At about tire time the order for the Pitts burgh, Bessemer and Lake Erie cars was placed the Pittsburgh and Lake Erie Railroad was de signing a hopper car along somewhat similar lines to the cars designed Carnegie Steel Company, and a sample car in accordance with these designs was built by the Youngstown Bridge Company, this car being completed and placed in service about March of 1897. In this car the centre sills consisted of 15-inch I beams, the sides of the car being built-up plate girders, with diagonal reinforcing angles extending from top to bottom and stiffening angles ex tending the length of the sides being riveted to the upper and -lower edges, thus forming a girder which was designed to carry the entire load. In order to reduce the weight of the car the side sheets below the floor line, from the bolsters to the ends of the car, were cut out. This car was of 100,000 pounds capacity and weighed 35,500 pounds. No pressed shapes whatsoever were used in its construction.
Up to this time all the cars built by the Schoen Pressed Steel Company were of the hopper bottom type, but the value of steel in freight car construction having been fully dem onstrated, orders for other types followed in rapid succession, so that to-day practically all forms of freight cars, including hoppers, flat bottom gondolas, flat and ballast cars, have been constructed from steel in large numbers.
The adoption of the idea of maximum train loads, and the consequent enormous increase in the tractive power of the locomotive, served to further increase the popularity of the steel car, as it early became 'evident that the draft rigging and underframe construction of the wooden car would prove inadequate for the severe service to which they were subjected. As a consequence many cars of the box, stock and gondola types were built with steel under framing and having a superstructure of wood as a substitute for the original all wood struc ture. Cars of this type have given very satis factory results in service, as with the com bination all the desirable features of the wooden body are retained, while the under trame is sufficiently strong to resist the most severe buffing and pulling strains. A further advance in the substitution of steel in cars of the combination type has recently been made by the use of steel posts, braces, plates and car lines as a substitute for those of wood, thus producing a complete steel frame car.
The successful results obtained from the introduction of rolled steel as the basic ma terial in many large engineering enterprises warranted its careful consideration in the in fancy of steel car construction, and when the Carnegie Steel Company specified that the major portion of its first order for steel cars was to be constructed of rolled section, it is evident that from the very beginning it was recognized that the ideal car would be one made throughout of standard commercial shapes. As
pressed steel, however, admitted of the pro duction of shapes of the *exact form desired, and the early development of the steel car being in the hands of those predisposed in favor, and interested in the manufacture, of pressed steel parts, it is natural that great progress was first made in the perfecting of this latter type of construction, while the car made of rolled sec tions remained for the time in its original crude state, being clumsy and heavy when com pared with the more highly developed pressed steel car. The advantages of constructing a car from a few standard commercial shapes, easily obtained in the open market, especially when considering the questionof repairs, rather than from numerous special parts, re quiring expensive machinery in their manufac ture, were too manifest, however, to permit of being long ignored, and that it was possible to build cars from standard rolled sections, hav ing all the advantages of light weight and maxi mum strength claimed for the pressed steel car, has been fully demonstrated by the later de velopments of the art, and is amply evidenced by the numerous structural steel cars now in service which compare favorably with the pressed steel types in the matters of lightness, strength and simplicity of construction.
With the increasing demand for the steel car it is natural that a very inviting field for the investment of capital was disclosed, with the result that we have to-day in the United States a score of large corporations actively en gaged in this line of manufacture. The Penn sylvania Railroad builds its own steel cars, both passenger and freight designs; and several other railroads build freight cars for their own use. Besides the very large domestic trade the steel car builders have developed a profitable and growing export trade which is destined to be much larger in the near future, as the Bel gium production, heretofore the chief com petition in the foreign markets, must necessarily be small for several years to come.