A 2-8-8-2 compound engine which weighs, exclusive of the tender, 241 tons
LOCOMOTIVES - 66
THE HUGE MALLET 2-8-8-2 COMPOUND LOCOMOTIVE, used in the coal service of the Virginian Railway. It weighs 347 tons complete in running order. It has been built for “pusher” services.
WHEN the Virginian Railway was built, the fathers of the enterprise realised the salient fact that the greater the tonnage of coal which they could move per train from the collieries to the coast, the higher would be the ton-mile revenue. Although the line is laid out in accordance with the very latest ideas concerning railway construction, with grades kept down and curves well opened, it was physically impossible to avoid one or two stiff banks, notably upon what is known as the Deep-water Division, comprising a distance of 14 miles between Elmore and Clark’s Gay, whereof 11½ miles have a ruling grade of 1 in 48.
In drawing up the train-operating arrangements the authorities decided that the very utmost which the huge freight engines could haul over the greater part of the line should be put over this bank intact, but that no more than three locomotives should be attached to the train for this purpose. The powerful Mikados, with from 103 to 120 (American) tons on the drivers, could handle a train comprising 80 loaded 50-ton cars under double-heading practice with ease upon the ordinary sections of the roads; but the climb through the Deepwater section, that became the key to the whole issue.
Accordingly, when the railway was opened, a fleet of four Mallets, of the 2-6-6-0 type, with 150 and 240 tons on the drivers, were built by the American Locomotive Company to serve as pushers. They were huge machines of their day, having a maximum tractive effort of 70,800 pounds. The Mikado road engines were kept at the head of the train, and a Mallet assisted them over the bank. The success attending this method of operation may be gathered from the fact that on one occasion a train of 120 cars, each of 50 tons carrying capacity, 5,340 feet in length — 60 feet in excess of a mile — and weighing no less than 9,140 tons exclusive of the locomotives and brake van, was run from the collieries to the seaboard.
Owing to the success of the first batch of Mallets a further instalment of eight machines was acquired. These locomotives were still more powerful, though of the same wheel classification, the tractive effort being 92,000 pounds. When these latter were brought into service, the former Mallets which had done duty as pushers were placed at the head of the train, thereby displacing the Mikados. At a subsequent date a still larger and more powerful machine of the 2-8-8-2 classification, and having a tractive power of 102,000 pounds, were built, and in turn took over the pusher service.
The success of these latter Mallets prompted the railway authorities to go still better, so they gave the American Locomotive Company the authority to design and build the largest and most powerful engine of this type which has yet emerged from the shops of this constructional organisation. It is a mammoth in very truth, because the engine alone measures no less than 66 feet in length by 16½ feet in height, and weighs 241 tons.
The engine is of the 2-8-8-2 compound type, the forward engine carrying the low-pressure and the rear engine the high-pressure cylinders. The former have a diameter of 44 inches, while the diameter of the latter is 28 inches, and the stroke is 32 inches. At the front end the diameter of the boiler, outside, is 100 inches, while that of the largest ring is 112 inches. The over-all length of the boiler is 50 feet 1⅛ inches. It carries 334 tubes, each 24 feet in length by 2¼ inches diameter, the heating surface of which is 6,462 square feet. The fire-box measures 11 feet in length by 9 feet wide, and some idea of this enormous size may be gathered from the fact that it is sufficiently spacious to accommodate the “Dinky” yard engine with ease. The heating surface of the fire-box is 380 square feet, bringing the total heating surface up to 6,842 square feet, while there are 1,310 square feet of super-heating surface. The grate area is 99·2 square feet. Steam is used at a pressure of 200 pounds per square inch.
The driving wheel base is 15 feet 6 inches by 15 feet 6 inches, the total wheel base of the engine being 57 feet 4 inches, while that of the engine and tender is 91 feet 5 3/16 inches. The driving wheels are 56 inches in diameter, and the weight on the eight pairs of driving axles is 237½ tons.
In the construction of the parts which are subjected to great strains, such as the engine frames, crossheads, driving wheel tyres, main driving axles, and crank pins, vanadium steel has been used freely, while vanadium has also entered into the composition of the cast-iron used for the cylinders and chamber bushes. The eight-wheel tender — two four-wheeled bogies — carries 212 (U.S.) gallons of water and 15 tons of coal, representing in running condition a total weight of 106 tons.
This enormous locomotive develops a tractive effort of 115,000 pounds when working compound, and 138,000 pounds under simple conditions of operation. It is used in the pusher service, the locomotives which it has displaced, and which were huge Mallets of their day, being turned into road engines. The general arrangement of working over the 14 miles’ hill, where a rise of some 1,330 feet has to be overcome, is to attach one of the 2-6-6-0 engines developing 92,000 pounds tractive power at the head of the train, and two of these monsters at the rear, representing a maximum total tractive effort of 368,000 pounds. By this collection of steam energy it is possible to move a train carrying 4,230 tons of coal over the hill.
The American Locomotive Company has built a considerable number of huge locomotives of the articulated Mallet type, but this represents its greatest achievement in this direction.
THE HUGE BOILER OF THE VIRGINIAN MALLET LOCOMOTIVE. The fire-box is large enough to hold the works’ shunting engine of the builders.
You can read more on “Articulated Locomotives”, “Giant American Locomotives” and “Northern Pacific RR Giant Freight Locomotive” on this website.
