| 摘要 |
PROBLEM TO BE SOLVED: To eliminate defects that U-shaped portion of a pin is engaged with protrusions after insertion of the pin into engagement part to cause the protrusions to be damaged and dropped and in response to this damage, the pin may drop from the engagement part and additionally even if a protruded part of one pipe is not inserted into the engagement part, the pin can be inserted into the engagement part, so whether or not they are positively connected cannot be visually acknowledged.SOLUTION: A connected part of a pin is provided with an elastic deformation part, at least one of both insertion portions is formed with an outward curved omission stopper. When a pin is inserted into an engagement part under a state in which a protrusion is inserted into the engagement part, the omission stopper is engaged with the engagement part within the engagement part to prevent the pin from dropping out of the engagement part and at the same time, when the pin is inserted into the engagement part under a state in which the protrusion is not inserted into the engagement part, the extremity end of the pin insertion part is oscillated inwardly around the omission stopper part as a fulcrum point, so that the pin cannot be fully inserted into the engagement part. |
