| 摘要 |
A field marker for mounting on an agricultural implement includes an elongated arm adapted to project outwardly laterally of the implement when i n its operating position and is adapted to carry a field marking device at its out er distal end for making a score mark on the ground. A mount for the arm at an inner proximal end thereof allows pivoting of the arm about first and second transverse axes whereby to allow the arm to swing upwardly and downwardly about the first one of said axes when operating on uneven ground while also allowing the arm to swing around the second one of said axes from its outwardly projecting operating position int o another position. The arm includes inner and outer arm sections secured together by a folding joint to permit the inner and outer arm sections to be folded into juxtaposition with one another and brought into the transport position. An extensible actuator effects relative rotation of the inner and outer arm sections, and a mechanism interacts with the inner and outer arm sections and the actuator such that as the inner arm section is pivoted through a selected angle, the outer arm section is pivoted about sai d folding joint relative to the inner arm section. A breakaway link on the arm permits the arm to swing as a whole relative to the mount about thesecond axis away from its outwardly projecting operating position when an obstacle is encountered and a predetermined force on said arm has been exceeded. The breakaway link has a resetting devi ce associated therewith for returning the arm to the operating position once th e obstacle has been cleared.
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