Steam turbines; a practical and theoretical treatise for engineers and students, including a discussion of the gas turbine . nds per square inch pressure. This reduction in pressure isobtained through a reducing valve, which may be adjusted togive any discharge pressure desired. High-pressure oil is carried direct to the oil relay, A, shown inFig. 174a. Depending upon the position of the oil relay plunger,this oil is admitted either below or above the oil operatingcylinder piston, B, and so raises or lowers the oil operating pis-ton, closing or opening the valves and so admitting a smaller orl
Steam turbines; a practical and theoretical treatise for engineers and students, including a discussion of the gas turbine . nds per square inch pressure. This reduction in pressure isobtained through a reducing valve, which may be adjusted togive any discharge pressure desired. High-pressure oil is carried direct to the oil relay, A, shown inFig. 174a. Depending upon the position of the oil relay plunger,this oil is admitted either below or above the oil operatingcylinder piston, B, and so raises or lowers the oil operating pis-ton, closing or opening the valves and so admitting a smaller orlarger amount of steam to the turbine. It may be noted thatthe secondary valve does not come into play until the lever armof the operating cylinder piston connected to the secondary valvehas moved until the adjustable screw on the top of the secondaryvalve comes in contact with the lever; so, as is obvious, onlythe primary valve is affected until the machine is loaded up tothe point when the secondary valve comes into play. The action of the complete mechanism is as follows: Assume GOVERNING STEAM TURBINES 299 gmqanx TO. 3oo THE STEAM TURBINE the machine running at some load. If the tendency is for theload to increase, before the valve has had time to act, the speedwill obviously fall off. This decrease in the speed causes thegovernor balls to close slightly, and through the linkage the float-ing lever is raised. The operating piston remaining stationary(for the moment), the oil relay plunger is raised, admitting oilabove the operating piston and at the same time connecting theoperating cylinder below the piston with the discharge outlet,which communicates with the general oiling system. Then theoperating piston moves downward until the oil relay plungershuts off the oil supply, at the same instant closing the oil dis-charge opening. If the operating cylinder has moved down-ward too far, admitting too much steam to the turbine, for theload required, the speed increases and the r
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