A “MALLET” 2-
AMERICANS are credited with a love of “big” things, and to this prevailing bigness their locomotives are no exception. Indeed, the majority of the largest and most powerful locomotives in the world have been designed to run on American metals. It is not merely for the sake of gratifying a desire for size that these giants of the rail have been built. There are many reasons why tractive power on so vast a scale has become necessary.
The most compelling of these reasons is the weight of American trains. In the earlier days of American railroading the operation of trains was often conducted in so reckless a manner, and accidents were so frequent, that a demand arose on the part of the American public for vehicles of more massive construction, better able to withstand the shock of collision. Gradually, therefore, there came into use all-
When, therefore, a train of American stock has been assembled, the total weight behind the engine tender is more than double that of a British train made up of a corresponding number of vehicles. An American express of twelve coaches, with passengers and baggage, will scale about 850 English tons; but nowadays trains of fourteen, fifteen, or sixteen coaches, or even more, are common. The total weight to be hauled may thus rise to well over the 1,000 tons. For this reason alone it is not surprising to find in America passenger engines that are twice the weight, size, and tractive power of the biggest steam locomotives that have ever been built in Great Britain.
For the working of freight traffic, the principle of small consignments and short hauls which characterizes so much of freight working in Great Britain is replaced in America by large consignments and long hauls. This is one reason why the use of high-
American conditions make it practicable to put together long trains of the large eight-
As for the slower freight, such as coal or minerals, on certain lines trains have been made up experimentally to as much as sixteen thousand tons weight, and have been hauled by one engine. The difficulty here has not been that of the haulage, but that of braking on falling gradients a train which may be a mile long. In American freight working, therefore, the need for exceptional tractive capacity is obvious.
But there are other features of American traffic operation that call for high tractive effort. Mention has been made in the chapter “Speed Trains of North America”, which begins on page 1037, of the many factors which hamper continuous high-
Lastly, there are the regions of America where heavy traffic has to be conducted through mountainous country, especially the vast area of the Allegheny Mountains and their outlying ranges in the Eastern States, and the far greater Rocky Mount-
Big American locomotives are, therefore, a necessity. In the development of this size, American railroads are greatly assisted by the fact that American railway pioneers looked farther ahead than did the British in deciding the space that should be left above and at the side of the tracks, to allow for the cross-
The competition of other forms of transport, and particularly of Diesel propulsion, during recent years, no less than the unceasing public demand for more and more luxurious travel, has certainly directed the attention of American railway engineers to the excessive weight of their trains. The tour across America and Canada of the British “ Royal Scot” train in 1933 was an object lesson in what can be done in building lighter stock. Some of the latest American passenger coaches, therefore, in the construction of which welding, alloy steels, and aluminium have been used, weigh considerably less than their predecessors. The problem of weight is being seriously faced, in freight as well as in passenger operation. But as the weight reduction is being used chiefly to permit the acceleration of the services to much higher speeds, there is little likelihood of much diminution in the size or power of future American locomotive designs. There are certain essential points in which American locomotives in general differ from those of Great Britain. One of the most important is the design of the main frames. In Britain the main frames of the locomotives consist of two lengths of steel plate, about 1¼-
Ample Loading Gauge
In many of the latest locomotives these bar frames are not assembled from steel sections, but are made as one steel casting from end to end. In some designs, indeed, not only the frames, but also the cylinders and valve-
The increased space available on either side of the engine, due to the more liberal American loading gauge, has considerably influenced cylinder arrangements. In Great Britain the maximum possible diameter of cylinders between the frames is
The ample American loading gauge allows designers in that country to mount boilers of immense size on their engines, and in general the proportion of heating surface and firegrate area to the volume of the cylinders is greater than in Great Britain. This is partly because the quality of American fuel is not the equal, in its calorific value, of that used in Great Britain, and greater space must be provided on the grate to allow of efficient combustion. In the bigger engines firegrates having an area of from 85 to well over 100 sq ft are common, as compared, say, with the 45 sq ft of a LNER “Pacific”. In such conditions it would be impossible, of course, for a fireman to keep the fire supplied by ordinary manual means, and mechanical stoking is therefore customary. The coal, which is broken small for the purpose, is brought forward from the tender on to the firegrate by means of a feed screw arrangement. The speed of rotation of this device regulates the amount of coal that is fired.
