THE MODERN HIGH-SPEED LOCOMOTIVE

The great increase that has taken place of late years in the size, weight, and power of fast passenger locomotives, is to be ascribed mainly to two causes. First, the increased weight of the trains, and second, the demand on the behalf of the public for faster trains. Of these two causes, the former has been the most active in influencing the design of the locomotive; for while there has been a decided increase in the speed of express trains, there has been a relatively greater increase in their weight, some of the trains being of a weight which, a few years ago, would have been considered prohibitive.

Contemporaneously with the increase in weight and power of express locomotives, there has taken place a decided change in type, Not many years ago the term "American locomotive," as applied to those that hauled passenger trains, was universally understood to mean an eight-wheel engine with a forward truck, four coupled wheels, and the cylinder driving the leading axle. The call for greater power and a larger boiler then led to the introduction of a third pair of driving wheels, giving us the six-coupled express engine which, for a while, held undisputed possession of the field for heavy fast passenger trains. This, in turn, was succeeded by the celebrated Atlantic type, a ten-wheeled engine with a forward truck, four coupled driving wheels, and a pair of trailing wheels beneath the firebox, the cylinder being connected to the rear driving wheels-a type that is in such wide use to-day that it may be considered the typical American locomotive of the opening years of the twentieth century. It has proved in every respect a most successful type, and some of the heaviest, fastest, and most famous trains in America are hauled exclusively by Atlantic engines The credit for the introduction of this type belongs largely to the Baldwin Company, and the first engines turned out by them sprang into immediate favor and prominence by the great work they accomplished in hauling the fast summer expresses between Philadelphia and Atlantic City.

The remarkable photograph shown on the front page of this issue represents the most powerful express engine of this type in existence. It was built for the Chicago & Alton Railway, for hauling, their fast passenger trains between Chicago and St. Louis during the World’s Fair. It is one of several that were ordered, and it formed part of the exhibit of the builders in the Transportation Building at St. Louis. Perhaps the best known of the large Atlantic engines are those which were built by the American Locomotive Company for handling the fast passenger traffic on the New York Central Railroad, and the great power of this Chicago & Alton engine can be understood by comparing its cylinder dimensions with those of the New York Central engine, which are 21 inches in diameter by 26 inches stroke. The Chicago engine has cylinders of 22 inches diameter and 28 inches stroke, and as the steam pressure, heating surface, and diameter of driving wheel are the same, the engine is, of course, more powerful than the New York Central engines, the tractive force or drawbar pull being 28,798 pounds. The weight on the drivers is 145,000 pounds, the weight of the engine in working order is 221,300 pounds, and the weight of the tender 166,000 pounds. The barrel of the boiler is 70 inches in diameter, and it contains 276 tubes, 2 inches in diameter and 20 feet long, whose aggregate heating surface is 3,234 square feet. The firebox contains 202 square feet of heating surface, giving a total heating surface of 3,436 square feet. The driving wheels are 80 inches in diameter.

The engine shown on our front page was engaged in hauling, during last summer, what are known on the Chicago & Alton road as trains No 2 and No. 11. Train No. 2, running from St. Louis to Chicago, consisted of eight cars which, with baggage and passengers, weighed 475 tons. Five stops were made, the average duration of stops being four minutes, and the average speed of the train was 40 miles an hour including these stops. The weight of train No. 11, running from Chicago to St. Louis varied from day to day, but frequently no less than fifteen cars were coupled on behind the big engine, in which case the weight of the train, passengers, and baggage exceeded 800 tons. This train was scheduled to make the same speed, and it had to do this in spite of four stops, the average duration of which was 4 minutes.

When we read of 80-inch driving wheels, 22-inch cylinders, and 70-inch boilers, the average reader receives no adequate impression of the resulting size of the locomotive. In the present case, the photographer selected a point of view that gives one a most impressive sense of the huge bulk and impressive dignity of this splendid engine.