Hi guys I work for a large transport firm around Leicester we have about 70 30 pallet trailers. I was wondering if any of you guys that use them as well have had any problems while coupling them to your units. IE They look coupled correctly but when you move away they fall off the unit? If you or your colleagues have had this problem please reply?
Nope, never had or heard of any problems with them, when it comes to coupling there’s no difference between standard trailers and LSTs.
It’s the back of the trailer that’s longer,the front ain’t any different so can’t see why coupling would be any different.
The block at the front that turns as the fifth wheel does is the difference not on a ordinary trailer
Leicester Driver:
The block at the front that turns as the fifth wheel does is the difference not on a ordinary trailer
Yep - you’ll have a mechanism for steering the back axle which I am sure can potentially make coupling a potential problem.
Another difference could possibly be the rear overhang in effect lifts the front of the trailer - like a counter balance effect. Maybe during coupling this could possibly, maybe, perhaps cause the king pin to ‘lift’ instead of the trailer positively transfer its weight onto the fifth wheel.
However - I am a firm believer that when a trailer falls off the back it is nothing but human error. If the human carries out the appropriate safety checks it will not happen.
These have steering rear wheels? There is a wedgebehind the kingpin that steers the wheels/rear axle. Make sure that the trailer is dropped with the rear wheels straight, and picked up in a straight line. If not, the wedge may prevent the kingpin properly engaging in the fifth wheel jaws.
Normally yes but we have never had this problem until we got the 30 pallet trailers about 5 have come off including one for a Kalmar shut unit we have over 300 trailers and only the 30 pallet trailers are doing this we are very highly trained on all aspects of H&S we get assessed every year just seems to many of them to be all driver error.
Checking my manifest this morning I had a 34 pallet trailer. Think it was wrong
Leicester Driver:
Normally yes but we have never had this problem until we got the 30 pallet trailers about 5 have come off including one for a Kalmar shut unit we have over 300 trailers and only the 30 pallet trailers are doing this we are very highly trained on all aspects of H&S we get assessed every year just seems to many of them to be all driver error.
The only reason a trailer falls of the back of the unit is if the kingpin has not been locked in the jaws of the fifth wheel. Or the kingpin breaks off, but that would be obvious…
After hooking up the the trailer, you do the pull test, and fit the dog clip.
If you can fit the dog clip, the kingpin has activated the springloaded locking mechanism, and the trailer is secure. If he kingpin for any reason has not activated the locking mechanism, the trailer is not secure, and you can not fit the dog clip.
If you have done these simple checks, you won’t drive off without the trailer.
as nodding donkey says…
drop it in a straight line
pick it up in a straight line.
It nowt wrong with trailer
It’s driver error every time .
midlifetrucker:
Checking my manifest this morning I had a 34 pallet trailer. Think it was wrong
It’s those unstrapped 390 pallet trailers that worry me
Leicester Driver:
Hi guys I work for a large transport firm around Leicester we have about 70 30 pallet trailers. I was wondering if any of you guys that use them as well have had any problems while coupling them to your units. IE They look coupled correctly but when you move away they fall off the unit? If you or your colleagues have had this problem please reply?
The management of the “large transport firm around Leicester” will be following this thread with interest [FACE WITH STUCK-OUT TONGUE AND WINKING EYE]
We have had them fall off with the dog clip fitted Nodding Donkey so all have been removed now we only have the spring loaded clip so if they are coming off with the dog clip fitted what does that say?
I would like some feedback from drives who have actually driven them and seen them close up so they know about the block at the front which normal trailers don’t have. We can all judge but unless you have had any actual experience driving them better not to say anything please.
my mate drives those things for RM at Crick.he’s not mentioned having any probs with them so far.
Leicester Driver:
We have had them fall off with the dog clip fitted Nodding Donkey so all have been removed now we only have the spring loaded clip so if they are coming off with the dog clip fitted what does that say?
But the trailers didn’t come off with the L bracket properly engaged, the dog clip situation was because there was too much movement on the kingpin and L bracket hadn’t fallen and the drivers never checked it because they trusted the dog clip. Dog clips where removed so the driver had to check the L bracket. I do believe oringinally those new JOST 5th Wheels didn’t come with a dog clip and only a L bracket, it was your company that speced it to have a dog clip.
The triangle block you are referring to is used on tons of trailers with a rear steer axle. Urbans, a lot of supermarket tandems etc not just trial trailers. It’s not new technology if you see what I mean. What you need to identify is what trailers it’s happened on, make note of the trailer numbers see if they are sister trailers ie come off the line one after another. You might see a pattern.
Me personally I think it could be hooking up after the last driver has left the rear wheel at an angle instead of straight. You hook up get a good sound, good tug but because it wasn’t straight there has been a slight resistance upwards leaving the pin on the cusp of the jaws. Speed bump, pot hole etc and your trailer drops. Trouble wae the wedge is you can’t see if the bar across the pin.
As far as I can tell there’s two types of these trailers.
There’s the ones with the passive rear axle (It isn’t actively steered, it just tracks behind the other axles. When you reverse it locks straight).
Then there’s ones with the active steering rear axle (what Tesco used to call command steered). I’m guessing this is the sort that you have from the problem you’re describing.
There’s a wedge behind the pin which fits in the cut-out behind the jaws on the fifth wheel. When your unit turns, this wedge is pushed by the fifth wheel which uses air (I think) to steer the rear axle.
If the trailer is dropped with the rear axle not in a straight line then the wedge will not be aligned straight and can stop or jam up the jaws from closing and give you a false tug test result. We had Tesco 10m stuff so the axle loads were quite light so the fifth wheel would usually sort the axle out, however if you’ve got a loaded 15m trailer, the axle weights might be too high for the mechanism to straighten the axle and couple properly too.
HTH
It is ‘possible’ for the fifth wheel jaws to move into the closed position but the king pin not be in the jaw. When this happens the ‘L bracket’ will drop and any dog clip will go in. On a quick visual check all looks ok but of course the king pin is not held securely.
In this state it’ll probably pass the tug test but the trailer won’t hang around for long.
No I haven’t got any experience of a fifth wheel with the rear steer mechanism but can’t see it can alter how the basic fifth wheel works but does seem to be the common element.
Leicester Driver:
I would like some feedback from drives who have actually driven them and seen them close up so they know about the block at the front which normal trailers don’t have. We can all judge but unless you have had any actual experience driving them better not to say anything please.
I have seen them close up, and know of the block you are referring to.
I have connected up to and pulled said trailers lots of times. I have never had a problem.
As others have said, if the rear wheels have not been left straight, it can be difficult to connect up.
We have been instructed to check rear wheels before coupling up.
If I find one with the rear wheels not straight. I couple up with the unit at the same angle as the rear wheels.