| 摘要 |
<p>PROBLEM TO BE SOLVED: To stably deliver a cable without damaging the cable, while securing constant cable slackness. SOLUTION: A motor speed control circuit for changing the speed of a variable speed motor M by sliding moving a variable resistor 7 to change the output frequency of a variable frequency power source 6 which is the power source of the variable speed motor M using a reversible motor (m) is constituted, and three self-reset switches S1, S2, S3 which are successively cam-operated with respect to the upward movement of a turning arm 3 are provided. The variable speed motor M is started at a preset low speed by a switch S1 to be operated first through the upward movement of the turning arm as the cable slackness is reduced, forward/reverse power source input terminals m1, m2 respectively of the variable motor (m) are switched alternately in conductive connection with a power source B using the rest of two switches S2, S3, and the variable resistor is driven in the forward/reverse direction according to the cable slackness, so as to change the output frequency of the variable frequency power source. An electric cable 1 can be delivered with prescribed slackness from a drum by controlling the rotational speed of a drum 2 through the variable speed motor M.</p> |
