Notes on the Working of a Rack Railway.” by WILLIAX TIIEODORELCCY, M
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“Notes on the Working of a Rack Railway.” BY WILLIAX TIIEODORELCCY, M. Inst. C.E. ALTIIOUG~this subject might appear to be of but limited interest, it may be pointed out that during recent years the loads hauled on rack railways have been largely increased, while their mileage has been steadilyextended. In Chilealone during,1913 there were opened to traffic, in the Arica-La Paz Railway and the Southern Longitudinal Railway, 1,072 kilometres (666 miles) of line which would not have been practicable without the use of the rack; and as regards loads it was stated in 1911 that the maximum tractive power employed in Switzerland was 11,000 kilograms (24,244 lbs.), while the work now under consideration may be takenas demanding 50,000 lbs. Th‘e interesting Paper presented to The Institution recently by Mr.Brodie H. Henderson, M. Inst. C.E., on “The Transandine Railway,”deals chiefly withthe location and construction of the two railwaysforming theroute betweenArgentina and Chile. The following notes are intended to give further information as to the practical details of working on the Chilian Transandine Railway, the more severe of the two lines, which the Author, while assistant manager, had opportunities of observing and modifying. J. Weber and S. Abt : “Rack Railway Locomotives of the Swiss Mountain Railways.” Proceedings Institution of Mechanical Engineers, 1911, vol. iii. Xinutea of Proceedings, Inst. C.E., vol. CYCP, p. 161 (and Plates S and 4). Downloaded by [ University Of Wollongong] on [16/09/16]. Copyright © ICE Publishing, all rights reserved. Procccdings.l LCCY OS THE ~VORKISG0~ A I;aci; i~~~tt-a~-.3 The chief feature of interest in this railway is the conibined rack and adhesion working on the so-called “rack ” section, between Rio Blanco (4,373 feet) and the summit tunnel (10,512 feet), a rise of 6,139 feet in 22 7miles. It consists of sevenadhesion sections and six rack sections, the most severe of these having gradients of 8 per cent. (1 in 12$) for a length of 1%mile, 7 6 per cent. (1 in 13.1) for 2k miles, and an average of 7 per cent. (1 in 14.3) for 5 miles. Theruling conditions of this“rack ” section of the line are :- Gauge l metre (3 feet 33 inches), Abt system, three-bar rack. Rulinggradient on adhesion sections . 24 percent. (1 in 40). ,, ,, rack ,, . 8 ,, ,, (1 in 124). Jfininiumcurves on adhesion :, . 120 metres = 6 chains. I, ,, ,, rack ,, . 200 ,, = 10 ,, Speed on adhesionsections. 30 kilometres (18.6 miles) ‘ { perhour. ,, ,, rack ,, . 10 kilometres (6.2 miles) ’ { perhour up. 15 kilometres (9.3 miles) ,I I, ,I ,, . ’ {.~ perhour down. ITeight of trainexclusive of engit~e . (say) l40 tons. During thefirst few months of working some dificulties occurred owing partly to lack of experience of conditions for which there was little precedent, and to anxiety on the part of the officials to deal with more traffic than that forwhich they were then prepared. At the beginning of 1911 the problems stillawaiting solution were the selection of themost suitable type of locomotive for the racksection, theadoption of betterbraking control, and measures generally to ensure safe and regular working. LOCOMOTIVES. The different types of locomotives then in use on the rack section were the Shay, the Borsig, the Kitson-Meyer, and the Esslingen. The Shay locomotive (59 tons),built by the Lima Locomotive Works, Ohio, is a geared engine driven by adhesion wheels only. Three vertical cylinders mounted on one side of the boiler drive a longitudinal shaft, which in turn, by means of bevel gearing, drives all the carrying axles. This shaft is connected by flexible couplings which allow of perfect freedom on the sharpest curves. The ratio of gearing is 1 : 2 * 21. This engine had done useful work during the construction of the line, owing to its simplicity and flexibility on the road, but its true sphereis limited to gradients up to 6 percent. Its full load up the 8-per-cent, gradient was 80 tons, and extreme carewas required B2 Downloaded by [ University Of Wollongong] on [16/09/16]. Copyright © ICE Publishing, all rights reserved. 