A holiday towing disaster - and how to prevent this happening to you | Auto Expert John Cadogan
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- Опубліковано 7 жов 2024
- It’s never good when your trailer overtakes your vehicle. But in this case, as I understand it, death and serious injury were narrowly averted. Incredibly enough. So, on the cusp of this holiday season, I want to make sure this does not happen to you.
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Here’s six preventative towing tips.
Number one: Minimise the mass of the trailer relative to the vehicle towing it. When it comes to trailers and safety, smaller is definitely better, and it terrifies me the people who e-mail me direct and say, basically, that they want to tow three tonnes with the smallest vehicle possible, because it’s also their daily driver.
That’s nuts. If you want to tow a heavy trailer, get a heavy vehicle. This is the fundamental stability solution. Personally I think it’s fairly insane to tow a trailer heavier than the kerb mass of the vehicle towing it.
Number two: get the trailer and the vehicle set up right, with five to 10 per cent of the loaded mass of the trailer as the static towball download. That’s ideal for stability. Measure the weights - do not guess, or read them off a spec sheet. Visit a weighbridge and do this right.
Number three, drive conservatively. That means, knock 10 or 15 kays off how you’d normally drive (conservatively). It can feel quite OK towing heavy at 100 - but it can also come unglued very rapidly, as you’ve seen. Just change your mindset here, and for Christ’s sake, let faster vehicles past at every opportunity. There’s no need to ramp up the tension on an already struggling road system.
Number four: Leave some ‘acceleration juice’ in the tank. Meaning: one of the reasons the driver of this ill-fated towing assignment crashed out is that if you drive a trailer and it starts to get the death wobbles, the best move is: accelerate gently and don’t try counter-steering. (Because acceleration reduces amplitude, and counter-steering often causes the amplitude of the subsequent swing to increase - and you only get about four swings until it’s all over, at speed, right?)
Number five: Get some driver training. This trains you to look as far down the road as possible, which is generally where you want the vehicle and the trailer to go, in that order. Under pressure, you generally steer where you’re looking and it’s less likely you’ll over-compensate with the steering.
Finally - number six: If you’re upgrading the vehicle, get one with a ‘trailer anti-sway’ algorithm built into the electronic stability control system. Computers are generally better at this than most/all drivers. Not only do they detect the problem and intervene sooner, but they also intervene better, by cutting power when it’s needed and applying the brakes to individual wheels to generate the yaw response needed to cure the problem.
The best cure here is prevention. Just don’t get in this situation. Tow a conservative trailer and drive conservatively.
this happened to me in the late eighties towing a 16 ft trailer yacht. driving at 80km i came upon a house truck doing about 50km. as no one was coming the other way i decided to pass. just as i had the trailer past the other vehicle she started to pendulum. instinct told me to accelerate and try to pull it straight, rather than brake and definitely end up a tangled mess. luckily the car i was driving was a large older heavy one and after what seemed like an eternity the dam thing fell into line behind me again. and yes i did have to change my pants! that yacht in itself was not particularly heavy, but the forces it generated were incredible as it tried to drag us off the road.
Proper inflated, or slightly over inflated tires helps prevent this.
All great tips, I after towing for 45 years would never personally overtake going down hill.
I seriously think it is time you stopped and had some rest. You are a danger to everyone else.
Yes. Of course I might overtake a tractor going down hill but basically I agree with you. The tow vehicle would need to be more than twice the mass of the trailer for me to be even interested in overtaking downhill. Even at relatively low speeds it is way too easy for the tail to wag the dog.
@@ranichso735 Well that was mean. I drive for a living and from 9+ yrs doing that the choices people make when driving are the problem.
Or you could just accelerate like a competent driver.
@@SirDeanosity it was a joke mate, as in 45 years without rest, get it?
I've been towing caravans for 30 years and was taught by the UK caravan club to "Never try to accelerate out of a Snake" as if snaking starts up again you are going even faster. Ease off the throttle and don't try to counter the snaking with the steering. Safe towing starts with the preparation, correct loading of the trailer and as you say never towing more than 100% of the tow vehicle weight.
Besides, how many tugs have that much power left in the tank to “pull it back into line”? A big US ute, “maybe”, but not the average tug available here in Australia! Besides, back to basics; accelerating when the trailer is snaking just adds even more energy into a problem created by an already over abundance of energy. Unless your moving slowly, accelerating into the problem is just going to make a bad ending badder.
Another Pom here (retired British Royal Corps of Transport) and yup taught same. I get the physics is a constant and in-theory method to counter the affects but wondering if the practical advice varies from country to country
I do the same if my 2 tonne boat gets the wobbles I just ease off the pedal down to 80kmh and keep the steering wheel straight. Never had any problems. PS don't touch the brakes.
Yet another quality report. Thank you, John! Happy holidays!
Not often I would say this. I agree with every word this guy said.
