PROBLEM TO BE SOLVED: To provide a plowing depth automatic control system for a tractor, enabling work to be continued with stable plowing depth maintained.SOLUTION: In the plowing depth automatic control system for a tractor, a working machine 2 is mounted on a tractor 1 so as to be liftable by a lift arm 17 there are provided a lift arm sensor 30 set on the lift arm 17 operating the working machine 2 liftably and a cover sensor 29 detecting the lift position of a working machine cover 23 covering the ground working mechanism 20 of the working machine 2 while an end of the cover 23 is in contact with the ground a cover plowing depth control is made based on a detected plowing depth value given by the cover sensor 29 so as to bring the plowing depth of the ground working mechanism 20 detected by the cover sensor 29 to a set plowing depth value a working machine position detection value detected by the lift arm sensor 30 is memorized, during the cover-plowing depth control, as a control reference value and thereafter, a lift control is made by the lift arm plowing depth control so that a working machine position detection value detected by the lift arm sensor 30 comes to the control reference value.COPYRIGHT: (C)2013,JPO&INPIT【課題】本発明では、トラクタの耕深自動制御装置において、安定した耕深を維持して作業を続けられるようにすることを課題とする。【解決手段】作業機2をリフトアーム17で昇降可能にトラクタ1に装着し、作業機2を昇降するリフトアーム17に設けるリフトアームセンサ30と端部が接地しながら作業機2の対地作業機構20を覆う作業機カバー23の昇降位置を検出するカバーセンサ29を設け、該カバーセンサ29の検出する対地作業機構20の耕深を設定耕深値となるようにカバーセンサ29の検出耕深値に基づくカバー耕深制御を行い、このカバー耕深制御の間にリフトアームセンサ30が検出する作業機位置検出値を制御基準値として記憶し、以後リフトアームセンサ30が検出する作業機位置検出値が制御基準値となるようにリフトアーム耕深制御で昇降制御してなるトラクタの耕深自動制御装置とする。【選択図】図3
