and another thing…this also relates to the “dobbing in bent companies” thread,coz any firm that that cuts corners on drivers hours regs,almost certainly cuts corners on maintenance…
tossers
had the same problem where i worked on a daf, with the silly wire release rather than the handle, there was a problem with wear and tear on those ones were the jaw was not locking into place,and once the ride hight sorted it self as a lot of dafs used to do" up down,up down " 
the first corner you would come to buy,buy trailor 
sudden rush of air,why’s the trailor not behind 
,might be worth checking the recal list on vosa site might still be on there ,can’t be sure though,but i know there was a problem with those type of connections,because all the others with pull handles same age off truck etc,etc were fine
commonrail:
we then asked him to back under a third time,but this time i went under and watched…the locking bar had only come part way across
I don’t know the brand of fifth wheel in this instance but … I do know in a JOST fifth wheel, the lock bar is physically connected to the release handle by a metal bar. If the lock bar isn’t all the way across, the release handle doesn’t go all the way in meaning the spring loaded safety latch can’t drop down - or the dog clip can’t go in.
I have known occasions where after coupling the driver has had to ‘wiggle’ or tap the release handle to get it to slide all the way in. That is a symptom of the lock bar not all the way across. A fifth wheel shouldn’t be used when it is like that. it indicates a lack of correct maintenance of extremely worn parts … but in the cases I have seen the driver carried on for weeks and didn’t defect it.
The fifth wheel should be fully inspected every 6 weekly vehicle inspection. This should involve checking the coupling procedure and that all the mechanism freely moves to the locked and unlocked position. it should also involve a test ‘pin’ being used to check for play. All the important parts are what i would class as ‘wear’ parts. They are expected to wear and are easily replaced.
The incident described above is not unusual. What didn’t happen was a proper check after coupling. Check the release handle is all the way in and secured on it’s locking notch. Check the safety device - whatever it is from a spring loaded latch to a dog clip. Check the position of the trailer rubbing plate to the fifth wheel - no gaps. Check whether the king pin can be seen. Finally if safe to do so - visibly check the lock bar has gone across (if the release handle is in - the lock bar is in).
My old office was up above the trailer yard. At times I would watch drivers couple up. Occasionaly i would see a driver struggle to get the fifth wheel to lock onto the pin. He would shunt in and out a few times, or what i would call ‘mess about’. On most of these occasions the driver hadn’t checked the height of the fifth wheel before coupling - just swing round, reverse under - no checks of anything (including trailer brake) before coupling. Out the cab and straight onto the cat walk doing his airlines. Disaster waiting to happen. I would make a call and the workshop manager or supervisor would walk down to see the driver and ‘explain’’ his errors.
In most cases where the fifth wheel doesn’t lock straight away - it is a height/alingment issue. I have read on here someone said don’t wind the legs to the floor and then lower the suspension before uncoupling. This is in my opinion wrong. Leave the vehicle at normal ride height - lower the legs to just touching the floor. Pull forward clear of the pin but still under the trailer - lower the suspension and allow the trailer to settle onto its legs. Even with a new pair of legs it’ll still settle a good few centimetres. When the next guy comes along - at normal ride height he should be just about right to couple. As the fifth wheel goes under it will take the weight of the trailer slightly - maybe even lift it a little. Once the fifth wheel is under the trailer - but before the pin, lift the suspension slightly and reverse the rest of the way onto the pin.
There seems to be a school of thought that the driver should lower the suspension right off, reverse under then lift up. The problem with this is that if you have reversed too far you can ‘come up under the pin’ and this can cause damage or a miss-couple. The pin is designed to slide into the fifth wheel, not push in from above.
In my opinion - 90% of these incidents are where proper safety checks have not been carried out. For this I blame the driver trainers followed by the employer - if nobody explains these dangers to the drivers - how do they know?
kindle530:
Harry, send a PM to Jessicas Dad, he had the same problem a few years ago.
for some reason jost had a lot of problems with fifth wheels round about 10 years ago, it was the locking mechanism that was faulty and then after critism changed it.
another problem with maintenance is they dont get maintained, at a service they just get a few blobs of grease on and thats its serviced. have a look under under the fifth wheel at all the grease and crap under them proves they are never serviced.
jessicas dad:
for some reason jost had a lot of problems with fifth wheels round about 10 years ago, it was the locking mechanism that was faulty and then after critism changed it.another problem with maintenance is they dont get maintained, at a service they just get a few blobs of grease on and thats its serviced. have a look under under the fifth wheel at all the grease and crap under them proves they are never serviced.
The fifth wheel is one of the big clumsy bits of so called engineering. It has been around in roughly the same form for years and never really changed. You can get powered versions and little bits of additions but the basics are the same.
It is this rough engineering and big clumsy bits pulled around by even bigger springs that makes it work so well.