The one item that always seems to be left off these lists is to make sure the trailer's wheels are aligned. I recently picked up a new single axle caravan. Bringing it home from the dealer, I could not safely exceed 90kmh as it would start to sway. Applying a little brake to the van would correct it. Once home, I found that there was toe out on both wheels where the recommendation is about 1mm of toe in. Having corrected this I now have a van that is happy to follow me and not try to overtake me.
I thought the number one rule of towing is to drive at 80km/h in a 100km/h zone, then accelerate to 110km/h for the length of overtaking lanes, then slow back down to 80km/h.
it is.
Unfortunately this isn’t restricted to just towing vehicles. Plenty of dickheads that aren’t towing do this as well!
Divided road sign in Australia means 'speed up in the left lane'
Sigh. Here we go again...so you actually believe a standard tug has the power to not just maintain 80km up an incline (where passing lanes are typically located), but can also not only accelerate up said incline, but can do so more quickly than your unburdened vehicle? Can you please tell me the name of the tug capable of such feats, I’d love me some of that action.
Yes here in Queensland speeding up in overtaking lanes then slowing down happens ,it seems, all of the time ,massively frustrating
This is the video that taught me to never question John Cadagon. He knows his stuff.
I always thought the answer was to slow down. I now see how that could have made it worse.
Remember buying an old 80s caravan. Seller told me that it may oscillate past 80km/h so accelerate as quickly as possibly to 100km/h as its very stable when being dragged on its side.
Honestly probably one of the best videos that you have done to date, while I don't tow I have been stuck behind plenty of caravans on twisty roads going 15km under the speed limit. I know theoretically that since they are towing a heavy load they need to go slower to be safe I have never bothered to have a look at some actual science of why they go slow, will have slightly more patience while stuck behind them in the future before I go full YOLO across some double white lines around a blind corner to save that vital 10min from the road trip.
I have watched a fair few of your videos now and one of your definite strengths that comes through is "Road Safety" these videos you do while stating the bleeding obvious at times are very entertaining but most importantly educational. Cheers John.
Great towing advice John.
I’ve been towing tandem trailers behind Commodore/Falcon cars for 20 years and most of what I’ve learnt by mistake you condensed. My main advice would be vision and anticipation, patience and attitude and being very gentle on steering and throttle. John’s explanation about a pendulum is spot on and an excellent way to think about trailers.
An anecdote, towing a car on a car trailer, I put the floor jack in the boot of the car on the trailer, so about 40kg up high. It made the whole combination unstable. Get your weight down low and lower your centre of gravity and don’t over load the tow ball, get the weight on the axles.
Well explained John! My father taught me the same thing 50 years ago!
We had the tail wag the dog once and it was a VERY unpleasant experience. Our tow vehicle was our old HJ60, loaded up with gear and a dinghy on top (so read heavy tow vehicle) and behind was our old (also heavy) 2 ton-ish tandem brick of a caravan. A fairly typical grey nomad rig for long term touring. We had been towing this combination on long drives for years and never had a hint of a problem. We were too slow to overtake anything but a really slow moving tractor and were on a straight stretch of road with no other traffic in sight. We were also loaded correctly (I am experienced at setting the rig up and knew where the weight should go) and on top of all this, we had what are laughingly called, anti-sway bars AND a Reece friction bar so everything should have been fine. Our undoing was a high ridge line where dense bushes suddenly gave way to clear ground and as we emerged from the sheltered section, we were nailed by a huge gust of wind. That was all it took to get the caravan wobbling and it was mere seconds before I could clearly see the whole side of the van sliding out into my side mirror view, first one side then the other. Having had no prior experience of this and never being told what to do if it happened, we were saved by pure instinct. There was no traffic so I got the 60 into the middle of the road and accelerated. We must have been mere seconds from being flipped over but it all came back under control, even though the caravan blew one of the tyres. That would give you some indication of just how far it was swinging out to get that sort of friction of the tread. So, even though we had done everything by the book, were driving conservatively (80kph ish), we still found ourselves in a very nasty situation. I think it was a large slice of luck and instincts gained from years of towing that saved us in the end. I am a firm believer that towing heavy trailers SHOULD require the driver to have formal training.
I subscribed your channel quite some time ago and being an engineer at myself as well as an high functional asperger autist I fall in love with your humor.
Yet this time watching your video I cought you doing a technical mistake the first time since I discovered your channel. You said (beginning at approximately in minute 10:40 in this video) that the only way to avoid desaster from happening after noticing the first swing of the trailer would be a gentle acceleration.
Actually we testet that theory twice at the Technical University of Darmstadt in Germany in the early 1990th at the vehicle design department. Once with a Subary Legacy and an 1.5 ton shitbox an wheels and once with an VW T4 and a 750 kg plattform trailer. Everybody has the feeling that a very gently acceleration would straigten the pendula, yet the mathematic said it just would put more energy in the system, thus the explorer in the engineer had to go on a test side to verify wrong from right and we discovered that there is only one way to prevent desaster from happen after the first swing occurs: don't steer and press the brake as fast and as strong as possible to kill the pendula energy.
