Hydraulic control means for a lifting device of agricultural tractors

Claim 1

A HYDRAULIC CONTROL MEANS FOR LIFTING DEVICES OF AGRICULTURAL TRACTORS, COMPRISING A TRACTOR, AN IMPLEMENT PIVOTALLY SECURED TO SAID TRACTOR, A FLITING DEVICE HAVING SWINGABLE LOAD ARMS PIVOTALLY CONNECTED WITH SAID IMPLEMENT AND A CONTROL APPARATUS MOUNTED IN SAID TRACTOR, CAM MEANS ROTATABLE WITHIN SAID LOAD ARMS, SAID LIFTING DEVICE BEING OPERATIVELY CONNECTED WITH SAID CONTROL APPARATUS, SAID CONTROL APPARATUS INCLUDING MANS FOR AUTOMATICALLY ADJUSTING SAID LIFTING DEVICE INTO ANY ONE OF A PLURALITY OF ANGULAR POSITIONS OF SAID LAOD ARMS, A GROUND FOLLOWING SENSING MEMBER OPERATIVELY CONNECTED WITH SAID LIFING DEVICE AND MEANS FOR TRANSMITTING TO SAID CONTROL APPARATUS FROM SAID GROUND FLOWING SENSING MEMBER VARIATIONS OF THE SOIL PENETRATION DEPTH OF SAID IMPLEMENT, SAID TRANSMITTING MEANS INCLUDING A LEVER OPERATIVELY CONNECTED WITH SAID ROTATABLE CAM MEANS INTERMEDIATE ITS ENDS, SAID TRANSMITTING MEANS FURTHER INCLUDING FIRST LINKAGE MEANS EXTENDING FROM SAID GROUND FOLLOWING SENSING MEMBER TO ONE END OF SAID LEVER, SECOND LINKAGE MEANS OPERATIVELY CONNECTING THE OTHER END OF SAID LEVER WITH SAID CONTROL APPARATUS, AND SAID ADJUSTING MEANS OF SAID LIFTING DEVICE INCLUDING A MANUALLY OPERATED LEVER OPERATIVELY CONNECTED WITH SAID SECOND LINKAGE MEANS AND PRESELECTING THE ANGULAR POSITION OF SAID LOAD ARMS.