Steam turbines; a practical and theoretical treatise for engineers and students, including a discussion of the gas turbine . Fig. 171. Brown-Boveri-Parsons Governing Device. GOVERNING STEAM TURBINES 293 Westinghouse-Parsons Governor and Valve Gear. Diagram-matically, the governor and valve gear of a Westinghouse-Parsons turbine are shown in Fig. 172. A small pilot valve,marked A in the figure, is actuated directly by the governor bymeans of levers and links. This pilot valve controls the steamsupply of the turbine by regulating the operation of the mainpoppet admission valve which opens and cl
Steam turbines; a practical and theoretical treatise for engineers and students, including a discussion of the gas turbine . Fig. 171. Brown-Boveri-Parsons Governing Device. GOVERNING STEAM TURBINES 293 Westinghouse-Parsons Governor and Valve Gear. Diagram-matically, the governor and valve gear of a Westinghouse-Parsons turbine are shown in Fig. 172. A small pilot valve,marked A in the figure, is actuated directly by the governor bymeans of levers and links. This pilot valve controls the steamsupply of the turbine by regulating the operation of the mainpoppet admission valve which opens and closes at uniformintervals when the turbine is in operation. Speed variations. Fig. 172. Diagrammatic Arrangement of the Governing Mechanism of aWestinghouse-Parsons Turbine. change the height of the governor balls which, in turn, changethe position of the collar F of the lever on the governor means of a system of links this lever varies the throw of thepilot valve relatively to the valve port. This pilot valve controlsthe main admission valve by means of the auxiliary piston valve Bin the same way as in the Brown-Boveri design which hasalready been explained. Reciprocating motion for operatingthe valve mechanism originates in an eccentric driven by the 294 THE STEAM TURBINE turbine from a worm on the main shaft. This eccentric gives anoscillating motion to the levers supported at D, F, and E. The governor is of the fly-ball type, the ball levers beingmounted on knife-edges instead of pins, to secure speed of the turbine may be varied, while running, withinthe limits of the governor spring by grasping a knurled handwheel at the top o
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