As the twentieth century opened, longer and heavier passenger trains began to tax the resources of existing locomotives — the American Standard (4-4-0), Mogul (2-6-0), Prairie (2-6-2), Ten-Wheeler (4-6-0) and Atlantic (4-4-2) types. The Pacific or 4-6-2 type was introduced in North America in response to this challenge. The name “Pacific” as applied to this wheel arrangement apparently came from the fact that the first locomotives built as 4-6-2s, constructed by Baldwin Locomotive Works for the New Zealand Railways in 1901-02, had to be shipped across the Pacific Ocean. Additionally, the first ones constructed for use in the United States were for the Missouri Pacific. An estimated 6800 or more Pacific type engines were built for North American railroads. The largest fleet was the nearly 700 owned by the Pennsylvania Railroad, its K4 class alone numbering 425 engines. The New York Central System was another major user, still listing some 380 4-6-2s in a roster published in 1940.

Introduction of the higher-horsepower Hudson (4-6-4) type by the New York Central in 1927 led to the displacement of Pacifics in heavy passenger service, and many railroads also turned to the dual-service 4-8-2 and 4-8-4 types. With the appearance of fast streamlined passenger trains in the 1930s, however, Pacifics were some of the first steam engines to be streamlined or semi-streamlined for this service. And the Pacific type never went entirely out of production while steam engines were being built for North American railroads. New locomotives were constructed for the Boston and Maine (1934), the Reading (1948) and the Canadian Pacific (1944-48). For more information on the Pacific type, visit the Pacifics page on Wes Barris’ site or read the Wikipedia article 4-6-2.

A vigorous promoter of the Pacific type was the American Locomotive Company (ALCO), which in November 1913 issued its 20-page “Bulletin No. 1016” with illustrations and specifications of 42 orders of 4-6-2s for U.S. and Canadian lines. Of special note is the first locomotive illustrated, Pennsylvania Railroad K29 Pacific No. 3395. It was the only one of its kind constructed, but was the prototype for the ubiquitous K4 class — none of which were built by ALCO.

My grandfather, Don M. Leonard, was secretary to the vice president of the Boston & Albany Railroad, and evidently acquired a copy of this bulletin from a railroad motive power official. My father, Dr. Richard D. Leonard, preserved it in his small collection of railroadiana, and I am presenting it here. The front page is damaged, so I have reproduced it below in HTML. The other pages, all scanned, consist of four pages of specifications followed by the illustrations. On this site I have placed the images first, with links to the applicable specifications which follow. Use the buttons to navigate through the bulletin.

Dr. Richard Leonard







Greater passenger carrying capacity, heavier construction of cars, and the introduction of steel equipment, are rapidly increasing the weight of passenger trains. To avoid doubleheading and to maintain limited schedules with these heavy trains is a problem with which many railroads are presented.

These factors require a passenger locomotive which can maintain high sustained tractive efforts at fast speeds combined with large starting efforts, together with a reserve capacity for heating and lighting the train, for the occasional addition of an extra car, or for bad weather conditions.

These requirements of a passenger engine necessitate ample boiler capacity and good steam engine efficiency. The Pacific type locomotive is remarkably successful because it provides this combination in very satisfactory designs.

The wheel arrangement of the Pacific type includes a four-wheel leading truck with excellent guiding qualities; six-coupled driving wheels, giving great adhesive weight, and trailing wheels rendering it possible to provide a long boiler with a suitable firebox, ample throat depth and large grate area.

A new standard of boiler proportions which represent years of experiment and experience has recently been adopted by the Engineering Department of the American Locomotive Company. With these proportions boilers are designed capable of sustaining the maximum cylinder horsepower, thus insuring a constant supply of steam for any speed the locomotive cylinders are capable of developing.

This boiler of large capacity, combined with a superheater and firebrick arch, provides great sustained capacity with minimum coal and water consumption.

Fuel is the largest single item of locomotive operating expenses. To save coal, therefore, is important, but to economize in coal, to make the coal do more work, is still more important. The introduction of fuel-saving devices has shown economy of 25 per cent. with only a slight increase in weight. Economy in fuel also means that every pound can be made to do more work, and by burning the same amount of fuel as before, the 35 per cent. economy becomes 33 per cent. increased capacity. Many roads have accomplished this result by larger locomotives with the latest and best improvements in design. Maximum capacity is thereby secured with minimum weight and minimum operating expense.

Several roads are using the Pacific type in fast freight service, where grades are not severe and where this kind of traffic is heavy.

These pages present a variety of successful designs combining the latest and best-known proportions of the locomotive itself, with the best fuel-saving devices. They were built to embody the results of years of experiment and experience in both design and materials for the production of maximum capacity and economy within the limits of our present knowledge, supplemented by the complete knowledge of the officials of the Motive Power Departments of the different railroads. They have more than fulfilled the expectations of the different railroad companies.

Our engineers are available for a conference with your officials and a study of your problems. Perhaps they may be able to suggest locomotive designs specially adapted to meet your conditions that will assist you in reducing operating costs.