| 摘要 |
PURPOSE: A circular manhole cover with supplementary opening/closing member is provided to facilitate opening and closing operation by rotating a roller in a roller room. CONSTITUTION: A thick part(26) forms an incline(25) on the bottom side of a main body(21) of a circular lid(20). A roller room(27) is composed on a thick part center. A bracket is fixed in both side of the roller room. A roller(40) is located between the brackets. Part of the outer circumference of the roller extrudes to more outside than the roller room. |
