887,070. Gas turbine jet propulsion plant. BENDIX CORPORATION. March 12, 1959, No. 8633/59. Class 110 (3). [Also in Group XXIX] Apparatus for controlling a gas turbine engine in response to an engine operating condition comprises a chamber or conduit connected to a source of fluid at a regulated pressure and having a variable area outlet controlled by a beam member pivotally mounted on a fixed pivot and operatively connected to a device responsive to the engine operating condition which tends to rotate the beam in a first direction and to an element responsive to the fluid pressure in the chamber or conduit which tends to rotate the beam in a direction opposite to the first direction, and one or a plurality of devices responsive to the fluid pressure in the chamber or conduit for controlling operation of the engine. As shown, a gas turbine engine 10, Fig. 1, comprising a turbine 14 driving through a shaft 16 a compressor 12 supplying air to the combustion chambers 18 to which fuel is supplied from a manifold 22 connected by a line 36 to a main burner fuel control unit 38, includes afterburner fuel nozzles 26 in the tail pipe connected to an afterburner fuel control unit 49 and a guide vane motor 30 which through a rack 32 and pinions 34 adjusts the compressor guide vanes 28. A pump 40 connected to a reservoir 42 supplies main fuel to the unit 38 whilst a pump 50 connected to the reservoir through an engine speed lock-out control 52 supplies afterburner fuel to the unit 49. A manual throttle lever 54 through links 56, 58 controls the afterburner and main burner units 49, 38. The guide vane motor 30, main burner unit 38 and lock-out control 52 are connected by pipes 66, 68, 70 respectively to speed control apparatus 64 operatively connected by a control arm 62 to an engine speed responsive weight member 60. The speed control apparatus comprises a pivoted control beam 80, Fig. 2, connected to the control arm 62 which carries a half-ball valve 84 controlling leakage from a control pipe 86, and a spring- loaded, feed-back bellows 104. The pipe 86 is supplied through a restriction 92 and a pressure regulator 88 from the pump 40 which through a metering valve 114 slidable in a sleeve 122 controls the fuel to the main burners. On, e.g., an increase in engine speed, the weight 60 moves the valve 84 towards closure to increase pressure in the line 86 which increased pressure expands the bellows 104 to adjust the valve 84 towards its open position so that the pressure in the line 86 is proportional to engine speed. This pressure is supplied through the line 66 to a bellows 112 to control the guide vane motor 30 and hence the guide vanes 28 as a function of engine speed. This pressure is also supplied through the line 68 to a bellows 116 which is operative with a governor spring 118 and the manual throttle lever 54 to adjust the position of a half-ball valve 120. The half-ball valve 120 carried on a pivoted lever 148 controls leakage of fuel at regulated pressure from a line 90 to position the metering valve 114 as a function of engine speed. The pressure in the line 86 is also supplied through the line 70 to a bellows 110 to control the speed lock-out control 52 as a function of engine speed. An additional bellows 124 may be fitted which through a lever 126 controls a half-ball valve 128 to control leakage from a chamber 130 beneath a piston 138 having a restriction 132 through which fuel at regulated pressure from the line 90 passes. The half-ball valve 128 adjusts the position of a rack 140 and through a pinion 143 adjusts an acceleration control cam 146 which through the lever 148 controls the half-ball valve 120 and hence the metering valve 114 during acceleration operation of the engine. The lever 148 is also connected to a valve 67 to adjust the guide vane motor 30 in certain ranges of engine acceleration. In a modification, the temperature of the air entering the compressor 12 is sensed by a temperatureresponsive member 160, see Fig. 1, and through a control valve 162, a temperature-responsive bellows 164, Fig. 3, adjusts the half-ball valve 84 controlling leakage from the line 86, which, as before, receives regulated pressure through a restriction from the pressure regulator 88. As before, the pressure in the line 86 controls the guide vane motor 30 and the main burner unit 38, this time as a function of compressor inlet temperature. In a further modification, an input control device 180, Fig. 4, may be responsive either to engine speed, compressor inlet or outlet pressure, compressor inlet temperature or turbine inlet or outlet temperature. This control device 180 positions a halfball valve 186 to determine the pressure in a chamber 188 beneath a piston 190 which receives pressure through a restriction from a pressure regulator 185. The piston 190 through a lever 192 controls the main burner unit 38 as a function of the input force and through a spring 194, a lever 196 carrying a half-ball valve 198 and a feed-back bellows 202. The half-ball valve 198 and the bellows 202 adjusts the pressure in a line 200 receiving pressure through a restriction from the pressure regulator 185 and this pressure through bellows 206, 210 controls the guide vane motor 30 and the engine speed lock-out control as a function of the input force. The temperature-responsive member 160, Figs. 1 and 3, may be used to control all the devices or only one in conjunction with engine-speed responsive control apparatus.