Hydraulic control mechanism for three-dimensional tracers

Claim 1

A MASTER CONTROL VALVE ADAPTED FOR USE IN HIGHPRECISION SERVO MECHANISMS, SAID CONTROL VALVE COMPRISING A HOUSING HAVING A FLAT END WALL PROVIDED WITH TWO PAIRS OF FLUID PORTS OPENING THERETHROUGH INWARDLY OF ITS PERIPHERAL EDGE AND WITH THEIR AXES DISPOSED AT THE CORNERS OF A SQUARE, A VALVE PLATE HAVING A FLAT SURFACE LYING FLUSH AGAINST SAID PORTED END WALL AND HAVING A CIRCUMSCRIBING LAND EFFECTIVE BARELY TO BRIDGE BOTH RADIAL EDGES AND CLOSE FLOW SIMULTANEOUSLY THROUGH ALL OF SAID PORTS WHEN IN ONE PREDETERMINED POSITION THEREOF AND ALLOWING SOME FLOW THROUGH BOTH PORTS OF AT LEAST ONE DIAGONALLY POSITIONED PAIR OF SAID PORTS WHEN MOVED IN THE SLIGHTEST AMOUNT TO ANY OTHER POSITION OF SAID VALVE PLATE, MEANS FOR LIMITING THE MOVEMENT OF SAID PLATE TO A FRACTION OF THE WIDTH OF SAID PORTS, MEANS FOR MOVABLY SUPPORTING SAID VALVE PLATE WITHIN SAID HOUSING, FLUID FLOW DUCTS IN SAID HOUSING IN COMMUNICATION WITH SAID PORTS, PASSAGE MEANS FOR SUPPLYING PRESSURIZED FLUID TO THE INNER PERIPHERAL SIDE OF SAID PORT CONTROL LAND, AND PASSAGE MEANS FOR CARRYING AWAY FLUID FROM THE OUTER PERIPHERAL SIDE OF SAID PORT CONTROL LAND.