There is no mistaking the distinctive look of a cylindrical covered hopper. What is less obvious is the important role they have played in the evolution of covered hopper design.
Early covered hoppers were built around a strong center sill that ran through the center of the car. Essentially, these cars were like open hoppers with a roof. The center sill created two problems; added weight and impediment to unloading. American Car and Foundry (ACF) was the first to find a way “a round” this design problem in 1966 with this cylindrical design. Taking advantage of the structural integrity of a cylinder, ACF made the carbody itself an integral part of the car’s structure. This is similar in concept to tank car designs which made a similar transformation in the same period.
The cylindrical covered hoppers were really the first step in the evolution of ACF’s Center Flow design – one of the most enduring on the railroad scene. Like the conventional cars which preceded it, and the smooth-sided cars which followed, cylindrical were made available in several sizes for different lading. Smaller cars are used for cement, sand and other dense materials. Larger cars were employed for plastics, phosphates and other very light loads. Perhaps the most common cars are the three and four bay mid-range cars used for grain service.
Most commonly associated with Canadian railroads, thousands of these covered hoppers have helped deliver the seasonal wheat rushes from the great plains of Canada to the world for over 40 years. Indeed, Canadian roads have stuck with the cylindrical design for decades and despite other revisions, new versions of these tubular cars continue to be built today. Many of the Canadian cars were funded by the government and have worn bright and lavish paint schemes over the years.
In addition to the popular Canadian cars, many U.S. railroads owned cylindricals as well. In fact the first prototype was owned by the New York Central. The car was transferred to Penn Central and Conrail and eventually converted to a scale monitor car before becoming part of Norfolk Southern’s roster. From the B&O to the Southern Pacific, ACF’s revolutionary design could be found all across the country. Many private owners, including chemical, salt and fertilizer companies, purchased these cars as well.
Distinctive, successful and historically important in their own right, perhaps the greatest contribution of the cylindrical design was their role in the development of the even more successful Center Flow ACF cars which followed. We’ll cover these important cars in coming weeks.