Covered hoppers for the 1950s

“Postdog” asked, along with questions about modeling the Super Chief, a question about the difference between 2-bay and 3-bay covered hoppers, and also about knowing what freight cars to use based on what “logos” (heralds) they are painted with. I thought I should put the freight car question in a separate thread from the Super Chief thread that started it, so people looking for freight car info would see it.

A quick history of covered cars, at least through “transition era”

This is a 2-bay covered hopper, one that might have been used from the 1940s. Notice that is has square hatches on top, two hoppers or “bays” underneath. It was used especially for hauling HEAVY commodities such as cement that needed to be kept dry. Even when covered hoppers started being built larger, this size was still used for heavy dense commodities such as cement. Another point about this model” notice the small triangular openings near the middle of the car. This was an early covered hopper design. Later designs had those openings filled-in (or rather, not cut in the first place. Otherwise almost identical. Once the closed design came in, ATSF kept the older cars and BOTH kinds were used.) You asked about logos. This car is painted in “mineral brown” a standard color on the Santa Fe for many freight cars during the 1930s, 40s, 50s, up to the late 1950s. But some covered hoppers were light gray with black lettering. (In the late 50s, Santa Fe started using a bright Indian Red for specially equipped “damage-free” boxcars.) Also notice the small Santa Fe herald, the cross in the circle
Inside a square. This was used on Santa Fe freight cars from the early 1900s up through the 1950s. In the late 1950s, they started using a large circle-cross not in a square, bigger, bolder, cleaner, mored modern. At first this was used only on special cars such as the “damage free” and “Shock Control” boxcars. Starting in 1960s for most freightcars.
http://www.walthers.com/exec/productin

One difference between and “airslide” and a “centerflow” covered hopper is that the airslide unit is hooked up to a source of compressed air while it is being unloader. The compressed air shakes and jostles a special surface inside the car to loosen the material inside the car (such as flour) so that less is left inside the car after unloading. The centerflow is more likely to carry grain such as wheat, corn etc. before it has been milled. Gravity is the primary mover of the grain during unloading. There is no internal mechanical aid as there is in an airslide type of car.

The airslide has a membrane in the car (like a cloth bag) that lets the compressed air into the product and causes the product to “fluidize” (kinda like boil) so it slides out of the car.
The Centerflow does not have a centersill that passes through the hoppers.

Another critical thing about covered hoppers is the bottom outlets. Larger and agricultural commodities tend to be shipped in covered hoppers with large hatches and large rectangular sliding gate outlets. Plastic pellets and resins and other chemicals are often shipped in cars with smaller round hatches on top and outlets with a pnuematic unloading tube under the center of the hopper (a round tube with a cap on each end). There was a magazine that ran an article about unit grain trains, but in the lead picture, half of the covered hoppers pictured were designed for hauling plastic pellets whose insides never saw a single kernel of grain.

Dave H.