Speed and directional control valve for double-acting lift cylinder

Claim 1

A HYDRAULIC CONTROL VALVE FOR GOVERNING FLOW OF PRESSURE FLUID TO AND FROM THE HEAD AND ROD ENDS OF A DOUBLE-ACTING LIFT CYLINDER, WHICH VALVE IS OF THE TYPE CHARACTERIZED BY A BODY HAVING AN INLET PASSAGE TO RECEIVE PRESSURE FLUID FROM A SOURCE THEREOF, SUPPLY PASSAGE MEANS CONNECTING WITH THE INLET PASSAGE, RETURN FLUID PASSAGE MEANS, AND A PAIR OF SERVICE PASSAGES RESPECTIVELY ADAPTED FOR CONNECTION WITH THE HEAD AND ROD ENDS OF THE CYLINDER, SAID VALVE BEING FURTHER CHARACTERIZED BY: (A) A VALVE ELEMENT IN THE BODY MOVABLE TO A PLURALITY OF OPERATING POSITIONS TO SELECTIVELY CONTROL COMMUNICATION BETWEEN THE SERVICE PASSAGES AND SAID SUPPLY AND RETURN PASSAGE MEANS, ONE OF SAID OPERATING POSITIONS COMPRISING A HIGH SPEED LIFT POSITION OF THE VALVE ELEMENT AT WHICH BOTH OF SAID SERVICE PASSAGES ARE CLOSED OFF FROM THE RETURN PASSAGE MEANS; (B) SAID SUPPLY PASSAGE MEANS COMPRISING (1) A FIRST BRANCH PASSAGE UNRESTRICTEDLY CONNECTED WITH THE INLET PASSAGE AND ADAPTED TO HAVE UNRESTRICTED COMMUNICATION WITH THE RODCONNECTED SERVICE PASSAGE IN SAID HIGH SPEED LIFT POSITION OF THE VALVE ELEMENT, (2) A SECOND BRANCH PASSAGE ADAPTED TO BE COMMUNICATED WITH THE HEAD-CONNECTED SERVICE PASSAGE IN THE HIGH SPEED LIFT POSITION OF THE VALVE ELEMENT, (3) AND PASSAGE DEFINING MEANS CONNECTING SAID SECOND BRANCH PASSAGE WITH THE INLET PASSAGE AND WITH THE FIRST BRANCH PASSAGE SO THAT THE SERVICE PASSAGES WILL BE COMMUNICATED WITH ONE ANOTHER AND WITH THE INLET PASSAGE IN SAID HIGH SPEED LIFT POSITION OF THE VALVE ELEMENT AND SOURCE FLUID TOGETHER WITH FLUID RETURNING TO THE ROD CONNECTED SERVICE PASSAGE WILL THEN FLOW TO THE HEAD CONNECTED SERVICE PASSAGE; (C) AND A LOAD HOLDING CHECK VALVE LOCATED IN THE SUPPLY PASSAGE MEANS BETWEEN SAID BRANCHES THEREOF SO AS TO BE IN THE PATH OF ALL PRESSURE FLUID FLOWING TO THE HEAD CONNECTED SERVICE PASSAGE EITHER FROM THE INLET PASSAGE OR FROM SAID FIRST BRANCH PASSAGE.