Tips to prevent caravan snaking and jack-knifing
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- เผยแพร่เมื่อ 14 ส.ค. 2018
- In this video we go through what caravan snaking and jack-knifing is, the steps you can take to prevent it from happening and some hints and tips on what to do if you do experience a snaking outfit.
Thanks to Towing Solutions for their help and advice in making this video.
For our video on loading click here: • Correctly loading your... and for noseweight click here: • Guide to caravan nosew... .
For more caravanning hints and tip visit our newsblog www.caravanguard.co.uk/news
Another wonderful and very helpful film. It's given me some confidence should I ever have my caravan snaking behind me. Thank you!!
Safe towing Olly
Why are you travelling so fast that the van gets the sways? You're going on holidays so take your time, don't drive like a knob, drive to the conditions.
And yes, do pack your van correctly, it all helps.
Colin - a sway can occur at any time or speed if the side force is great enough and without any proactive control system in place the risk is always there. What a fool I would look if my system will not work. There is nothing like it on the market or patent system that can solve this problem.
Very informal video!
Here is the critical feature that is needed for full control ( when an equal and opposite force is applied to the return to equilibrium at or before the equilibrium state.) this is provided without any electronics or motors in the system I have developed. This may come as a shock to the common beliefs of loading and some of the brightest sparks in the industry, however, I always explain my comments by facts so listen up -
I have carried two electric bikes on the rear of my single axle Bailey for the past 7 years and covered 35,000 miles on the busiest autoroutes in France with the caravan loaded to maximum pulled by a standard Peugeot 407 saloon so nothing special there. Except I do have my proactive "Differential Stability"(c) fitted on the Van. I am a Qualified Transport Engineer and have operated a fleet of HGVs and LGVs for over 20 years. I would like to dispel the myth of loading a caravan. Loading with all the heavy weights just over the axles is very bad if you are trying to prevent snaking (Uncontrolled sway). Concentrating the load in the middle of the caravan over the axle means that the front and rear of the van means that the ends of the base are very light weight and that means any side force makes it easier to push the caravan around the circular path of the axle and so with no device to prevent this rotation starting until it reaches the limit of the sway very quick and the potential energy is released when it hits the overrun brake or when it reaches the limit of SHM you have the classical disaster in 3 seconds. So prove this hypothesis - Wind turbines are designed to taper at the ends to reduce weight and be more responsive to circular motion and the same is with an aircraft wing since they also need to be responsive to elevator control and the same is with a high wire artist who uses a long pole to give him more stability except in the opposite cause ie he does not want the pole to rotate quickly so the heavier he can make the extremes the better. The chassis maker will design a beam to be strong enough to carry a specific weight along the length of the beam and so loading any vehicle should be done by spreading the load evenly along the full length and in the case of a caravan bias the weight to give a positive load on the ball. Inertia is only generated when the force acting on the object is converted into movement as in a flywheel and you can test this by suspending a flywheel on a pivot and the see how much energy it takes to get get it spinning but once it does move that energy is stored for as long as it takes to stop it in theory. So what is needed is a proactive system to increase the resistance to any force being applied before it gets moving. None of the offerings by the industry do this - ATC needs 4 light or two heavy sways to trigger then hopefully slow the 3.5 tonne plus combination down by which time it could be too late ie 3 sways and game over. Friction hitch locks are another myth
since the laws of friction mean once it moves it is game over. Differential Stability (c) has been designed to operate proactively with approximately 98% accuracy at preventing sway from starting - there are to many variable to be100% in all scenarios. However, under normal use these variables are very remote.
Thank you
As soon as the see your caravan start to snake. You take your foot of the accelerator (and no violent) no violent movements on sheering wheel. And that will stop the snake. Stop it.
At highway speed, say 60mph, from the time the 'snaking' starts till the time you jack-knife you have about 5 seconds. By the time you realise your caravan is snaking you have about 2-3 seconds to do whatever it is you think will save you from the inevitable disaster. Better to have already installed an electric trailer only braking capability to slow the caravan down without touching your cars brake pedal. Even better install an automatic trailer braking system on the trailer that senses when the trailer begins to snake and applies only the trailer breaks without any input from the driver. But most of all plan your trailer/car combination and the matching hookup system, load your trailer and car correctly and drive to road conditions.
One thing not metioned is trailer braking. I know that not all trailers have brakes, but some do. Applying those trailer brakes help, when sway first starts.
So take this scenario - if you can control the snake with a really badly loaded trailer it follows that you have a control system that actually does what it takes.
Whilst I do take on-board the professionals advice I would just like to mention that on one occasion I was in a situation where my caravan was oscillating quite erratically( myself, wife , two large breed dogs along with awning in the car )on the M42 where the traffic from the M6 merge with the M42 and I was in the lane to take in the direction of the M5 when two 40ft trucks one either side of me which I believe created the snaking. I immediately took foot off the accelerator hoping for the unit to stabilise for what seemed like a good minute but I'm sure it was only seconds without success, so my next thought was to put my foot back on accelerator and slowly pick up speed, thankfully this did straighten out the car and caravan. My speed at the time the trucks was merging was 57mph looking to get the best fuel consumption I could so was not speeding and had no signs of snaking either before or after the incident. It would be good to know why on this occasion speeding up eradicated the snaking which seems totally against the physics
The same situation happened to our car and caravan, the car weighs 1600 kg and the caravan 1200 kg, and carefully loaded with 70 kg nose weight and alko atc. Equipped. A lorry was passing on an off ramp and we were travelling at 50 mph, when the lorry got up beside the caravan it started snaking, I figure air is like the bow wave on a ship and as the lorry braked coming off the dual carriageway and I continued on the outfit straightened its self, and I never felt the atc system work, maybe it wasn't severe enough of a snake. I hope it doesn't happen to either of us again.
