Tractor weight transfer control

Claim 1

IN A TRACTOR HAVING A PAIR OF TRAILING DRAFT LINKS AND A HYDRAULIC SYSTEM INCLUDING A RAM CONTROLLED BY A SPRING POSITIONED CONTROL ROD, THE IMPROVEMENT COMPRISING, IN COMBINATION, FIRST AND SECOND HYDRAULIC ACTUATORS RESPECTIVELY COUPLING SAID PAIR OF DRAFT LINKS TO SAID RAM SO THAT PRESSURE IN THE RAM LIFTS THE LINKS THROUGH THE FLUID IN THE ACTUATORS, A LINE HYDRAULICALLY COUPLING SAID FIRST AND SECOND ACTUATORS SO THAT ONE DRAFT LINK CAN RAISE AND THE OTHER FALL WITHOUT VARYING THE PRESSURE IN SAID LINE, A THIRD HYDRULIC ACTUATOR ANCHORED ON SAID TRACTOR, MEANS MECHANICALLY COUPLING SAID THIRD ACTUATOR TO SAID CONTROL ROD SO THAT THE SPRING FORCES ON THE ROD REACT AGAINST THE FLUID IN THE THIRD ACTUATOR, VALVES IN SAID LINE FOR SELECTIVELY BLOCKING FLUID FLOW BETWEEN SAID FIRST AND SECOND ACTUATORS SO AS TO PREVENT RELATIVE VERTICAL MOVEMENT OF THE DRAFT LINKS, AND MEANS FOR HYDRAULICALLY COUPLING SAID RAM TO SAID THIRD ACTUATOR SO THAT THE LIFTING FORCE IN THE RAM IS SENSED BY THE CONTROL ROD.