MECHANICAL ENGINEERING

the branch of engineering concerned with the design, manufacture, installation, and operation of engines and machines and with manufacturing processes. It is particularly concerned with forces and motion. the branch of engineering concerned with the design, manufacture, installation, and operation of engines, machines, and manufacturing processes. Mechanical engineering involves the application of the principles of dynamics, control, thermodynamics and heat transfer, fluid mechanics, strength of materials, material science, tribology, mathematics, and computation. Increasingly a knowledge of electronics and, in particular, of microprocessors is required. Originally engineering meant military engineering, and it was not until the end of the 18th century that nonmilitary engineering, or what became known as civil engineering, was recognized. The Institution of Civil Engineers, the first professional engineering society, was founded in 1818 in Great Britain with Thomas Telford as its first president. In 1847 a group of railway engineers, who felt that the Institution of Civil Engineers was uninterested in the new breed of engineers resulting from the development of railways, formed the Institution of Mechanical Engineers, again in Great Britain, with George Stephenson as its first president. If the Industrial Revolution could be said to have started at any particular date, a logical year to pick would be 1712, when Thomas Newcomen produced the first practical steam engine for pumping water out of mines. James Watt was responsible for developing the double-acting steam engine and introducing the separate condenser that greatly improved the engine's thermodynamic efficiency; he also produced the first rotative engines. Richard Trevithick's development of the high-pressure steam engine in 1802 opened the way for his construction of the first locomotive in 1803. The locomotive was further developed by other engineers, including George and Robert Stephenson. Steam locomotives have been largely replaced in the second half of the 20th century by diesel- and electric-powered locomotives. Steam engines were developed for powering pumping stations, factories, ships, traction vehicles, and the first electric generators. Late in the 19th century Sir Charles Parsons invented the steam turbine, which largely replaced the reciprocating steam engine in most applications. Coal was used to fire the boilers for raising steam, although from the mid-19th century it was increasingly replaced by oil. With increasing scarcity of oil, nuclear power for electrical-power generation partially replaced other sources of thermal energy. The first nuclear-power station to produce power commercially went into operation in Great Britain in 1957. Steam was used for the steam-traction engines and some early automobiles, but it was replaced by the more convenient and compact internal-combustion engine pioneered by Siegfried Marcus, Gottlieb Daimler, and Carl Benz that remains the main power plant for automobiles. The internal-combustion engine was also extensively developed for aircraft propulsion, but for large aircraft it has been replaced by the gas-turbine jet engine, which resulted from the pioneering efforts of Sir Frank Whittle. Gas turbines are also used for standby power generation, pumps and compressors on oil and gas lines, and the propulsion of warships. Yet another form of internal-combustion engine, the diesel engine, is used extensively for bus and truck engines, ship propulsion, standby power generation, and increasingly for automobile engines because of its high thermal efficiency. Mechanical engineering is concerned with textile machinery, packaging machines, printing machinery, metalworking machines, machine tools, welding, air conditioning, refrigerators, agricultural machinery, and a multitude of other machines and processes that are essential to an industrial economy. There has been a great increase in the understanding and application of new materials such as high-strength steels, aluminum alloys, titanium, plastics, and composite materials such as glass fibre and carbon-reinforced resins. The computer, particularly the microprocessor, is increasingly used by mechanical engineers to speed and control design and manufacturing. Computer-aided design and drafting enables the designer to express ideas on a video screen and carry out the necessary analyses for stresses, fluid flow, heat transfer, etc., and then to produce a final dimensional drawing. Computer-aided manufacture allows the transfer of final design of components directly from the computer to the workshop, where the components are manufactured on computer-controlled machines. Machine tools, transfer devices, and robots are increasingly being controlled directly from a central computer that can, for instance, decide on the allocation of work to particular machines and the particular tools to be used and can keep an inventory of stocks of material and tooling. This is known as a flexible manufacturing system. Additional reading General historical information may be found in Institution Of Mechanical Engineers, Engineering Heritage: Highlights from the History of Mechanical Engineering, 2 vol. (196366). Robert H. Parsons, A History of the Institution of Mechanical Engineers, 18471947 (1947); and A.F. Burstall, A History of Mechanical Engineering (1965), are also of interest. The science and practice of control engineering, relevant to mechanical engineering as well as to chemical, electrical, and aerospace engineering, are examined in Madan G. Singh (ed.), Systems & Control Encyclopaedia: Theory, Technology, Applications, 8 vol. (1987), and supplements (1990 ). Among further sources are C.T. Porter, Engineering Reminiscences (1908, reprinted 1985); J.E. Shigley, Theory of Machines & Mechanisms (1986), and Mechanical Engineering Design (1989); Edward H. Smith (ed.), Mechanical Engineer's Reference Book, 12th ed. (1994); and Eugene A. Avallone and Theodore Baumeister III (eds.), Marks' Standard Handbook for Mechanical Engineers, 10th ed. (1996). John Fleetwood Baker, Baron Baker Peter McGregor Ross The Editors of the Encyclopdia Britannica