Central Uruguay Railway Locos; Converted to Tanks

Transcription

1 The Second World War Period Led to: Considerably more drastic reconstructions or rehabilitations of locomotives, one such is a class of engine upon the Central Uruguay Railway in which the obtaining of in-creased power from even older locomotives has been desirable. The necessity of obtaining or retaining potential power by any practicable means ' became crucial owing to the failure of customary oil-fuel supplies upon which the disposable tractive power in great measure depended, and the forcible recourse to inferior coals and wood-fuel, which naturally lessened the effectiveness of power output. Further, the impossibility of obtaining new locomotives, and even new boilers, during wartime was aggravated by a further collapse of fuel-oil supplies during the course of the series of conversions, so that as will be seen the last two engines were turned out as wood-burners and having tenders. The maintenance of adequate motive power despite these war-time difficulties both of fuel and materials had therefore to be achieved by the utilization of serviceable material which was available owing to the scrapping and reconstruction of other engines, and the process might well be considered as rehabilitation on the most economical basis. These C.U. Railway reconstructions were carried out by Mr. P. C. Dewhurst, M.I.C.E., M.I.Mech.E., the Chief Mechanical Engineer, in the Company's Workshops, Pefiarol, Uruguay. Figure 1 shows the engines as built in 1884; extended smoke boxes being fitted in 1893, and their scope increased in 1909 by the application of large capacity double-bogie tenders, whilst about 20 years ago they had been equipped to burn oil-fuel, from which date they have been as shown in Figs. 2 and 3, until recently; when reconstruction was the alternative to the scrapping of the engines. They were considerably underboilered combined with small coupled wheels for the relatively fast freight trains of recent years. The reconstructed engines are shown in Figs. 4 and 5, and in their altered form is incorporated material, including boilers, frame-extension plates, trailing pony trucks, frame cross-stays, also rear buffer-beams, buffers and cow-catchers, which were available from previously retired engines; whilst the whole of the original engines except the boiler and cab is re-used. At the same time their previous large tenders were released to substitute smaller capacity tenders upon another class of modernized engines. The duty required in their new form being to handle shunting rakes of 42 loaded cattle wagons, equalling 900 tons exclusive of locomotive, upon branches with gradients of 1 in 60, and to handle heavy trains at relatively slow speeds over a similar main line gradient. It can be seen that a considerably larger and more powerful locomotive has emerged; the boilers themselves being drafted down from more recent types of locomotives as part of the policy of modernization in which the more powerful classes of locomotives are fitted with larger boilers, and in most cases with up-to date valve gear, etc. and their boilers passed down to lesser-powered engines which in their turn also become more effective tractive units. The new fuel and water capacity requirements called for a type tank locomotive which also conveniently allowed the installation of the longer boiler. The extension framing, as the before mentioned, is derived from portions of the main frames of locomotives converted some years previously. Fig. 6 shows the construction at the trailing end and the old frame plates suitably arranged to incorporate the trailing pony-truck, bunker, etc.; owing to the narrowness of the between-frame space on these particular engines and the necessity of carrying the boiler considerably higher than that of the ' original framing, a certain amount of scheming was required, and although there is a relatively sparse distribution of rivets, electric welding entered largely into the splicing-on of the extension; the trailing pony-trucks were originally under the leading ends of some locomotives previously scrapped. The boilers used in these reconstructions, which had been superheated some years ago to 277 sq. ft. a rather low ratio, have their superheater units shortened in these reconstructions to produce 210 sq. ft., furnishing a ratio of superheating to total evaporative surface of 1 to 6.28, and reconstructions in service up to two years have had no trouble whatever with their partly balanced "D" -pattern valves of bronze working on vertical port-faces; a piece of experimental data of some interest as indicating that a medium-low proportion of superheat can "be taken advantage of even with old-fashioned valves. In order to accommodate these much larger boilers, the steam-pipe entrances to the steam chests were changed from the back to the front end, the connections being made by drilling the steam-chests and screwing in a suitable steam pipe connection; a simple process which service has shown to be effective.

2 The principal particulars of the engines before and after reconstruction, additional to those upon the diagram are given in the following table: Original Engines before conversion Modified Engines CONDITIONS : Gauge; 4 ft. 8½in. Curves, min radius Main line 13½ chains, sidings 8 chains Ruling gradient; 1 in 60 Rail weight per yard; 65 lb. PRINCIPAL DIMENSIONS: Cylinders, two; 18inch x 24 inch 18½ inch x 24 inch Diameter of pony wheels leading and trailing; 2 ft. 9 inch 2 ft. 9½ inch Diameter of driving and coupled wheels; 3 ft. 10 inch 3 ft. 10 inch Firebox shell width; 4 ft. 0½ inch 4 ft. 1 inch Grate length; 5 ft / 16 inch 7 ft. 1 13/ 16 inch Grate width; 3 ft. 5⅜ inch 3 ft. 6 inch Flues, number and O/D 21 5 inch Tubes, number and O/D 171 1⅞ inch 134 1⅞ inch Superheater, tubes and O/D 84 1⅝ inch Heating surfaces: Tubes and flues; 1,072 sq. ft. 1,193 sq. ft. Firebox; 100 sq.ft. 127 sq. ft. Total evaporative; 1172 sq. ft sq. ft. Superheater surface: 210 sq. ft. Equivalent H.S. = total evaporative H.S superheater surface Grate area: 1600 sq. ft. Grate area: 20 sq. ft. 25 sq. ft. Boiler pressure per sq. in.: 140 lb. 160 lb. TRACTIVE FORCE: At 82s% boiler pressure: 19,524 lb 23,570 lb. RATIOS: Adhesion weight Tractive force (at 82½% B.P.) Rated tractive force (at 82½% B.P.) Equivalent heating surface Total evaporative surface Grate area Total evaporative surface 6.28 Superheating surface

