Locomotive
Locomotives, machines used to move trains, may be powered by steam, Diesel fuel, or electricity. The steam locomotive's energy is produced when wood, coal, or fuel oil burned in a "firebox" creates heat that turns the water in a boiler to steam; the steam is fed into cylinders, where the pressure it produces drives the piston s (steel rods) that move the locomotive's driving wheels. The Diesel locomotive's engine functions when air is compressed in its cylinders until its temperature is high enough to ignite the fuel that has been injected into the cylinder; the resulting power is transmitted to the driving wheels. The electric locomotive uses electricity transmitted from a power plant by special overhead wires or an electrical third rail. Around the middle of the twentieth century, Diesel locomotives began to replace their steam-driven predecessors. There are now more than 20,000 Diesel locomotives in the United States; less than 100 are powered by electricity, and only about 50 steam locomotives still operate (mostly for the benefit of tourists).. Although primitive wooden tramways (along which horses pulled loaded wagons) were operating in Transylvanian mines as early as the sixteenth century and in English coal mines by the seventeenth century, the concept of using a steam engine to propel vehicles along a track was not developed until the early nineteenth century. Richard Trevithick, an engineer employed at the Penydaren Tramway and ironworks in South Wales, is credited with inventing the locomotive, although he never received full recognition or compensation for his invention. Trevithick adapted steam engines made by Thomas Newcomen and James Watt into lighter, more compact devices that produced higher steam pressure. By 1796 he was designing steam locomotives, one of which pulled a passenger train in 1801. In 1804 he introduced what is considered the first working steam locomotive; on its maiden voyage, it carried 10 t. (9.07 t) of iron, 70 men, and 5 wagons, traveling 9.5 mi. (15.3 km) at about 5 mph (8 kph). This locomotive was never actually used because the tramways available at the time were unsuitable. In 1808 Trevithick built a demonstration locomotive called Catch-Me-Who-Can and, setting it up on a circular track in London's Euston Square, offered the public rides for a shilling. Although Trevithick is considered the first to prove that smooth metal wheels moving on smooth metal tracks could supply enough traction to pull trains, his work was overshadowed by that of the more successful George Stephenson. Although he did not invent the steam locomotive, George Stephenson played an important role in its development. As a teenager, Stephenson went to work in England's Killingworth Colliery, where he was in charge of the water-pumping engines. Stephenson distinguished himself by building stationary engines and trains to replace the horse-drawn sleds that had previously been used to move loads on the mine tracks. Stephenson's employers, concerned by the high cost of horse feed, commissioned him to build a steam-driven locomotive. Finished in July 1814, the Blucher featured an important innovation: the flanged wheel, equipped with a guiding rim that projected from the top of the wheel. Stephenson established a locomotive company at Newcastle in order to make locomotives for a new railroad that was to be established between the towns of Stockton and Darlington, a distance of about 30 mi. (48 km). The railroad opened in 1825 with Stephenson's Locomotion No. 1 at the head of its fleet. The famous Rainhill trials were held outside London in 1829 to determine the feasibility of steam locomotives for transporting goods and people. Stephenson's Rocket won the contest, impressing the onlookers with its speed of 29 mph (46.7 kph). The next year, Stephenson became chief engineer for the Liverpool-Manchester Railway, the first in the world to carry passengers. Initially operating with eight locomotives on a line that was only 30 mi. (48 km) long, the railway eventually reduced the travel time from London to Edinburgh from 12 days to a mere 50 hours. Robert Stephenson also excelled in his father's profession, producing in the Northumbrian and the Planet a standard locomotive type that would be used all over Europe and America. Although the steam locomotive was invented by the English, American engineers and manufacturers contributed significantly to its development, responding to the challenges of their own country's terrain and transportation needs. The first full-sized locomotive to operate on a commercial railroad in the United States was the Stourbridge Lion, made in England and introduced by a Pennsylvania Company in 1829. Old Ironsides, built in 1827 by manufacturer and philanthropist Matthias Baldwin, was made of wood and iron and could travel at 28 mph (45 kph), pulling a load of 30 t. (27.2 t). The manufacturing company established by Baldwin had, by the time of his death, made over 1,500 locomotives. The South Carolina Canal and Rail Road Company's Best Friend of Charleston, which went into operation in December 1830, was the first American steam locomotive to be used for regular passenger and freight service. Earlier that year, Peter Cooper of New York--a prosperous manufacturer, inventor, and philanthropist--had staged a race between his diminutive locomotive, Tom Thumb, and a locally renowned horse in an effort to convince businessmen to use locomotives instead of horses for their transportation needs. Although the horse won, due to a minor mechanical problem with the locomotive, Cooper's enthusiasm for the steam locomotive was to prove justified.