Caravan Tuggers - I sympathise with you and know how irritating it is when all and sundry accuse you of speeding or just a plain stupid driver. First thing you did was unwittingly take your foot of the gas, this actuated the overrun brake that was already building up a store of energy at each swing so it would make the situation lethal. By accelerating you pulled the overrun off but you were lucky that there was an opposing push from one of the two trucks that straightened your combination and allowed you to clear the two. I took my initial concept from my PPL flying where we controlled the steering using differential braking with the foot pedals, however, you have no foot pedals on a caravan - it requires some clever engineering to sense any out of line movement and actuate the corresponding trailer brake smoothly then let go at a specific instance. Now braking one wheel can cause the caravan to accelerate back so it needs the opposite brake to actuate at the centre of equilibrium and prevent it going past all automatically and without any electronics or such sensors. Very clever stuff and it does not slow the combination down so you can get clear of any traffic efficiently - you will never feel any sway at all.
@@paulwest6262 Again you were lucky that the truck braked allowing you to get ahead, had he continued along side your ATC would have kicked in and hold you back in the slip stream where no amount of trailer braking would prevent a severe side slam into the truck - just watch some of the videos to see this in action.
@@Cruner62 the atc only operates momentarily and doesn't slow the outfit much, it just brakes the caravan enough to straighten it up, if i took my foot off the accelerator the car and caravan would slow gradually together and the caravan overrun brake doesn't activate, it only comes on if i brake, i know braking whilst the outfit is snaking wil make it worse.
@@paulwest6262 That is the theory, however, it will not stop the sway from staring in the first place and it is annoying that at every twitch of a side wind etc the ATC activates and pulls the trailer in a straight line you hope. If the sway is a strong swing the brake will trigger at the extreme of the swing and can result in the potential energy increasing the swing back to equilibrium too violently for the light touch braking to stop the swing and because it brakes both wheels it cancels out the correcting effect. The overrun brake does activate when a large sway occurs and this is what triggers the potential energy to accelerate the swing back towards the opposite side with the kinetic energy induced. ATC is a sticking plaster for some minor sway correction I sincerely hope you never get a severe or concentrated push from the side Yes you are correct that slowing down gradually does necessarily activate the brake even wind resistance can slow you down. I know people that have towed for years and manage to get some control over sway and the one one day get hit with a big one or just simply lose concentration for a second and bang in three seconds it's game over - just watch some videos - these people have towed for years and then !!!
Not all Caravans leave the factory gates balanced on both sides.Mine ! ( drivers side ,kitchen full stove fridge toilet 38kl battery ) ...( passager side , shower bench seat and table ) No fancy tracking device will help unless the weight is even both sides. I feel sick, When I have a 2 ton SUV with a 2.500 ton caravan pass me doing 110 kl. on a duel hi way with the tale wobble He did beat me to the caravan park. He had only had the caravan and SUV for 2 weeks and this was there first trip??????
Easy stop driving so fast !! Almost every caravan I see on the motorways are going to fast !! SLOW DOWN
best advice is put on the trailer brakes to slow it down
Yes, agree 100%!
I wonder why the trailer brakes were not mentioned at all.
Using engine braking will work as long as the trailer has overrider brakes.
If the caravan has electric brakes, then engine braking will be counterproductive to straightening the tow as the caravan will push harder against the vehicle.
Additional advice is to not drive as fast or in a similar fashion to how you drive when not towing.
@@keijomusto3654
With electric brakes you may be able to manually apply the caravan brakes from the driver's seat. That helps.
@@keijomusto3654 I lost you you on a couple of points - Electric brakes on a caravan are not used in Europe they are all overrun and are the best system for light weight vehicles, however, the problem starts when a side force pushes the trailer out of line with a force higher that the tyres can resist and then the slip angles allow the trailer steer or swing out ( radial tyres have a smaller slip angle than cross ply and so resist a lot more but this means that the energy is diverted towards the tow vehicle so if you have overrun brakes it will push the brakes on but this means it allows the potential energy in the swing to be multiplied and so the velocity of the return is increased ( Why you should never brake the caravan at the point of the extreme of the swing) Now there are suggestions that the tow should be fitted with an manual independent trailer brake and I must warn all of you on here that this is the last thing you should do since if the caravan does not have ABS then the risk of locking the brakes on the van and will cause a severe jacknife and that will be game over. Most on here have very little knowledge of the physics involved in towing a caravan and the myths on loading and speed are every where. Non of the offerings on sway are what you think and should be taken with a pinch of salt like the friction hitches that are a waste of time except for making it safer for preventing coupling failure not anti snaking. See my other posts.
With an overrun braking system the brakes are applied on the caravan if a snake gets going without any action by the driver and it is this that accentuates the return velocity that then leads to total out of control as each swing gathers more kinetic energy. Never apply the brake on the return to equilibrium on the wheel that is returning/ clockwise since it will accelerate the opposite wheel and game over especially if you don't have ABS on the van.
trailer brakes?