JP2869268B

PURPOSE:To make it possible to prevent a tilling device from sinking even if field is muddy and prevent excess load to engine and to enable tilling depth control in good accuracy even in the case where set tilling depth is changed halfway. CONSTITUTION:Difference and changing ratio between standard number of revolution of engine 10 indicated when a rotary tiller 2 is lowered to a prescribed tilling depth and number of revolutions of engine changed according to tilling operation are operated and the value of the set target tilling depth is corrected based on characteristics preliminarily determined from the difference and the changing ratio and thus control of tilling depth is carried out, and when it is detected that the prescribed tilling depth by tilling depth setting device PM2 changed, data correcting operation is stopped and then the number of revolutions of engine indicated when the tiller 2 is lowered to the prescribed tilling depth after the change is reset as the standard number of revolutions.