Governor

Device for controlling the speed of a motor. It may act on the supply of steam to the distributing valves by diminishing its pre ure, throttling governors; or direct upon the distribution valves, varying the point at which admi ion of steam to the cylinder shall cease, cut-off governors. Isochronous governors are those which will keep or bring back the engine to a given speed under all variations of load, from nothing to the maximum. This may be sought by transmitting the effort of the engine to overcome the resistance through a system of springs in the driving wheel on the shaft, which becomes also the governor. The more usual plan is to allow variation in the load to affect the speed of the engine, and this variation in speed to affect the steam supply. Two general principles of design are recognized, which give rise to the IMG:content-0363.jpg:[blocks in formation] cla es Centrifugal and Resistance governors. In the former, with vertical axis, a conical pendulum revolves, and as the speed increases, the balls rise, and their rise shuts off steam supply, and vice vers a. Where the weight of the balls alone is depended on to balance centrifugal force (Watts' type), the governor is sluggish and le nearly isochronous than when the balls are made light, and the power of the governor to move the valve is derived either from an axial weight (Porter type), or from springs (Water's and Pick ering type). The more usual centrifugal governor in the high-speed engines of to-day is the type in which the weights revolve in a vertical plane, around a horizontal axis, which is the driving shaft of the engine. The resistance to centrifugal force is given by springs, and isochronism is sought by the method in which the levers are pivoted. This type of governor has the advantages of