protect the fire door. In certain boomstives with still longer boxes there will be a wall of brick about 6 feet in front of the atomizer, and the arch springs from this wall, so that there is a combustion space between the wall and the tube plate. With Texas oil the Great Eastern loomotives have hauled fast trains on a consumption of 17-6 pounds per mile, as against 34 pounds of coal, the train load being 225 tons (2.240b,. On a test run with a train of 620 tons a four coupled passenger engine consumed 31 pounds of Texas el per mile. These engine are fitted with air heating arrangements. On the Japanese Government railways, Borneo oil Fig. 25. FIRE-BOX OF AMERICAN OIL-BURNING LOCOMOTIVE on the Holden system showed an evaporation as high as 14-42 and averaged 12-6 the year round as against 64 pounds for coal. Quoting from the annual report of the Japanese Government, the adoption of oil fuel for an estimated annual locomotive mileage of 7.000.000 would save 448,000 yen per year, or nearly £44,800. An important item in connexion with oil fuel on locomotives is the lengthened life of the internal firebox. After some service the sides of an ordinary firebox present a series of convex surfaces between the stays, which are each and all subjected to constant abrasion by the small ashes, sparks, etc., drawn from the fire by the action of the blast. As a result of this wearing away of the surface of the plate, it gradually becomes thinned, and eventually cracks develop between the stay holes, with the consequence that the box must be patched or renewed after a comparatively short existence. With oil fired engines an extension of time of some 50 per cent. can secured, as no such destructive action exists. These remarks on abrasion apply equally to the tubes, smoke box, chimney, etc., and the economies in this direction are of considerable value when large numbers of locomotives are affected. be On the long fast runs it is difficult to keep a steady steam pressure with a coalburning engine during the later portions of the journey, owing to the "dirty" grate. With oil burners the fire is of equal intensity throughout, and as clean at the end of the day as at the start, and an engine can be run indefinitely as regards the fire. The average life of copper fire boxes of five G.E. Rly. engines, No. 754 to 758, with coal, was found to be 5 years, and that of two other sister engines, No. 760 and 765, using liquid fuel, was respectively 8 years 4 months and 8 years. The form of atomizer used on later locomotives is that of fig. 27. This burner is designed to vaporize the lighter portions of the oil, and to carry out this operation sufficiently quickly to prevent the burner being choked by coke which might be formed if the decomposition process is carried too far. The oil enters by the first branch on the burner and passes through a long tapered cone surrounded for the greater part of its length by an annular space open at the lower end, through which steam is allowed to pass from a second branch on the burner casting. The steam is highly superheated and raises the temperature within the inner cone before it passes through the orifice from which it escapes and comes in contact with the oil. The oil and the steam then pass along together at a sufficiently high velocity to induce a current of heated air through the third branch of the burner. The air thus drawn in by the aspirating action of the jet, allows the oil vapour on the outer surface of the jet to ignite and thus raises the temperature of the whole of the jet so that as soon as this is allowed to come in contact with the air for combustion, which passes through the firebars, ignition takes place immediately, and the combustion is completed. In fitting these burners to ordinary boilers they are connected by means of pipes to a hinged joint or trunnion. This does not require any special description beyond that the ports in the moving portion are so arranged that when the burner is swung out of position, the supplies of steam and oil are cut off, so as to prevent the risk of fires in the stokehold. Where, as is often the case, a crude oil contains water in such quantities as to extinguish the fires there is considerable danger. The oil following immediately after is--if the furnace temperature is sufficiently high-violently exploded, or, if the furnace is allowed to become too cold, the oil falls through the ashpits and on to the stokehold floor, where it spreads out into a thin film probably at a temperature approaching the flash point, and therefore in a highly inflammable state. The specific gravity of most fuel oils being 0.86 to I the rate of settling at low temperatures is very slow, but the difference in the specific gravity becomes much. more marked if the temperature is raised, and a very usual practice has been therefore to heat up the whole contents of the oil bunker or tank to such a temperature as without approaching the flash point of the oil, will make the density difference sufficient very much to accelerate the settling rate. The objection to this practice is that a large amount of heat is required, the radiation surface of a bunker of any size being considerable; the heating process at its best is slow, and unless it is completed before any of the contents are drawn off, the lower layers of the tank will consist either of pure water or oil with a large percentage of water mixed up with it. To obviate this difficulty, a floating suction is used which consists of a long pipe pivoted upon the side of the bunker or tank, and guided in the vertical plane by means of a tee or angle iron set to correct radius. The suction pipe has a small steam pipe led along its side, which terminates in the coil immediately below the suction opening. The steam passes through this and heats the oi immediately below the orifice of the suction pipe, and this oil rises up into the pipe and leaves the water behind it. The float is proportioned and arranged to keep the mouth of the pipe about 6 inches below the level of the oil in the tank. This apparatus is certain in action and requires but little heat, as this is only applied to that portion of the oil immediately under the mouthpiece of the suction pipe, and there is little or no radiation from the bunker sides, and the heated oil at once moves off to be used while still hot. See fig. 9a for similar device. The latest general arrangement of a Great Eastern Railway locomotive is that of fig. 26, which shows the application to a locomotive with firebox 2 feet 6 inches wide. For a smaller firebox one atomizer only is necessary. The apertures in the firebox are made by inserting a copper tube beaded over at the ends, into this a wrought iron ferrule is drifted which makes a perfectly tight joint. The nozzle of the atomizer is placed about in. above the centre of the aperture, and the face of the ring inches from the front of same. When liquid fuel is used alone, steam is first raised in the boiler by a wood and a coal fire to 25 pounds or 30 pounds pressure, the fire is levelled over and covered with a layer of broken fire-brick of not more than 3 inches cube spread, so that it is thinnest about the centre of the firebox, and well packed round the sides and corners. A few pieces of waste or wood are thrown in to cause a flame before the liquid fuel is introduced. Dry steam is taken to a steam fitting, two cocks on which admit steam to the cones and rings on the injector respectively; a third cock blows steam through the fuel pipes and atomizer should they become choked; and there is a cock for the steam coil placed in the tank to prevent the fuel solidifying in cold weather. The fittings for a locomotive, as illustrated, consist of the following 2 atomizers and regulating valves. 1 steam fitting. 1 stop cock on tank. 1 four way piece. 2 tee pieces. 2 copper tubes and ferrules. For a locomotive with firebox under 2 feet 6 inches wide, the following fittings are required The air heater is shown in the smoke box, fig. 26, and consists of a number of tubes laid round the smoke box crown and springing from two headers into one of which the air is drawn and out of the other it passes to the atomizer. The regulating gear is shown in fig. 23, this being the latest form so arranged that a simple movement of the lever closes both oil valves without affecting their separate adjustment when open. |