| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device for opening and closing a manhole lid safely and easily by a little force and by one person. SOLUTION: A square manhole lid 2 provided in a manhole opening part is vertically lifted up to a predetermined height by driving a pair of left and right hydraulic jacks 32, 49 provided on both left and right outer sides of the manhole lid 2. After that, the manhole lid 2 is rotated in outer direction using an outer side of its front side or rear side as the center of rotation by further driving the hydraulic jack 32 on one side which is connected by the manhole lid 2 and a traction member 46 to open the opening part of a manhole M.
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