I was travelling to Cornwall down the A30 two weeks ago doing about 65 mph. I always carry all water containers awning in the car so to keep the caravan clear for when we stop for a break. I don’t carry much in the side lockers. So apart from clothing in the wardrobe and things in the fridge I don't carry much in the caravan. Well getting to the point as I said travelling down the A30 the van started to snake quite bad. I had just overtaken a lorry and could feel the drag as I past it. The same happened on our return journey home two weeks later, just overtaken a lorry and the drag started the caravan to snake again not quite as bad but it was frightening. My caravan is a 2014 Compass Rallye 574 factory fitted AL-KO ATC, the green light is constant on. It seems to me the ATC did not stop the snaking, Have anybody else had this happen? Just wondered what I can do to stop the snaking. Could the caravan be too light? Keith
Weight distribution, noseweight, tyre pressures car and caravan, speed, 60mph is the legal limit on dual carriageways and above. A well matched balanced unit does not need any stabilisation, it's there for secondary protection.
The simple answer is you were travelling too fast with a caravan in tow especially those who have anti-snaking gadgets like yourself who get complacent and think it's a magic wand to permanently cure any swaying. The science behind is that if you have a head wind speed of say 20 mph. and you are doing 55 mph. the pressure on the front of the caravan is actually proceeding at 75 mph. so the faster you go the more likely of losing control of the steering. When you extend the speed to beyond the limits of safety the wind pressure at the front of the caravan will start to lift the hitch and towball which will start to lift the rear of the car leaving just the two front wheels on the ground which stability is lost creating the snaking process. This is exactly what happened in your case but there are other factors such as having the correct noseweight etc. but they recommend not to tow in excess pf 60 mph. for a valid reason which you chose to ignore and put your lives and others in danger.
The ATC will be working but It's programmed to cut in under certain circumstances only, either a couple of violent snakes or several smaller ones.
Being sucked towards a lorry, though disconcerting if unexpected, will not activate it. When it does activate it merely brakes both caravan wheels to slow things down, and you would feel this very clearly in your car. It's not anything like as sophisticated as a car stability system.
From what you say about loading the van, weight seems to be at the sides and perhaps the rear, but not at the front and not on the floor (which would aid stability). I would experiment with this, notwithstanding your desire for a mid-journey cuppa, and also check your noseweight is at the towbar max.
With regard to your speed, while this was illegal it should not be dangerous per se, in the same way cars don't become dangerously unstable at 75mph. I understand that modern caravans and tyres are rated to around 80mph should the law permit. But air turbulence and resistance build exponentially, both from your own rig and from other traffic, so these factors at 65mph are much greater than at 60mph. This is why I get 35mpg at 56mph, but at only 4 mph more this drops to 28 - or less again with a headwind.
------------- Camping Gear expands so as to fill the space available for its transportation.
I always put the awning in the caravan when towing, plus I put it directly over the axel and have never had any snaking.
I agree with others that I've had my van pull (or pushed) when being overtaken by vans etc. but these are only minor and quickly settle themselves down.
Also, like everyone has said, a well loaded caravan doesn't really need stability control, load up a van properly with the right nose weight, and you should never get a snake.
Hi Kieth
I have a post here on this subject look for "Caravan Stability." Until you have a device like my Differential Stability you will always be subject to the possibility of uncontrolled lateral snake. ATC will only assist you in the event you encounter the many combinations that trigger the so called snake. The reality is that since there has never been a solution, until now, that actually stops snaking from occurring proactively in the first place many adopt inconclusive methods - speed control, weight distribution, ridiculous hitch friction devices, and so on. I have over 40 years of study on the subject of vehicle stability issues in all types of vehicles mainly commercial and I have covered this one in the posting mentioned above. On the subject of weight distribution without my stability system you need to follow these guidelines.
Assuming all your Tyre pressures are correct, load your car with all the gear you can first, load your excess payload evenly along the van floor to avoid stressing the floor with point loads, ensure that you bias your load to the limit of your tow bar capacity.
I have encountered a particular issue when all the above have been followed through it was discovered that if the overrun damper is duff the van can "bounce" on the tow vehicle and allows the van brakes to apply on and off rapidly and destabilize the tow vehicle thus creating uncontrolled snake.
Just one of many things that occur without a true stability control system.
ATC is a safety aid, it's not a magic pill.
If the green light is on, it's fine (it does a little self diagnostic' when you first connect it.
I'd be more inclined to look at unequal tyre pressures on the van or loose wheel nuts/bearings.
The ATC if functioning as designed would have addressed the snake but you would have been aware of it happening.
That you escaped to retry it and can report back without also reporting the thing flipped over suggests that after a fashion it was operating. If its operating was not very evident then it needs checking by somebody competent to do so; easier said than found IMO. Even towing with my 260 BHP car the van's ATC makes its presence known as it gives reassuring checks if I flick it too enthusiastically out of roundabouts, as it should.
That you got into this predicament can be from several causes that include such things as poor vehicle characteristics, poor weight distribution and tram grooves in the road. The easiest to check is that the noseweight is as high as the kit you have tolerates.
Most experienced caravan users have learn to live with the possibility of an uncontrolled lateral sway the difficulty for most is knowing when it is just a normal sway when something passes and when it swings back increasing in velocity and it can become tiresome on a long run especially with ATC cutting in to govern the speed at which you can go. For caravans it is quite common for the period of oscillations to become worrying when the speed exceeds 50mph. The device I have developed ensures that there is automatic correction at very low levels of sway ( 3-4 degrees) and without the need for speed correction to change the period rate. On my outfit taking a roundabout a little too fast with the two bikes on the back would normally lead to a large outswing of the van but this just cannot occur with DSS because the relevant side brake immediately pulls the van back inline, you do not even feel the operation it is so fast.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.
Topic: Alko STC Not working