Our professor had another idea. He said that you just have to accelerate gently enough. Finally he drove the assembly of Legacy and shitbox instead of our professional test driver and the last words via walkie talkie we heard before it crashed was: "it is hard swinging now, I do accelerate!"
Surviving physicaly unharmed he repeated the try-and-error-experiment with a more heavy tow car, the Volkswagen T4 Minibus and a lighter trailer, a 750 kg DIY-stuff transportation plattform trailer and with being even more gentle at the trottle.
Again his last words before the trailer made the tow car doing some salto mortales where "its swinging. I'm accelerating."
Conclusion: mathematic in physic can't fail.
Pendula is energy
Putting more energy into it, as gentle as you can do, is raising the energy level is raising the pendulas amplitude.
DON'T ACCELERATE!
SLOW DOWN!
Just like the stabilisation control does (if programmed in) by braking (not accelerating) one or another wheel at the tow car (and on bigger rigs even the trailer).
Thank you John, I have learnt a lot from your post, this is the type of info that saves lives on the road !!! Very much appreciate your advice, cheers from Wagga , ps Merry Xmas to you and fam
I feel that this video is one all should share with their friends and family whom may be off doing caravans, trailer bound adventures this holiday season. You'd be giving a gift that could very well save their life and others on the road.
Number 5 should be Number 1 for all of us drivers on the road whether we tow or not. Thanks John
One of the best reports I have seen. A tow ED course helps all to understand the variables as mentioned.
Thank you so much for producing this video, hopefully it will change some peoples' mentality and avoid unnecessary tragedy. The degree of arrogance, entitlement and impatience on our roads is something else. This video is far more informative then some of the motherhood platitudes from the road authorities. Happy Festivus to you John! Regards Arnon
Thanks John. I do enjoy these type of lessons. Information to bank in my brain for when I need it.
I tow a 1700kg max camper trailer with my GU patrol. Comfortably under the Patrol's weight. I try to stick to 90kmh for economy but ease back a little further when there's no traffic. Can't believe the size of the 20' plus caravans behind twin cabs these days! Then they have racks on the back for tyres, bikes or BBQs...
Went to the Big Red Bash at Birdsville last year. The road from Windorah to Birdsville was the harshest I've ever seen. A couple of caravans had apparently landed on their sides off the road, the lack of structural integrity leaves a scene like a bomb site.
Another caravan (quite a small one, fortunately) was being winched on to a truck for a flat bed ride for a 300km run into Birdsville. Its single axle had apparently rotated 45degrees forward on the right when the right leaf became independent. That would have been an exciting event for the driver. New seat covers recommended.
Braidwood Rd crossing Tianjara ck NSW. The downhill run is steeper than the video shows.
As John mentioned, not long afterwards all that bush was destroyed by the fires and there are areas along that road that still look like a wasteland.
Perfect timing for a great video, John. We're about to tow an enclosed car trailer behind our 40ft. motorhome. Last time we towed was a 21ft. European caravan behind our Kluger. There was absolutely nothing that made that sway even an inch while travelling at 100.
All the advice you have given in this video is what I was taught when learning to drive, although that was way back in 1993. They dont make drivers like they used to.
Great video 👍🌞😎
M.G. It appears that whilst you may have critical thinking well applied on paper/data analysts/spread sheeting and or modelling software. Please be aware, having an opinion to share is wonderful and a privilege - not a right.
If you don’t want to come off as a socially stunted know it all, with a well below average emotional intelligence. You may wish to provide a SOAP (summary on a page) - perhaps create a video or artefact to that affect. Outlining why you feel that ALL the advice JC gave was wrong.
You want to create a difference in the world with your comment, say it whilst protecting the integrity of the forum you choose to interact in.
@@Matthias_Fischer Using the trailer brakes only will pull the trailer straight so it wont overtake the car. So with a brake controller installed you can use that to slow the trailer down hence reducing sway. I don't think ABS would have saved the day though mate, feel free to correct me.
@@Matthias_Fischer 😂🤣😂🤣😂 how many years actual driving experience do you have? Got ya Uni degree hey. That won't save you on the road. 😂🤣😂🤣😂
@@Matthias_Fischer I appreciate the conversation thus far and also that you have had a moment of reflection. Which a lot of people do not do and if they did, the world may be in a better place for it. Never doubt that people do and may care in general. The ignorant may one day have an epiphany and those open to having a constructive discussion may expand their subject matters into fields that are unfamiliar and uncomfortable. That is where TRUE growth can happen. I have eyeballed the ISO 9815 and agree with the data and results as presented in those controlled examples. In saying that, the example JC has reviewed, has multiple vectors of data that dramatically change the outcome. If we can hold off commenting straight away due to "knowing something, with the eagerness to share/correct", we may often be surprised by the general feel of a discussion and how it may influence someone's actions moving forward. How does that sound?
