Cassiers Magazine

SUBJECT AREA: Architecture and building, Electricity, Land transport, Railways and locomotives

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Graduating from the United States Naval Academy, Annapolis, in 1878, Sprague served at sea and with various shore establishments. In 1883 he resigned from the Navy and obtained employment with the Edison Company; but being convinced that the use of electricity for motive power was as important as that for illumination, in 1884 he founded the Sprague Electric Railway and Motor Company. Sprague began to develop reliable and efficient motors in large sizes, marketing 15 hp (11 kW) examples by 1885. He devised the method of collecting current by using a wooden, spring-loaded rod to press a roller against the underside of an overhead wire. The installation by Sprague in 1888 of a street tramway on a large scale in Richmond, Virginia, was to become the prototype of the universally adopted trolley system with overhead conductor and the beginning of commercial electric traction. Following the success of the Richmond tramway the company equipped sixty-seven other railways before its merger with Edison General Electric in 1890. The Sprague traction motor supported on the axle of electric streetcars and flexibly mounted to the bogie set a pattern that was widely adopted for many years.

Encouraged by successful experiments with multiple-sheave electric elevators, the Sprague Elevator Company was formed and installed the first set of high-speed passenger cars in 1893–4. These effectively displaced hydraulic elevators in larger buildings. From experience with control systems for these, he developed his system of multiple-unit control for electric trains, which other engineers had considered impracticable. In Sprague's system, a master controller situated in the driver's cab operated electrically at a distance the contactors and reversers which controlled the motors distributed down the train. After years of experiment, Sprague's multiple-unit control was put into use for the first time in 1898 by the Chicago South Side Elevated Railway: within fifteen years multiple-unit operation was used worldwide.

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GW / PJGR