weeto:
Following on from another post, So, can some explain this myth? Since when on straight road will my artic jackknife if I break “to hard?”, seems to me there a lot of misinformed drivers out there telly stars included!
Modern trucks don’t jackknife on there own, I can only think of one major scenario were this is likely to happen, but hard braking? I don’t think so.
Why don’t you get yourself an artic perhaps not loaded that evenly heavier on the front say get her up to full steam on the limiter and then stand on them for all your worth, then come back and tell us that it’s a myth.
Done it mate, and it was on a diesel soaked road fully freighted, no drama what so ever, also done it on an ice covered road, not even a hint of it jackknifing.
A badly maintained truck could account for some we hear on the traffic reports, but the rest of what I have seen, the vehicle had left the road before it had jackknifed, not from heavy braking!
weeto:
Following on from another post, So, can some explain this myth? Since when on straight road will my artic jackknife if I break “to hard?”, seems to me there a lot of misinformed drivers out there telly stars included!
Modern trucks don’t jackknife on there own, I can only think of one major scenario were this is likely to happen, but hard braking? I don’t think so.
Why don’t you get yourself an artic perhaps not loaded that evenly heavier on the front say get her up to full steam on the limiter and then stand on them for all your worth, then come back and tell us that it’s a myth.
Done it mate, and it was on a diesel soaked road fully freighted, no drama what so ever, also done it on an ice covered road, not even a hint of it jackknifing.
A badly maintained truck could account for some we hear on the traffic reports, but the rest of what I have seen, the vehicle had left the road before it had jackknifed, not from heavy braking!
You really are some driver I take my hat of to you, top man.
I don’t mind you professional drivers taking the ■■■■, but just remember its mainly the young drivers who don’t know everything killing them selves out there, but hey no one seems to care, stuff em eh.
weeto:
I don’t mind you professional drivers taking the ■■■■, but just remember its mainly the young drivers who don’t know everything killing them selves out there, but hey no one seems to care, stuff em eh.
So you tell them you can’t jacknife by braking hard, and you personally can brake hard on ice and on a slippy surface and somehow this is helping them to stop them killing themselves by jacknifing. How ?
weeto:
I don’t mind you professional drivers taking the ■■■■, but just remember its mainly the young drivers who don’t know everything killing them selves out there, but hey no one seems to care, stuff em eh.
If you’ve been loaded with 20 pallets of bubble wrap up front and 6 IBCs at the back, stamp on the brakes on a greasy road and there’s good chance you might jacknife. When you brake the unit lurches forward taking weight off the drive there’s not enough weight on pin, or even a slight upward force and the back gets pushed round. Moffett trailers have counterweights in the headboard to prevent this but are still very twitchy in the wet.
It’s similar to how a badly loaded car trailer with the weight at the back will snake.
If your trailer starts to swing around the side of you, then you floor the accelerator (in the dry and straight) and flick the trailer brake/handbrake to effectively “jerk the combination straight again”.
If you’re going around a corner, it won’t work. If it’s icy it won’t work. If it’s wet, it might still not work.
There’s a reason of course that we have a yellow airline as well as a red one. You can drive it around on “only” the red, but I wouldn’t advise it. Shunters do it all the time, but even they run into the occasional bother come the rain and snow…
weeto:
I don’t mind you professional drivers taking the ■■■■, but just remember its mainly the young drivers who don’t know everything killing them selves out there, but hey no one seems to care, stuff em eh.
But you are not helping them!
A lot of drivers seem to have it in there mind they are going to jackknife if they brake to hard, highly unlikely but that slight risk would still be better than ploughing in to a stationary vehicle.
I’ve driven a few trucks which didn’t have ABS and trailers with out skid check and had a few arse twitching moments with them, but a modern truck with ABS, decent trailers never had a problem.
It just seems to be the mentality of this site that some would rather take the ■■■■ than offer constructive advice!
Winseer:
If your trailer starts to swing around the side of you, then you floor the accelerator (in the dry and straight) and flick the trailer brake/handbrake to effectively “jerk the combination straight again”.
If you’re going around a corner, it won’t work. If it’s icy it won’t work. If it’s wet, it might still not work.