@@Matthias_Fischer seems like you have it all figured out my learned friend. I wish you all the happiness in the world that you allow yourself to experience.
Remember there are two things guaranteed in life. How you think you will be remembered and how you actually are - if you are remembered at all.
P.S.: I appreciate your commentary and can sense there is a lot more to you than you are portraying.
@auto expert John cadogan, excellent report, but you need to lead by example... unsecured loads are another BIG problem when towing. That tractor tire must be legally tied down, regardless of the high sided trailer. If the load moves in the trailer or you are involved in a collision that tire can be ejected from the trailer and cause a very dangerous situation.
I have an 2004 Nissan t30 xtrail manual and the owners manual states it will tow up to 2T braked, bloody insane in a vehicle that weighs 1400kg.
I love the channel!
This is why you need a trailer brake that can be applied independently. Accelerating out of it only works some of the time, and could actually make the situation far worse because you are now going even faster than the speed at which you first lost control. Much better to brake the trailer to stop it trying to overtake you.
A contributing factor was the slight downhill grade which increased the effective ball weight.
I'm just grateful there are no more bloody Kombis around on single lane highways these days.
I can still remember the 5 kilometer long queues on the Bruce highway doing 70 - 80kmh and those bloody Kombis refusing to let anyone pass.
I was going to lobby for it to be legal for all highway cars to carry RPGs to resolve this problem back in the day.
Perfect. I do recall about a year ago. This will be played at the beginning of all gatherings as a value moment that we have over Christmas. It will be military like, no excuses.
You just said something that shocked the black out of me. I drive a fairly big car (Hyundai H-1/imax/i800) and find myself accelerating very hard when I overtake a truck or anything slow.
Your words just got me thinking, "what I do if 1 tyre burst while overtaking and I needed to gently accelerate out of that situation?"
Answer: "you would not be able to accelerate out of the situation and might end up in real trouble"
My worst towing experience was pulling a medium sized caravan behind a Ford Mk3 Escort in the UK (so mid 80s). My wife was driving on the M25 and the caravan started to sway violently as we exited a tunnel. I don't remember if my wife chose to slow down or try to increase speed, but thankfully, as we got clear of the tunnel it came back under control. What I do remember is looking behind us and seeing a sort of rolling road block with all three (it might have been four) slowed down line abreast behind us. We did have one of those anti sway bar things, which might have saved us tipping over the caravan and spreading its contents across the motorway. It was damn scary - I do remember that. Since living in New Zealand I have towed a 635 Buccaneer with a big 225hp outboard behind a Pajero, and never had the slightest wobble. I now drive a 2017 Highlander which has antisway and a 5000lb towing capacity, but have never pulled anything more than a load of garden waste to the tip.
Dear god John, sware you read my mind at times. Great story to revisit with the upcoming holidays.
Followed a clown like this on the newly opened highway between Ballina and Coffs Harbour on Friday 11th in very heavy rain. Any time he got over 90km/h the tail waged the dog. Yes, I am one of those, I called the police and would do again.
The death trap consisted of a Delica on a car trailer, towed by a VW Transporter dual cab with 5 motorbikes on the tray along with a complete car engine, gearbox attached, camping gear, 4 portable fridges and a cabin with 5 or 6 adults and extras on board and a roof rack packed full.
The rear of the tow vehicle near hit the ground over larger bumps and also helped induce death wobbles to which those on board started laughing.
A few hours later passing the opposite way I saw the death trap with a patrol car behind with red and blue lights ablaze parked under an overpass, while the car and trailer sat with towbar tongue snapped and witness marks on the road.
Some douche appeared out of the dust cloud then instantly overtook me (GU Patrol, rooftop tent so creating a massive pressure drop) on the Oodnadatta Track towing a huge double axle caravan behind an Amarok. I slammed on the anchors, safely, as soon as I realised he was towing as that thing was definitely on the edge of control & I didn't fancy wearing the caravan as an accessory. As we can't control the external dickhead factors when driving, be on the lookout for anyone overtaking with a large tow behind them & slow down as much as it's safe to do so to let them past. The lowest common denominator of both genetics & intelligence are definitely out there amongst us, so stay vigilant & stay safe 👍
Great advice John!
Your "hero" seems to have been trailering down a hill towards a bridge.
I'm sure you know this, but some may not:
Towing down-grade further exacerbates vehicle instability as, at a constant speed, a trailer feels a small decelerating force. Up hill, the trailer feels acceleration and is thus more stable than going down hill: Lower your speed when even more when trailering down a hill.
In other words, the load starts pushing the tow vehicle going down hill!
I guess keep the speed down and try to avoid coasting when going down
hill .... I know that sounds contradictory!
Thanks John I hope your Tips on Towing safely help some people avoid a bad situation.
I hate towing stuff I like my car to be as capable as it can be without additions. Motel Vs Caravan Motel for me every time and I don't have to store it for the rest of the year.
