King pin disconnection from trailer
King pin disconnection from trailer
(OP)
We have a serious probelm and could not find a solution or initiatives to solve, I hope to find a proper solution or suggest through this forum.
We have a fleet of trailers where the tank is engaged to tractor through two plates and they connected by a KING PIN. This king pin is subjected to repetitive loose/break that caused the tank and tractor disengaged. This happened several times and caused many incidents.
I appreciate if anyone has practical solution or idea to prevent such incidents, thanks.
We have a fleet of trailers where the tank is engaged to tractor through two plates and they connected by a KING PIN. This king pin is subjected to repetitive loose/break that caused the tank and tractor disengaged. This happened several times and caused many incidents.
I appreciate if anyone has practical solution or idea to prevent such incidents, thanks.





RE: King pin disconnection from trailer
I think we need a lot more information ie photo's of the pins that break, drawings or pictures of the joints and materials involved.
desertfox
RE: King pin disconnection from trailer
RE: King pin disconnection from trailer
In the meantime (and jumping to conclusions about the sort of arrangement you've got), a couple of lines for investigations might be:
Have you got the right size of kingpin? 2 inch is fine for most applications, but there comes a point where you need to step up to 3 1/2". In among the advertising, there's some useful guidance in
http:/
Also worth checking that you've bought pins machined from forgings, not from bar stock.
A.
RE: King pin disconnection from trailer
Would you mean by this that his equipment breaks because he bought forgings, or that he should buy kingpins machined from bar stock?
RE: King pin disconnection from trailer
Step 2: Solve the problem.
A problem of this of this criticallity is well beyond what you should be expecting to have solved for free on an internet forum.
While we would love to SPECULATE on the cause of your failures you need to hire a qualified forensic engineer.
You should do this even if the manufacturer is looking into the problem. Most manufacturers jump directly to step 2. This rarely produces a satisfactory result.
RE: King pin disconnection from trailer
Forging: More suitable
Bar stock: Less suitable.
I think that's what my posting implies as well: Happy to discuss why if you want to raise it in the Engineering Language/Grammar Skills Forum.
A.
RE: King pin disconnection from trailer
Typical size king pin for this application.
what is the material normally used.
what are the manufacturing methods & heat treat.
an audit is required of the manufacturing.
what type of test are required for reliability.
Non destructive test to ensure there is no cracks
or other defects.
have an accredited lab analized the failed king pins
spectra analysis of the material type. is it what it's should be. are there any evidence from the micro sections.
is there evidence of embitterment.
take some of the kink pins an do destructive test.
what are the results.
take penetrant & or magnaflux test is there any evidence of
indications.
my two cents
RE: King pin disconnection from trailer
If the King Pin is failing in shear or otherwise, I would look as to where the pin was made and the quality of the steel.
Mike McCann
MMC Engineering
RE: King pin disconnection from trailer
Your OP is very much lacking in detail.
Also it seems you are not at ease with English language and the wording in the OP does not clearly define your problem.
In order to get a useful response here you need to take the time to formulate a better worded, clearer more detailed question./ As previously suggested, a picture or drawing would help a lot.
The meaning of repetitive loose/break is one statement that is not clear.
Regards
Pat
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RE: King pin disconnection from trailer
-Lack of proper engagement due to (a)wrong plate thickness for the kingpin model being used or (b) Lack of flatness of the trailer skidplate (often due to how the skidplate is welded to the trailer structure) or (c) Unauthorised use of plastic 'lube' plate between mating surfaces.
-Lack of strength/rigidity in the skidplate supporting structure
-High torsional loading of the connection due to use of wrong fifthwheel type (especially important for torsionally rigid trailers like tankers)
This is not an exhaustive list but might be a starting point in your investigation.
RE: King pin disconnection from trailer
If the pins were wearing (getting loosened in the connection, or getting looser in the slot and jiont) abormally, the loosened pin is more subject to bending and failure.
So the ultimate failure is the break,
but the symptom is the loosening that leads to the broken pin,
but the root cause is whatever is causing the pin to loosen in the socket and joint in the first place.
RE: King pin disconnection from trailer
Is it a welded style king pin? Failure modes, welds, king pin shaft, fifth wheel jaws.
Is it a bolted king pin? Failure modes, king pin forging, bolt failure (loosening, shear), fifth wheel jaws.
Is it a drop in king pin? Failure modes, king pin forging, King pin fit taper damage (king pin or mount), Retaining nut tightness, fifth wheel jaws.
Take your pick.
rmw
RE: King pin disconnection from trailer
Perhaps they closed the office, so he doesn't have access to the computer anymore...or the person typing on the keyboard is in holiday now.
RE: King pin disconnection from trailer
rmw