Implement draft and position control for tractors

Claim 1

IN A TRACTOR OF THE TYPE ADAPTED TO CARRY AND PROPEL AN EARTH WORKING IMPLEMENT AND INCLUDING A SOURCE OF PRESSURE FLUID, A FLUID MOTOR AND LIFT MEANS CONNECTED TO THE IMPELEMENT AND TO THE FLUID MOTOR ADAPTED TO RAISE AND LOWER THE IMPLEMENT IN RESPONSE TO ACTIVATION OF THE FLUID MOTOR, THE COMBINATION OF A SHIFTABLE ELEMENT, SENSING MEANS CONNECTED TO THE IMPLEMENT, YIELDABLE IN RESPONSE TO VARIATIONS IN DRAFT REACTIONS FROM THE IMPLEMENT, INITIATING MEANS CONNECTED TO SAID SHIFTABLE ELEMENT AND TO SAID SENSING MEANS FOR SHIFTING SAID SHIFTABLE ELEMENT IN RESPONSE TO YIELDING OF SAID SENSING MEANS, FOLLOW-UP MEANS CONNECTED WITH SAID LIFT MEANS AND WITH SAID SHIFTABLE ELEMENT AT A POINT SPACED FROM SAID INITIATING MEANS, A HAND LEVEL PIVOTALLY MOUNTED ON AND SUPPORTED FROM SAID SHIFTABLE ELEMENT, AND DETENT MEANS FOR RETAINING SAID HAND LEVER IN ANGULAR ADJUSTMENT RELATIVE TO SAID SHIFTABLE ELEMENT, VALVE MEANS ON THE TRACTOR, CONDUIT MEANS CONNECTING SAID VALVE MEANS WITH SAID SOURCE OF PRESSURE FLUID AND WITH SAID FLUID MOTOR, AND ACTUATING MEANS DIRECTLY CONNECTED WITH SAID HAND LEVER AT A POINT BETWEEN SAID INITIATING MEANS AND SAID FOLLOW-UP MEANS, AND SAID ACTUATING MEANS BEING ALSO DIRECTLY CONNECTED WITH SAID VALVE IN ACTUATING RELATION THEREWITH.