My parents had various single axle caravans in New Zealand in the 70's and 80's and I learnt to drive in the 80's towing. It's interesting how sensitive the caravans were to the placement of the annexe inside. It had to be fairly well forward to get the right weight on the towball.
don't forget the trailer sway brake and tap the trailers brake controller to stop the sway
bonus points for dual axles when you blow a tyre
Good advice John! A couple of other things to consider... trailer based ESC and applying trailer brakes to pull the combination into line. This is common practice with truckers towing dog trailers. Apply the trailer brakes and throttle at the same time to straighten the combo.
Never sore this one but couldn't agree with number 4 more. The driver tried to use that down hill run and maximum throttle input to overtake the two cars in front. Like you said, when it started to sway their was no power left to pull it straight.
My assumption is the driver of the boat trailer knows that road very well, looking at how, when and where they tried to overtake. Given the blind corner on the other side the bridge is so close.
10 years of Interstate b-double experience is want im going to use to back my opinion.
It was interesting see the aerodynamics at play, never thought about it until you pointed it out. Very cool.
Outstanding! I never had this kind of driver’s education!
Great advice, my mate was towing a load of sand, (my guess over the trailers ATM) and it did exactly this and came around and wacked his old man's brand new Landcruiser in the driver's door on a bridge. He then raced home to get....a broom!!!
John, hope you don't mind...I've posted a link to your video on the Facebook page for caravanning and camping. We'll see how much of a shit-fight ensues!!! hahaha
as an old retired truck driver, a 6 axle truck, trailer is 42500km. The PRIME MOVER weight is 22500kg, 6000kg on the steer axle, 16500kg on the drive axles, trailer weight is 20000kg. when i was driving if your axle weight is not wright you don't go anywhere until those weight are corrected, along with a $3000.00 fine. Probably a more substantial fine than that know.
1. Balance your load!
2. Do NOT speed (pace your self!)
3. Do NOT use cruise control
4. Both hands on the wheel (steer hard and strong)
And probably what made this worse was the two counter weights hanging high of the back of the boat
Another quality report cheers John 👍😍😍
2 common practices in North America:
1) Get a sway control hitch - see “Equalizer 4 point sway control hitch” as a great example - I know John worries about snapping something with one of these
2) As others have mentioned, get a trailer brake controller for your (electronic) trailer brakes inside your vehicle, so that as soon as you notice instability you can give the trailer brakes a squeeze while keeping the tow vehicle moving forward. This should have a similar stabilizing effect to accelerating... without the extra dangers involved with ... you know... going even faster!
In aviation, it’s called “Pilot Induced Oscillation” (PIO) wherein the (pilot’s/operator’s) control inputs into the system (A/C) become in-sequence to the deviation(s) to the intended path/direction thus amplifying the divergence from the intended path/direction.
Thanks John. Regarding the feature for anti-trailer sway that's built into a car's ESC, that's a good idea. Also, and I don't know why it isn't mandatory on all caravans, for example, are the products that Al-ko and Dexter make - ESC and Anti-sway respectively.
Every van being sold new in the local caravan dealer comes without it. Sales droid tells us that it's a $1,500 add-on. Apparently there are rules that now stop slide-out BBQs being included in the vans but they don't have to have such a basic safety feature as ESC.
Inclined to agree. My caravan ESC cost $2K. Maybe (although I don’t know how effective the vehicle ESC systems are with trailers), is that it should be mandatory to have at least one ESC in the chain?
Anti-sway braking systems should be mandatory on all tow loads over 1000kg. Even these systems should be coupled to the car steering better. I can imagine a system that during sway, lowers the power-steering amount even further to deter the driver from turning the wheel the other way.
The boat stayed upright and was on the water 3 days later, yes it does need a bit of gel coat touch up ......... bravo!
People forget or dont relise that the dynamics change towing on level ground to downhill or up hill , you might be able to tow at 110kph up hill but down hill even 90kph can get sketchy . Electric brakes are worth their weight in gold to counter any trailer shenanigans.
The self-proclaimed best drivers are often the ones doing those maneuvas 😎
Bull shit
One thing that I have noticed is that not many people know what the manual brake button does on the brake controller. Knowing how to apply this quickly but gently, could have prevented this accident. I am always ready to press the manual button if there is a chance of instability caused by trucks etc.
Hello John. I think this crash actually starts when the overtaking driver drops a wheel onto the shoulder on the right. You can see that at 4:12 . In moving back onto the road surface, he starts the chain of losing control of his unstable rig. The air cushion later complicates the process. Regardless, all of your recommendations are spot on.
Great work, John! Wonder how many people have ANY understanding of the physics of towing at all? Then they hook up an overloaded trailer to an underpowered and too-small vehicle and off they go.
Aah the good ole Dunning-Kreuger effect in action. I've always said that if you want to tow your cash up bogan water ski device, or dunny on wheels, you should have a specific license for it. Maybe call it an LC (Light Combined) license. It's worrying that anyone with a C license can roll up to Ford and say grab a Ranger, then go tot the boat joint next door, and grab any boat, and then merrily make their way to the nearest body of water, with no training or further licencing. Truckies need a special license class and training, so should those who tow boats, caravans, even the mate's clapped out VN.
