SPEED AND ECONOMY

Evening Post, Volume CXVIII, Issue 13, 16 July 1934, Page 7

SPEED AND ECONOMY

DIESEL-ELECTRIC

TBAINS

SOME STRIKING FIGURES

A striking Hew advance in the railway world is the fast streamlined train of the Diesel-electric type, such as is being developed in the United States, Germany, Holland, Denmark, and Kussia, writes David Brownlio in. the "Manchester Guardian. '' Details have now been made available concerning a recent run by one of these trains on the Union Pacific Railway in the United States between Denver and Chicago, a distance of 1015 miles. This journey was accomplished in 13hr smin at an average speed of 77.6 miles an. hour, with 112.5 miles an hour at some points. The nature of the advance is indicated by the fact that fast DenverChicago steam expresses of the usual type take 12hr 40min longer fox this journey. ■ Daring the run, on a specific distance of 400 miles between Denver and Harvard; (Nebraska), the average speed was 79.1 miles an hour, which is far faster than the ordinary steam-driven' trains. Thb'Eoyal Scot on the LondonGlasgow route averages about 56 miles an hour for the 420 miles.

The stream-lined train is one of the answers of the railways'to the formidable competition of tho motor-vehicle and of tho aeroplane. It is stated that on this 1015-milo run the' Diesel engine used was operated with cheap heavy oil, costing four cents per gallon, and that the total fuel bill was only about \ 68s. When coal is used the fuel cost is- approximately £45—that is, thirteen times as much as oil. Conditions as regards the price of oil and coal arc, of course, somewhat different in the United States, but there is no reason why stream-lined trains of. this typo should not be driven in Great Britain by" coal-fired boilers and steam turbines of the condensing type, which, would effect an enormous economy.

HALT THE WEIGHT.

'•■ The weight: of a stream-lined train, made almost. entirely of aluminium alloys, is about 40-60 per cent. of. that o.f ~an ordinary train. In addition ,wind resistance. is reduced to a minimum, 'because of. the low centre of gravity and the intensified streamlining. So far as can be ascertained, up to 25: per cent, of the total power of the engino is required on the ordinary express train to overcome wind .resistance, and certainly at least 10 per cent, of the power used on conventional locomotives of all types could be saved, if the whole train were designed on stream-lined' and low centre ■of gravity: principles. .. -It is not generally realised that the railways of the world are amongst the .chief consumers of -coal. Taking ap'-' proximate figures, at the present tiniu 'about 12,000,000 tons of coal per annum ai'O used, on British railways and more ,tliah'. 100,000,000 tons on' the United State;; railways, with, say, 14,000,000 ton's, in- Germany, 4,000,000 in Japan, and 10,000,000 tons in Eussia. It is riot possible to obtain detailed statistics for many other countries. But at least 20 per cent, of the total.coal used in ,the .world is consumed by railways. ■Assuming the world's coal (arid brown coal) production at the present timo to.be approximately 1,100,000,000 tons jjer ; annum, this means that railways aTe/consuming 220,000,000 tons of coal <#ery_- -year. ~. -. .-,..-.. ■■'.... ._•..- ■. . *^

WASTES FUEL,

• The average steam : locomotive, in spite-of many advantages, is a great waster .pf fuel. Probably the average .thermal efficiency does not exceed 0-7 per cent.—that is, of the 220,000,000 ,tpns, of, coal used per annum for.the railways over 200,000,000 ■ tons are r wasted because of the use of a hibh-' pressure," fairly high*speed, non-condens-ing,, steam engine. .

' Some indication of the hundreds^ of millions : of : tpns of coal that have been squandered by locomotives is given by ,the>. advances in efficiency that have already been made, especially by the use .of higher steam pressures and temperatures of superheat. Thus, for example, in .the^TJnited.States the average freight' train performance in the year 1920,.-was,l74 pounds of coal per 1000 gross- ton miles, whereas at the present time this has been cut down to ■about 120. pounds, a saving of over 30 per cent, in coat Similar reductions 'haiverrbeen; madeI with passenger locomotives. The new streajn-lined trains .allow further substantial fuel economies to be effected, whether they use oil or cbal.': . .

For. a considerable period the world's -production of coal (and brown coal) has been almost stationary, and the past few years show a decline. Thus, for example, the figure was approximately 1,500,000,000. tons in 1929, the.disastvous year in which the world trade slump began, with a fall to 1,400,000,000 tons in 1930, 1,250,000,000 tons in 1931, and 1,100,000,000 tons at the present time. The main reasons are not only the formidable competition of oils, natural gas, and water power, and the world-wide depression, but also the increasing efficiency in the' utilisation of coal. :