| 摘要 |
PROBLEM TO BE SOLVED: To prevent the backlash of a side drain body and a side drain lid and springing up of the side drain cover by forming a slope or a curved surface that a corner formed by a horizontal lid engagement portion and an internal wall point contacts by the cross section at the bottom of the side drain lid. SOLUTION: The slope 12 of a side drain body 1 forms an obtuse angle, namely an angleθ3 greater than 90 degrees and smaller than 180 degrees. A nearly perpendicular corner 7 of the end of a horizontal lid engagement portion 3, namely a corner 7 formed by the horizontal lid engagement portion 3 and the inwall may point contacts a continuous corner 13 between the first slope and the second slope by its cross section. The side drain lid 11 is mounted to the side drain body 1, retaining fixed clearances 4 and 5 on the right and left sides of the horizontal lid engagement portion 3. In the clearances 4 and 5, dust or the like enters and thereby functions as a kind of a cushion material or a buffer material, thereby preventing backlash or spring up of the side drain lid without specially providing a cushion material or a buffer material.
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