Covered hoppers for the 1950s

[leighant]

“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/productinfo/238-7020

These are more 2-bay covered hoppers but these have “closed sides”. I can’t tell for sure from the picture but I think these also have square hatches on the top. Appropriate for late 1940s almost to the present.
http://www.walthers.com/exec/productinfo/381-1860210

Still another 2-bay hopper. The prototype was built by Pullman Standard and called their PS-2 design. Introduced about 1950? Notice the ROUND hatches on top. Less corner place for particulate matter to get trapped.
http://www.walthers.com/exec/productinfo/150-31861

Now here is a 3-bay hopper. PS-2 design but one bay longer than previous picture. Started
Appearing in the early to middle 1950s. These cars would generally be TOO BIG for heavy materials like cement, because filling them to volume capacity would overload them on weight. But they were increasingly used for grain. Think how much easier they are to load through the top hatch and unload out the bottom hopper, instead of having to install grain doors in a boxcars to load, and shovel the grain out to unload, or pick a whole boxcar up and pour it. By the late 1950s, you would see solid trains of these 3-bay covered hopper cars in harvest season in grain country.
http://www.walthers.com/exec/productinfo/160-73893


Here is another 3-bay cover hopper. This design of car construction ran on the Santa Fe increasingly after 1955, but this paint scheme with big Santa Fe letters became standard about 1960. So you could use this car in a 1955-1957 scene but the car should be painted differently, with the small circle-cross inside a square like the first 2-bay hopper we showed.
http://www.walthers.com/exec/productinfo/223-1761

Here is later 3-bay covered hopper. I think this is a 1960s or 70s design, with different length, volume capacity and number of ribs from previous 3-bay cars but similar design.
3-bay 18-rib 4750 cu.ft. LO
http://www.walthers.com/exec/productinfo/85-65346

In the middle 1950s, a type of covered hopper called the AIRSLIDE (trademark) appeared. Compressed air was used to help fine granulated material flow out of the car. Especially used for FLOUR. Appeared both in railroad-owned cars, and cars privately owned by companies such as Pillsbury. The bottom unloading mechanism was a little longer down the length of the car than the hoppers used on normal cars. A single-bay Airslide is about as long as a 2-bay ordinary covered hopper, and this 2-bay Airslide car is about as long as a normal 3-bay car.
http://www.walthers.com/exec/productinfo/150-38631

Around 1960, builders started making covered hoppers with a cylinder shape instead of a box shape. Also notice, instead of having a bunch of small hatches, there is a long “trough” hatch running a long ways down the length of the car. The spout used to fill the car doesn’t need to line up quite as critically with this kind of hatch.
http://www.walthers.com/exec/productinfo/85-60108

ACF (American Car and Foundry) came up with what it called a centerflow. I’m not quite sure how that differs from the Airslide, but the hoppers look more like the proportion of the normal covered hoppers. Here are a couple of ACF center flow cars with cylindrical bodies.
http://www.walthers.com/exec/productinfo/150-39082
http://www.walthers.com/exec/productinfo/489-92000

And here is a 4-BAY center-flow.
http://www.walthers.com/exec/productinfo/490-3469

And that’s a quick overview of covered hoppers to give you an idea of what would be appropriate and what would be a little late for a 1950s layout.

[Anonymous]

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.

[dehusman]

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.