Our caravan has a sparewheel bracket and dedicated harness for 2 large gas bottles in the front locker.
With nothing else loaded, it is way over the recommended nose weight.
As Kelper pointed out, manufacturers seem to have different criteria.
Quote: Originally posted by phathamster on 17/11/2016
so your saying your idea already exists......
why do you need "an equal and opposite force at the center of equilibrium"
my understanding that the braking would in fact cause the force at this point to be nullified as the car is still moving at the same speed/force?
also i think the effect of braking each tyre individual would be relatively small, both tyres are heading sideways at the roughly the same lateral speed? so a small amount of braking applied to the wheels, would effectively 'tug' the rear of the unit straight.....
Hello,
I have a post on this if you Look foe Caravan Stability most will be covered. But just to outline what you are asking/commenting I will try to address them here. Differential braking has very different characteristics than current offerings for overrun brakes in Europe have. For a visual on this go to the Dexter Sway Control on YouTube as posted here. I have my prototype fitted and perfected for "Overrun brakes" on my Caravan. Controlling sway using this concept means that the caravan is steered without slowing the combination down since the inner and outer wheel cancel out any increase or decrease in the wheel speeds. Now this may seem quite a simple thing to do when you see how the brake cables are fitted, however,
it can actually increase the risk of uncontrolled sway if not done correctly. The center of equilibrium is when the caravan is perfectly inline with the tow car.
However, this is the where the caravan reaches the fastest point in the pendulum swing. So, to stop it passing this point and going across to the other side one needs to present an equal and opposite force to stop the swing at or very near this point. In practice this proactively stops any sway even starting in the first place because it can smooth out any sway from as little as 3 degrees of movement. Couple this with an extremely powerful damping system and you will never lose control again. This does not mean the caravan is rigid - it will still turn when required or even move when hit by a side force of a specific amount but it will always return to the center under full control.
In this conundrum other issues are involved and clearly the likes of ALKO and BPW felt the same as you have commented upon. Like most of the improvements in geometry and stability in cars etc have been small with very big results from the Model T to present day.
A simple test for you to try is - put your brake on the caravan and then try to turn the van - you will find it won't turn, take the brake off and away you go. Now put a brick under one of the wheels and hey presto you will be able to turn the van - simples
I hope this helps you and others but please keep asking if still not clear or it sounds daft. Like the concept that a locked wheel accelerates faster than a free spinning one which it does.
John
Ps When referring to the speed/force we are not meaning the speed of the combination - it is the speed/acceleration of the caravan swing as it goes from right to left.
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Quote: Originally posted by SGThomas on 17/11/2016
Our caravan has a sparewheel bracket and dedicated harness for 2 large gas bottles in the front locker.
With nothing else loaded, it is way over the recommended nose weight.
As Kelper pointed out, manufacturers seem to have different criteria.
Hello Stuart,
This is what you do: You buy a weigh bar to weigh all the points on your van - nose, left and right axles then you load you car to the weight limits. You look up what the nose height of your caravan recommendations. You then load your caravan evenly along the floor right to the back if required and take a nose reading. If it is within a few kgs of the limit, you then weigh your axles on the van - if within the limits you are as good as it gets for loading. Make sure your Tyre pressures are ok for the weight of the car and caravan. When on the road take care when passing trucks. If you feel any sway don't brake and do not turn your steering into the turn - resist the temptation to correct the steering at this point - just let it smooth out within the lane you are in and get clear of the truck you just past.
Good luck is when preparation meets opportunity.
John
Quote: Originally posted by SGThomas on 17/11/2016
Our caravan has a sparewheel bracket and dedicated harness for 2 large gas bottles in the front locker.
With nothing else loaded, it is way over the recommended nose weight.
As Kelper pointed out, manufacturers seem to have different criteria.
Plenty of vehicles out there with a 150kg nose weight limit. Are you saying yours is above that?
Which bottles did you fit a pair or 47kg ones?
Whats the gross weight 1100kg or less? Long chassis section ahead of the axle but very little behind it?
Not the best design, although stable adding anything that far in front of the axle will have a large affect.
You seem to post links to information on trailers with electric brakes and designed differently to the UK caravans.
If i have the right van in mind (Re: SGThomas above) then having the axle further back and a long A frame section helps stability, although that gives noseweight issues.
Are you now giving information away that your system brakes each side independently? But uses mechanic methods and not electrical?
