Hydraulic valve and control means therefor

Claim 1

A HYDRAULIC VALVE AND CONTROL MEANS THEREFOR COMPRISING A VALVE BODY HAVING A PISTON MEMBER SLIDEABLY MOUNTED THEREWITHIN AND A MOVABLE BETWEEN FIRST AND SECOND LIMITING POSITIONS, A FIRST FLUID CHAMBER WITHIN SAID VALVE BODY IN FLUID COMMUNICATION WITH ONE END OF SAID PISTON MEMBER, A SECOND FLUID CHAMBER WITHIN SAID VALVE BODY IN FLUID COMMUNICATION WITH THE OPPOSITE END OF SAID PISTON MEMBER, A FLUID INLET PORT AND A FLUID OUTLET PORT COMMUNICATING INTO SAID SECOND FLUID CHAMBER, MEANS COUPLED TO SAID PISTON MEMBER FOR VARIABLY OBSTRUCTING THE PASSAGE TO FLUID BETWEEN SAID INLET AND OUTLET PORTS IN ACCORDANCE WITH THE POSITION OF SAID PISTON MEMBER, A THIRD PORT COMMUNICATING INTO SAID FIRST FLUID CHAMBER, AND MEANS FOR FORCING FLUID INTO AND OUT OF SAID FIRST FLUID CHAMBER VIA SAID THIRD PORT AND SEALING SAID FLUID TO POSITION SAID PISTON AT ANY DESIRED POSITION BETWEEN SAID FIRST AND SECOND LIMITING POSITIONS, THEREBY PRODUCING ANY DESIRED RATE OF FLUID FLOW BETWEEN SAID INLET AND SAID OUTLET PORTS BETWEEN A MINIMUM RATE DEFINED BY ONE OF SAID LIMITING POSITIONS OF SAID PISTON AND A MAXIMUM RATE DEFINED BY THE OTHER LIMITING POSITION THEREOF, THE AREA OF ONE END OF SAID PISTON IS LARGER THAN THE AREA OF THE OTHER END THEREOF, WHEREBY EQUAL PRESSURES IN SAID FIRST AND SECOND FLUID CHAMBERS PRODUCE DIFFERING