Trailer snaking accident

[Goaty]

I wrote a defnder 130 and Ifor Williams twin axle 16ft off at 40mph. The Land Rover went to Nottingham uni for research.

It was caused by a set of springs having broken leaves in it. On the trailer.

Hindsight given was inspect trailer regularly. Boss got done for no maintainence records.

The wheelbase configuration was lousy due to short wheelbase of towing vehicle relative to first axle in trailer.

3 axles which were new out at the time would've been more stable.

[Johnsond]

Hi Joe

First of all good to hear you walked away from it that's the main thing as for the rest whilst its definitely a hassle it can all be replaced. A lot of the advice and comments you have already had is very relevant but as is always the case in something like this there are so many variables to factor in. I'm 49 now driving since 17 started off in HM Forces with 109,s and a Sankey trailer HGV 1 since 21 and have owned and abused a number of Ifor Williams trailers.

Nose weight and load distribution is critical and often overlooked, I am a pain when loading mine at builders etc watching the guys put on dumpy bags or whatever and always have them over axles but slightly biased to the nose.

Tyre pressures are often overlooked but I know you said not in this case, As has been stated already the high pressure smaller tyres fitted to some ifors seem far more stable to me than the larger ones. Tramlining on some roads can really grab the trailer and initiate sway.

My own experience with a brand new LM 166 tri axle which I towed from Windsor to Northumberland behind a 3.2LWB Shogun ( Worst thing I ever owned ) was initially a nightmare and would start an uncontrollable sway at anything over 45MPH. That was down to the incorrect height of the tow bar on the shogun and once sorted it was ok. The advice to accelerate out of it yeah ive heard that on many occasions but for me to have tried that would have just made things far far worse. My own solution has always been to brake often quite hard, is this the correct solution ?? not sure but going faster certainly wasn't. Best tow vehicle I ever owned was a LWB 3.0 Patrol it just seemed to shake off any wiggles from behind and carry on as though nothing had happened. Currently I use a 3.2 Ranger with a TT126 tipper and have no problems with towing with a pick up, Mind you I am like another member here in so much that I sit at 50-55 steady away when towing. Next purchase is gonna be another Tri axle LM166 as my own experience is they are far more tolerant of the load position etc than twin axles.

I guess you will never know for sure what triggered it but once again as has been said don't beat yourself up over it as you aren't the first and definitely wont be the last

Regards

Dave

[donnk]

damn scary when it happens for sure.

 

Only had it once,was towing a cherry picker, own wheels not on a trailer, with a new defender 90. On the M5 it just started to go for no reason I could discern other than road surface. I just took foot of throttle and let the train weight slow it down until the snake stopped. Back up to 55/60 again same as before and no snake again.

 

I dont think its the motor or trailer or it would do it all the time. Some combination of truck, trailer, road surface and weather more likely. My money on sidewind.

[Tom D]

We had a landrover written off due to this a while back. I have also had a very near miss myself with the same trailer (snaking across all 3 lanes of the M8). Luckily there was a gap in the traffic.

I have been towing heavy trailers for 20+ years with a variety of vehicles, so here's my tuppence worth.

 

Snaking is caused by the drivers response to a small movement which, if timed correctly (or incorrectly depending on how you look at it) exacerbates the yaw. So you feel a small wag and unconsciously apply opposite steering pressure at the exact moment that the trailer is moving back in the same way. This makes the yaw bigger not smaller. The thing to do is learn to not react to the initial wag. Just hold your line.

 

Accelerating out of a snake is best avoided. It doesn't always work and if it doesn't work you are going faster than you otherwise would have been so the resulting accident will be worse.

 

Best policy in my experience is to lift off the gas and don't brake. Try, if there is room, to make a slow turn, change lanes on the motorway for example. Don't try and make corrections to the steering, try and hold your line or your turn if you have room to make one.

 

The best policy overall is prevention.

Do not have any tail weight, you need positive pressure on the drawbar at all times.

Do not however have too much nose weight as in the picture earlier in the thread this lifts the front wheels and severely reduces braking performance. I discovered this to my cost when I went up the back of a lorry on a wet road towing a tractor on an ifor.

Use a trailer with indespension type axles rather than leaf springs, these are much better in my experience.

Make sure the towing vehicle is up to spec. Our defender that rolled had no anti roll bar on the rear axle, (many don't) our other one does. There is a noticeable difference in towing performance between the two.

Make sure your tyre pressures are correct, soft tyres help exacerbate the yaw, especially on trailers with high walled tyres, sot so much of a problem on the modern low profile jobs.

 

Finally, test your load, I always do this. Once loaded you set off and at a moderate speed, 30-40 mph, on a quiet straight bit of road give the steering a wee jerk. This will make the trailer wag, then hold your line and watch it in the mirror. If it comes back into line immediately then all's well. If it keeps wagging for any length of time then stop and adjust your load, if you can't adjust it then you will need to drive accordingly, i.e. slowly!

[kevinjohnsonmbe]

We had a landrover written off due to this a while back. I have also had a very near miss myself with the same trailer (snaking across all 3 lanes of the M8). Luckily there was a gap in the traffic.

I have been towing heavy trailers for 20+ years with a variety of vehicles, so here's my tuppence worth.

 

Snaking is caused by the drivers response to a small movement which, if timed correctly (or incorrectly depending on how you look at it) exacerbates the yaw. So you feel a small wag and unconsciously apply opposite steering pressure at the exact moment that the trailer is moving back in the same way. This makes the yaw bigger not smaller. The thing to do is learn to not react to the initial wag. Just hold your line.