They are also fairly low maintenance and sometimes all the ‘mechanic’ will do is spread a bit of grease around - and at times that is all the maintenance it needs. What is important is that drivers defect - and continue to defect - any issues and I do mean ANY issues.
If your fifth wheel starts to stick a bit and doesn’t always engage - it wants looking at. Defect it, make sure you do all the safety checks after each coupling and it will be fine until the next inspection. mention it to the manager, fitter, mechanic - anyone. Hand your defect sheets in and point it out.
If you pick the vehicle up next day and the fifth wheel is the same - take yourself straight to the TM or higher and ask for a different vehicle - one that has had the fifth wheel maintained .
Fifth wheels should work everytime. It is important the driver checks it has worked
shep532:
There seems to be a school of thought that the driver should lower the suspension right off, reverse under then lift up. The problem with this is that if you have reversed too far you can ‘come up under the pin’ and this can cause damage or a miss-couple. The pin is designed to slide into the fifth wheel, not push in from above.
But it saves slobbering grease all over the trailer swivel plate lip which then transfers so easily to drivers trousers and susies.
Does a Jost 5th wheel need a dog clip? Jost make no mention of it in that video. They are already double locked - usually by the handle and sprung L clip.
How bloody ridiculous that safe coupling is not covered in the DCPC.
Furthermore I would strongly recommend that ANY defect you report you should keep a personal record of, reg, miles, defect and defect number.
Nobody can ever come back at you and claim no defect was ever reported should the defect ticket mysteriously go missing, always worth covering your arse in this job in the modern age of vosa and the courts. I recommend a ■■■■ plug 
Have you ever tried to get a truck defected for a dodgy 5th wheel? ive tried and it just doesnt happen, ive even had to call out fitters for a dodgy 5th wheel that just wouldnt engage no matter what i tried, yet when the fitter comes straight in first time this 5th wheel even had to have the handle wiggled to get the clip in.
Thankfully now its been sorted after one of RMs own guys complained and said he wasnt gonna drive it, but they just dont listen to agency think its more money they are costing us
BTC made a 5th wheel whilst they were operating and instead of having a locking bar slide slide behind the pin they had 2 side jaws that wrapped around it tensioned by 2 pull springs underneath it and if 1 of the springs broke it would allow 1 of the jaws to flap about and the trailer could become detached.
That was a long time ago but York big D and the Jost etc once the bar is across and the dog clip in it is virtually impossible to lose it providing it has been connected properly. Forget the " tug test" as you call it the only way to be sure is to pop your head underneath and check the locking bar is across, you will need a torch for night time connections but it,s a ■■■■ sight easier than trying to sort out the mess that a dropped trailer causes.
DonutUK:
Did the driver do a visual check of the jaws i.e. got underneath the trailer and looked?This would really be a “belt and braces” step because if he has done a tug test, checked the handle is engaged and was able to lock the safety clip, then he has done as much as reasonably possible to ensure the trailer is coupled correctly. This should mean that his liability for any damage ends there.
I make you right there, if the safety clip can engage then there’s not much else a driver can do.
I have dealt with 4 similar incidents over the past three years,whereby trailers have uncoupled from the unit on main roads and at locations with sharp turns.
The driver is adamant that he coupled up correctly,now,my findings along with VOSA were the same driver error,all down to when being coupled up and it depends on the angle / height that the trailer is at when coupling up,all the trailers in question had run over the top of the fifth wheel,and gave the impression that they were coupled,when driven and a sharp turn of lock put on the trailer just goes straight ahead uncoupling from unit.
The pin has been engaged and the clip placed on,all of these incidents have happened at night when very dark,this could be the reason why the driver has missed how it has happened.
I am not saying that faulty 5th Wheels don’t occurr all I am saying is that mistakes can sometimes be made,in certain circumstances can be missed,there has also been extensive testing of the vehicles being coupled up to different trailers and various angles,and on two occassions we got it to jump over the top of the 5th wheel,then once the tug takes place it feels as if it is coupled up correctly.
So,for me I always try and keep an open mind in these things as if a pin fails there is nearly always signs that there is excessive wear to show that a failure might have been the cause.
Stefluc
A regular cause of pin overshoot is because the suspension on the trailer has sunk as air pressure is lost, causing the front of the trailer to see-saw upwards.
As has been said already there should no be no gap whatsoever between the fifth wheel and the trailer wear plate, just checking underneath that the bar has slid across will confirm nothing if the pin is sitting on top of the jaws.
papermonkey:
DonutUK:
Did the driver do a visual check of the jaws i.e. got underneath the trailer and looked?This would really be a “belt and braces” step because if he has done a tug test, checked the handle is engaged and was able to lock the safety clip, then he has done as much as reasonably possible to ensure the trailer is coupled correctly. This should mean that his liability for any damage ends there.
