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Norfolk Southern's Top Gons  

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Norfolk Southern’s Top Gons
From prototype to model
The main focus of these models is the Class G85R & G86R gondolas, the “R” standing for rebuild. To build accurate models the first step is always a little research. Luckily for a railroad as large as Norfolk Southern there is ample information in print and on the Internet. A little time spent unearthed a wealth of good information, including photos, dimension and load data and even a drawing or two.

It was Norfolk Southern’s Roanoke Shops that first converted a hopper car to a gondola in 1991. The car-rebuilding program was to create large numbers of gondolas using various cars already on the roster. The re-bodying program started with two prototypes, an H11a and H11b. These first two rebuilt gondolas became NS20000 and 20001; both class G84R gondolas. In all nine classes of hoppers were converted into eight classes on Top Gons (see table).

To keep costs down NS retained the hopper form of the body, including the 30degree sloped sheets on the ends. This design added to the overall stability of the car by placing the taller body bolster above the center of the trucks. Another added benefit was the continued placement of the brake equipment under one of the sloped ends. This kept the brake system accessible and less vulnerable to damage.

The center sills of the original car were retained, as were the ridge beams that originally supported the chutes. These ridges provide anchors for the diagonal internal braces. Essentially these are gondola versions of re-bodied hoppers, but with a flat floor. It is this floor, which is recessed in from the sides, that is one of the primary spotting features of these cars.

Early re-bodied cars had five exterior strapping supports that were attached to the side sills. In July 1996 a new design of the floor was introduced and the supports were no longer required. This change incorporated a corrugated floor, in halves on each side of the center sill. Ten internal corrugations in the 9/32” ASTM242 steel allowed for the omission of the side supports. Also removing the chutes, doors and door gear assemblies was a considerable reduction in the weight of the cars. These changes achieved a light weight of 58,600 lbs., however the cubic capacity of the design was not great enough to take advantage of the relatively low car weight.

The class G85R, G86R and G88R, rebuilt from various classes of H11 & H12 hoppers, had an internal length of 46’4” instead of the 45’ internal length of the other classes of Top Gons. The longer body gave these cars a rated capacity of 200,000 lbs., and increase of 275 cu. Ft. over the 45’ cars.

A total of 2020 G85 cars and 2762 G86 had been created as of 1997. Most of these cars were built in 1992-93 and 1996-97, with 1993 having the most G86 cars (1377). Both of these class of cars, as well as the G88R’s had an inside length of 46’4” and an overall length of 47’5”. The car width is 10’ 6 5/8” and 23 3 1/2” in height. This allows the 59,000 lbs cars to have a 3,850 cubic foot capacity.

The models constructed are representative of the G85R class Top Gons. I first created a set of working drawings so I could fabricate the model. A paint schematic drawing from Norfolk Southern, along with the overall dimensions of the cars was used to create the drawings. It is important to note that the rivet locations on the model are approximate. They were included to give the feel of the prototype. It also needs to be noted that this model is one of a series of over one hundred produced so some detail had to be omitted to reduce the cost of the project.

It is necessary to develop an overall plan before starting a project like this. A fact that is even more important when you complete seventy of more as I do with the Top Gon. My plan was to develop a set of masters for the sides, ends and floors, then make molds of these flat sections for a series of casting. The model would also incorporate separately manufactured parts including brake components, ladders, stirrup steps, and of course trucks and couplers.

One of my main methods for scratchbuilding with sheet styrene is to use a layered approach. In this case a .040 sheet would be layer “0”. The outlines were lightly scribed with an Xacto then I moved on to a sheet of .005 for the rivet strips. Using a NWSL sensi-press with riveter attachment two rows of rivets were embossed in the scale 9” wide strips. The long strips were cut from the sheet styrene, and then cut to length. A small bead of cyanoacelerate glue was used to attach the rivet strips to the side of the car. After all the strips were attached the ribs were fabricated form scale 1x3 styrene strip. Using the edge of my knife two of the corners were rounded over (see illustration). I then cut the ribs to length, also cutting the bottom of the ribs at a 30degree angle. These were then glued along the center of the rivet strips. A length of 1x6 was glued along the bottom edge and lastly a length of scale 2x6 was attached to the top. This completed the major fabrication of the sides, now onto the ends.

