| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to tense up a string to an arbitrary intensity while preventing a slack of the string by providing the inside of a case having an oblique side with a bridge having a through-hole turnably via a ratchet mechanism, projectingly providing the outside of a case with a revolving shaft coaxial with the bridge and tightening the string while preventing the reverse rotation by the tension of the string wound around the bridge. SOLUTION: In the case 1, one piece of a hollow rectangular parallelepiped made of a metal having oppositely facing open parts is formed on the oblique side. A supporting shaft 2 is installed in proximity to the diagonal portion of the case and the center of the supporting shaft 2 is bored with the through- hole 3. The inside of the case 1 is turnably provided with the bridge 4 in the direction orthogonal with the supporting shaft 2. A ratchet plate 6 is formed by circumferentially boring the outer periphery of a metallic disk with many pieces of the slant portions of a specified direction. The ratchet plate 6 is coaxially mounted at one end of the bridge 4. A revolving shaft 7 is a square shaft fixed to the center at the end face of the bridge 4 and the end thereof is projectingly disposed through the hole formed at the case 1.
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