| 摘要 |
PROBLEM TO BE SOLVED: To facilitate the installation of a passage preventive device with a hydraulic driving device, the restoration of its damage or the like. SOLUTION: The passage preventive device is composed of a bottomed cylindrical base member 14 being set in a ground and having an opening 14' facing outside the ground, a passage preventive member 15 capable of being lifted and lowered between a passage preventive place extended to the upper section of the opening 14' of the base member and a passage permissible place lower than the passage preventive place, a hydraulic type movable member (a piston cylinder) 20 being set in the cylindrical base member 14, being continuously contacted with the passage preventive member 15 and lifting and lowering the passage preventive member 15 and the hydraulic driving device 18 with a driving hydraulic power source (a hydraulic pump) 22 for driving the hydraulic type movable member.
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