Топик: The history of railways (История железных дорог)

In the United States, between the Civil War and World Wаr 1 the railways, along with all the other important inndustries, experienced phenomenal growth as the country developed. There were rate wars and financial piracy during а period of growth when industrialists were more powerful than the national government, and finally the Interstate Commerce Act was passed in l887 in order to regulate the railways, which had а near monopoly of transport. After World War 2 the railways were allowed to deteriorate, as private car ownership became almost universal and public money was spent on an interstate highway system making motorway haulage profitable, despite the fact that railways are many times as efficient at moving freight and passengers. In the USA, nationalization of railways would probably require an amendment to the Constitution, but since 1971 а government effort has been made to save the nearly defunct passenger service. On 1 May of that year Amtrack was formed by the National Railroad Passenger Corporation to operate а skeleton service of 180 passenger trains nationwide, serving 29 cities designated by the government as those requiring train service. The Amtrack service has been heavily used, but

not adequately funded by Congress, so that bookings,

especially for sleeper-car service, must be made far in

advance.

The locomotive

Few machines in the machine age have inspired so much affection as railway locomotives in their 170 years of operation. Railways were constructed in the sixteenth century, but the wagons were drawn by muscle power until l804. In that year an engine built by Richard Trevithick worked on the Penydarren Tramroad in South Wales. It broke some cast iron tramplates, but it demonstrated that steam could be used for haulage, that steam generation could be stimulated by turning the exhaust steam up the chimney to draw up the fire, and that smooth wheels on smooth rails could transmit motive power.

Steam locomotives

The steam locomotive is а robust and

simple machine. Steam is admitted to а cylinder and by

expanding pushes the piston to the other end; on the return stroke а port opens to clear the cylinder of the now expanded steam. By means of mechanical coupling, the travel of the piston turns the drive wheels of the locomotive.

Trevithick's engine was put to work as а stationary engine at Penydarren. During the following twenty-five years, а limited number of steam locomotives enjoyed success on colliery railways, fostered by the soaring cost of horse fodder towards the end of the Napoleonic wars. The cast iron plateways, which were L-shaped to guide the wagon wheels, were not strong enough to withstand the weight of steam locomotives, and were soon replaced by smooth rails and flanged wheels on the rolling stock.

John Blenkinsop built several locomotives for collieries, which ran on smooth rails but transmitted power from а toothed wheel to а rack which ran alongside the running rails. William Hedley was building smooth-whilled locomotives which ran on plateways, including the first to have the popular nickname Puffing Billy .

In 1814 George Stephenson began building for smooth rails at Killingworth, synthesizing the experience of the earlier designers. Until this time nearly all machines had the cylinders partly immersed in the boiler and usually vertical. In 1815 Stephenson and Losh patented the idea of direct drive from the cylinders by means of cranks on the drive wheels instead of through gear wheels, which imparted а jerky motion, especially when wear occurred on the coarse gears. Direct drive allowed а simplified layout and gave greater freedom to designers.

In 1825 only 18 steam locomotives were doing useful work. One of the first commercial railways, the Liverpool & Manchester, was being built, and the directors had still not decided between locomotives and саblе haulage, with railside steam engines pulling the cables. They organized а competition which was won by Stephenson in 1829, with his famous engine, the Rocket , now in London's Science Museum.

Locomotive boilers had already evolved from а simple

flue to а return-flue type, and then to а tubular design, in which а nest of fire tubes, giving more heating surface, ran from the firebox tube-plate to а similar tube-plate at the smokebox end. In the smokebox the exhaust steam from the cylinders created а blast on its way to the chimney which kept the fire up when the engine was moving. When the locomotive was stationary а blower was used, creating а blast from а ring оf perforated pipe into which steam was directed. А further development, the multitubular boiler, was patented by Henry Booth, treasurer of the Liverpool & Manchester, in 1827. It was incorporated by Stephenson in the Rocket , after much trial and error in making the ferrules of the copper tubes to give water-tight joints in the tube

plates.

After 1830 the steam locomotive assumed its familiar form, with the cylinders level or slightly inclined at the smokebox end and the fireman's stand at the firebox end.

As soon as the cylinders and axles were nо longer fixed in or under the boiler itself, it became necessary to provide а frame to hold the various components together. The bar frame was used on the early British locomotives and exported to America; the Americans kept со the bar-frame design, which evolved from wrought iron to cast steel construction, with the cylinders mounted outside the frame. The bar frame was superseded in Britain by the plate frame, with cylinders inside the frame, spring suspension (coil or laminated) for the frames and axleboxes (lubricated bearings) to hold the

axles.

As British railways nearly all produced their own designs, а great many characteristic types developed. Some designs with cylinders inside the frame transmitted the motion to crank-shaped axles rather than to eccentric pivots on the outside of the drive wheels; there were also compound locomotives, with the steam passing from а first cylinder or cylinders to another set of larger ones.

When steel came into use for building boilers after 1860, higher operating pressures became possible. By the end of the nineteenth century 175 psi (12 bar) was common, with 200 psi (13.8 bar) for compound locomotives. This rose to 250 psi (17.2 bar) later in the steam era. (By contrast, Stephenson's Rocket only developed 50 psi, 3.4 bar.) In the l890s express engines had cylinders up to 20 inches (51 cm) in diameter with а 26 inch (66 cm) stroke. Later diameters increased to 32 inches (81 cm) in places like the USA, where there was more room, and locomotives and rolling stock in general were built larger.

Supplies of fuel and water were carried on а separate tender, pulled behind the locomotive. The first tank engine carrying its own supplies, appeared tn the I830s; on the continent of Europe they were. confusingly called tender engines. Separate tenders continued to be common because they made possible much longer runs. While the fireman stoked the firebox, the boiler had to be replenished with water by some means under his control; early engines had pumps running off the axle, but there was always the difficulty that the engine had to be running. The injector was invented in 1859. Steam from the boiler (or latterly, exhaus steam) went through а cone-shaped jet and lifted the water into the boiler against the greater pressure there through energy imparted in condensation. А clack (non-return valve)

retained the steam in the boiler.

Early locomotives burned wood in America, but coal in Britain. As British railway Acts began to include penalties for emission of dirty black smoke, many engines were built after 1829 to burn coke. Under Matthetty Kirtley on the Midland Railway the brick arch in the firebox and deflector plates were developed to direct the hot gases from the coal to pass over the flames, so that а relatively clean blast came out of