Today, a big box of passenger car diaphragms arrived in the mail from “S”cenery Unlimited* and, since I was in the mood, I immediately got to work installing them on some passenger cars.
The diaphragms are quite nice. They consist of a flexible rubber bellows, fitted with steel plates inside, and a brass striker plate on the end.
Some quick dry-fitting made me realize I would have to modify the stock diaphragms. For one thing, the brass striker plate includes interlocking tabs that connect adjacent cars. It also includes etched “Made in Korea” and “Scenery Unlimited” markings. Obviously, these are intended for passenger trains that run as units, without switching. On my layout, the exposed ends of the passenger cars would look odd with tabs and writing. Also, on my layout, the 42″ radius curves are a little tight for full, working diaphragms.
Once I decided how I would modify the parts, the work went quickly. I had four cars fitted in about two hours.
I started by determining that I would use the brass striker plate as the mounting plate for the car. That would require removing the two tabs designed to interlock with an adjacent diaphragm. I clipped these shorter with a side-cutter, then carefully filed away the remaining material:
(Stock diaphragm on the left. Modified diaphragm on the right)
Each diaphragm has a bellows with three folds. They were too deep for my purposes, and I determined that I would have to remove one of the folds. I carefully sliced the rubber between two of the aluminum plates with a sharp knife to remove the fold farthest from the brass plate, then trimmed the rubber with a pair of scissors:
(Stock diaphragm at left. Sliced diaphragm at right. Remove the aluminum plate from the sliced-away rubber and save it)
I repurposed the aluminum plate from inside the third fold as my new striker plate. I blackened the edges of the plate with a permanent marker. I noticed that one side of the plate has sharp edges, while the side is smooth. I glued the plate to the thinner diaphragm with CA, so that the smoother side is facing outward:
(Stock diaphragm on the left. Modified diaphragm on the right, ready to install on a car)
I glued the diaphragm to the end of a car with CA, positioning the brass plate adjacent to the car end. At this point, I realized that despite removing one third of the thickness of the diaphragm, it still projected beyond the coupler. This, I knew, would cause no end of problems:
(Asking for trouble)
Since I already modify all of my couplers, the fix was pretty straightforward. Normally, as part of my coupler tuning procedure, I replace the spring in the draft gear with a piece of styrene, as shown here:
This prevents the coupler from sliding in and out of the pocket, thus minimizing the slack action. (There’s still a bit of slack, but it’s all in the coupler knuckles – not in the shanks.) I realized I could solve my diaphragm clearance problem by moving the styrene spacer to the other side of the draft gear post, as shown here:
(Extended shank installation)
The coupler works the same as it did before, but it now enjoys a longer shank – and it now projects sufficiently to solve my diaphragm clearance problem:
In addition to preventing the diaphragms from pushing passenger cars off the rails on my curves, I’ll also be able to get a manual uncoupling tool into position between a passenger car and a freight car or locomotive.
In operation, adjacent diaphragms don’t quite touch. This photo shows two cars equipped with modified diaphragms, and with the slack stretched:
(Mind the gap…)
I can live with that gap. It’s certainly better than the space between cars before the diaphragms were added. In addition, my mixed trains only had one passenger-carrying car on them, and I’m not sure the diaphragms would even have been hooked up between the combine and adjacent express car during normal operation on the line to Port Rowan.
I’ve now done the four passenger cars that I regularly run in mixed train service, and I bought extra diaphragms for future projects.
I think they look rather striking…
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