Special text: Unusual railways Special text: Underground railways
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1. workings—горн, выработки 2. shield — щит (машина для проведения подземных выработок и туннелей, ограждающая рабочих от обрушивающихся пород и осуществляющая выемку и погрузку вынутой породы в вагонетки) 3. shuttle trains—челночные поезда ESSENTIAL VOCABULARY
THEME: RAILWAY ELECTRIFICATION I (1) World railways are now busy in search of ways to increase their economic efficiency and the speeds of passenger and goods trains. One essential condition to achieve this is electric traction. (2) The first attempt to apply electricity to transport purposes was made by Jacobi, a Russian physicist and electrical engineer. In 1838 he ran an electric boat at a speed of about 5 kph on the Neva river. (3) Another major success in using electric power was made by Werner von Siemens who was the first to produce a passenger electric locomotive. His locomotive was demonstrated at the ,exhibition in Berlin in 1879, It was a miniature four-wheeled loco hauling up to thirty passengers at a time round a narrow-gauged track 275 m long. The locomotive was so small that the (driver straddled it like a horse. But it was a practical locomotive which was furnished with power from the third rail placed in the track between the two running rails.1 4) Two years later, a small electric railway, the first one in the world, was put into operation in Berlin. This line was soon followed by an electrically-operated railway brought into use in the British Isles. It was an underground railway in London opened to traffic in 1890. (5) The Soviet engineers always took interest in railway electrification. As is known, it was V. I. Lenin who put forward the idea of the country's electrification. To realize this idea 200 outstanding Russian scientists, engineers and economists set to work. As a result, the GOELRO Plan was worked out in 1920. According to the plan the first railways to be electrified' were the ones carrying both heavy freight and passenger traffic as well as the suburban railways near big cities, such as Moscow, Leningrad and Kiev, с Since that time railway electrification advanced rapidly. (6) The world's longest Moscow—Lake Baikal electric railway put into service in 1961. Now the Soviet Union has about a quarter of the whole electrified network in the world. (7) In spite of having a relatively short history electric traction has made a remarkable progress. Now, one can say that electric railways perform valuable service on every continent. II (8) When we study the geographical location of the routes over which electric traction is employed, we see, first of all, that the suburban railway routes of big cities with their dense and constant traffic are operated by electric trains. We see, again, that the heavily-used trunk lines are most efficiently operated by electricity. Further, railways in mountainous country, with heavy gradients,2 are among the earliest to be converted to electric haulage. (9) The chief attractions of electric haulage are four in number. One is great rapidity of acceleration. The next advantage is that the electric locomotive is always ready for use and can remain1 in Service for practically the whole of, twenty-four hours continuously. It follows that under electrification the maintenance and operation costs are relatively cheap. Yet another essential benefit to be obtained is the ability of electrics to haul very long and heavy trains for there is practically no limit to the energy to be taken by the locomotive from the catenary. Besides, of all the existing kinds of traction it is the electric haulage that is most promising as regards speeds. (10) The electric rolling stock is of two types, namely, locomotive-hauled trains and multiple-unit (m-u) trains, the latter being composed of motor coaches and trailers, that is, coaches without traction motors. (11) Thanks to their rapid acceleration m-u trains are most suitable for suburban railways with their frequent stops and frequent services. As to electric locomotives they are mainly used to haul long-distance goods and passenger trains. (12) Electric railways may use either direct or alternating current. For the electric current to be fed to the trains the conductor rails or a system of overhead wires, often called the catenary, are needed. It is the power supply system that makes railway electrification a costly business since electric haulage makes it necessary for railways to be equipped with a whole system of electrical substations and cables to bring the power to the track. Because of a high construction cost railway electrification is justified on the railways with a high density of traffic. Thus the greater the density of traffic the more favourable situation for the operation of electric trains. (13) There are some other drawbacks of electric haulage to be mentioned. For example, the electric trains cannot run anywhere beyond the lines equipped with the catenary. Besides, any serious breakdown in the power supply system can bring a large number of trains to a stand. In hard winter conditions the icing of the overhead wire or the conductor rail causes many troubles on electrified lines. Yüklə 471,05 Kb. Dostları ilə paylaş:
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