Biskis

Claim 1

IN A TRACTOR HAVING IMPLEMENT-ATTACHING MECHANISM FOR SUPPORTABLY ATTACHING AN IMPLEMENT THERETO, A LIFT MEANS MOUNTED ON THE TRACTOR AND OPERABLE FOR RAISING AND LOWERING SAID IMPLEMENT, A POSITION-RESPONSIVE MEMBER AFFIXED TO AND CONSTRAINED FOR ROTATIVE MOVEMENT WITH SAID LIFT MEANS AND OPERABLE BY SAID LIFT MEANS ATTENDANT THE RAISING AND LOWERING MOVEMENTS OF THE IMPLEMENT, DRAFT-RESPONSIVE MECHANISM CONSTITUTING A PORTION OF SAID IMPLEMENT-ATTACHING MECHANISM AND WHICH IS SUSCEPTIBLE TO MOVEMENT UPON BEING SUBJECTED TO VARIATIONS IN DRAFT LOADS ON THE IMPLEMENT AND INCLUDING A LEVER ARM ROTATABLE ATTENDANT SUCH MOVEMENT, A POWER UNIT HAVING PORTIONS EXPANDABLE AND CONTRACTIBLE RELATIVE TO ONE ANOTHER WITH ONE SUCH PORTION PIVOTALLY CONNECTED TO SAID LEVER ARM AND ANOTHER SUCH PORTION PIVOTALLY CONNECTED TO SAID LIFT ARM AND IN WHICH SAID UNIT IS SELECTIVELY EXPANDABLE AND CONTRACTIBLE FOR RAISING AND LOWERING SAID LIFT MEANS AND ALTERNATIVELY OPERABLE AS A RIGID MEMBER FOR CONSTRAINING THE MOVEMENTS OF SAID LEVER ARM AND LIFT MEANS WITH ONE ANOTHER WHEN SUCH MOVEMENTS ARE THE RESULT OF VARIATIONS IN DRAFT LOADS, AND CONTROL VALVE MEANS ACTUABLE FOR CONTROLLING THE OPERATION OF SAID POWER UNIT, THE IMPROVEMENT COMPRISING: FOLLOWUP MECHANISM INTERCONNECTING SAID CONTROL VALVE MEANS, SAID POSITION-RESPONSIVE MEMBER AND SAID POWER UNIT FOR EFFECTING ACTUATION OF SAID CONTROL VALVE MEANS RESPONSIVE TO CERTAIN MOVEMENTS OF SAID POSITION-RESPONSIVE MEMBER AND FOR PREVENTING ACTUATION OF THE CONTROL VALVE MEANS RESPONSIVE TO CERTAIN OTHER MOVEMENTS OF SAID POSITION-RESPONSIVE MEMBER; SAID FOLLOWUP MECHANISM INCLUDING A FIRST FORCE-TRANSMITTING MEANS INTERCONNECTING SAID CONTROL VALVE MEANS AND SAID POSITION RESPONSIVE MEMBER AND OPERATIVE FOR ACTUATING SAID CONTROL VALVE MEANS IN ACCORDANCE WITH MOVEMENTS OF SAID POSITION-RESPONSIVE MEMBER THAT RESULT FROM EXPANSION AND CONTRACTION OF THE RESPECTIVE PORTIONS OF SAID POWER UNIT, AND A SECOND FORCE-TRANSMITTING MEANS INTERCONNECTING SAID ONE SUCH PORTION OF SAID POWER UNIT AND SAID FIRST FORCE TRANSMITING MEANS AND COOPERATIVE THEREWITH IN SUCH MANNER AS TO CAUSE SAID FIRST FORCE-TRANSMITTING MEANS TO BE INOPERATIVE FOR EFFECTING THE ACTUATION OF SAID CONTROL VALVE MEANS IN RESPONSE TO MOVEMENTS OF SAID POSITION-RESPONSIVE MEMBER WHEN SUCH MOVEMENT IS PRODUCED BY A MOVEMENT OF SAID DRAFT-RESPONSIVE MECHANISM RESULTING FROM VARIATIONS IN DRAFT LOADS ON THE IMPLEMENT.