| 摘要 |
PROBLEM TO BE SOLVED: To grasp the required length of a coil clearly at a glance by making up a chain coil for stringing a cable of an expandable coil structured by forming a synthetic resin linear substance into a continuously spiral shape, and by providing markings at constant intervals in the longitudinal direction on the outside circumference of the coil. SOLUTION: A chain coil 10 for stringing a cable is structured with a freely expandable coil that is prepared by continuously forming synthetic monofilaments in a spiral shape, and markings 11 are provided at constant intervals in the longitudinal direction on the outside circumference of this coil. Specifically, the marking 11 is provided every five pitches as a constant number of coil windings L1 of the coil 10. The distance L1 for the five pitches is equivalent to an interval of three centimeters. When ten pieces of this coil 10 are extended at the coil pitch of 28 cm, it corresponds to the extension distance of approximately 15 m. As a result, the required length of the coil can be grasped clearly at a glance, and the safety and efficiency of work can be improved.
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