Trailer snaking accident

[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.

[Justme]

 

Now, for the past 13 months I've been running a German trailer (Unsinn Web 28) with secondary gas strut stabilisation on the suspension. It is a requirement for towing at 100km/h in Germany and I thought why not, so specced it.

 

Since then, I've towed a lot (17k miles) with on some occasions badly loaded trailers. Sometimes so little nose weight that you have to stand on the drawbar to get it to sit on the tow hitch (not advising this, but 20ft beams are frankly too long for a 14ft trailer). Since getting the new trailer, I've not had so much as a whiff of snaking, whether that was towing with the van or the Landrover.

 

I'm not sure if it's definite proof, but the gas struts seem to have made the difference and for that reason I'd not buy a trailer without them again.

 

Once again, very glad you are OK

 

The damper might be reducing the snaking but its not going to stop jack knifing due to no load on the rear of the truck if you brake heavy on a bend or the road is slippy.

 

Dont use a damper to correct a badly loaded trailer. You need some nose weight at all times. What you have when you force it on is negative nose weight. Not good.

 

Re the OP, most likely a combination of factors.

 

To little nose weight

trailer not riding level to slightly nose down, never have it nose up

excessive steering input (the landrover syndrome of rocking the wheel back & forth)

To much weight on the rear of the trailer or even on one side.

If its got solid sides then wind or the effect of larger vehicles passing or being passed causing pressure to move from in front of the wheels to behind (or vis versa) causing the wag / snake.

[Wood wasp]

My friend experienced a trailer snake on motorway while driving a discovery with another one on trailer. The rear rims were knackered as the back end had been getting pushed around so much, things finally came to a head when front corner of the trailer dug into the motorway and tipped the trailer and towing vehicle.. Whilst the disco on trailer broke free and flew over towing vehicle to land on its' roof. Thankfully he was ok but both land rovers were write offs, incidentally a lorry behind saw what was happening, moved across both lanes to hold the traffic back and give my friend the whole motorway to try and rectify situation.