I drive on the French autoroute's often. It may surprise you to hear, fairly regularly I see as I am at the limit of 130 kph (gps) cars whizzing past with a trailer. Often loaded high with bicycles, canoes even wardrobes. once even a collection of Dr Poo's Turdis's (portaloo's) needless to say I knock off the cruise control & let them get well ahead so it won't go shit shaped near me.
That’s one of the best video I’ve seen 💪🥊☝️
You nailed that one John. I tow a medium sized caravan and I take it very seriously, for the unwary the bloody things are an accident waiting to happen. Merry Christmas mate.
I was one of two tow truck drivers that recover that boat .the boat had moved back on the trailer the winch support had come loose sliding back. The owner had said every time he got to 100 K the car would start to wobble. The vehicle combo was also not weight balanced correctly
Makes you wonder then, he knew it was a problem and yet, instead of finding the root cause he proceeds to drive 100km/h +, makes him a certifiable idiot. I hope he was charged with negligent driving.
@@nobody6056 I know he had to pay for guard rail repair
Whilst generally interaction effects between two objects moving through a fluid are small, as pointed in this case they're enough to excite the trailer into swaying and subsequently yawing from the connection point at the vehicle. In the case of big ships the forces are significant enough to cause ships to collide and be torn off moorings.
There's actually multiple phases that occur here when overtaking an object (in this case two cars).
1. As the overtaking car interacts with the pressure wave of the car in front it sways away and surges back from the car getting overtaken.
2. Whilst alongside, the fluid moving between the two cars is restricted and flows faster when compared with the air flow on the outside of the two vehicles. This causes the overtaking car to sway towards the car getting overtaken
3. As the overtaking car interacts with the pressure wave of the car that has been overtaken it sways away and surges forward.
This can be noticeable when you overtake a truck on the highway as there is a much longer uniform mid section, where your car will attempt to sway towards the trucks and the truck creates larger pressure waves for you to interact with at the beginning and completion of an overtaking manoeuvre.
You didn't mention applying the trailer brakes (electric brake controller) whilst accerating, it would have stopped the pendulum very easily!
You're assuming the boat had brakes and that the car had a brake controller unit that worked right, I'm asking.
Definitely would have pulled the trailer straight, if fitted, but still would have needed quick reactions.
Boat trailers are usually hydraulic braked
Not only electric brakes but one can also use air brakes (of old) to apply the trailer brakes, thereby "stretching" the car-trailer combination. So that is POINT 7 that John did not mention: get brakes on a trailer that can be applied by the driver within the towing vehicle.
Surely a trailer that size had brakes
Thanks John
I found this informative and further re-enforced the knowledge I have already gathered, the only thing I haven't done is the weighbridge, but I did get the scallies to weigh my Caravan so almost there John, I to keep to 100km/hr on the freeway and 90km/hr on rural/single lane roads. Safety is the game, my only question is I can't find a speed limit for Towing vehicles. Western Australia has the speed limit posted everywhere 100km/hr but not NSW, Vic or SA.
Your first point is the reason we use a 2 tonne Outlander PHEV to tow our 1200kg caravan and 1450kg boat. Tows safely at 90 to 100, but we use 90 as a rule, and efficient for our daily drive of 30 to 40km per day.
Pat Sparks. (I know you hate UA-cam handles)
Back in my days of motorcycling I had a saying sucked in at the front and spat out the back. This term came from overtaking a truck or a bus at speed. Wind direction can also play a hand into it as well for eg a strong cross wind. Buses were the worst because they are basically a mobile brick! Nothing much on a bus to disrupt the air flow, a truck ie mainly a semi has gaps where the vortex gets disrupted and the rapid turning of many wheels at head height just scares you to death!
A bus at speed creates a vortex at the front rotating clockwise as it pushes through the air, potentially sucking in an unwary motorcyclist as you or it goes by. Then when you think you've recovered from that it hits again at the back, either potentially blowing you into the guard rail or into other vehicles, who knew you had to be a lab rat to survive on a motorbike.
In saying all that 2 things still blow my mind that these two simple things are not made obviously clear to new motorcyclists. It could be the difference between injury or even death.
The rest of the community just reports it as the rider lost control.
Getting back to the video the concept is the same, just an overtaking car+boat on an unstable platform+ speed a potential disaster.
In my day 80k was the top speed you could travel at towing a laden trailer this mostly prevented this type of accident. Fast forward some years and some goose decided, that's just old hat and now you can travel at maximum speed! Disaster just waiting to happen.
Another thing about trailers is in NSW you no longer need rego inspections. I took my boat up to the north coast this year & the trailer looked fine. Put the boat in the water & when retrieving it the drawbar broke in half. No sign of rust until then when it became obvious there was plenty on the inside. Lucky for me & anyone else on the road it didn't happen at 110 kph on the freeway!! $2000 later I feel much safer. I now wonder about other trailers (especially home built ones) & how they are maintained.
