Duryea cushion underframe installation
George Toman shared his latest workbench update. He’s upgrading a kit with Duryea underframe parts.
The Duryea underframe is a cushioning device used to reduce damage. The center sill can slide about 12 to 16 inches to cushion impact when coupling. This requires different mounting than the more conventional AAR underframe. National Scale Car has captured the Duryea underframe in great detail using resin castings and photo etched parts in their MK 106 kit that upgrades an Intermountain 1937 Modified AAR boxcar model.
Here are the resin and photo etched parts included in the Rock Island mini-kit. Not pictured are the included decals. You will need to supply a modified AAR 10-ft, 6-inch boxcar with 5/5 ends such as the Intermountain Railway part # 49899 kit.
After reviewing the instructions, I choose to model a Rock Island car in series 148800-149049 built in 1945. This series of cars used a Superior seven panel door that matched the Southwest Scale Productions part # 672 door.
Here’s an in-process photo showing the sliding center sill and cross bearers that are some of the main pieces for the underframe. I glued a piece of 0.020 x 0.060-inch styrene between the center sills. This raises up the center area for the pieces to fit properly.
Note the cross bearers form a cradle structure that allows the center sill to slide. I also trimmed the cross bearers on the side sill end to allow the center sill to just fit on the model. National Scale Car has cast these longer to allow for different models of future projects.
Here’s the center sill glued in place with the cross bearers trimmed and glued, too. I had some bad cyanoacrylate cement (CA) that ruined some of my parts, so I made some new ones from Evergreen styrene.
Here’s my interpretation of the underframe piping and brake parts. I differed from the instructions a bit by moving the AB brake reservoir and three-way valve to follow what I observed in available prototype photos.
I discussed the slack adjuster with Ryan Mendell of National Scale Car. I had no information on the part or location, so this is my best guess. I mounted the brake cylinder and slack adjuster on brass Z-bars between two of the cross bearers and not the center sill. You can see the train line does not go through but rather over the center sill. This is because the center sill moves so fixed hardware cannot be mounted to it.
My slack adjuster was made from styrene and mounted to the brass Z-bar that I formed from 0.005-inch thick brass; these were not part of the kit.
I used a number of parts to detail the B end of the car. Yarmouth Model Works 18-inch, 7 rung ladders (YMW304), Kadee Universal brake housing and wheel, and Plano Morton photo-etched running board and brake step. The draft gear is from Smokey Mountain Model Works and I trimmed them to extend past the end sill. I removed some bolt detail from the top ends of the draft gear as the Dureya underframe center sill slides and would not be bolted to the car end frame
I primed the car with Badger Stynylrez Neutral Primer. I like this when spaying any boxcar color that has a shade of red or mineral red. To my eye, the primer makes the reds pop.
I painted the underframe with Vallejo Gray Black 70.862. You can see how that the train line passes over the underframe and not through it, as would be typical of a car with a fixed center sill.
I custom mixed the car color using Vallejo Black Red 70.859 (75%) and Flat Yellow 70.953 (25 %) for the final Rock Island color. These are the Vallejo Model Color so they need to be thinned for airbrush use. I use a Grex TSG airbrush with a 0.5mm needle sprayed at 20 psi. Thanks to Lester Breuer for providing this formula.
Here’s the finished car with a bit of weathering. I used the airbrush to spray some dirt along the bottom sill and ends. Darker streaking was done with Pan Pastels using blacks and neutral grays. A coat of Model Masters flat clear was sprayed over the weathering.
This National Scale Car product was a well-designed and enjoyable kit to build. I did have some problems gluing the resin parts that turned out to be the CA glue going bad. A new bottle fixed the problem, but I ruined some of the parts.
I would like to thank both Steve Hile and Ryan Mendell for helping me with questions while building this car. Thanks for reading my workbench notes on my Rock Island boxcar.
Many thanks to George Toman for sharing his work installing the Duryea underframe parts.
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