PROBLEM TO BE SOLVED: To achieve work in a curving state in a field.SOLUTION: A clutch linkage mechanism C is provided with clutch linkage changeover means S1 changing over a work clutch mechanism 48 between a state that the work clutch mechanism 48 is linked with engagement or disengagement on the basis of operation of an operation lever 56, and a state that the clutch engagement is held even if the operation lever 56 is operated to the other side, that a diff-lock mechanism 41 is brought into a diff-lock release state, and that the work clutch mechanism 48 is linked with the clutch engagement. A diff-lock linkage mechanism D includes diff-lock linkage changeover means S2 changing over the diff-lock mechanism 41 between a state that the diff-lock mechanism 41 is brought into a diff-lock state or a state of releasing a diff-lock on the basis of operation of the operation lever 56, and a diff-lock release state of holding the diff-lock release state even if the operation lever 56 is operated to one side/a state that the work clutch mechanism 48 is made to be the clutch engagement.COPYRIGHT: (C)2014,JPO&INPIT【課題】圃場での曲進状態での作業を具現化しようとする。【解決手段】クラッチ連繋機構Cに、前記操作レバー56の操作に基づき作業クラッチ機構48を入り又は切りに連動する状態と操作レバー56が前記他方側へ操作されてもクラッチ入りを保持し、デフロック機構41をデフロック解除状態とし作業クラッチ機構48をクラッチ入りに連動する状態に切り替えるクラッチ連繋切替手段S1を設ける。また、デフロック連繋機構Dに、前記操作レバー56の操作に基づきデフロック機構41をデフロック状態又はデフロック解除とする状態と、操作レバー56が前記一方側へ操作されてもデフロック解除状態を保持してデフロック解除状態・作業クラッチ機構48をクラッチ入りとする状態とに切り替えるデフロック連繋切替手段S2を備える。【選択図】 図7