Superheated Steam Locomotive for the Royal Prussian State Railways.
The engine shown herewith was built by the Berlin Machine Building Company (Berliner Maschinenbau-Actien-Gesellschaft Vormals L. Schwartzkopff) from the designs of Gen. Baurat Garbe, and is intended for hauling fast goods trains, passenger and express trains on heavy lines. The following are the principal dimensions:
Mogul (2-6-0) Locomotive with Superheater for Prussian State Railroads.
The engine is the 2-6-0 type. The cylinders are simple and the valve motion is of the Heusinger type with piston valves 5.9 in. in diameter. In the smoke-box is a Schmidt superheater, in which live steam is superheated, before entering the cylinders, up to 570 to 660 degrees Fahrenheit. The superheater consists of bunches of pipes, bent to the shape of the smoke-box shell and ending into two steam chambers in top of the smoke-box. The superheater is heated by gases of high temperature (1,470 to 1,830 degrees Fahrenheit) coming directly from the grate through a flame tube of 12 in. diameter. This superheater has given excellent results on all the locomotives to which it has been fitted, and upon the lines of the Prussian State Railways, the use of these superheated locomotives is increasing very rapidly. During recent months a series of important and exhaustive trials I have been made with the locomotive illustrated herewith, in order to ascertain its relative efficiency, in respect to speed and economy, in the operation of goods as well as in the heavy mountain express services. The superheated steam mogul locomotive has proved itself superior to an ordinary mogul locomotive of the same weight and also to a four-cylinder compound ten-wheel engine of 15 tons heavier weight, the average saving in water amounting to 18 to 20 per cent.; in coal 12 to 15 per cent., while the cost of maintenance and repairs were less. The superheated engine hauled on a line 124 kilometers (77 miles) long, with many curves and with grades of 1 in 100, an express train of 42 axles, 322 tons, and a total weight of engine and tender of 424 tons at an average speed of 80 kilometers (50 miles) per hour, the maximum speed reached being 105 kilometers (65.3 miles). The average cut-off in the cylinders on this trial was 23 per cent. With the heaviest of loads, the starting is effected without any difficulty, which in a great measure demonstrates the advantages of superheated steam, which also, with cold cylinders, only gives a small loss of condensation. All parts coming in contact with the highly-superheated steam—such as pistons, piston valves and stuffing boxes—have worked satisfactorily while there has been found no difficulty whatever with the superheater. The average temperature of the steam was 626 degrees Fahrenheit, and the steam pressure has been throttled down to 135 lbs. in the steam chest, so that there was an abundance of steam in the boiler during the trials. The engine is fitted with pneumatic sanding apparatus on the Bruggeman system, and with a speed indicator of the Haushalter type. The pistons and piston valves are lubricated automatically by means of oil presses.
