Elevator control system

Claim 1

A CONSTANT SPEED LOWERING CONTROL MEANS FOR A HYDRAULIC ELEVATOR SYSTEM INCLUDING A JACK CYLINDER CONTAINING HYDRAULIC FLUID, AN ELEVATOR CAR PLUNGER RECIPROCABLE THEREIN, A PUMP AND A RESERVOIR, COMPRISING A VALVE CASING INCLUDING AN INLET CHAMBER, AN INTERMEDIATE CHAMBER AND A DISCHARGE CHAMBER, SAID INLET CHAMBER BEING IN CONTINUOUS COMMUNICATION WITH SAID INTERMEDIATE CHAMBER THROUGH A FIRST PASSAGEWAY OF VARIABLE EFFECTIVE SIZE AND SAID INTERMEDIATE CHAMBER BEING IN SELECTIVELY CONTROLLABLE INTERMITTENT COMMUNICATION WITH SAID DISCHARGE CHAMBER THROUGH A SECOND PASSAGEWAY, AN INLET PORT IN SAID CHAMBER ADAPTED TO BE CONNECTED TO THE JACK CYLINDER OF A HYDRAULIC ELEVATOR SYSTEM WITH WHICH THE CONTROL MEANS IS ADAPTED TO BE USED, A DISCHARGE PORT IN SAID DISCHARGE CHAMBER ADAPTED TO BE CONNECTED TO THE RESERVOIR OF A HYDRAULIC ELEVATOR SYSTEM, SELECTIVELY OPERABLE SPEED CONTROL VALVE MEANS DISPOSED IN SAID FIRST PASSAGEWAY FOR CONTROLLING THE VARIABLE EFFECTIVE SIZE THEREOF, SAID CONTROL VALVE MEANS HAVING TWO OPERATIVE POSITIONS CORRESPONDING TO TWO LOWERING SPEEDS OF AN ELEVATOR CAR PLUNGER WITH WHICH THE CONTROL MEANS IS ADAPTED TO BE USED, REGULATOR VALVE MEANS DISPOSED IN SAID SECOND PASSAGEWAY FOR REGULATING FLUID FLOW THEREIN, SAID REGULATOR VALVE MEANS INCLUDING PRESSURE RESPONSIVE MEANS ASSOCIATED THEREWITH ADAPTED TO SELECTIVELY SEAL SAID SECOND PASSAGEWAY AGAINST HYDRAULIC FLUID FLOW FROM SAID INTERMEDIATE CHAMBER TO SAID DISCHARGE CHAMBER TO INTERRUPT COMMUNICATION THEREBETWEEN, AND POSITIONING MEANS COUPLED TO SAID REGULATOR VALVE MEANS AND SENSITIVE TO THE PRESSURE DIFFERENTIAL BETWEEN SAID INLET AND INTERMEDIATE CHAMBERS FOR ADJUSTING SAID REGULATOR VALVE MEANS TO PROVIDE A PRESSURE IN SAID INTERMEDIATE CHAMBER SUCH THAT THE PRESSURE DIFFERENTIAL BETWEEN SAID INLET AND INTERMEDIATE CHAMBERS REMAINS SUBSTANTIALLY CONSTANT UNDER VARYING PRESSURE CONDITIONS IN SAID INLET CHAMBER.