Tractor hitch control devices

Claim 1

FOR USE WITH A GROUND TILLING IMPLEMENT TOWED BY A TRACTOR BY MEANS OF A THREE-POINT HITCH INCLUDING RIGID LINK MEANS PIVOTED AT ONE END TO SAID TRACTOR AND AT THE OTHER END TO SAID IMPLEMENT: A DEVICE FOR CONTROLLING THE OPERATION OF SAID IMPLEMENT AND COMPRISING A CYLINDER FIXED TO SAID TRACTOR, A PISTON SLIDABLE WITH A LIQUID-TIGHT FIT IN SAID CYLINDER SO AS TO FORM THEREWITH A VARIABLE VOLUME CHAMBER FILLED WITH LIQUID, SAID PISTON BEING OPERATIVELY CONNECTED WITH SAID LINK MEANS TO CONTROL THE POSITION THEREOF WITH RESPECT TO SAID TRACTOR, A PRESSURE ACCUMULATOR COMPRISING A VESSEL SUPPORTED BY SAID TRACTOR AND A RESILIENT DIAPHRAGM DIVIDING SAID VESSEL INTO A COMPARTMENT FILLED WITH A GAS UNDER PRESSURE AND A COMPARTMENT FILLED WITH LIQUID, MEANS COMMUNICATING THE LAST MENTIONED COMPARTMENT DIRECTLY WITH SAID VARIABLE VOLUME CHAMBER OF SAID CYLINDER, A CONTINUOUSLY OPERATING LIQUID PUMP SUPPORTED BY SAID TRACTOR, MEANS FIXED TO SAID TRACTOR DEFINING A HOUSING HAVING A CYLINDRICAL WALL IN COMMUNICATION WITH SAID PUMP, SAID HOUSING BEING PROVIDED WITH A DISCHARGE OPENING IN THE CYLINDRICAL WALL THEREOF, A CONDUIT IN COMMUNICATION WITH SAID VARIABLE VOLUME CHAMBER AND OPENING INTO THE CYLINDRICAL WALL OF SAID HOUSING, A SPRING LOADED CHECK VALVE IN SAID CONDUIT OPENING TOWARD SAID VARIABLE VOLUME CHAMBER, A SLIDE VALVE SLIDABLY SUPPORTED IN SAID HOUSING TO CONTROL THE COMMUNICATION BETWEEN SAID PUMP AND SAID DISCHARGE OPENING, SAID SLIDE VALVE HAVING A NEUTRAL POSITION IN WHICH COMMUNICATION BETWEEN SAID PUMP AND SAID DISCHARGE OPENING IS ESTABLISHED, SAID SLIDE VALVE BEING ADAPTED FOR DISPLACEMENT THEREOF FROM SAID NEUTRAL POSITION IN ONE DIRECTION TO CUT OFF THE COMMUNICATION BETWEEN SAID PUMP AND SAID DISCHARGE OPENING, MEANS CARRIED BY SAID SLIDE VALVE FOR COOPERATING WITH SAID CHECK VALVE FOR POSITIVELY OPENING SAID CHECK VALVE UPON DISPLACEMENT OF SAID SLIDE VALVE FROM SAID NEUTRAL POSITION IN A DIRECTION OPPOSITE SAID ONE DIRECTION WHEREBY SAID CHAMBER OF SAID CYLINDER WHICH IS FILLED WITH LIQUID IS THEN PLACED INTO COMMUNICATION WITH SAID DISCHARGE OPENING, A CONTROL LEVER PIVOTALLY SUPPORTED ON SAID TRACTOR AND ADAPTED TO OCCUPY WITH RESPECT THERETO A MULTIPLICITY OF DIFFERENT POSITIONS, AND FOLLOW UP MEANS OPERATIVELY CONNECTING SAID CONTROL LEVER BOTH WITH SAID SLIDE VALVE AND WITH SAID LINK MEANS FOR OPERATING SAID TWO VALVES FOR A GIVEN POSITION OF SAID CONTROL LEVER AND UPON DISPLACEMENT OF SAID LINK MEANS TO ESTABLISH THE PRESSURE OF THE LIQUID ENTRAPPED IN SAID VARIABLE VOLUME CHAMBER IN ACCORDANCE WITH THE HARDNESS OF THE GROUND SO THAT THE POSITION OF SAID PISTON IN SAID CYLINDER AND THAT OF SAID TILLING IMPLEMENT IN THE GROUND ARE FIXED FOR A GIVEN POSITION OF SAID CONTROL LEVER IRRESPECTIVE OF THE HARDNESS OF THE GROUND.