Automatic alternating marker system

摘要

The automatic alternating marker system is adapted for use with an agricultural planter assembly which has a plurality of planter units, which is adapted to be mechanically and hydraulically coupled to a tractor, and which has hydraulically actuated, first and second extendable markers, each mounted on one side of the planter assembly. Each marker is used to mark, respectively, the track that a tractor wheel should follow on a return planting sweep of the planter assembly for planting properly spaced adjacent rows after the planter assembly has made a first sweep to plant a plurality of rows. The system includes an electrical control circuit for causing extension of the first marker and retraction of the second marker upon the raising of the planters and the turning of the tractor 180 DEG , and for causing extension of the second marker and retraction of the first marker upon the next raising of the planters and the next turning of the tractor 180 DEG . The electrical control circuit includes a pressure sensitive switch connected to the input of a toggle bistable multivibrator which has first and second outputs connected to driver circuits which in turn are connected to first and second solenoid operated valves for operating a respective piston and cylinder assembly for causing extension or retraction of one of the markers.