Freight Car Friday – Covered Hoppers

14 10 2011

Open hoppers were in use hauling coal, stone, ore and more for decades before their covered cousins began to hit the rails. Today they are among the most common cars on the rails, hauling everything from corn to chemicals.


The PS-2 was among the first wide-spread covered hopper designs and could be found all across the continent for decades.

The first covered hoppers hit the rails in the 1930s and included some unique cars like the Pennsylvania’s H-30 with its distinctive exterior truss construction. Cars were generally used in cement and sand service. In the 1940s, Pullman Standard and ACF introduced new 34′ cars which became standard designs used by dozens of railroads and private companies.

cylindrical hopper

The first Center Flow cars were cylindrical in design. These remained popular in Canada for decades.

The next major revolution in hopper designs came in the 1960s. ACF introduced its “Center-Flow” design, which greatly improved capacity and unloading time by eliminating the center sill, similar to what had been done in tank cars around the same period. With these changes large-capacity covered hoppers became a practical application, opening new markets.

Large hopper

Larger covered hoppers revolutionized rail transportation for many commodities.

Larger covered hoppers made shipping grain and other products by rail much more economical. The revolution was so dramatic that one covered hopper, Southern’s “Big John,” made a name for itself all the way to the Supreme Court. The cars made shipments so cheap, the railroad’s rates were called into question. Prior to this, grain was loaded in 40′ boxcars. Loading and unloading were a very laborious process, and capacity was extremely limited.

ACF Demonstrator

ACF's Center Flow design has been marketed in many sizes for different loads and remain common today.

Since then, the car designs have continued to evolve. In addition to grain and agricultural products, these super-hoppers now haul fertilizers, chemicals, and more. Some cars feature special pressurized and pneumatic systems to ease unloading. Smaller cars for heavier bulk commodities still remain common as well.



One response

7 12 2011
Andrew Falconer

The Magor Car Company’s “Big John” Southern Railway aluminum body 4-Bay Covered Hoppers have not been produced in O Scale yet. The paint scheme has been applied to various other covered hoppers, but the exact replica model has never been made. Norfolk Southern still operates the “Big John” 4-Bay Covered Hoppers.

There has not yet been a factory made model of a Pressure-Differential Covered Hopper produced in O Scale. The three most common 1970-2000 era choices are the ACF Center Flow Pressuraide 4-Bay Cylindrical Hopper, North American Car Company PD 3000 3-Bay Cyindrical Hopper, and North American Car Company PD 5000 5-Bay Cylindrical Hopper.

There are still more common Covered Hoppers to be produced in O Scale.

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