“There has recently been introduced on the Union of South African railways a large 2-6-6-2 Mallet type locomotive, built from the designs of Mr. D. A. Hendrie, the chief mechanical engineer of the South African railways, to serve experimental purposes. The engine works on the compound system, and has no superheater, while the driving coupled wheels of the high and low pressure engines are of different sizes (3 feet 10 inches and 4 feet 3 inches diameter, respectively), in order to increase the hauling capacity on the heavy gradients. The engine has total heating surface of 33,385 square feet with a grate area of 49.5 square feet and a tractive force at 50 per cent cut-off, of 45,200 pounds. The wheelbase of the engine is 41 feet 6 inches, and the total wheel-base of engine and tender 66 feet 9 inches, while the total length is 74 feet 10¼ inches and the height from rail level to chimney stack is 12 feet 10 7/8 inches. In working order, the engine weighs 103 tons 2 hundredweight and the tender 50 tons 17 hundredweight.
“Forward end of tender showing the coal crusher”
“The most interesting feature in the Mallet type of locomotive is its equipment with the ‘Street’ mechanical stoker, the salient features of which are shown in the pictures here. The tender is of the ordinary type, carried upon two 4-wheel trucks. It has a carrying capacity of 4,000 gallons of water and 10 tones of coal. The tender is fitted with a crusher of the moving jaw type, worked by an engine placed behind the brake pillar. The fireman shovels the coal into the hopper of the crusher, which reduces it to a uniform size. The coal falls from the crusher, through a chute, into a receiver fitted behind the drawbar of the locomotive, whence it is picked up by buckets working on a belt in the pipe and is discharged into the central hopper on the firebox above the firehole door. The buckets rise full on the left-hand side, and are worked by another small engine placed on the top of the firebox on the left hand side. There are three delivery pipes from the central hopper to the inside of the firebox. The delivery of the coal is controlled by three steam cocks operated by adjustable cams on the main shaft of the auxiliary engine, and can be directed by means of a conical tray, either to the middle or the right or left coal-feeding pipe, whence the fuel is blown into the firebox by the steam jets, the force of which is regulated by the cams, so as to deposit the coal just where it is required.
“Rear view of the locomotive showing the pipes which feed the furnace with coal”
“While it is premature to discuss the merits or otherwise of this stoker, it is claimed to have given better results, so far as locomotives are concerned, than any that have yet come under notice. It is undoubtedly a complicated machine, the fireman having to attend to two auxiliary engines in addition to handling the same amount of coal. Of course, the labor of shoveling form the tender into the firebox is avoided, but every ounce of coal burned has to be transferred by hand to the crusher. A very noticeable feature of this device is the noise. First there is the crusher working at a rapid rate, next the circulation of the conveyor belt, and finally the Maxim gun like reports of the steam cocks controlling the feeding, which all tend to contribute to produce a racket that is deafening to one who is unacquainted to the working of the machine.”