Best Of Notes on body-mount couplers (work-in-progress)

[ednadolski]

Awright!   I now have a train that is fully converted to the body-mounted, Z-scale Bowser/Lee English couplers!   Here is a video, with a count of the cars being left as an exercise to the viewer!

Most of these cars are installed with the etched brass coupler pockets. In a few cases (such at the Atlas coil cars and Athearn 2-bay hoppers) the car already had an integral body-mounted pocket that would have been hard to remove cleanly, so I just installed the Z-scale coupler in that.  Even tho the integral pockets are significantly oversized, it is not noticeable enough to me to be bothersome when in a running train. Here are a few before/after pics showing this kind of conversion:







I'm particularly struck by how much larger these stock couplers appear, compared to the Z-scale coupler.


On some of these cars I installed the etched pocket by simply gluing it to the underside of the car with CA. I wasn't sure that this would be strong enough, so I tested it out by locating these cars right behind the engines, where they have to bear the full weight of the rest of the train.  As you can see in the video, this turned out to be strong enough even in a very long train like this one being pulled up grade through some pretty sharp curves.


The centerbeams were an interesting conversion, both the 68' and 73'.   In addition to gluing the pocket in place, I also lowered the car by installing a new bolster made from a strip of .060" x .125" styrene.   To do this, I had to trim back some of the die-cast metal weight on the underside of the car:





It isn't terribly pretty, but I figure that no one is looking underneath the car when it is rolling on the layout.  Besides, the greatly improved appearance made by lowering these cars is well worth the tradeoff, IMHO .

One other point: with body-mounted couplers, the 73' RC centerbeams have too much overhang to track reliably thru the very sharp S-curves that I have there at East Walong (16.5" radii, plus the >2% grade).  I consider this to be a function of the track geometry with respect to body-mounted couplers on long cars, and not an issue with the Z-scale couplers themselves.  To compensate, I used an experimental version of the coupler pocket that had an additional pivot hole etched closer to the front face of the pocket.  This allows the coupler to swing with a greater angle, and thus track better thru the very sharp curves. You can see in the picture above that the pivot screw is installed in this other hole.   Note that this was not needed on the shorter MT centerbeams.

The other operational concern with the centerbeams is of course that they are very lightweight for their length.  Thus it is more reliable to run them near the tail of the train.   I found this to be true even when running these centerbeams with their factory-installed couplers, so no surprise there.  (Actually, the light weight seemed to make them more susceptible to the slinky effect, which thankfully is now a thing of the past with these Z-scale couplers)


Ed

[Chris1274]

P.S. The biggest challenge I have had with pusher ops so far is when a consisted rear unit, with long-shank Kato couplers, pushes against a truck-mounted couplers and torques the last freight car truck off the rails.  The combination of body-mounts on the freight cars, and the shorter shank FT couplers on the locos will solve that - and look way better to boot.   (The current incarnation of short-shank Kato couplers produce the wrong coupler height on the Dash-9's.   )

Thread necromancy ...

I'm not 100% sure that this will work for the Dash 9's, but I had similar coupler height issues on my AC4400s and GEVOs when I wanted to replace the long shank couplers with the standard short shanks. They ended up too high. I then tried the short shank couplers for the NW-2, which have a straight shank (instead of an underslung one) and the height was just right.

Here's a TB thread I started a while back about it: http://www.trainboard.com/grapevine/showthread.php?147987-Kato-GEVO-couplers-why-so-high

[Iain]

How do I purchase some of the FT couplers?

Also, how can I get in on the coupler pocket etch?  Would it be possible to get the drawing so that I can include it in a larger etch I plan to do for some cars?

[GaryHinshaw]

The couplers may be purchased directly from Lee English at Bowser:

https://www.therailwire.net/forum/index.php?topic=21980.msg324793#msg324793

but his minimum order is 50 pair @ $1.60/pr.  For the pockets and/or artwork, you'll need to contact Ed, but he will probably respond to this post.

Best,
Gary

[ednadolski]

Hi John, I do have some pockets on hand.  Please see this post for details, and send me a PM if you are interested.

Thanks,
Ed

[dcutting]

Ed, I have sent you a PM about these.

David Cutting
Cutting Edge Scale Models
http://cescalemodels.wix.com/cesm

[Coxy]

The other operational concern with the centerbeams is of course that they are very lightweight for their length.  Thus it is more reliable to run them near the tail of the train.   I found this to be true even when running these centerbeams with their factory-installed couplers, so no surprise there.  (Actually, the light weight seemed to make them more susceptible to the slinky effect, which thankfully is now a thing of the past with these Z-scale couplers)

Great progress Ed. Thanks for sharing.

As you're probably aware, running centerbeams toward the end of a train is not unprototypic. Prototype centerbeams are comparatively light cars when empty. Railroads generally have operating rules governing the positioning of light cars like centerbeams and autoracks on heavier trains in mountain territory. In general, lighter cars are usually not allowed at the head end and have to be placed further back in the train.

These empty centerbeams and boxcars stringlined at Caliente horseshoe in the summer of 2010 when train forces exceeded their ability to hold the rails.

[ednadolski]

Those are some mean-looking pics Steve -- tons of steel lying around just like little plastic toys!   One thing I noted was how the trucks stayed on the one overturned car, I thought they were only held together by gravity but I guess they don't just pop off in all cases.

So what was the cause of that stringline - perhaps some DPUs went dead?   what part of the train were those centerbeams in?  BNSF may need to revise their operating rules.  Man, I would not want to be the guy responsible for that.

Back on to the couplers: has anyone done any work on these lately?   I've been tied up with etching projects and the GP9, but I did manage to get started on another batch of conversions.


Ed

[Iain]

Actually, I'm looking at these for my narrow gauge stuff.  I've read through the thread, and I can't seem to find the diameter of the coupler's screw hole.

[PGE_Modeller]

Actually, I'm looking at these for my narrow gauge stuff.  I've read through the thread, and I can't seem to find the diameter of the coupler's screw hole.

On the samples I have, 0.0465" passes through; 0.048" does not.

Regards,

[peteski]

Isn't the hole designed for a 00-90 screw?

[Iain]

Thanks, y'all!

[GaryHinshaw]

Isn't the hole designed for a 00-90 screw?

Not sure if it was designed for that, but it fits perfectly.

[ednadolski]

It is designed for a 00-90 tap. I don't recall the exact diameter, but the drawing had to be a bit smaller to compensate for the etching process (which leaves holes a bit bigger than drawn).  So there inevitably will be some tolerance.

I don't much use the 00-90 screws any more (and the metal is a bit thin for holding onto the threads anyways).   I prefer the 0.040" styrene rod, and so far none have failed or fallen out.

Ed

[PGE_Modeller]

Not sure if it was designed for that, but it fits perfectly.

Following on from Gary's comment, I suspect the hole in the coupler shank was simply designed to fit the pivot pin in the Full Throttle coupler box - which measures between 0.044" and 0.0445" diameter - and it is purely fortuitous that a 00-90 screw fits so well!  For this application, my real preference would be for a 00-90 screw with the threaded portion stopping about 0.046" - 0.048" from the screw head so that the coupler had a smooth pivot pin.  Ed's use of 0.040" rod accomplishes the same thing with a little more end play for the coupler.

Cheers,