There’s a reason of course that we have a yellow airline as well as a red one. You can drive it around on “only” the red, but I wouldn’t advise it. Shunters do it all the time, but even they run into the occasional bother come the rain and snow…
99% of jackknifes the back of the unit comes round, unless it’s in a film when 100% the trailer comes around
If a truck decides to go then it’ll go, there’s so many variables from the angle of the road to a slight imbalance in the braking system causing one side to pull harder than the other, most times a driver can catch it again, or on a modern truck the ABS and other electrickery can keep everything in line in amazing ways (See that Volvo emergancy brake video).
Empty trailers can be worse as the weights not set up as the trucks been designed too, I used to drive a 3.5 Tonner with a faulty load sensing valve and that could be VERY interesting on a wet road!
dew:
If a truck decides to go then it’ll go, there’s so many variables from the angle of the road to a slight imbalance in the braking system causing one side to pull harder than the other, most times a driver can catch it again, or on a modern truck the ABS and other electrickery can keep everything in line in amazing ways (See that Volvo emergancy brake video).
Empty trailers can be worse as the weights not set up as the trucks been designed too, I used to drive a 3.5 Tonner with a faulty load sensing valve and that could be VERY interesting on a wet road!
But it also seems to be modern trucks, which I did quote in the original post, that seem to be jackknifing, and it’s that what I was trying to get at, I very much there will be many trucks on the road working commercially that are old enough to not have ABS.
I will agree that an old truck with out ABS would be very easy to jackknife, but not a modern truck!
FarnboroughBoy11:
I only jackknife when I’m empty and it’s wet… But a bit of opposite lock always brings it back. They don’t call me drift king for nothing you know.
Opposite lock won’t work if it’s jacknifing under braking.Drifting is another term for powersliding which in that case means jacknifing because of loss of traction under power.A jacknife under braking on a straight road is just a case of the unit trying to stop first before the trailer usually starting with the steer axle which makes the nose of the unit dive and the drive axle lift then the trailer tries to push the unit out of the way by pushing the light,possibly locked up,drive axle sideways.The answer to that situation is to have a system which balances the braking more in favour of the the trailer axles than the steer axle or in some cases in the past in North America removal of the steer axle brakes altogether.Weight distribution of the load is also a factor.If it’s heavy on the trailer axles and light on the unit rear/drive axle/s it’ll also be more likely to happen.
FarnboroughBoy11:
I only jackknife when I’m empty and it’s wet… But a bit of opposite lock always brings it back. They don’t call me drift king for nothing you know.
Opposite lock won’t work if it’s jacknifing under braking.Drifting is another term for powersliding which in that case means jacknifing because of loss of traction under power.A jacknife under braking on a straight road is just a case of the unit trying to stop first before the trailer usually starting with the steer axle which makes the nose of the unit dive and the drive axle lift then the trailer tries to push the unit out of the way by pushing the light,possibly locked up,drive axle sideways.The answer to that situation is to have a system which balances the braking more in favour of the the trailer axles than the steer axle or in some cases in the past in North America removal of the steer axle brakes altogether.Weight distribution of the load is also a factor.If it’s heavy on the trailer axles and light on the unit rear/drive axle/s it’ll also be more likely to happen.
OMG you’re at in on here too Yeah lets take the front brakes our lorries, that’ll make them stop better ffs
by Winseer » Fri Apr 12, 2013 4:27 pm
If your trailer starts to swing around the side of you, then you floor the accelerator (in the dry and straight) and flick the trailer brake/handbrake to effectively “jerk the combination straight again”.
Yeah right Of course you have plenty of room to do this and still avoid whatever it was that caused you to brake hard in the first place
The camber of the road can contribute to a jacknife, as can a slight turn on the steering as you brake, a tiny angle between the unit and trailer and the weight and momentum of the trailer will increase that angle to the point where you have a cab full of trailer
Now to answer the OP, the reason it happens on modern vehicles with all their safety gadgets and electronic stabilty controls is because drivers drive lorries as if they’re fitted with a bunch of safety gadgets and electronic stability controls, they expect that the magic electronic signals are going to sort it all out for them, but physics (mass & momentum) are always going to beat electronics in some circumstances, that’s why lorries jacknife
