Fluid flow control system

Claim 1

AN APPARATUS OF THE TYPE FOR CONTROLLING THE FLOW OF A FLUID HAVING A CHECK VALVE MECHANISM WITH AN INLET AND AN OUTLET UPSTREAM OF A CHECK VALVE AND AT LEAST ONE OUTLET DOWNSTREAM OF SAID CHECK VALVE, THE COMBINATION THEREWITH OF A VALVE MECHANISM HAVING AN INLET COMMUNICATING WITH SAID UP STREAM OUTLET AND AN OUTLET, A CONTROL SPOOL FOR OPENING AND CLOSING COMMUNICATION BETWEEN THE INLET AND OUTLET OF SAID VALVE MECHANISM, MEANS FOR BIASING SAID CONTROL SPOOL TOWARD ITS OPEN POSITION, SAID CONTROL SPOOL DEFINING AN ACTUATING AREA, A SOURCE OF FLUID PRESSURE FOR COMMUNICATING WITH SAID ACTUATING AREA TO MOVE SAID CONTROL SPOOL TOWARD ITS CLOSED POSITION, MEANS FOR COMMUNICATING SAID ACTUATING AREA WITH A SOURCE OF LOW PRESSURE, A LEVELING NEEDLE CARRIED BY SAID CONTROL SPOOL AND ADAPTED TO BE ACTUATED BY SAID SOURCE OF FLUID PRESSURE SO AS TO PROJECT OUTWARDLY OF SAID CONTROL