The rugged American landscape posed challenges to those who, like Cooper, wished to promote the growth of railroads across the vast expanses of the United States. Unlike their English predecessors, American railroads were built on curved routes. The problem of negotiating sharp curves was resolved by John B. Jervis, who in 1832 designed an engine equipped with a four-wheel "truck" affixed to its underside that allowed it to swivel when the tracks curved. The train proved a great boon to the settlement of America's frontier, and between 1830 and 1890 an average of 2,500 mi. (4,022 km) of track per year was laid across the country. Innovations added to the locomotives included flashy bells and whistles, headlights, cowcatchers, and cabs to protect the operators. American locomotive manufacturers found ways to use cheaper materials, and they designed a modified car body--featuring a long, open, single compartment with seats arranged on both sides of a center aisle, doors at each end, and platforms outside each door. Another significant contribution to the development of the locomotive was made by Elijah McCoy (1843-1929), an African-American engineer educated in Scotland who, because of his race, was forced to take a menial job with the Michigan Central Railroad. While working as a fireman, McCoy became interested in the problem of train lubrication. In 1870 he invented a lubricating cap that eliminated the need to stop machines in order to lubricate them. This revolutionary device was soon used in many different types of machines and became so essential that users referred to it as "the real McCoy" (hence the origin of that expression). McCoy held over 50 patents for his inventions--mostly in the realm of lubrication--and his lubricating systems are now used all over the world. At the end of its first 100 years of existence, the locomotive had doubled in size from 20 or 30 tons. (18 or 27 tons) to 60 tons. (54.4 tons) or more. By 1938 the trip from New York to Chicago, which had taken 37 hours in 1875, had been reduced to only 16 hours. The peak popularity of trains is said to have occurred around 1916, when 77 percent of intercity freight traffic and 99 percent of intercity passenger traffic were conducted on trains. A major change was the advent of the Diesel locomotive, which was first introduced in 1923. Although Diesel locomotives were more efficient, they cost twice as much as steam locomotives. During the high-demand years of World War II, however, the efficiency of the Diesel locomotive was favored, and an improved system of mass production helped to reduce its cost. By 1960 Diesels had replaced all but about 260 steam locomotives in service in the United States. The electric locomotive dates from about the 1830s, when attempts were made to power trains with electricity. In 1842 Robert Davidson successfully operated a battery-electric locomotive on the Edinburgh and Glasgow Railway; moving at a speed of 4 mph (6.4 kph), it hauled 6 t. (5.4 t). Ernst Werner von Siemens (1816-1892) operated an electric railway at an exhibition in Berlin, Germany in 1879 and later in Brussels, Belgium, and London, England. In the latter years of the nineteenth century, many engineers and inventors--including Thomas Edison--contributed to the development of the electric locomotive. Because electric trains are quiet and emit no smoke or exhaust, they are particularly well-suited for urban areas and underground use, and some proponents predict that they will eventually replace Diesel locomotives. Two notable modern electric trains are Japan's Shinkansen or "bullet trains," which travel at speeds up to 130 mph (209 kph) and France's Ligne à Grande Vitesse, which reaches speeds up to 136 mph (218.8 kph). In 1990, the French train achieved a record speed of 320 mph (515 kph). These "bullet trains" generally speed along tracks that are very straight and pull cars that are sleekly designed with curved fronts and sides to reduce drag, or wind resistance, that would slow a train down. They also usually have special disc brakes similar to those on jet airplanes.
The newest pulling technology for high-speed trains is called Maglev (for magnetic levitation). These locomotives use a set of magnets to lift or levitate the train above the ground, and although they run on rails, they actually do not touch the rails but rather float just above them by means of strong magnetic forces. Maglev technology uses an electromagnetic charge on the underside of the train which repels the opposite charge on its top. Using giant magnets and linear motors (electrically run with no moving parts), a Maglev train experiences none of the friction of a train running on a rail, and not only runs very fast and efficiently, but also gives an extremely smooth and quiet ride. In 1979, a model Maglev train was tested in Japan and reached 320 mph (515 kph). Germany's Transrapid 06 Maglev train began in 1984 as an intercity project that would run a high-speed train on a raised track. In the 1990s, plans were made in several eastern cities in the United States for commercial Maglev trains. In the future, super-Maglevs may eventually travel thousands of miles per hour.
Until this new technology becomes commonplace however, diesel and electric locomotives will continue to improve to do the jobs in which each specializes. Among the major improvements begun to be developed in the 1990s were wedge-shape "unibody" locomotive design; microprocessor engine control with electronic fuel injection for medium-horsepower diesels; reduced fuel consumption and emissions; electronically-monitored and controlled brakes; and in 1996, the first 6,000 horsepower diesel locomotive.
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Locomotive from World of Invention. ©2005-2006 Thomson Gale, a part of the Thomson Corporation. All rights reserved.
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