| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel roof gate applicable to a channel having an inverted trapezoidal cross section by solving a technical problem that a cross section of a channel possible to be provided with a steel roof gate is limited to rectangle. SOLUTION: Dimension of a clearance between a rectangular door body of a main roof gate provided in a part having a constant depth at a central part of the channel formed with the inverted trapezoidal cross section and a side end of a triangle door body of an auxiliary roof gate provided in a bank is formed to be changed in response to rise and fall of the roof gate by expanding and shrinking an air bag provided in the clearance.
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