Curious as to how fast acting your mechanical method is?
Quote: Originally posted by Grampian91 on 17/11/2016
Plenty of vehicles out there with a 150kg nose weight limit. Are you saying yours is above that?
But few if any UK or Continental touring caravans with chassis rated at over 100kg noseweight, even if they because of their mass can have hitches that are capable of over a 100kgs.
If it is not the car, then it is going to be the van's chassis that limits almost all caravans to 100 kgs.
Quote: Originally posted by Grampian91 on 17/11/2016
You seem to post links to information on trailers with electric brakes and designed differently to the UK caravans.
If i have the right van in mind (Re: SGThomas above) then having the axle further back and a long A frame section helps stability, although that gives noseweight issues.
Are you now giving information away that your system brakes each side independently? But uses mechanic methods and not electrical?
Curious as to how fast acting your mechanical method is?
All the same questions that have been asked of JohnMW in the past, but he has refused to answer.
There seems to be a lot of talk here about common sense, but this is misleading. Caravan stability under tow requires some application of science (physics) and is not always so intuitive. The best way is to do plenty of reading from caravan sites (including this one) and seek advice from experienced caravanners. Both Clubs have excellent advice regarding loading and towing. A novice caravanner may think that they are doing the right thing in accordance with common sense, but could in fact be creating a lethal outfit inadvertently. Seek advice!
------------- The Sun always shines on TV.(and not on my caravan!)
A lot has been said about 'experienced' caravanners. Experienced just means you have done something many many times. But whether you have done it 'correctly' many many times is another matter. I watched a bloke earlier this year jack his van up on the legs till the tyres almost raised.
I never said anything to him, but i would be almost certain he was a caravanner of many years. Obviously he didnt have a sign up saying as much, but you have a good idea of who is 'new' to it and who isnt.
Was this guy worthy of being deemed 'experienced' enough to impart knowledge?
Quote: Originally posted by Grampian91 on 17/11/2016
Quote: Originally posted by SGThomas on 17/11/2016
Our caravan has a sparewheel bracket and dedicated harness for 2 large gas bottles in the front locker.
With nothing else loaded, it is way over the recommended nose weight.
As Kelper pointed out, manufacturers seem to have different criteria.
Plenty of vehicles out there with a 150kg nose weight limit. Are you saying yours is above that?
Which bottles did you fit a pair or 47kg ones?
Whats the gross weight 1100kg or less? Long chassis section ahead of the axle but very little behind it?
Not the best design, although stable adding anything that far in front of the axle will have a large affect.
The nose weight limit is stated as 85 kg on the car.
The A frame is so short that the jockey wheel handle in the raised position, fouls the opening of the forward hatch.
Major weight , toilet and kitchen, across the rear. Factory weight 950 kg, gross permissible 1100kg
Quote: Originally posted by Mick S. on 28/11/2016
A lot has been said about 'experienced' caravanners. Experienced just means you have done something many many times. But whether you have done it 'correctly' many many times is another matter. I watched a bloke earlier this year jack his van up on the legs till the tyres almost raised.
I never said anything to him, but i would be almost certain he was a caravanner of many years. Obviously he didnt have a sign up saying as much, but you have a good idea of who is 'new' to it and who isnt.
Was this guy worthy of being deemed 'experienced' enough to impart knowledge?
Depends, some will thank you and take notice, others will thank you and call you names as soon as your backs turned and ignore you or you may get someone that takes offence and knows better.
No matter how many times you go camping/caravanning there is usually someone on site doing something slightly differently that may work for some and not others.
Or a caravan with something slightly different that makes sense. My waste pipes were at the rear but had a few occasions where access was difficult, so moved them to the side.
Raising the caravan an inch or two to get the awning nice and tight (depending on pitch).
Quote: Originally posted by SGThomas on 17/11/2016
Our caravan has a sparewheel bracket and dedicated harness for 2 large gas bottles in the front locker.
With nothing else loaded, it is way over the recommended nose weight.
As Kelper pointed out, manufacturers seem to have different criteria.
empty my bailey ranger would have been over 100kg on the nose with the gas bottles and spare wheel in the front locker.
the trick was (again common sense) to place more items rear of the axle when traveling to balance out the nose weight to the required value. like pair of scales.
my coachman is not so bad but still care has to be taken when loading to ensure the nose weight is correct.
------------- First van bailey ranger 550/6
Now the proud owner of a coachman amara