has any body ever had the misfortune ofa jacknife? ive seen a few over the years and seeing one puts the fear of god in me! wot causes a rig to jacknife on a dead straight motorway? i no its when the trailer pushers the unit round but wot starts the process in the first pace?
when the drive axel loses traction I believe, one wheel spins faster than the other.
Makes you wonder when you feel that twitch just behind you and you think… christ I just went over some ice.
Being born with half a brain cell.
Drive to the conditions and you will have no trouble at all. I think some drivers still continue to drive as if they are on clear tarmac on a sunny summers day, then they jack-knife and ■■■■ up everyone elses day
slamin ancors on starts its off then gravity takes over, to stop trailor commin through ya door take your foot off the brake peddle an hope fa best 
Engine brakes aren’t going to help in bad conditions either, they slow the tractor unit down but not the trailer.
Engine brake off, gentle braking, steering and imagining constantly that you are driving on glass should get you through the day
depending on the road etc you don’t even have to be braking to jacknife.
happened to me once on a trading estate so was only travelling slowly, had to turn round on a sloping area and the trailer simply took a short cut across instead of following.
At that time I was driving a Ford TC, so the whole of the fibreglass skirts at the bottom rear of the cab went.
Loss of a tractor unit drive axle’s traction under load or grip under braking.In either case it’ll send the drive axle sideways and what happens next is all down to luck not judgement whatever some on here would like to think.
i went on lymm one morning after it rained, it was bloody cold, i headed past the garage to park against the fence, but as i turned i noticed the trl getting closer and closer to my side door 
the fella parked up jus infornt of me was ■■■■■■■■ it but i stopped sliding bout 10 yards away, managed to get out of it eventually, but snapped my abs line housing on trl.
This may be caused by equipment failure, improper braking, or adverse road conditions such as an icy road surface. In extreme circumstances, a driver may attempt to deliberately jack knife the vehicle in order to halt it following brake failure.
Simply it is situation when your trailer goes faster than your tractor, it’s much easier to jack-knife with empty trailer than with loaded.
As some guys above said - foot far from breaks and luck may help I would add advice to steer your tractor to the side wher trailer goes and back ( if it is jack-knifing to right steer slightly right and back to left - but that works only when it’s starts )
A new device called the “Atlas AJSS” has recently been invented that automatically engages at a speed of 45 miles per hour (72 km/h) and stays engaged unless manually released. It is actuated electronically and operated pneumatically from the truck’s accumulator air supply. The device prevents the trailer and the truck from becoming over 15° out of alignment with each other. Under normal operating (highway) speeds, this 15° swing does not interfere with driving even on the most winding roads; of course, the system disengages under 45 mph to allow for the hair-pin curves of winding mountain roads which are traversed at speeds under 45 mph.
And something to watch : youtube.com/watch?v=xz1NNTNxxhE
youtube.com/watch?v=7ydqNqtjeOU&NR=1
What became of the Hope anti-jacknife device? Sorry if this has been asked before.
Don’t let Curryfart see that 2nd clip…all those axles!! He’d be dribbling for a week…amongst other things…and starting a new thread 
. Years ago i was heading north up the M23 around Gatwick and there was a jacknifed Waitrose wagon in n/s lane, driver sat on the bank emptying his under-crackers,no other vehicles around him and road was dry but there was a n/s drive axle lock up looking at the marks and another time when i was clogging on anti clock around M25 around the Hemel turn (before limiters), a car load of people (heading back to Slough i guess ) came passed and pulled back in front. He got about 20/30yds in front and then proceeded to do the best 180 i have ever seen…i near on ■■■■ meself as i came face to face wth this car,female passenger was having a mental and everything suddenly stopped to avoid mass carnage. The car…turned round n ■■■■■■ off. Got back to yard n spent half hr picking my bedding up of the floor along with things i didn’t even know were in the wagon 
MisterStrood:
This may be caused by equipment failure, improper braking, or adverse road conditions such as an icy road surface. In extreme circumstances, a driver may attempt to deliberately jack knife the vehicle in order to halt it following brake failure.Simply it is situation when your trailer goes faster than your tractor, it’s much easier to jack-knife with empty trailer than with loaded.
