer cannot be held liable if something does happen.
I was just trying to say that, if a design was meant to have a particular margin of safety, then I would not want to accept responsibility of reducing this factor to less than what was intended.
I certainly wouldn't want to try an emergency brake from 80mph with a fully loaded car and caravan just to see whether I this margin is still large enough.
Don't forget that, compared to modern cars, caravan chassis are relatively low-tech designs. For example, virtually no caravans have disc brakes. It's therefore quite a tribute to the manufacturers that they have optimised their simple constructions to suit current levels of speed but I would not want to push it further without technical improvements.
Good points made by Lutz - probably best summed up by the advice -"just because you can does not mean that you should".
Whilst the guy that would not go over 40mph is clearly a menace and gets us all a bad name, similarly a guy that drive at the limit of his equipment is also dangerous.
Why are caravan chassis so basic? As I have said before I tow a lot of varried things. Ifor Williams trailers are superb bits of kit. Why hasn't the caravan industry picked up on this technology?
Whilst the guy that would not go over 40mph is clearly a menace and gets us all a bad name, similarly a guy that drive at the limit of his equipment is also dangerous.
Why are caravan chassis so basic? As I have said before I tow a lot of varried things. Ifor Williams trailers are superb bits of kit. Why hasn't the caravan industry picked up on this technology?
Why are caravan chassis so basic? Easy, cost!
For the production volumes involved, it just doesn't make business sense to develop a high-tech caravan chassis so long as the speed limits are what they are. Few people would be prepared to pay the extra price for a sophisticated design which is guaranteed safe at higher speeds so long as these speeds are not permitted on the road. It's a sort of chicken and egg situation. The speed limit is low because the design is cheap but as long as the speed limits are not higher, there's no incentive to put more money into the design.
For the production volumes involved, it just doesn't make business sense to develop a high-tech caravan chassis so long as the speed limits are what they are. Few people would be prepared to pay the extra price for a sophisticated design which is guaranteed safe at higher speeds so long as these speeds are not permitted on the road. It's a sort of chicken and egg situation. The speed limit is low because the design is cheap but as long as the speed limits are not higher, there's no incentive to put more money into the design.
Yes I see that - Just seems a shame that the Ifor williams trailer I tow is most often used to transport some sort of cr*p (usually Horse) from A to B and it has a suspension and build quality far in excess of anything I have seen under a caravan.
And believe me I dare not go to fast with a load of manure on the back!!
For Mick,
Speed is the most significant factor in any moving vehicle accident. If vehicles do not move they cannot collide.
The relative speed between colliding objects determines the energy that will be dissipated in the collision, The bigger the speed or mass the more energy that is available damage human beings and bend metal
All moving vehicles have a degree of instability. The speed at which that instability becomes greater that the drivers ability to control it varies according the to driver, and the prevailing conditions. The driver has control over speed, and therefore speed is always a factor in a moving vehicle accident.
In general and with the benefit of hind sight, most drivers would agree that the accident they have been involved in could have been avoided if the speeds of vehicles had been less.
Speed is the most significant factor in any moving vehicle accident. If vehicles do not move they cannot collide.
The relative speed between colliding objects determines the energy that will be dissipated in the collision, The bigger the speed or mass the more energy that is available damage human beings and bend metal
All moving vehicles have a degree of instability. The speed at which that instability becomes greater that the drivers ability to control it varies according the to driver, and the prevailing conditions. The driver has control over speed, and therefore speed is always a factor in a moving vehicle accident.
In general and with the benefit of hind sight, most drivers would agree that the accident they have been involved in could have been avoided if the speeds of vehicles had been less.
For Clive,
The towing characteristic of a caravan is affected by much more that the just the chassis, a point I an sure you can agree on. So the caravan manufacture is just as much responsible as Te chassis manufacture for how the caravan tows. I suspect that to make any significant improvement to towing characteristics would need some fundamental engineering as a joint effort between Te chassis manufacture and the caravan coach work builder. - Having said that Te use of shock absorbers on trailers can make a big difference, and I bet it is only cost that stops manufactures fitting them to all vans.
The towing characteristic of a caravan is affected by much more that the just the chassis, a point I an sure you can agree on. So the caravan manufacture is just as much responsible as Te chassis manufacture for how the caravan tows. I suspect that to make any significant improvement to towing characteristics would need some fundamental engineering as a joint effort between Te chassis manufacture and the caravan coach work builder. - Having said that Te use of shock absorbers on trailers can make a big difference, and I bet it is only cost that stops manufactures fitting them to all vans.
True, John L, but the towing characteristics are affected by the car, too (rear overhang, suspension compliance, tyre and wheel equipment, underbody stiffness, etc.).
You're also right about fitment of shock absorbers.
The caravan builders should be encouraged to do their bit but the emphasis will still be on the chassis manufacturers as the 2 biggest ones together cover probably 90% of the entire European market and therefore they have the best resources for engineering development.
