Re: [SergentEng] Coupler bining in draft gear boxes

Nathan Rich

After having installed about 300 of these couplers, I have found through experience that a couple of swipes up and down on both top and bottom of the shank with a mill file will remove any burrs of metal or dried CA and permit very smooth action in the coupler box. I would not be afraid to thin the shank quite a bit, just make sure you do more on the top and less on the bottom plate. As long as the couplers are within about 1/4 of the head height of nominal, and you are not using tightlocks, you're golden. Real cars can and do vary in coupler height. Tightlocks are where coupler height is critical.

Reaming the center hole is not a bad idea, but do a little at a time and test fit as you go, taking care to stop as soon as it operates freely.

As to longer shank couplers, I find that whatever looks right is probably the best. In practice on 1:1 I have seen some pretty long drawbars on centerbeam cars, but not autoracks. Racks are loaded circus-style, with the cars being driven through 4 or 5 racks before they get to where they need to be, and as such they want the railcars closer together. This is of course limited by your tightest curve that the cars are going to operate through, two racks coupled with standard shank E's will probably not go through your usual 22" radius curve. That will require probably 42" or greater, but larger equipment looks better on broader curves anyway.

On locomotives, I like to set my coupler so that the inner face of the coupler (where it pushes against the next knuckle, not the pulling face of the knuckle) is right at the outer tip of the pilot or whatever the furthest protrusion of the pilot is. This enables locomotives to be realistically close but not touch. How else is your HO scale fireman going to get back to that third unit and take it off the line because it's not putting out any power? (Note: Milwaukee Road modelers need not worry)

Nathan Rich

On Aug 17, 2015 5:02 AM, "TS egroupstuff@... [SergentEng]" <SergentEng@...> wrote:

The other way to try if you don't like the idea of thinning the shank
is to build up the coupler box with some thin styrene, effectively
making the coupler box deeper. I'll have to do this with some of
my stuff.

Another thing to watch out for, since you bought up the centre post in
the coupler box, I have found on not so great designed models this can
be fattened by the lid screw making it hard to get the coupler over the
post but the post is still the right diameter where the coupler sits.
Reaming the coupler in this case would make it a sloppy fit on the
centre post. I haven't figured out a good way of dealing with these
except to force the coupler onto the post.

Best to you all,


On 17/08/2015 03:04, Alan Hummel ahummel72@... [SergentEng] wrote:
> Hi,
> I'm still in the experiment stage with mounting Sergent couplers in
> various rolling stock & diesel draft boxes.
> So far,Intermountain rolling stock is mostly a "drop in" procedure.
> Tangent 4750 cvd grain hoppers & Athearn,represent varing degrees of
> problems.
> Tangent is a "NO GO" as when the coupler cover is installed the couplers
> won't turn side to side to at all. They come with Kadee #58s
> installed,&they work about right. I compared the shank thickness &
> there's a "tad" bit more thickness on the Sergent coupler,which is all
> that's required for failure to swing back & forth,but am reluctant to
> start filing down the coupler shank. Could it be that the post spreads
> just enough when the screw is installed that's holding the coupler from
> swinging instead of the shank thickness? If this is the case,I bought
> the Sergent Reamer. I need to do more experimentation,but just wondered
> if anyone else has had this similar problem & has the answer for me.
> Also,should I use longer shank SBE couplers on SD40-2s & on cars such
> as 72ft centerbeam flat's & 89ft auto carriers?
> Many thanks to all for your help.*:) happy
> Al Hummel

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