| 摘要 |
<p>A draft control apparatus for lifting and lowering an agricultural machine, such as a plow, which is attached to a tractor via a hydraulic lift unit, in such a manner that a plowing depth set in advance by a plowing depth setting device in accordance with an increase and decreased in the traction resistance detected by a draft sensor can be attained. When the lift unit for the agricultural machine is shifted from a lifting position to a lowering side, the agricultural machine is lowered suddenly with the draft control operation interrupted for a predetermined short period of time or by a predetermined short distance. When the relation between a detected value from the draft sensor and a set value from the plowing depth setting device is not on the agricultural machine lowering side, this sudden lowering operation is not carried out. Therefore, when the agricultural machine is lowered, it is driven into the earth excellently, and, moreover, it does not float above the ground surface after it has been driven into the earth.</p> |
