fsmyth

This may be a newbie question, but ....
Are all trailer kingpins the same size?
I just had problems trying to latch to an old flatbed.
Never did get it to catch.

Hvytrkmech

Yes they are, even the fifth wheel campers are the exact same as otr trailers. How old was the flatbed?

fsmyth

Dunno how old it was, but it had been sitting in a yard
for a _while_. Looked pretty old, but had decent rubber,
so I imagine that it has been used it the last few years.

Did a little digging.... Wallace Forge shows all as 2",
except one as 3.5". What is this used for?

Hvytrkmech

I do not know, I have never run across a 3.5" pin.

2006BLKMegacab

I"ve never seen one that size either so dont feel bad haha

the only differencei was ever aware of was they are made differently for different thicknesses of the plate you want to weld them into

deerslayer1979

I have never seen the 3.5, but I know they are out there, but no idea what the application is. My only guess would be military, since everything they order has to be different from the norm.
As for as not latching onto the trailer, did you make sure you 5th wheel jaw was closing around the pin? The jaws should have at least grabbed the pin, might have been really loose, but should have grabbed it. Might be an issue with your 5th wheel, not the trailer pin.
DS79

fsmyth

Found the problem. The trailer has a plate, which removed,
reveals a floating(?) kingpin. The kingpin is just dropped in
the hole, and can be removed completely. So, apparently
it was riding up on top of the fifth wheel plate and never
dropping entirely in the jaws.
Anybody have any ideas on why this was constructed in this manner?
What other means of attachment could conceivably fit there?

Hvytrkmech

I have never seen that in my life. Not saying that type is not out there just that I have never seen one. If this trailer is something you are going to be using on a regular basis then I would have that pin welded in permanently.

Sorry I could not be of more help.

pind

Floating kingpins are common in lowbed applications, where you have necks that are removable/flip/etc to allow different pin settings for tandem/tridem trucks, single/tandem jeeps, jeeps with sliders, trucks with jeeps with sliders, you get the picture.

Frequently these trailers have 2 - 4 different pin holes, and you need to be able to get the unused ones out of the way, so, there is usually a removable lock pin in the boss above the top of the kingpin.

Not at all common on utility style trailers though, unless they were making a primitive gooseneck/fiver conversion. Scary thought.

fsmyth

OK... I dropped the trailer nose, and apparently-
the pin is loose so it will not dig in the dirt or be
damaged by concrete. Or possibly, so the trailer
nose will contact the pavement without a gap.
Good idea, but I think it should have some type
of retainer so that it is stable while loading the
trailer onto the fifth wheel.
Thanks to all.
<als>

1-5-3-6-2-4

this tractor is 3.5" kingpin. M911 C-HET 6x8. its also 85,000lbs gvwr. dual 45,000lb braden winches for yanking dead tanks on the trailer. came into the shop for an inframe on the 8v-92 and service the Allison CBLT750.


what a brute.

chaikwa

I can tell it needs an in-frame just from the fact there's no puddle of oil under it.

Great pics, thanks for posting them!