Control mechanism for adjustable gas turbine nozzle

Claim 1

A CLOSED-LOOP ERROR DETECTING SERVO SYSTEM FOR CREATING AN OUTPUT DISPLACEMENT IN ACCORDANCE WITH A SIGNAL GENERATED BY EXTERNAL CONTROL MEANS, COMPRISING A HOUSING, A SLAVE PISTON SLIDABLY RECEIVED BY SAID HOUSING AND ADAPTED TO CREATE SAID OUTPUT DISPLACEMENT BY VIRTUE OF AT LEAST TWO DISTINCT FLUID PRESSURES ACTING THEREAGAINST, PORTING MEANS FORMED IN AND CARRIED BY SAID SLAVE PISTON, A SERVO VALVE SLIDABLY RECEIVED IN SAID SLAVE PISTON AND ADAPTED TO BE ROTATED TO SELECTED POSITIONS WITH RESPECT TO SAID HOUSING AND SAID SLAVE PISTON BY SAID EXTERNAL SIGNAL GENERATING MEANS, AND A CONTOURED VALVE MEMBER CARRIED BY SAID SERVO VALVE, SAID PORTING MEANS COOPERATING WITH SAID CONTOURED VALVE MEMBER TO BE EFFECTIVE UPON ROTATION OF SAID SERVO VALVE IN A FIRST DIRECTION WITH RESPECT TO SAID SLAVE PISTON TO INCREASE ONE OF SAID DISTINCT FLUID PRESSURES THEREBY CAUSING SAID SLAVE PISTON TO MOVE AXIALLY IN ONE DIRECT ION THEREBY CREATING A CORRELATIVE OUTPUT DISPLACEMENT, SAID PORTING MEANS ALSO BEING EFFECTIVE UPON ROTATION OF SAID SERVO VALVE IN A DIRECTION OPPOSITE TO SAID FIRST DIRECTION TO DECREASE SAID ONE OF SAID DISTINCT FLUID PRESSURES THEREBY CAUSING SAID SLAVE PISTON TO MOVE AXIALLY IN A DIRECTION OPPOSITE TO SAID ONE DIRECTION THEREBY ALSO CREATING A CORRELATIVE OUTPUT DISPLACEMENT.