Litespeed,
Bath Uni, School of Mech Eng studies? There's about 10 or more reports that have found their way onto the internet each looking into different aspects.
Some were the usual 2 year long studies for a PhD, some were commissioned by one or more caravan manufacturers, all require the ability to read technical documents with more than a bit of mathematical skills required - bedside reading they aren't
Probably over the last 10 years too, so some aspects have been re-covered as cars and caravans have changed.
Robert
Bath Uni, School of Mech Eng studies? There's about 10 or more reports that have found their way onto the internet each looking into different aspects.
Some were the usual 2 year long studies for a PhD, some were commissioned by one or more caravan manufacturers, all require the ability to read technical documents with more than a bit of mathematical skills required - bedside reading they aren't
Probably over the last 10 years too, so some aspects have been re-covered as cars and caravans have changed.
Robert
Hi Euro
"Our friends locals serve Leffe..." Leffe Brune is a reasonable choice, better than the usual Heineken that tastes like it's already been drunk once.
OK, Heineken's not that bad and their winter Bokbier is very good - but if I leave the office late on a friday night, I'll usually stop at a small family run hotel in Damme (Belgium) and enjoy some top rate food and a beer before driving home to the UK on Saturday morning.
Robert
"Our friends locals serve Leffe..." Leffe Brune is a reasonable choice, better than the usual Heineken that tastes like it's already been drunk once.
OK, Heineken's not that bad and their winter Bokbier is very good - but if I leave the office late on a friday night, I'll usually stop at a small family run hotel in Damme (Belgium) and enjoy some top rate food and a beer before driving home to the UK on Saturday morning.
Robert
Returning to the findings of Bath University that the critical speed of a caravan outfit is around 55 to 60mph, I have no reason to question this result. It means that it may be perfectly safe to tow at speeds in excess of 60mph so long as nothing happens which could cause instability (such as sudden crosswind when coming out of a cutting). Below the critical speed the caravan will recover on its own without any necessary action by the driver. Above the critical speed, instability will be self-amplifying unless the driver (or any active stabiliser system) takes appropriate action.
Hello Lightspeed,
I do not know what the incident rates are abroad, but I am convinced that whilst speed is a very significant factor, it is far from being the only one. It would be dangerous to assume that speed is the main factor.
However I do not know of any condition where voluntary increasing speed reduces the danger of instability.
What is important is to maintain control of your vehicle with due regard for speed limits, regulations, your outfits handling and the conditions that you encounter.
Some caravan manufacturers state in their handbooks or other documentation the top speed the caravan is designed to cope with, exceeding it in any country is foolhardy, and probably illegal.
Speed limits set by authorities are arbitrary choices, not devised in consideration of the performance of current cars or caravans. To exceed them is still illegal.
Even if the Bath University studies established an average speed at which a car and caravan becomes unstable, how many outfits are average? And how do you know where your outfit sits in the league table?
Rob -Jax, I agree that car design has moved on significantly in the last ten years, I have not seen any startling new technical advances in he UK caravan and chassis design over the same period.
As Lutz has pointed out on many occasions, the two most effective technical advance would be the inclusion of some form of active braking system for trailers. This is not new technology, artic HGV's have active air brakes, I have used a exhibition 5th wheel trailer with electrically operated trailer braking.
And
Suspension dampers.
Even with these advances I do not advocate raising of speed limits, but it might to an even lower figure the numbers of incidents involving caravans.
I do not know what the incident rates are abroad, but I am convinced that whilst speed is a very significant factor, it is far from being the only one. It would be dangerous to assume that speed is the main factor.
However I do not know of any condition where voluntary increasing speed reduces the danger of instability.
What is important is to maintain control of your vehicle with due regard for speed limits, regulations, your outfits handling and the conditions that you encounter.
Some caravan manufacturers state in their handbooks or other documentation the top speed the caravan is designed to cope with, exceeding it in any country is foolhardy, and probably illegal.
Speed limits set by authorities are arbitrary choices, not devised in consideration of the performance of current cars or caravans. To exceed them is still illegal.
Even if the Bath University studies established an average speed at which a car and caravan becomes unstable, how many outfits are average? And how do you know where your outfit sits in the league table?
Rob -Jax, I agree that car design has moved on significantly in the last ten years, I have not seen any startling new technical advances in he UK caravan and chassis design over the same period.
As Lutz has pointed out on many occasions, the two most effective technical advance would be the inclusion of some form of active braking system for trailers. This is not new technology, artic HGV's have active air brakes, I have used a exhibition 5th wheel trailer with electrically operated trailer braking.
And
Suspension dampers.
Even with these advances I do not advocate raising of speed limits, but it might to an even lower figure the numbers of incidents involving caravans.
Hi John,
Regarding caravan chassis improvements, I was thinking of the AL-KO Delta / Euro axle that was designed to improve stabilty and ride - especially coupled with factory fitted shock absorbers.
Robert
Regarding caravan chassis improvements, I was thinking of the AL-KO Delta / Euro axle that was designed to improve stabilty and ride - especially coupled with factory fitted shock absorbers.
Robert
Hello Rebrt,
Thanks for pointing that out, but I believe the delta has been in production for over ten years now - I could be wrong though.
How safe are caravan tyres at high speeds? I recall getting a new ranger back in 2000 and I am sure the handbook gave the speed rating of the tyres at 81mph/130kmh, exactly the same as the maximum french speed limit. Therefore you are running the caravan tyres (which are only commercial tyres I think) right on the limit, compared to your average car tyres which have a speed rating of about 130+ mph, and how often are they going to be pushed to the limit?
All other matters aside, I think I'd rather not push my van tyres to the edge.
All other matters aside, I think I'd rather not push my van tyres to the edge.
If the handbook says 81mph (130km/h) is the limit then this is unlikely to be due to the tyres. The lowest speeed rating for any tyre is an 'N'-rating which is good for 140km/h but to my knowledge most proprietary caravan tyres carry an 'R' or an 'S' index simply because the tyre manufacturers cannot be bothered with producing lower rated tyres just for the caravan industry.
I am not a tyre expert, but in all other walks of life where engineering solutions are required, designers will specify permitted working limits to be substantially inside its real maximum limits. This provides the manufacture with a safety margin, and reduces the threat of litigation.
So I would be confident that if a tyre was rated for summer use at 750Kg load at 60psi (cold), and a maximum speed of 130kph, the tyre would survive these conditions. (not withstanding faults in manufacture)
Correct tyre inflation is of course vital, too soft for the load, and the tyre will develop a larger footprint and the walls flexing too much genereating extra heat, or in extreme cases rubber to rubber friction and wear. Early warnings would be increased loss of rubber on the shoulders.
Over inflation will cause excessive centre line wear, and stiffer side walls might suffer tension stressing inside where you cannot see it.
So I would be confident that if a tyre was rated for summer use at 750Kg load at 60psi (cold), and a maximum speed of 130kph, the tyre would survive these conditions. (not withstanding faults in manufacture)
Correct tyre inflation is of course vital, too soft for the load, and the tyre will develop a larger footprint and the walls flexing too much genereating extra heat, or in extreme cases rubber to rubber friction and wear. Early warnings would be increased loss of rubber on the shoulders.
Over inflation will cause excessive centre line wear, and stiffer side walls might suffer tension stressing inside where you cannot see it.
I think your confidence is quite legitimate, John. Otherwise, only 8 people would dare get into a lift although the sign says "max. loading capacity 10 persons".
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