SERVOMOTOR OF CONTROL-VALVE UNIT FOR STEAM TURBINE CYLINDER Russian patent published in 1999 - IPC

FIELD: steam turbines. SUBSTANCE: servomotor functions to control two valves, first one directly and second valve, through leverage. Servomotor has one piston coupled with rod that directly controls first valve and other piston concentrically arranged inside first one. Internal piston is connected through rod to leverage. Internal-piston rod is passed through external- piston rod. Rods are provided with opposing contact surfaces. Areas of mentioned pistons are chosen so that force developed by external piston is sufficient to open first valve but insufficient to open second valve; force developed by second piston is chosen to be lower than that required to open second valve but sufficient for its opening jointly with second piston. EFFECT: provision for attaining reasonable proportioning of servomotor forces. 1 dwg