5th Wheel

Author
Discussion

mondeoman

Original Poster:

11,430 posts

272 months

Friday 31st May 2002
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Coming up from London to Brum this morning, there was a bit of an accident on the M40. Looked like someone had fallen asleep/stopped concentrating (I was there at 7, it must've happened around 5:30/6:00), 'cos an artic had crumpled a Fiesta(?), and then run up the embankment, back onto the road and then overturned, blocking two of the three lanes..... Didn't look like any fatalities thank god.

However, what struck me was the fact that the trailor had become seperated from the tractor unit: the trailor (a tanker of some description) was on its side, the tractor was upright a bit further on, with apparently minimal damage (mudguards gone, tank dropped, about it) How can this happen??

Fatboy

8,064 posts

278 months

Friday 31st May 2002
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I think the 5th wheel is designed to take loads horizontally, not vertically in the sort of twisting motion that would occur when the trailer rolled (bearing in mind the tractor unit has a much lower centre of gravity than a full tanker trailer unit), which would probably overload the rataining mechanism in the 5th wheel, allowing the trailer to uncouple backwards (i.e. the tractor to pull away from it)?

>> Edited by Fatboy on Friday 31st May 10:32

gtir

24,741 posts

272 months

Friday 31st May 2002
quotequote all
Or the driver commited the cardinal sin and didnt attach the saftey catch to the locking mechanism.

This means the trailer could have just "slid off" and caused the crash or it was a result of the crash, either way if the catch is not in the driver is in serious trouble.

I have heard of fully loaded trailers shooting the tractor unit forward like a bullet, and actually lifting clear off the ground, because the pin was not connected properly or the catch was not fastened!

SBD

462 posts

277 months

Friday 31st May 2002
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You were lucky there Mondy man, by 8:00 I think the queues were up to about 8 miles.
Unit here pulled away last week without locking in properly trailer nose dived and impact bent the spine of the trailer, mind you it did have 27 tonnes of steel on it. Had to borrow a 30 tonne forklift to wheel the trailer back into the bay. The driver needless to say no longer works for us.

stc_bennett

5,252 posts

273 months

Friday 31st May 2002
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some tankers have a safety system to detach when cerain limits are exceeded. this is mainly for fuel tankers though,ment to save the drivers life, looks like it did on this on