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Traction Engine

type, engines, threshing and designed

TRACTION ENGINE, an engine designed for drawing loads on ordinary roads or across country, and thus distinguished from the locomo tive which hauls loads over steel or iron rails. The traction engine is designed to withstand severe jolts and to climb gradients of at least 1 in 10 and on a surface which sinks some what beneath the weight of the engine, thus presenting a continual slope upwards in front of the wheels. The speed seldom exceeds eight miles an hour and consequently it is usual to reduce the speed of the driving-wheels from that of the engine shaft by intermediate gearing. Usually attached to the main axle is a winding drum, by which heavy loads may be drawn up bad hills on a wire rope, the engine having previously ascended, light, to the top. A heavy fly-wheel and a high-speed gov ernor are provided. The driving-wheels of a traction engine have tires or treads of great breadth to distribute the weight of the boiler and engine over a large area of yielding road way. The tires are also usually corrugated or roughened to give adhesion. A very efficient means of steering is always provided in the trac tion engine to enable it to make the sharp turns required in ordinary roads, and it is further more usually so designed that by throwing out the intermediate gearing from connection with the traction-wheels, the steam-engine proper can he used as an agricultural engine for threshing, milling, pumping and other similar purposes. Light traction engines were once

favorites in drawing plows but have been dis placed by the tractor of the internal-combus tion engine type, although these are really trac tion engines. It is, however, usual to limit this term to the older type of land engine pro pelled by steam. This type appears to hold its place in America for hauling threshing ma chines from place to place and for driving them. In roadless countries, such as parts of Australia, Africa, etc., a heavy type of tfac tion engine is employed to haul trains of wag ons, as well as to act as portable engines for providing power for threshing machines etc. Engines designed for threshing outfits are sup plied with fire-boxes capable of burning wood, straw and refuse fuel. Since the opening years of the present century the steam traction engine has 'been displaced to a very great ex tent by tractors and engines of the internal combustion type. (See TRACTOR). Consult Maggard, James H., The Traction Engine: Its Use and (3d ed., Philadelphia 1915).