Micro Trians coupler question

[inkaneer]

No this isn't the usual how do I fix the yo-yo or what coupler do I use question.  Instead something more legit.   Havinbg a 5 day weekend from bus driving while the furniture is moved into the new high school I decided to use the time to take care of those little things that got pushed back due my time being devoted to moving into our new digs.  So I laid in a stock of MT coupler bulk packs and started to convert my recent purchases [three years worth] to MT couplers.  In doing so I noticed that MT has new packaging on their bulk couplers and someting I never noticed before there are instructions on which kingpin to use on different cars.  Now none of this was new to me as I have been using MT's since day one or thereabouts.  But reading the instructions I came across this:

"Make sure bulge part of kingpin hole is toward center of car, to give added clearance for coupler draft gear box."

What is that???????   Isn't the kingpin hole part of the car underframe and thus not subject to being turned around?   Or is there something I am missing here?  This is the first time I have seen this.   Anyone know what they are talking about?

[M.C. Fujiwara]

If you look at the beam coming off the hole, you'll see that it's not centered but shifted to one side.
The instructions are reminding you that the trucks are direction-specific and one way will allow more clearance for the couplers.

Never saw directions for that, just took me three years to firgure out why some cars curved better than others 

[inkaneer]

If you look at the beam coming off the hole, you'll see that it's not centered but shifted to one side.
The instructions are reminding you that the trucks are direction-specific and one way will allow more clearance for the couplers.

Never saw directions for that, just took me three years to firgure out why some cars curved better than others 

I am still not understanding this.  What hole and what beam?  These are MT 003 10 041   (1035-10) Barber Roller Bearing trucks with couplers.  Of course they are direction specific the couplers have to be on the ends of the cars. 

[Hiroe]

When using body-mount couplers, the trucks still have the kingpin hole off-center (more often than not, although I've seen MT trucks both centered and off-center). If so, install the trucks so they sit farther out towards the ends, and not towards the middle.

[bbussey]

If these are trucks with coupler pockets,  then ignore that part of the directions.  It only applies to truck frames without coupler pockets.

The only truck frames remaining that have a centered bolster pin hole are those with a medium extended coupler pocket.  All the others have an offset bolster hole.

[Sokramiketes]

I am still not understanding this.  What hole and what beam?  These are MT 003 10 041   (1035-10) Barber Roller Bearing trucks with couplers.  Of course they are direction specific the couplers have to be on the ends of the cars.

"Beam" is the truck bolster.  "Hole" is the truck pin through hole, or bolster hole.  The hole is not centered on the bolster.

[inkaneer]

If these are trucks with coupler pockets,  then ignore that part of the directions.  It only applies to truck frames without coupler pockets.

The only truck frames remaining that have a centered bolster pin hole are those with a medium extended coupler pocket.  All the others have an offset bolster hole.

Thank you.  It occurred to me afterwards that the same instructions were printed for the trucks without couplers as the ones with couplers.  So it makes sense for the trucks sans couplers but not for the ones with couplers.