To solve such a problem in an automatic horizontal control device making the vehicle height of a machine body constant based on the set reference vehicle height that the horizontal control device is stopped in the middle when automatic control is switched to manual control while the reference vehicle height cannot be maintained during the automatic control, then the reference vehicle height is reset to the vehicle height not maintained at the reference vehicle height if the manual control is again switched to the automatic control in this state, thus the reference vehicle height is changed against the intention of an operator.
The initial value set in advance is read to set the reference vehicle height when a key is turned on, and the vehicle height is controlled to the reference vehicle height during the automatic control operation.
NOSAKA AKIRA
ITOHARA ATSUYA
