PROBLEM TO BE SOLVED: To improve accuracy in draft sensing of a mixed lifting controller.SOLUTION: The lift controlling means is constituted to control lifting of the soil working implement (2) in such a way that a mixed value locates in a dead zone set by a position setting means (12), wherein the mixed value is obtained by respectively multiplying weight constants set by a draft ratio setting means (20) by a difference between detected traction load value by the draft detecting means (8) and the predetermined objective traction load value and a difference between detected position value and the predetermined position value, and adding obtained values, and the dead zone is constituted as variable according to the weight constant set by the draft ratio setting means (20).COPYRIGHT: (C)2008,JPO&INPIT【課題】ミックス昇降制御装置におけるドラフト感知精度の向上を図る。【解決手段】ドラフト検出手段(8)による検出牽引負荷値と予め設定する牽引目標値との差、及び検出ポジション値と予め設定するポジション設定値との差に、ドラフト比設定手段(20)で設定した重み定数を夫々乗じた値を加算してミックス値とし、このミックス値がポジション設定手段(12)にて設定した値に対し不感帯内に入るよう対地作業機(2)を昇降制御する昇降制御手段を構成し、前記不感帯はドラフト比設定手段(20)で設定した重み定数に応じて変更すべく構成する。【選択図】 図4