I make you right there, if the safety clip can engage then there’s not much else a driver can do.
That’s a load of ■■■■■■■■. Just making sure it tugs and the clip goes in is not a sufficient check of the coupling.
The driver MUST carry out a visual check of the coupling. Look for a gap between fifth wheel and trailer rubbing plate. Look for any possible sign of the king pin. if safe - check the view from the rear ( ) to see if the lock bar is across. Maybe even look at the gap between trailer and cab to see if it might be smaller than usual (overshot pin)
The problem is that in the right circumstances the fifth wheel mechanism can close when the pin is not properly within it - the clip then goes in
Given the potential severity of an incident involving trailer loss - surely it warrants a good few minutes checking it? WHo cares about liability? if a driver was involved in a trailer coming off the back - red line snaps - brakes lock on, for Fiesta behind him ploughs into it killing mum and leaving 3 year old jessica with no Mum - liability or not, would you want to live with that?
Drivers need to carry out a thourough check of the coupling
Stefluc:
I have dealt with 4 similar incidents over the past three years,whereby trailers have uncoupled from the unit on main roads and at locations with sharp turns.
The driver is adamant that he coupled up correctly,now,my findings along with VOSA were the same driver error,all down to when being coupled up and it depends on the angle / height that the trailer is at when coupling up,all the trailers in question had run over the top of the fifth wheel,and gave the impression that they were coupled,when driven and a sharp turn of lock put on the trailer just goes straight ahead uncoupling from unit.
The pin has been engaged and the clip placed on,all of these incidents have happened at night when very dark,this could be the reason why the driver has missed how it has happened.
I am not saying that faulty 5th Wheels don’t occurr all I am saying is that mistakes can sometimes be made,in certain circumstances can be missed,there has also been extensive testing of the vehicles being coupled up to different trailers and various angles,and on two occassions we got it to jump over the top of the 5th wheel,then once the tug takes place it feels as if it is coupled up correctly.
So,for me I always try and keep an open mind in these things as if a pin fails there is nearly always signs that there is excessive wear to show that a failure might have been the cause.
Stefluc
An overshot pin would mean the trailer headboard would be about 12 inches closer to the trailer than normal. Surely this would stand out?
Habving said that - one incident I investigated the driver confiormed in interview that when he got on the catwalk to connect the lines he struggled to fit “I thought the trailer was a bit close to the cab” he said … I put that particular incident down to 2 things. Lack of common sesne and lack of training
15 years ago eurohitch fifth wheels had some problems with theirs, i remember the firm i was with having too take 5 new trucks back too the dealer too get the fifth wheels changed due too eurohitch recalling a certain batch of them
shep532:
I have been trained by JOST in fifth wheel repair and maintenance and know the components very well.There would have to be more than a substantial amount of wear for a properly coupled pin and fifth wheel to seperate leaving the jaws closed and release handle still ‘in’. A fifth wheel with that amount of wear would be terrible to drive with - knocking and banging. I doubt a driver wouldn’t notice this.
It is feasible that during coupling if the fifth wheel is set too low for the pin - the base of the pin can ‘trigger’ the jaws and therefore the lock bar. Once the lock bar slides across the release handle will go in and the dog clip can be fitted. it would seem to be coupled. A ■■■■■■ test would more than likely feel ‘wrong’ or different but it would more than likely tug the trailer and to an unobservant driver seem OK
it is all about visibly checking the coupling. Look for gaps between the fifth wheel and trailer rubbing plate. Look for the king pin - shouldn’t be able to see it. If it is safe to do so - look for the lock bar across the back of the fifth wheel ‘throat’. Check the safety latch/dog clip etc
I am delivering coupling training to a company on Saturday. I think they have had an incident recently. We are doing a 7 hour DCPC session followed by this coupling training which unfortunately isn’t part of the DCPC course. We will cover the braking system and why just dropping the red line isn’t sufficient. How trailer brakes work - specifically the park brake. The workings of the fifth wheel. Why rollaways happen and finally how to couple correctly and what safety checks to carry out after coupling.
I know some of the drivers will resent being shown what they already know how to do but hopefully by raising the issue it might prevent a more serious incident.
Hopefully if this link works you should get a decent video showing how the jaws lock onto the king pin etc http://www.youtube.com/watch?v=atKelxzvoHA This is the LOST fifth wheel. Other makes work in a very similar manner but I believe JOST to be the best there is
We had a spate of this when i was working for Asda,I actually witnessed it in the yard. All new scanias, all with the “new style” locking bolt. i had the chief instructor from fontaine visit the site and inspect our 5th wheel locking pins, and he showed me exactly how it is possible to do as Shep532 describes above. I alway teach, and use the use of the air suspension to raise the trailer up BEFORE engaging the pin, this should make sure that 5th wheel is in contact with the trailer rubbing plate, and should engage properly