Hydraulic installation for tractors

Claim 1

A DISTRIBUTOR FOR THE CONTROL OF A HYDRAULICALLY OPERABLE POWER UNIT, COMPRISING A HOUSING WITH AN INLET PORT CONNECTABLE TO A SOURCE OF HYDRAULIC FLUID, AN OUTLET PORT CONNECTABLE TO A RESERVOIR FOR SAID FLUID AND AT LEAST ONE FURTHER PORT CONNECTABLE TO A PISTON CYLINDER OF THE POWER UNIT, AND A VALVE MEMBER DISPLACEABLY MOUNTED IN SAID HOUSING; SAID VALVE MEMBER BEING PROVIDED WITH A CHANNEL AND A PLURALITY OF PASSAGES COMMUNICATING WITH SAID CHANNEL AND RESPECTIVELY ALIGNABLE WITH SAID PORTS IN DIFFERENT OPERATING POSITIONS OF SAID VALVE MEMBER; SAID PASSAGES INCLUDING AT LEAST ONE FIRST PASSAGE REGISTERING WITH SAID INLET PORT IN A FIRST POSITION, A SECOND POSITION AND A THIRD POSITION, AND A SECOND PASSAGE OF RELATIVELY WIDE CROSS-SECTION REGISTERING WITH SAID OUTLET PORT IN SAID SECOND POSITION, A THIRD PASSAGE OF RELATIVELY RESTRICTED CROSS-SECTION REGISTERING WITH SAID OUTLET PORT IN SAID THIRD POSITION, AND AT LEAST ONE FOURTH PASSAGE REGISTERING WITH SAID FURTHER PORT IN EACH OF SAID POSITIONS, SAID PASSAGES BEING SO DIMENSIONED AS TO ENABLE FLUID FROM SAID CYLINDER, ADMITTED INTO SAME FROM SAID SOURCE IN SAID FIRST POSITION BY WAY OF SAID INLET AND FURTHER PORTS, TO BE DISCHARGED VIA SAID OUTLET PORT IN SAID SECOND POSITION WHILE CREATING IN SAID THIRD POSITION A PRESSURE DIFFERENTIAL IN SAID CHANNEL EXERTING UPON A PISTON IN SAID CYLINDER A HYDRAULIC FORCE SUBSTANTIALLY LESS THAN THAT EXERTED THEREON IN SAID FIRST POSITION.