A SMOOTH STREAMLINED EXTERIOR is a feature of Baltimore and Ohio Railroad for working its new fast services, such as the “Abraham Lincoln”. This is the new 4-
The first of these wide fireboxes, spreading right across the frames, that were fitted on American locomotives were known as Wootten fireboxes. In not a few of the earlier engines so equipped it was thought that the size of the firebox might interfere with the look-
Some tests conducted recently with a typical modern 2-
5 ft 9-
The test trains each consisted of 141 freight cars, all eight-
THE ENGINES OF CRACK EXPRESSES are now painted to harmonize with the coaches of their trains, and this powerful “Pacific” of the Central Railroad of New Jersey, used on the “Blue Comet” express from New York to Atlantic City, is further embellished with electro-
A total of 75,900 lb of coal was fired on each trip, which works out at 8,686 lb an hour, or 71.4 lb on every square foot of the firegrate every hour; and a total of 62,219 US gallons of water was evaporated. Throughout the journey the average pull on the train was 43,921 lb (nearly 20 tons), and the horse-
To feed such huge engines as these, tenders of colossal size and capacity are needed. Most modern American locomotives are equipped with twelve-
Such high capacities as these make it possible for these powerful locomotives to run for considerable distances without
replenishment of their supplies, although they add materially to the weight that the locomotives have to haul. In design, American tenders vary considerably, from the ordinary flat-
Prominent American Features
In external appearance there are many ways in which American locomotives differ from British. In addition to the steam dome, on the top of the boiler, a dome of larger size and somewhat misshapen appearance houses the sand-
Well above the wheels, in a straight line from one end of the engine to the other, is the running-
A feature that has persisted from the earliest days is the assemblage of steel bars mounted in front of the buffer-
During recent years there has been a tendency to “clean up” the external lines of American engines. There is little doubt that the visit of the Great Western Railway 4-
FOR 1,765 MILES CONTINUOUSLY 4-
But in the special designs that have been evolved for ultra-
To assist in maintaining high speeds, the driving wheels are increased in size from the general American average of 6 ft or
6 ft 3-
The tender, with 4,000 gallons of fuel oil and 13,000 gallons of water, weighs 110½ tons in running trim, the joint weight of engine and tender being thus 235½ tons. The tender itself has a curious wheel arrangement, with a six-
A Streamlined Train
But the most striking feature of the engine is the streamlined sheathing, extending upwards from the track to the chimney, which is completely hidden at the leading end, and then down the full length of the engine and tender from front to rear. The casing is raised from the cylinders onwards sufficiently high to clear the motion and the lower part of the wheels, so making these details accessible. To attract attention, the streamlined casing is beautifully finished off in gamboge colour, similar in shade to that which was once worn by the locomotives of the English London, Brighton and South Coast Railway. The design of the coaches, which have been reduced in weight from the general standard of 75 to 85 American tons to 50 tons apiece, has also been carefully studied for weight-
For working the high-
In working order this locomotive, which carries 44½ tons on its coupled wheels, weighs 95½ tons, which is no more than one of the LNER “Pacifics”. With the tender, which accommodates 14 tons of coal, and 8,000 gallons of water, it weighs 165 tons. In this considerable reduction of traditional American locomotive weight the use of alloy steels has played a considerable part. The “Lady Baltimore” has been painted blue, to harmonize with the new streamlined aluminium stock which it has been designed to haul.
A similar 4-
The mention of oil fuel in connexion with the streamlined “Hiawatha” 4-
An Unusual Design
Of these engines perhaps the most interesting are the enormous articulated examples of the 4-
BUILT FOR PUBLICITY, this giant 4-
But they are easily exceeded in size by some vast machines built in 1930 by the Baldwin Locomotive Works for service on the Northern Pacific Railroad through the heavy gradients of the Rockies. Their wheel arrangement is 2-
“PRESIDENT WASHINGTON”, a Pacific type locomotive, named after the first President of the United States, is one of a series of twenty-
The barrel of the boiler tapers from an inside diameter of 8 ft 7¼-
World’s Largest Locomotives
Twelve of these locomotives have been placed in service, and they have been built to work 4,000-
One feature of locomotive running on the North American continent creates records which have no parallel in any other part of the world. It is the enormous distances that are run continuously by steam locomotives without change. For example, on the Canadian Pacific Railway it is customary to run one locomotive unchanged on the important transcontinental trains between Winnipeg and Calgary, a distance of 836 miles. The journey occupies all but twenty-
The Chicago, Milwaukee, St. Paul and Pacific Railroad has an even longer turn of locomotive duty, through from Minneapolis to Harlowton, Montana, a distance of 914 miles. The Baltimore and Ohio Railroad has unchanged locomotive runs over the 786 miles from Washington to Chicago. But all these records are broken by the Southern Pacific Railroad, which succeeds in running its principal trains from Los Angeles, on the Pacific coast, right through to New Orleans with only one change of locomotive, at El Paso (Texas). The Los Angeles to El Paso stage is 815 miles, and the El Paso to New Orleans stage no less than 1,193 miles in length, the two together thus totalling 2,008 miles. The advantage of such methods, of course, is that of reducing the idle time of engines between trips.
Some important experiments designed to increase locomotive efficiency have been carried out over a series of years by the Delaware and Hudson Railroad, one of the underlying principles being the use of higher working pressures than before. The first experimental engine was built towards the end of 1924, and was named “Horatio Allen”. Its boiler is a kind of comb-
Compound propulsion is used, with one high-
It cannot be said that “Horatio Allen” is a handsome machine, but, as has been emphasized previously, in locomotive work “handsome is as handsome does” is the most reliable maxim.
On test this remarkable locomotive, on a series of test runs with heavy freight trains over a line with a continuously rising gradient of 1 in 200, showed a coal consumption no greater than 2.31 lb per drawbar-
In the later engine the appearance was somewhat improved by casing the water-
The superheating surface now became 700 sq ft, and brought the total heating surface up to 3,821 sq ft. Tractive effort remained 84,300 lb simple, or 70,300 lb compound, with 18,000 lb more available by the use of the booster. The weight of engine was 135 tons, or 284 tons with tender.
Next, in 1930, there came a third high-
The fourth in this remarkable line of succession is “L.F. Loree”, which was turned out in 1932. A short reference to this locomotive, which is illustrated on pages 596-
The wheel arrangement is 4-
The eight coupled wheels are of 5 ft 3 in diameter, the combined evaporative and superheating surface 4,427 sq ft, the grate area is 76 sq ft, and the weight of the engine in working order 170½ tons. The tender, carrying fifteen and a half tons of coal and 11,700 gallons of water, has a two-
When starting “simple”, the engine can exert a tractive effort of about 90,000 lb, or 108,000 lb with the addition of the booster; when working triple expansion, after it has got its load well on the move, the tractive effort is in the neighbour-
DISK DRIVING WHEELS, with holes for weight-
You can read more on “Locomotive Giants”, “Modern Locomotives”, “North American Railroads” and “Unconventional Locomotives” on this website. You can read more on “Mammoths of American Railroads” in Wonders of World Engineering