And something to watch : youtube.com/watch?v=xz1NNTNxxhE
youtube.com/watch?v=7ydqNqtjeOU&NR=1
A loaded trailer will want to go relatively even faster than the unit than a lightly loaded one if it gets the chance in a jacknife type situation because of the laws of mass and inertia.In that context it’s the loaded trailer situation that will be the more likely one to not have a happy ending because of the forces involved.The only difference with a lightly loaded trailer is that there’s less weight on the drive axle so it’s more likely to lose traction or grip.But with a loaded trailer the drive axle has more dynamic sideways forces imposed on it ‘if’ it loses traction or grip,which in the wrong circumstances of road adhesion,is always more of a hazard than a lightly loaded artic jacknifing by comparison.But it’s my guess that the stunt driver throwing the artic around was’nt doing it with a loaded 40+ tonner 
and the drawbar outfit video seems like a case of trying to solve a problem that does’nt exist,in the same way as artics,if it’s in the context of jacknife issues.
Actrosman:
Don’t let Curryfart see that 2nd clip…all those axles!! He’d be dribbling for a week…amongst other things…and starting a new thread
No but I’d be having the last laugh driving that past a typical artic in a bad winter that’s driver has lost it in a big way. 
Was driving with my old man down the M6 a few years ago and his airline suzie snapped off. The trailer jack knifed to the left as we were overtaking another artic. Luckily he managed to avoid us but he ended up with half his wheels on the grass verge the other side of the hard shoulder. Luckily we were going in a straight line and the motorway was reasonably quiet. We were all OK and only blocked a few lanes off.
the closest i have had was an empty trailer slide out in aberdeen. i was going down the hill where there is a tesco on the left before you cross the river before reaching the A96 roundabout. 03 plate scanias exhaust brake kicked in unexpectedly and all i heard was SCRRRRR as the trailer slid across the white line. the car coming off the roundabout changed its mind and reversed back onto it. luck unquestionably played a part as nothing came from the right. the only thing i could do was floor it and pull out of it although i doubt a proper jack-knife would be able to recover like that. lesson learned - switch the exhaust brake off when empty or running on wet or icy roads 
bubsy06:
Being born with half a brain cell.
Drive to the conditions and you will have no trouble at all. I think some drivers still continue to drive as if they are on clear tarmac on a sunny summers day, then they jack-knife and [zb] up everyone elses day
Easily said,i was on the M74 this morning doing around 15/20 mph,lightly stepping on the brakes every now and then and the trailer kept stepping out sideways,only about 4 tonne on the back,half loaded…yeah you do drive to the conditions EXACTLY but Jacknifing doesn’t mean your a reckless individual driving like a ■■■■■■■
Was driving with my old man down the M6 a few years ago and his airline suzie snapped off. The trailer jack knifed to the left as we were overtaking another artic. Luckily he managed to avoid us but he ended up with half his wheels on the grass verge the other side of the hard shoulder
I understand what you are saying, but that is not what I would call a jacknife, merely the trailer brakes locking and it following the camber of the road. That used to be a regular occurence in the days before anti lock brakes
A jacknife(IMHO) is when the rear axle(S) of the unit loose traction and the trailer , because of its greater momentum, pushes the unit rear axle sideways whilst continuing (more or less) in a straight line itself.
Its exactly the opposite force to the one you apply when reversing an artic.
maybe the explanation is a bit woolly, but I know what I mean
Bikemonkey:
bubsy06:
Being born with half a brain cell.
Drive to the conditions and you will have no trouble at all. I think some drivers still continue to drive as if they are on clear tarmac on a sunny summers day, then they jack-knife and [zb] up everyone elses dayyeah you do drive to the conditions EXACTLY but Jacknifing doesn’t mean your a reckless individual driving like a [zb]!!!
Not according to the government. 
del949:
Was driving with my old man down the M6 a few years ago and his airline suzie snapped off. The trailer jack knifed to the left as we were overtaking another artic. Luckily he managed to avoid us but he ended up with half his wheels on the grass verge the other side of the hard shoulder
I understand what you are saying, but that is not what I would call a jacknife, merely the trailer brakes locking and it following the camber of the road. That used to be a regular occurence in the days before anti lock brakes
A jacknife(IMHO) is when the rear axle(S) of the unit loose traction and the trailer , because of its greater momentum, pushes the unit rear axle sideways whilst continuing (more or less) in a straight line itself.
Its exactly the opposite force to the one you apply when reversing an artic.
maybe the explanation is a bit woolly, but I know what I mean
del949 I reckon some of them are confusing the real thing with a trailer slide.If it was the real thing they’d know it.But it’s very rarely that anyone gets to hear from those drivers who’ve experienced a unit in a v shape against the trailer.Everyone also seems to be forgetting the type of jacknife caused by loss of traction in which if you back off the accelerator as the wheels let go,which is the natural reaction,you’ll be facing backwards against the side of the trailer before you know it.
C/F , at least you understood what I meant