Interesting....I have read to slow down if this happens, not accelerate! And apply max trailer brakes by manually pressing the switch on your brake controller. The most important thing is situational awareness and having a plan if this does happen, ie...hit the trailer brake manually
Great video and a well covered topic. More beer garden physics please!! Also glad no one was hurt in that crash. Would love to see something on the impact of trailer braking systems on this dynamic. Happy Holidays!
Gently applying the trailer brakes also helps stop sway. Unfortunately not possible with a trailer with shitty spring activated brakes though.
And to add to the below, once I slowed down a bit and still in death wobble motion I did hit the noise pedal with linear pressure,
Bernoulli effect 's best demonstration.
John. Why no cmment on application of emergency override on brake control unit? Also, with throttle up idea I get that it reduces amplitude... until acceleration ceases then you're back to an unstable system, just with more energy. Just a worse outcome isn't it?
I wonder how many cameras were used for that tyre pick up shot. Very well made and edited. Great report as always.
John, I thought the sway bar linkage is supposed to stop this. well unless the person was a DH not having the power to get out of a wobble. This happened to me in the late
70's going into Adelaide. Planting it got the overloaded trailer out of its wobble. The power in the old Galaxie and weight of that Yank Tank saved us. The Valient with its light weight and only a 265 six I got sway bars for the caravan. I kept them for the Fairlane even the Cerato, Though I can't see the Cerato towing a van.
“Sway Bars” are actually load levelling devices, they shift a % of the tow ball down-weight back onto to the front wheels which in turn reduces the potential to develop sway. The are very useful to prevent swaying, but far from perfect and they create other issues. Many people use them, not to reduce the likelihood of sway, but to redistribute the rigs mass across multiple axles to comply with weight distribution requirements. For example it’s not uncommon for a vehicle to come in under its CGM but “bust” the weight limit on the rear axle. A load leveller transfers weight across more axles (reduces the rear and increases the front axle loads especially), and one can adjust the weight distribution so the vehicle can come in under its front and rear axle load limits, and even tweak the ATM. Of course, load levellers cannot change the CGM. Personally, I don’t like load levelling devices, they simply mask an underlying problem/inadequate setup.
Did anyone notice the 2020 FO put on the WD-40...? So hilarious...😂
Nice report John . Here in North 'merica weight distribution bars , also known as anti sway bars , are quite popular . You didn't mention them at all , don't they have them down under ?
I managed to tow just over 3 ton in a old modified little hot hatch. The car weight just under 850kg driver not included. Small vehicle's can tow heavy trailers safely but it did take alot of conservative driving. I had to go slow and be very mindful of both winds and very long and gradual braking and acceleration zones and also going real slow in areas where surprises can happen. I also checked the weight distribution before driving and strategically placed cement bags inside the car to have the maximum weight as low as possible. Although this can be done safely I would not advise doing this if it can be avoided and certainly not if you are not a very experienced and responsible driver.
For anyone curious it was a race modified starlet kp60 and yes I had to take brakes to cool of the brakes several times along the drive.
Big fan of ALSO adding sway control and weight distribution. Great vid John. I would say it's a toss up as to what is the best safety invention of our generation: ESC or ABS. Thoughts?
ESC
Problem is John, a lot of these people would not understand most of what you said
Great tips John and very well explained. All the best for Christmas and travel safe everybody 👍🍻
Thank you very much. You too - all the best.
Been in a similar situation.. Load shifted slightly in the car I had on the car trailer I was towing and all hell broke loose. Took over a kilometre to ride it out in the old Hilux before I could slow down, pull over and fix it..... And change the shorts :). I was just lucky it was double lanes both ways and very little traffic.
My old man died towing a trailer in an old Landrover, not much a chance to survive when they roll.
I'm always carful when I tow the boat.
My Dear old Dad taught me if the trailer starts swinging floor it to pull the trailer out of the swing then slow down once stable
I make it worse going down hill .Going up hill strong acceleration will pull your trailer straight again.I have done this and it workes .Im also a semi driver so a little about towing .If you have electric brakes and are very competent in using them adding slight drag to your trailer when going down hill will also help keep thing straight.Be mindfull of overheat your brakes though
I think you missed a point John. In my mind, impatience bought the whole of this on. People need to have patience when you are on the edge of ability in a vehicle.
Quite true. Please read my comment about what probably caused the impatience.
Was on a motorbike behind a car towing a BIG trailer with probably 10-15 roller doors on the back.. same thing happened but the trailer snapped off.. flipped across 2 lanes of traffic and end up near some bemused cows.. really wish I had the camera running for that one.. nobody injured.. amazingly.
The German motoring association ADAC does not recommend accelerating when the trailor begins to yaw. They say deceleate slowly, in an emergency hit the brakes hard shortly just when the trailer is straight behind the car.
