US Patent 7469648 Front fold planter lift and fold hydraulic control system

A hydraulic control system for use with a front fold planter is configured to move the tool bar of the planter between a first height corresponding to a planting position, a second height corresponding to a field transport position and a third height corresponding to a road transport position. A first set of hydraulic cylinders is mounted to the tool bar for moving the frame between the first height, the second and the third height. A second set of hydraulic cylinders is mounted to the tool bar for moving the frame between the first height and the second height. The first and second set of cylinders are arranged in a master/slave relationship relative to each other and operable independent of each other.