 

Accelerating out of a snake is best avoided. It doesn't always work and if it doesn't work you are going faster than you otherwise would have been so the resulting accident will be worse.

 

Best policy in my experience is to lift off the gas and don't brake. Try, if there is room, to make a slow turn, change lanes on the motorway for example. Don't try and make corrections to the steering, try and hold your line or your turn if you have room to make one.

 

The best policy overall is prevention.

Do not have any tail weight, you need positive pressure on the drawbar at all times.

Do not however have too much nose weight as in the picture earlier in the thread this lifts the front wheels and severely reduces braking performance. I discovered this to my cost when I went up the back of a lorry on a wet road towing a tractor on an ifor.

Use a trailer with indespension type axles rather than leaf springs, these are much better in my experience.

Make sure the towing vehicle is up to spec. Our defender that rolled had no anti roll bar on the rear axle, (many don't) our other one does. There is a noticeable difference in towing performance between the two.

Make sure your tyre pressures are correct, soft tyres help exacerbate the yaw, especially on trailers with high walled tyres, sot so much of a problem on the modern low profile jobs.

 

Finally, test your load, I always do this. Once loaded you set off and at a moderate speed, 30-40 mph, on a quiet straight bit of road give the steering a wee jerk. This will make the trailer wag, then hold your line and watch it in the mirror. If it comes back into line immediately then all's well. If it keeps wagging for any length of time then stop and adjust your load, if you can't adjust it then you will need to drive accordingly, i.e. slowly!

 

I had to look that up....

 

Extreme 4x4 Ltd ANTI ROLL BAR UPGRADES & KITS

 

https://en.wikipedia.org/wiki/Anti-roll_bar

 

Another school day!

[Tom D]

I had to look that up....

 

Extreme 4x4 Ltd ANTI ROLL BAR UPGRADES & KITS

 

https://en.wikipedia.org/wiki/Anti-roll_bar

 

Another school day!

 

The standard factory ones are ok too.

[difflock]

We had a landrover written off due to this a while back. I have also had a very near miss myself with the same trailer (snaking across all 3 lanes of the M8). Luckily there was a gap in the traffic.

I have been towing heavy trailers for 20+ years with a variety of vehicles, so here's my tuppence worth.

 

Snaking is caused by the drivers response to a small movement which, if timed correctly (or incorrectly depending on how you look at it) exacerbates the yaw. So you feel a small wag and unconsciously apply opposite steering pressure at the exact moment that the trailer is moving back in the same way. This makes the yaw bigger not smaller. The thing to do is learn to not react to the initial wag. Just hold your line.

 

Accelerating out of a snake is best avoided. It doesn't always work and if it doesn't work you are going faster than you otherwise would have been so the resulting accident will be worse.

 

Best policy in my experience is to lift off the gas and don't brake. Try, if there is room, to make a slow turn, change lanes on the motorway for example. Don't try and make corrections to the steering, try and hold your line or your turn if you have room to make one.

 

The best policy overall is prevention.

Do not have any tail weight, you need positive pressure on the drawbar at all times.

Do not however have too much nose weight as in the picture earlier in the thread this lifts the front wheels and severely reduces braking performance. I discovered this to my cost when I went up the back of a lorry on a wet road towing a tractor on an ifor.

Use a trailer with indespension type axles rather than leaf springs, these are much better in my experience.

Make sure the towing vehicle is up to spec. Our defender that rolled had no anti roll bar on the rear axle, (many don't) our other one does. There is a noticeable difference in towing performance between the two.

Make sure your tyre pressures are correct, soft tyres help exacerbate the yaw, especially on trailers with high walled tyres, sot so much of a problem on the modern low profile jobs.

 

Finally, test your load, I always do this. Once loaded you set off and at a moderate speed, 30-40 mph, on a quiet straight bit of road give the steering a wee jerk. This will make the trailer wag, then hold your line and watch it in the mirror. If it comes back into line immediately then all's well. If it keeps wagging for any length of time then stop and adjust your load, if you can't adjust it then you will need to drive accordingly, i.e. slowly!

 

That ALL made sense, especially the last paragraph:thumbup:

I have survived a few attempted tail-wags, by simply backing off the throttle and holding the wheel steady (with well clenched buttocks)

Though with sensible trailer loading it should NOT happen, specially with a stabilizer fitted.

[peatff]

Many years ago I had a bad snake in a council Land Rover 110 towing a trailer full of rubble. It was on a downhill dual carriageway and it was so bad it was lifting the rear wheels of the vehicle off the road. I took my feet of everything and let the steering wheel slide through my hands not trying to fight it and by the time it dropped below 40 it was all back in line. There were 3 of us in the cab and we got home a lot slower that day.

[kevinjohnsonmbe]

Many years ago I had a bad snake in a council Land Rover 110 towing a trailer full of rubble. It was on a downhill dual carriageway and it was so bad it was lifting the rear wheels of the vehicle off the road. I took my feet of everything and let the steering wheel slide through my hands not trying to fight it and by the time it dropped below 40 it was all back in line. There were 3 of us in the cab and we got home a lot slower that day.

 

 

Speed!

 

Must be a critical factor. I'm "driving miss daisy" when loaded up. Couldn't give a monkeys for speed jockies breaking their neck to get past.

 

Some of the wagons I see flying around with heavy trailer loads makes me cringe!

[richy_B]

 

Some of the wagons I see flying around with heavy trailer loads makes me cringe!

 

Sweeping generalisation but X5 or range rover sport towing a speed boat on a weekend! I see then all the time doing 80 down the M3. Crazy.