Like nearly all large railroads, Southern Pacific had on its roster a few heavy-duty flat cars, both depressed-center types and straight-deck cars. I am going to address the latter here, specifically the 4-truck cars of 200 tons capacity. There were five of these in the transition era, all essentially comprising one-piece steel underframe castings from General Steel Castings (GSC), with very minor differences among them. These have been described as welded cars, but in fact the car bodies were essentially one-piece steel castings, with a sheet-steel deck welded on the body.
The first four cars, classed as F-200-1, were assembled from GSC castings and delivered by Mt. Vernon Car Company in 1941, and were numbered 44091–44094. In June 1953 they were followed by a single car, SP 44095, also built from a GSC casting, classed as F-200-2. This time the car was completed at the T&NO shops in Algiers, Louisiana.
(More about these cars can be found in my Volume 3 of the series, Southern Pacific Freight Cars [Signature Press, 2004], covering automobile cars and flat cars. As that volume is unfortunately out of print, I will summarize here, repeating some material from the book.)
Included below is a photo from General Steel Castings, showing the underframe/body casting for the F-200-1 cars. You can see that no deck is present. The cars had independent brake systems at each end of the car, thus no need for brake rodding to pass through the heavy cast ribs in the center of the underbody (GSC photo).
These cars rode on pairs of trucks under span bolsters. They were 100-ton trucks, with 6 x 11-inch journals, but unlike most trucks this heavy, had a wheelbase of only 5 feet in order to fit under the car. Note that the top of the span bolster lies below the wheel height (Mt. Vernon Car Co. photo).
The completed cars of the two classes are difficult to tell apart other than by car number; the earlier four cars have slightly sharper corners where the side sill profile drops down at car center. Here is a photo of SP 44093 when new (Mt. Vernon Car Co. photo). The choice of the “B” end is arbitrary, as each end has an independent brake system and handbrake wheel.
A nearly identical design and assembly was used for the additional fifth car in this group, SP 44095, built in 1953, though this car was assigned to a different class, F-200-2. All five cars were only 45 feet long. Here is a view of the new car at Sacramento General Shops.
These cars were of course used for extremely heavy loads. I will just show a single example, a pair of chemical reactor vessels that required a 200-ton flat car for each vessel. The nearer flat car is SP 500600, formerly SP 44091. (This SP photo, negative N-7731, is from the Richard Buike collection.)
Though these are rare cars, they offer the opportunity to modelers for interesting loads, and thus are something we often wish to model. I will turn to modeling in future posts.