You're also right about fitment of shock absorbers.
The caravan builders should be encouraged to do their bit but the emphasis will still be on the chassis manufacturers as the 2 biggest ones together cover probably 90% of the entire European market and therefore they have the best resources for engineering development.
I fitted gas shocks (de-carbon) to the Range Rover a year or so ago. The effect was stricking. Virtually no role and smoother ride off road.
No shock absorbers on my caravan though I have seen kits to fit them.
Would you recommend fitment?
I fitted gas shocks (de-carbon) to the Range Rover a year or so ago. The effect was stricking. Virtually no role and smoother ride off road.
No shock absorbers on my caravan though I have seen kits to fit them.
Would you recommend fitment?
No shock absorbers on my caravan though I have seen kits to fit them.
Would you recommend fitment?
From feedback on past threads on the subject of shock absorbers (I can't confirm this though) it appears that all AlKo chassis already have provisions for installing shock absorbers and that AlKo even offer shock absorber kits which only need to be bolted on. With BPW chassis it's not so easy as the necessary brackets are missing and need to be welded on.
Small correction there, Roger. In Germany you only need shock absorbers fitted (among other things) if you want to tow at 100kph. Without them you're limited to 80kph.
Sorry to go back to basic physics, but none of the replies has pointed out that stopping distances etc. (and impact damage0 rise with the square of the speed of travel / impact, not in a linear manner.
So the difference between 50 and 60 miles/hour is not 10 but between 50 squared (2500) and 60 squared (3600) i.e a 50 % increase.
Nature loves this "square law effect" which applies to drag increasing with speed etc. and as usual it it foolish to ignore nature.
So the difference between 50 and 60 miles/hour is not 10 but between 50 squared (2500) and 60 squared (3600) i.e a 50 % increase.
Nature loves this "square law effect" which applies to drag increasing with speed etc. and as usual it it foolish to ignore nature.
Ray thats a rather simplistic way of looking at it, there are many many more factors which come into play. Such things as road surface, conditions, type of car, conidiotn and type of brakes etc etc. Say you pitched your car against an f1 race car and you were braking from 50mph and the f1 from 60mph would you like to bet your car would outbreak the F1? Your physics equation is way too simplistic
If you've ever driven behind a car with defective shock absorbers you'd have seen how the wheels bounce and loose at least partial contact with the road surface as they jump up. When adhesion is lost, they can no longer transfer braking forces fully and do not provide as much lateral support, thus increasing the risk of instability (i.e. a snake).
When i last had my van serviced (my coachman laser prior to selling it) i noticed on the service center wall at glossop caravans there was a notice saying shock absorbers must not be fitted to new coachman vans, this was about 18 month ago, i did not take too much notice of it as i have never really concidered them necessary but it now makes me wonder why glossop would not fit them ? anybody else know ?.
I too would like to know that John, as I have a new coachman and am considering fitting the shocks from the alko website.
I'd hazard a guess that some caravans may not provide enough clearance to allow shock absorbers to be fitted. Perhaps they have wider wheels which reduce the space between the chassis frame and the tyre.
Just rang glossop and they say that at the time it was a precaution due to the weight of coachman vans, however they now have no reason to not fit shock absorbers to coachmans but they said they would have to check each van with alko, this is apparently as a precaution due to some problems in the past. don't know which coachman you have kanga but if you have read some of my posts in the past you will know that i had poor stability on both my coachman pastich (2002) and my vip (2003)both where 520/4, however my laser a 2003 model was rock solid as is my new ace celebration 590. in contrast to my pastich and vip, my parents have a pastich 530 (2005) and this van is great to tow absolutely no need for shock absorbers. are you having problems with your coachman or do you just feel the need for shocks, i'm interested becouse next year i want to go back to coachman (family pressure resulted in the ace).
That the weight of the caravan should have an influence on whether you can fit shock absorbers or not sounds weird and I suspect somebody was just giving that reason as an alibi. Regardless of how heavy the caravan is it still needs the same amount of suspension travel as if it were light. Otherwise, the suspension would constantly be bottoming out on bad roads. The amount of travel is what determines the operating stroke of the shock absorber. A heavier caravan would probably need a harder setting but that shouldn't be an issue because shock absorbers can easily be made to any specification.
Not too sure either lutz, the guy did seem a bit vague about it when i rang, but thinking about it in the way you have put it regarding the vans needing heavier duty shocks to cope with the weight maybee the vans could have suffered from the extra stress caused by the shocks, i really do not know, i just remembered seeing the notice at glossop. Any way they say they will now fit shocks if you want them as long as alko and the van manufacturer agree which i supose is just covering theire own back.
If that were the case, why do people buy cars capable of (much) more than 70mph? If improved technology were available, caravaners would certainly buy it for increased peace of mind if nothing else
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