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State intervention began in England withpublic demand for safety regulation which resulted in Lord
Seymour's Act in 1840; the previously mentioned Railway
Gauges Act followed in 1846. Ever since, the railways havebeen recognized as one of the most important of nationalresources in each country.

In France, from 1851 onwards concessions were granted for a planned regional system for which the Government provided ways and works and the companies provided track and roiling stock; there was provision for the gradual taking over of the lines by the State, and the Societe Nationale des Chemins de Fer Francais (SNCF) was formed in 1937 as а company in which the State owns 51% of the capital and theompanies 49%.

The Belgian Railways were planned by the State from the outset in 1835.
The Prussian State Railways began in 1850; bу the end of the year 54 miles
(87 km) were open. Italian and Netherlands railways began in 1839; Italy nationalized her railways in 1905-07 and the Netherlands in the period 1920-
38. In Britain the main railways were nationalized from 1 January 1948; the usual European pattern is that the State owns the main lines and minor railways are privately owned or operated by local authorities.

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 the chimney and the cheaper fuel could be burnt. After 1860 this simple expedient was universа11у adopted. Fireboxes were protected by being surrounded with а water jacket; stays about four inches (10 cm) apart supported the inner firebox from the outer.

Steam was distributed to the pistons by means of valves. The valve gear provided for the valves to uncover the ports at different parts of the stroke, so varying the cut-off to provide for expansion of steam already admitted to the cylinders and to give lead or cushioning by letting the steam in about 0.8 inch (3 mm) from the end of the stroke to begin the reciprocating motion again. The valve gear also provided for reversing by admitting steam to the opposite side of the piston.

Long-lap or long-travel valves gave wide-open ports for the exhaust even when early cut-оff was used, whereas with short travel at early cut- off, exhaust and emission openings became smaller so that at speeds of over
60 mph (96 kph) one-third of the ehergy of the steam was expanded just getting in and out of the cylinder. This elementary fact was not universal1y accepted until about 1925 because it was felt that too much extra wear would occur with long-travel valve layouts.

Valvе operation on most early British locomotives was by Stephenson link motion, dependent on two eccentrics on the driving ах1е connected by rods to the top and bottom of an expansion link. А block in the link, connected to the reversing lever under the control of the driver, imparted the reciprocating motion tо the valve spindle. With the block at the top of the link, the engine would be in full forward gear and steam would be admitted to the cylinder for perhaps 75% of the stoke. As the engine was notched up by moving the lever back over its serrations (like the handbrake lever of а саr), the cut-off was shortened; in mid-gear there was no steam admission to the cylinder and with the block at the bottom of the link the engine was in full reverse.

Walschaert's valvegear, invented in 1844 and in general use after 1890, allowed more precise adjustment and easier operation for the driver. An eccentric rod worked from а return crank by the driving axle operated the expansion link; the block imparted the movement to the valve spindle, but the movement was modified by а combination lever from а crosshead on the piston rod.

Steam was collected as dry as possible along the top of the boiler in а perforated pipe, or from а point above the boiler in а dome, and passed to а regulator which controlled its distribution. The most spectacular development of steam locomotives for heavy haulage and high speed runs was the introduction of superheating. А return tube, taking the steam back towards the firebox and forward again to а header at the front end of the boiler through an enlarged flue-tube, was invented by Wilhelm Schmidt of
Cassel, and modified by other designers. The first use of such equipment in
Britain was in 1906 and immediately the savings in fuel and especially water were remarkable. Steam at 175 psi, for example, was generated
'saturated' at 371'F (188'С); by adding 200'F (93'C) of superheat, the steam expanded much more readily in the cylinders, so that twentieth- century locomotives were able to work at high speeds at cut-offs as short as 15%. Steel tyres, glass fibre boiler lagging, long-lap piston valves, direct steam passage and superheating all contributed to the last phase of steam locomotive performance.

Steam from the boiler was also for other purposes.
Steam sanding was introduced for traction in 1887 on th
Midland Railway, to improve adhesion better than gravity sanding, which often blew away. Continuous brakes were operated by а vacuum created on the engine or by соmpressed air supplied by а steam pump. Steam heat was piped to the carriages, arid steam dynamos
[generators] provided electric light.

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