Spool valve with magnetic hold

Claim 1

AN AUTOMATIC FLUID PRESSURE OPERATED VALVE FOR CONTROLLING MOVEMENTS OF A FLUID PRESSURE RESPONSIVE DEVICE, SAID VALVE HAVING A BODY WITH A BORE THEREIN OPENING THROUGH OPPOSITE END WALLS OF THE BODY, A FLUID ENTRY PORT FOR INTRODUCING FLUID UNDER PRESSURE INTO THE BORE, A PAIR OF IN-AND-OUT FLUID PORTS EACH PERFORMING TO CONVEY FLUID OUTWARDLY TO THE FLUID RESPONSIVE DEVICE AND BACK THERFROM THE BORE, AND A PAIR OF PRESSURE DIMINISHING PORTS EXHAUSTING TO ATMOSPHERE FROM SAID BORE, AN ELONGATED UNITARY VALVE SPOOL WITHIN AND SHIFTABLE LONGITUDINALLY OF SAID BORE BETWEEN TWO OPERATIVE POSITIONS, SAID VALVE SPOOL INCLUDING A PISTON ADJACENT TO EACH END AND SPACED LANDS INTERMEDIATE AND SPACED FROM THE PISTONS AND FIXED RELATIVE THERETO AND TO ONE ANOTHER, THE PISTONS AND LANDS BEING SNUGLY RECIPROCABLE IN THE BORE AND THE SPACED LANDS AND PISTONS PROVIDING THREE FLUID DISTRIBUTION GROOVES LOCATED TO DIRECTG FLUID FROM SAID ENTRY PORT TO ONE OF THE IN-AND-OUT FLUID PORTS WHILE PLACING THE REMAINING IN-ANDOUT FLUID PORT IN FLUID COMMUNICATION WITH ONE OF SAID EXHAUST PORTS IN EACH OF ITS TWO SHIFTED POSITIONS, MEANS FORMING A FLUID CHAMBER AT EACH OF THE OPPOSITE ENDS OF THE BORE AND INTO EACH OF WHICH THE ADJACENT END OF THE BORE OPENS, AN ARMOATURE CARRIED BY EACH END OF THE VALVE SPOOL FOR RECIPROCATION THEREWITH AND LOCATED WITHIN THE ADJACENT FLUID CHAMBER, A MAGNET SECURED IN EACH CHAMBER IN A POSITION TO ATTRACT THE ADJACENT ARMATURE, THE MAGNUETS AND ARMATURES BEING SO SPACED AS TO HOLD THE SPOOL AT EITHER OF THE LIMITS OF ITS LONGITUDINAL SHIFTING MOVEMENT WHENEVER THE SPOOL IS SHIFTED BY A FORCE IN OPPOSI TION TO THE HOLDING FORCE OF ONE OF THE MAGNETS, MEANS WHEREBY EACH OF THE FLUID CHAMBERS HAS A CONSTANT FLUID COMMUNICATION WITH ONE OF THE IN-AND-OUT FLUID PORTS OF THE VALVE BODY, AND MEANS FOR ADJUSTING EACH OF THE ARMATURES LONGITUDINALLY OF THE VALVE SPOOL FOR CHANGING THE LONGITUDINAL STROKE OF THE SPOOL.