3 Central Uruguay Railway Locos; Fig 1. C.U.R as built in 1884 Fig 2. C.U.R as altered to burn fuel oil Fig 3. C.U.R No. 24, oil fired

4 Fig 5. C.U.R T No 23

5 from 1 st Page Central Uruguay Railway Locos; The somewhat unusual placing of the oil-fuel tanks at a high level and adjacent to the boiler enabled a simplified arrangement of the fuel heating equipment; thus the system differs somewhat from the standard generally used on the C.U. Railway in that there is no re-heater, the fuel passing from a shallow well in the bottom of the tank into a casing containing a steam-heated coil and so by gravity to the burner. An inspection door to this equipment will be seen just above the rear coupled wheels on the left side of the engine. As will also be seen, the fuel-oil filler is mounted on the top of the boiler, both tanks being filled simultaneously. Fig. 7 shows the heater coil set in the outlet area in the rear portion of the left side fuel tank together with the various pipes, valves and controls. As the water filler-hole is located in the bunker, an iron ladder is placed on the left side to facilitate access thereto, balance-pipes of ample dimensions conveying the water to the sidetanks. In future conversions, when certain fuelling stations which were the motive for placing the fuel-oil tanks in the upper part of the side tank will have been modified, the fuel-oil will be accommodated in the bunker-space. The side tanks and bunker are of welded construction suitably stayed, pockets being arranged for the leading sandboxes and openings provided between the intermediate and driving wheels, the left hand opening accommodating the mechanical lubricator for the axleboxes and the right hand side serving for inspection and oiling the eccentrics, etc. As will be seen, top-feed injector delivery, electric lighting for headlights and in the cab, also the Central Uruguay Railway system of snifting valves applied to the superheated side of the superheater header working in combination with a circulating valve communicating to the saturated side are incorporated. A hydrostatic lubricator provides lubrication for the valves and cylinders, whist mechanical lubrication is provided for the coupled axle boxes, the operating gear for which appears in the photographic illustrations. A vacuum brake having two 21 inch cylinders has taken the place of the original steam brake, the vacuum chambers being placed under the cab roof. For use on ballast-trains needing to remain a considerable time on a section remote from a water supply, the rear of the engine has fittings enabling it to be coupled to a tender (the latter being specially provided with buffers, etc.) by which means an unusually large water supply becomes available for continuous service. Greater stringency occurring in both fuel-oil and coal supplies during the conversion of this class led to some of the reconstructions being carried out so as to enable the locomotive' to employ wood fuel. In this modified form all the features, with the exception of the side tanks, of the designed reconstruction as tank engines were retained, so that the engines can be completed as originally intended when normal fuel supply conditions return. Figs. 8 and 9 illustrate the engines as Wood-burners, their dimensions only differing from the tank engine conversions in respect to the fuel and water capacities, which are 665 cubic feet (including 125 cu. ft. provided in and on the bunker) and 2,600 gallons respectively; the consequent altered axle-weights appear in Fig. 8, whilst the cylinders are 18¼ in. diameter instead of 18½ in. Besides differences in the ashpans and, of course, a wood-burning chimney, which is of the inverted-cone and arched-netting pattern, a very low blastpipe orifice combined with a low "petticoat" is provided in the smokebox. The accompanying tender itself is arranged with a receiving-space at the rear and a flexible wire-netting apron which fastens to the usual woodcarrying match wagon, and in this manner runs up to 150 miles can be made without stopping for refuelling, the wood-passer throwing up fuel from the match wagon when in motion, the netting avoiding risk of derailment from odd pieces of wood falling between the tender and the match wagon. In order to assimilate these tenders without interfering unduly with the design of the rear end of the reconstructed engines, the cab and bunker are retained in exactly the same form as for the oil-burning tank engines, except that a central passageway from the footplate to the tender is left through the bunker, the remainder of which space and also above the bunker provides extra storage space for wood-fuel where it is stacked conveniently within the interior structural members of what will later become the fuel-oil tank. This passageway, and the general appearance of the rear end of these wood-burning engines, is shown in Fig. 10, whilst Fig. 11 shows the normal bunker-end of the tank engines, thus illustrating the relatively few changes by which the adaptation has been accomplished.

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7 It will be observed that the adhesion factor at 82½ per cent. the customarily taken 85 per cent, of modern engines is considered too high when the relatively low superheat and the odd-style valves, etc., is taken into account is 3.83 upon the habilitated wood-burner, and this may be considered upon the border-line. In practice, however, these engines have shown no tendency to slip, a result to which the adequately long connecting-rods no.doubt contribute greatly. The reconstructed locomotives as turned out for wood-burning have a somewhat unusual appearance and their fireboxes appear short in the photographic illustration Fig 9, an illusion arising fro the fact that two-fifths of length of the firebox is within the cab, and also because of their tank engine type of cab. They have however, proved favourites with the operating staff, as with the firemen operating in the bunker area and in the forward portion of the tender, whilst the wood passer operates on the tender, and when required on an additional match wagon behind the tender, (a very convenient fuel line results). Further although for heavy mainline work a hard wood is found indispensable having the severe gradients which signalise the Central Uruguay Railway. For ballast trains and similar duties a cheap local wood fuel; eucalyptus was successfully used.