| 摘要 |
PROBLEM TO BE SOLVED: To secure the grasping amount by judging the grasping amount of a bucket from driving current at the time of winding-up by a grasping amount judging part and adjusting the winding-down amount at the time of sinking by a winding-down amount adjusting part according to the grasping amount. SOLUTION: At the time of sinking after the second time and succeeding times, a previous time winding-down amount arithmetic circuit 71 already obtains the winding-down amount at the time of previous time sinking. A motor speed command arithmetic circuit 72 obtains a motor speed command at the time of this time sinking by multiplying a motor speed command at the time of previous time sinking by an increase variable K3. This motor speed is imparted to a motor 4. When the grasping amount of the previous time is insufficient, the rope length paid out within winding-down time becomes longer than that at the previous time and the winding-down amount is increased because the motor speed command of this time is increased more than that of the previous time. Therefore, the biting amount of a bucket 1 into a load is increased and the grasping amount of this time is increased. This grasping amount of this time is judged by a gasping amount judging part 6 at the time of winding-up and is utilized for the next time sinking.
|
