Hydraulic centering device

Claim 1

A CONTROL VALVE COMPRISING A HOUSING MEMBER HAVING A BORE THEREIN, A SPOOL TYPE VALVE MEMBER MOVABLE IN OPPOSITE DIRECTIONS FROM A NORMALLY NEUTRAL POSITION WITHIN SAID BORE, AN INLET PORT, AN OUTLET PORT AND TWO CYLINDER PORTS, FIRST AND SECOND ANNULAR INLET CHANNELS AND AN ANNULAR OUTLET CHANNEL LOCATED THEREBETWEEN FORMED IN SAID BORE, FIRST PASSAGE MEANS LOCATED IN SAID HOUSING MEMBER FOR COMMUNICATING SAID INLET PORT WITH BOTH OF SAID ANNULAR INLET CHANNELS, SECOND PASSAGE MEANS LOCATED IN SAID HOUSING MEMBER FOR COMMUNICATING SAID OUTLET PORT WITH SAID ANNULAR OUTLET CHANNEL, FIRST AND SECOND ANNULAR CYLINDER CHANNELS FORMED ON SAID VALVE MEMBER, EACH OF WHICH IS LOCATED BETWEEN ONE OF THE ANNULAR INLET CHANNELS AND THE ANNULAR OUTLET CHANNEL TO PERMIT DIRECT FLUID FLOW FROM SAID INLET PORT TO SAID OUTLET PORT WHEN SAID VALVE MEMBER IS IN SID NEUTRAL POSITION, THIRD PASSAGE MEANS LOCATED IN SAID HOUSING MEMBER FOR COMMUNICATING ONE OF SAID CYLINDER PORTS WITH ONE OF THE ANNULAR CYLINDER CHANNELS, FOURTH PASSAGE MEANS LOCATED IN SAID HOUSING MEMBER FOR COMMUNICATING THE OTHER OF SAID CYLINDER PORTS WITH THE OTHER OF SAID ANNULAR CYLINDER CHANNELS, FIRST ORIFICE MEANS INTERPOSED IN SAID FIRST PASSAGE MEANS FOR REGULATING THE FLOW OF FLUID FROM SAID INLET PORT TO ONE OF SAID ANNULAR INLET CHANNELS, SECOND ORIFICE MEANS INTERPOSED IN SAID FIRST PASSAGE MEANS FOR REGULATING THE FLOW OF FLUID FROM SAID INLET PORT TO THE OTHER OF SAID ANNULAR INLET CHANNELS, AND MEANS LOCATED IN SAID FIRST PASSAGE MEANS FOR VARYING THE EFFECTIVE AREAS OF SAID FIRST PASSAGE SECOND ORIFICE MEANS TO CONTROL THE PRESSURE DIFFERENTIAL AT SAID FIRST AND SECOND CYLINDER PORTS, SAID MEANS INCLUDING A SINGLE MANUALLY MOVABLE CENTERING PLUNGER FOR SIMULTANEOUSLY INCREASING THE EFFECTIVE AREA OF ONE OF SAID ORIFICES WHILE CORRESPONDINGLY REDUCING THE EFFECTIVE AREA OF THE OTHER OF SAID ORIFICES.