| 摘要 |
PROBLEM TO BE SOLVED: To efficiently mount an air duct which is set during execution of tunnel construction, into an air duct cassette. SOLUTION: There is provided an air duct shortening apparatus which is comprised of a cassette mounting stand 4 on which the air duct cassette 2 is mounted, a gripping ring 5 for gripping the air duct 1, and a cylinder 7 for drawing the air duct 1 to the side of the air duct cassette 2 via a wire 6 connected to the gripping ring 5.
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