PROBLEM TO BE SOLVED: To provide a lift controller having a simple structure and capable of preventing the formation of unplowed ground and the excessive pile of soil as much as possible at the beginning of plowing work.SOLUTION: This lift controller for regulating the lifting up and down of a plower 400 linked with a vehicle main body 50 as capable of being lifted up and down, by a lifting up and down actuator 220 is constituted as, at the beginning of the plowing work of performing an automatic plowing depth-regulation at a set plowing depth position by descending the plower 400 from a non-plowing state position under an automatic height regulation, and for a definite time or definite division from a time point that the rotating angle &thetaD of a rear cover 437 reaches to a prescribed angle, the regulating conditions in the automatic height regulation and/or automatic plowing depth regulation are corrected so as to moderate the regulating accuracy of the lifting up and down regulation of the plower 400 and also change the corrected amount of the regulating conditions in accordance with the descending speed of the plower 400 from the non-plowing state position.COPYRIGHT: (C)2007,JPO&INPIT【課題】耕耘作業の開始時において、未耕地の発生及び土盛り量の過多の発生を可及的に防止し得る構造簡単な昇降制御装置を提供する。【解決手段】車輌本体50に対して昇降可能に連結された耕耘機400を昇降用アクチュエータ220によって昇降制御させる昇降制御装置は、耕耘機400を非耕耘状態位置から自動高さ制御において下降させて設定耕深位置での自動耕深制御を行う耕耘作業の開始時に、リヤカバー437の回動角度θDが所定角度に達した時点から一定時間又は一定区間においては、耕耘機400の昇降制御の制御精度が緩和するように自動高さ制御及び/又は自動耕深制御における制御条件を補正すると共に、制御条件の補正量を、非耕耘状態位置からの耕耘機400の下降速度に応じて変更するように構成されている。【選択図】図14