Again using .040 sheet for the major part of the ends, all the layout lines were drawn first. Only 2 rows of rivet strips would be needed, and the rivets did not need to go down the entire length of the end. The .005 strips were glued to the top of the ends, followed by lengths of scale 2x4 (see drawing). The bottom cross-member was fabricated from a length of 4x6. The edges do not receive any structural pieces at this time as the sides already have the corners on them. Both ends are identical with the exception of an additional rib for the brake stand, and of course the brake stand itself. The additional rib is simple made from a 2x3 strip. The brake stand is from the Detail Associates AB brake kit. With the four major sides fabricated, I then took a large sheet of .060 styrene to make the floor.

I ripped the sheet into a strip 9’3” (scale feet) wide, then cut it to 37’6” long. I marked a centerline on the piece. It was at this point that I fabricated the center sill extensions from .060x.250 styrene strip. The deeper floor was made form a box using 6 x 12 styrene strip to form four sides. A small sheet of .020 styrene cut to 9’3” x 26’6” was used for the floor bottom. This was attached to the main floor section. For the center sill the four sections 6’6” long were laminated together in pairs to make the beam the correct height. These were attached to the end of the floor, matching up to the centerline. One additional strip, 4’long, was added at the centerline of the floor out to the ends, overlapping the previously laminated sections. The gap in length allows for a Kadee coupler pocket. After the solvent glue on this assembly was fully cured the holes for the truck and coupler pocket screw were drilled. A brass washer was attached to the floor at the hole for the truck screw to give the car the proper height.
Two flat panels measuring 1’9” xx 9’3” were cut from the .060 sheet to be used as the lower end panel to connect where the slope meets the floor. Two other pieces measuring 5’ x 9’3” were cut for the sloped floor. One edge f all four of these was beveled at 30 degree for a proper fit. This concluded the fabrication of the structural body pieces. I then set these up to make a mold and then the castings.

With the first sets of castings complete I lightly sanded the backside of them and washed then with soap and water. The key here is to use warm water, but not too hot as it could warp the castings. When dry I began attaching the castings to each other, starting with the sides and ends. With all four sides assembled I carefully set in the floor, making sure the car was square. Small beads of glue were used to place the lower ends and sloped sheets. A Top Gon car-body was ready for detailing.

The brake equipment was modeled using Detail Associates AB brake set. #79 holes were drilled to accept the brass wire for the piping and then the air cylinder was glued in place. The Detail Associates set includes very nice brackets for mounting the cylinder & valve. These make this part of the assembly much faster. The small mounting lug need to be removed and then the brake cylinder is attached to the side of the center sill. The valve assembly is next and it rests on the center sill with the pipe openings facing towards the air tank side of the car. The brass wire was bent and installed connecting the three components. The rest of the brake rigging was omitted on these models.
Mounting holes were drilled on the underside of the side sills to accept the stirrup steps. Metal steps were used, and though not prototypically accurate, these steps will not be as apt to get damaged during handling, as the more prototypical plastic ones would. Ladders were cut to length and attached at the far right of each side and the far left of each end. #80 holes were drilled on the left of each side for the secondary rungs. Holes were also drilled on the ends to accept eyebolts and the coupler levers were installed. Additional holes were drilled to accept grab irons on the lower beam of the ends. The cars were now ready to be washed, to remove and oil and dirt, and then off to the paint shop.

The photos I have found on these cars have varied from blue-gray color to light gray. For the first set of cars I selected a primer color. Two coats of color were applied to the models along with a gloss coat was applied, with sufficient drying time between coats. The decals from Shell Scale are very complete, allowing you to decal many classes of Top Gon. After decaling I used Floquil’s flat finish, to give the cars an even clean finish.

The final assembly including adding the car weight, for which I used metal binder plates, from my local hardware store. A few dabs of silicone both on the weight and in the car will hold it in place. The coal load was from Chooch, but had to be cut to fit in the body. A few drops of glue will hold the load in place. Kadee number 5 couplers were assembled in their boxes and attached the car with a 2-56 x 1/8” screw. Lastly the trucks need to be attached to the car. For the trucks I selected Walther’s roller bearing (#933-1007). These are close to the prototype, and I am confident they will run smoothly. All of these steps were repeated many, many times to build over seventy Top Gons.

This project involved many different disciplines including dimensioning, drawing, scratch building, and working with the resin castings. Many different manufacturers’ products were used in the completed models. The essential key to the project was the research. The data information and the photographs I gathered was key to making the Top Gons. It is the same for any modeling project based on prototypes.


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