Hydraulic servo control mechanism

Claim 1

A TWO-DIMENSIONAL TRACER CONTROL SYSTEM FOR CONTROLLING IDENTICAL MILLING OPERATIONS SIMULTANEOULSY ON TWO SIMILAR MACHINE TOOLS IN ACCORDANCE WITH CONTROL INFORMATION SUPPLIED FROM A MASTER PATTERN SECURED TO THE CARRIAGE OF ONE OF SAID MACHINE TOOLS, SAID CONTROL SYSTEM INCLUDING SLACE FOLLOWER DEVICES ADAPTED TO BE MOUNTED ON SEPARATE ONES OF SAID MACHINE TOOLS AND EACH INCLUDING A HYDRAULICALLY CONTROLLED ACTUATOR OPERABLE TO MOVEL A POWER DRIVEN MILLING CUTTER IN A COMMON PLANE AND IN A PATH AT RIGHT ANGLES TO THE PATH OF MOVEMENT OF ANOTHER HYDRAULIC ACTUATOR OF THE RESPECTIVE DEVICE AND A FAITHFUL UNISON WITH THE MOVEMENT OF THE CONTROL STYLUS OF THE MASTER CONTROL UNIT, A RIGIDLY SUPPORTED MASTER CONTROL UNIT HAVING A CONTROL STYLUS ADAPTED TO BE ADVANCED IN CONTACT WITH A MASTER PATTERN, A UNITARY CONTROL VALVE MOVABLY SUPPORTED IN SAID MASTER CONTROL UNIT FOR MOVEMENT IN A PLANE PARALLEL TO SAID COMMON PLANE MOVEMENT OF EACH OF SAID SLAVE FOLLOWER DEVICES, AND MEANS CONNECTING A COMMON PRESSURIZED SOURCE OF HYDRAULIC FLUID TO SAID MASTER CONTROL UNIT AND TO EACH OF SAID SLAVE FOLLOWER DEVICES WHEREBY MOVEMENT OF SAID UNITARY CONTROL VALVE IS EFFECTIVE TO CAUSE SAID MILLING CUTTERS TO MOVE IN PRECISE UNISON WITH SAID CONTROL STYLUS.