A control system for use with a tractor and flexible implement arrangement in which the tractor includes a source of fluid pressure, a fluid reservoir, and a power-operated hitch movable through a vertical range and the implement includes a center frame section connected to the tractor hitch to be raised and lowered thereby between raised transport and lowered working positions, a pair of transversely extending outer frame sections having inner ends pivotally connected to the center frame section for vertical movement, a pair of gauge wheel means adjustably secured to and supporting the outer frame sections, and a pair of hydraulic cylinders connected between the outer frame sections and the gauge wheel means to raise and lower the outer frame sections on the gauge wheel means when supplied with fluid under pressure and when fluid is exhausted therefrom, the control system comprising: means including valve means interconnecting each of the hydraulic cylinders with the tractor source and reservoir each of the valve means being movable to opposite sides of a neutral fluid blocking position to selectively interconnect its respective cylinder with the source and reservoir depth sensing means secured to each of the outer frame sections operatively interconnected with the valve means and each being responsive to deviation of its respective outer frame section from a selected working position with respect to the ground to move its respective valve means from the neutral position to adjust the respective outer frame section on its gauge wheel to the predetermined working position manually-operable means operatively interconnected with the depth sensing means and their respective valve means to selectively render the depth sensing means inoperative and move the valve means in a direction to interconnect the hydraulic cylinders with the source and thereby raise the outer frame sections to a transport position draft load sensing means on the tractor operatively interconnected with one of the valve means and responsive to unbalanced draft loads on opposite sides of the tractor hitch to move the one valve means from its neutral position in a direction to vertically adjust the respective outer frame section in a direction to establish balanced draft loads on opposite sides of the tractor hitch and second manually operable means operatively interconnected with both the depth sensing means for the one valve means and the draft load sensing means to selectively and alternately bring the one valve means under the control of one of the sensing means therefor and render the other sensing means for the one valve means inoperative.Ģ.

John deere draft control