| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent breakage of a buried article by converting lowering speed of a wire by lowering of a boom to rotational speed, finding the lowering speed from the rotational speed and when the lowering speed is higher than a specified value, stopping rotation of a rotation axis. SOLUTION: A hole is drilled by rotating an earth auger 4 of a pillar construction machine 1, and a boom 3 is lowered. Thereafter when a wire 17 moves downward by weight of a dead-weight in accordance with lowering of the boom 3, a pulley 18 is rotated. Thereafter, rotational moving quantity of the pulley 18 is enlarged by an enlarging gear 19, converted to an electric signal by an encoder and transmitted to a speed indicator. Then, lowering speed of the wire 17 is computed by a computing part of the speed indicator and it is compared with a lowering speed critical value by a comparison part. Additionally, in the case when the lowering speed of the wire 17 is higher than the lowering speed critical value, a signal is output from the speed indicator to a buzzer and earth auger drive device, and simultaneously when an alarm is generated, the auger 4 is stopped.</p> |