Couple of things.
The part about the Bernoulli effect, which you say occurred between the passing vehicles is not the cause of the fishtale in my opinion. I drove semis , ride a motorbike and currently drive a box van. When a semi passes you on a two lane road, that is probably the largest amount of air dam/ Bernoulli effect you could possibly experience. Cars with huge caravans pass semis going in the same or opposite directions all the time all over Australia and they dont get into a massive tank slapper. What I think happened is the boat bloke was in a hurry to get past the couple of snoozers who werent going fast enough for him. So out he went, downhill with his foot thru the floor. The first force then was the weight of the whole rig was thrown to the right, he was then preparing to pull all that weight into line as he approached the bridge. As the rig then reached the apron where the bridge started it flattened the suspension of both car and trailer and there is often a little drop right at the transition from road surface to bridge surface and the compression of the trailer springs caused a slight sterring effect of the axle which caused one set of wheels to be further rearward than the opposite one. Like you used to steer your Dinky toys as a child . The ones with the slightly loose front end. And from then on ,in seconds, it was all over.
Also, you suggest to slightly accelerate to straighten out the coming armageddon and then contradict yourself by saying the computer algorithim, whatever that is, will stop you from accelerating when things get wobbly. So basically you are effed and should just hang on for that 6 second eternity and hope you and your loved ones dont die. I remember years ago that trailer puleers of any sort werent allowed to exceed 80ks. In Victoria . I think thats the best answer. Ive been in a small tank slapper once and it is terrifying to go against your natural instincts to to put both feet on the brake pedal and instead press that other pedal.
Hilarious about the tractor tyre in your vid.. In my local area , in the old days ,when Poppy wasnt 70 , if you saw a large tyre outside a factoryette you would assume there was a tyre repair shop there, but no, it is a place where middle aged men and women go to lift heavy vehicle tyres . Ugh. I used to have to lift those 10 double Os for a job . They go there to grunt and groan and pay for the privilege. What's happened to the world?
1. The video evidence and your version disagree. The trailer does not lurch right when the vehicle moves to the right side of the road. It lurches left at the exact time it draws alongside each car. Boats are a different shape to caravans, and increase the Bernoulli effect. Caravans are just boxes generating huge turbulence, which is slipperier than laminar airflow. So there's that.
2. ESC trailer sway control will cut the power IF IT NEEDS TO. I did not contradict myself. Do try to keep up.
3. The purpose of exercise is to crush your soul and thereby inspire you to be less pathetic in future. Tractor tyres are perfect for this.
4. A "couple of things" is two things...
One of your best videos.
Where I live, a trailer with a GVWR of 1,360 kilos or more is required by law to have trailer brakes installed, connected and functioning when being towed.
The biggest contribution to the trailer wagging is having more of the mass of the load behind the trailer axle. If most of the weight is ahead of the axle, it is less likely to go out of control.
That's true, but too much weight forward puts too much weight outboard of the tow vehicle's rear supension, with loss of control at the front. With a heavy two getting this balance right is critical, and the heavier the tow is relative to the towing vehicle the harder it is to get right.
Two years ago in Italy, I saw a Fiat Panda towing a 45ft powerboat! Amazing.
At 160km/h on the Autostrada?
I saw a 45ft boat towing a panda on skis
That's beyond insane! I mean, they couldn't afford a real towing vehicle?! And if that trailer starts the Death Shimmy, it's all over but the sirens and emergency equipment.
@@xpusostomos That's........NOT quite the same thing. But rather entertaining.
Really excellent, thank you for all your effort.
Fascinating
Slow down when towing. I was in this situation many years ago towing a car trailer and car behind a light car. I was on the Monash FWY and happily going 80k's but a down hill slope and it rose to 100k's then the death wobble. I was able to bring the car and trailer under control by taking my foot off the noise pedal and hold the steering wheel bolt straight. The experience was hair raising to say the least.
i have found when the trailer starts to sway take foot off excelerator,normally its just over 80ks.Look at problem and solve.I did not know about the wind pressure problem but he was driving offensively
Over here in usa, it's always been published by oem's to aim for 10-15% on trailer tongue. I am in total agreement with NOT maxing out ones trailer weight to vehicle oem's upper limit.
What about a trailer brake control system?
Being able to brake the trailers imposes the same differential acceleration as accelerating the towing car with the added benefit of slowing the speed and doing it at the same time the vehicle accelerates to a greater effect if its needed
The Dash Cam shows that vehicle doing 103km/h. Guy pulling heavy boat trailer pulls out and overtakes downhill on a highly cambered, narrow road reaching what, 110km/h + and the whole rig gets handed over the law of stupid things that happens to stupid people. Seriously, there is no cure for the wilfully stupid.
And here I am with a 750Kg Camper behind a 120 Prado seeing if there really isn't more weight that can be removed. To me 3.5T behind 2.1T Vehicle (typical ute) is asking for that Trailer to take command of the situation at the slightest sparrow fart.