PROBLEM TO BE SOLVED: To constitute a rod member of a cover-flipping down device for urging a rear part cover of a rotary tiller in the grounding direction so as to be expandable in the longitudinal direction by a screw-type expansion and contraction structure to reduce the force for lifting the rear part cover, and to enable the expansion and contraction distance of the rod member to be easily recognized when carrying out the tillage in a state of the rear part cover floated a little from the ground.SOLUTION: The cover-flipping down device is equipped with a supporting rod, a screw shaft, a lift and a holder. The lift is screwed on the screw shaft so that the lift may be moved in the longitudinal direction of the supporting rod by the rotation around the shaft center of the screw shaft, and a machine frame or the other part of the rear part cover is linked to the holder so that the rear part cover may be lifted or lowered by the movement of the holder in the longitudinal direction of the supporting rod. A spring for pushing the holder to the lift side to urge the rear part cover to the grounding direction is also installed.COPYRIGHT: (C)2008,JPO&INPIT【課題】 ロータリ耕耘機の後部カバーを接地方向に付勢するカバー弾下装置のロッド部材を、後部カバーの持ち上げ力の軽減を図るべくネジ式伸縮構造によって長さ方向伸縮可能に構成すると共に、後部カバーを地面から少し浮かせた状態で耕耘する場合に、ロッド部材の伸縮量が容易にわかるようにする。【解決手段】 カバー弾下装置は、支持杆とねじ軸とリフトとホルダとを備え、 ねじ軸の軸心廻りの回転によりリフトが支持杆の長手方向に移動するようにリフトがねじ軸に螺合され、ホルダの支持杆長手方向への移動により後部カバーが昇降移動するように、ホルダに機枠又は後部カバーの他方が連結され、後部カバーを接地方向に付勢すべくホルダをリフト側に押圧するバネが設けられている。【選択図】図1