4 LUCP ON TEE WOBKISG OF A CACX HAILWAY. Ofinutes of in bringing thatload down thesame gradient, though the subsequent addition of therepression brake has made it easier. Its maxi- mum speed of 15 kilometres (9 * 3 miles) per hour rendered this type unsuitable for running on the intermediate adhesion sections, and thereforeits use forregular tr.aflic requirements could not be entertained. The Borsig locomotives (48 and 56 tons), built by the firmof A. Borsig, Berlin,were acquired duringthe years 1904-6, when theline was open only to partial and lighter traffic. Theyare carried in a rigid plate frame on three pairsof adhesion wheels and a radial axle at each end, the heavier engine, with a larger boiler but of the same tractive power, having a four-wheel bogie at the trailing end. The adhesion wheels are driven by outside cylinders, while the two sets of rack-pinions, which are carried in the usual way on a frame suspended on the leading and driving axles, are driven by inside cylinders. These engines did good work in their day,and werecapable of haulingtrain-loads of 70 and even occasionally 80 tons, both the rack and adhesion cylinders being used on the heavygradients. The chief difficulty withregard to them was that, owing to the limitationsof width and space imposed by the metre gauge, all the bearings and connections were narrow, the clearances of revolving and reciprocating parts were small, and the accessibility left much to be desired. This type of engine is, however,useful wherethe loads are within its capacity, where skilled attention can be constantly given, and where the adhesion sections of the line are not too long nor thespeed required too high. When it became evident, inview of the increasing and anticipated traffic, that a more powerful and robust engine was required, the consultingengineers of the Company, Messrs. Livesey, Sonand Henderson, were asked in 1906 to advise on the acquisition of a suitabletype capable of hauling a train-load of 120 tons. They consequentlyapproached the MaschinenfabrikEsslingen, a firm having considerable experience in the design of rack locomotives at that date, who, in conjunction with Dr. Roman Abt, endeavoured to work out a design for an engine capable of hauling the above- mentioned load, but came to theconclusion that it was not feasible : Dr. Abt wrote in emphatic terms that the project was a physical impossibility, and that any attempt to haul such loads would lead to disaster. In view of the economic necessities of the case, the consulting engineerswere then asked to design an engine themselves, and to endeavour to obtain the co-operation of some English firm who would be prepared to build one as an experiment, the conditions laid down being that the engine should be capable of hauling a, Downloaded by [ University Of Wollongong] on [16/09/16]. Copyright © ICE Publishing, all rights reserved. Proceedings.] LUCY ON THE WORKING OF A RACK RAILWAY. 5 train of 120tons up an 8-per-cent. (1 in 123) gradienton the rack at a speed of 10 kilometres (6 * 2 miles) perhour, and of descending the gradient safely with the same train, any assistance from the adhesionwheels to be ignored in both cases, as it was then considered that no reliance could be placed on the adhesion at certain times of the year owing to the condition of the rails, due to ice and snow. Theengine was also to becapable of working a train of the same weight over adhesion gradients of 25 per cent. (1 in 40) at a ‘speed of not less than 25 kilometres (15%miles) per hour, and of traversing curves of 100 metres (5 chains) radius on the adhesionsection ; while the mRximum axle-loadwas fixed at 12tons. Theengineers came tothe conclusion thatthe bestsolution would be an engine of the articulated type, and they prepared a designsimilar tothe Kitson-Xleyerengines described later, but with a somewhat larger boiler and with only four cylinders, two on one bogie working the adhesion wheels, and two on the other bogie drivingthe rack-pinions. Messrs. Kitsonand Company, of Leeds, undertook to construct such an engine. At this stage the officials of the railway then in power insisted on the need of the addition of a third rack-pinion and an extra pair of cylinders on the adhesion bogie, which also involved a reduction in the boiler-power in order to keep the axle-loads within reasonable limits. hlthough the consulting engineers withheld their approva of these modifications, they were ultimately adoptedby the Company, andthe result w;ts theproduction in 1907 of the firstKitson- hleyer engine, weighing 90 tons, which was followed by others in 1908 and 1909 of the same type, but slightly heavier. In its originalform this type of engine w-as hamperedby unnecessarycomplications, and at first it was often under repair owing to troubleswith cletails whichhave since been overcome; yet, notwithstanding the warningsof Dr. Abt, it successfully hauled the loads for which it was designed. Later experience proved that the original plans of the consulting engineers would have produced a far less complicated :incl more powerful engine. In view of this success, the Ksslingen Company again approached the consulting engineers on the subject, and after obtaining their views as to the lines upon which the design should be worked out, undertook to build an engine of their own type to meet the speci- fied conditions,which they did successfully. Theirfirst engine, weighing 85 tons, was supplied in 1909, followed by a second1 in 1911 weighing 92 tons.