Hydraulic systems

Claim 1

IN A PRESSURE CONTROL SYSTEM ADAPTED FOR RAISING AND LOWERING A WORK LOAD COMPRISING: A FLUID PRESSURE INLET, CONTROL VALVE OUTLET PASSAGE MEANS, A WORK PASSAGE MEANS COMMUNICATING WITH SAID CONTROL VALVE OUTLET PASSAGE MEANS, RETURN PASSAGE MEANS COMMUNICTING WITH SAID CONTROL VALVE OUTLET PASSAGE MEANS, CONTROL VALVE MEANS FOR COMMUNICATION DURING RAISED POSITION AND CUTTING OFF COMMUNICATION DURING NEUTRAL AND LOWERING POSITION OF PRESSURE TO SAID CONTROL VALVE OUTLET PASSAGE MEANS FROM SAID PRESSURE INLET, FIRST VALVE MEANS FOR COMMUNCIATING SAID RETURN PASSAGE MEANS WITH SAID CONTROL VALVE OUTLET PASSAGE MEANS WHEN IN OPEN POSITION AND CUTTING OFF SAID LAST NAMED COMMUNICATION WHEN IN CLOSED POSITION, SECOND VALVE MEANS FOR COMMUNICATING SAID WORK PASSAGE MEANS WITH SAID CONTROL VALVE OUTLET PASSAGE MEANS WHEN IN OPEN POSITION AND CUTTING OFF SAID LAST NAMED COMMUNICATION WHEN IN CLOSED POSITION, SAID FIRST VALVE MEANS BEING SO CONTRUCTED AND ARRANGED AS TO BE BIASED INTO CLOSED POSITION BY PRESSURE COMMUNICATED TO SAID CONTROL VALVE OUTLET PASSAGE MEANS FROM SAID PRESSURE INLET BY SAID CONTROL VALVE MEANS, MEANS BIASING SAID SECOND VALVE MEANS INTO CLOSED POSITION, SAID SECOND VALVE MEANS BEING SO CONSTRUCTED AND ARRANGED AS TO BE OPENED AGAINST THE FORCE OF SAID BIASING MEANS BY PRESSURE COMMUNICATED TO SAID CONTROL VALVE OUTLET PASSAGE MEANS FROM SAID PRESSURE INLETS BY SAID CONTROL VALVE MEANS, MEANS OPERATIVELY CONNECTED TO SAID CONTROL VALVE MEANS AND SAID FIRST VALVE MEANS TO OPEN SAID FIRST VALVE MEANS WHEN SAID CONTROL VALVE MEANS IS IN LOWERING POSITION, AND ABUTMENT MEANS OPERABLY ASSOCIATED WITH SAID FIRST VALVE MEANS FOR ABUTTING SAID SECOND VALVE MEANS AND SIMULTANEOUSLY OPENING THE SAME WHEN SAID FIRST VALVE MEANS IS OPENED THEREBY PROVIDING PASSAGE MEANS FROM SAID WORK PASSAGE MEANS PAST SAID SECOND AND FIRST VALVE MEANS TO SAID RETURN PASSAGE MEANS.