| 摘要 |
PROBLEM TO BE SOLVED: To provide a manhole structure with a locking mechanism which positively protects a manhole cover from being opened without permission, prevents the deposition of sediment in a space between a claw bar hole and a blocking piece, and the wobbling of a closing plug when a lock is released, and always allows smooth lock releasing operation. SOLUTION: The locking mechanism is formed of a lock weight 11, the closing plug 12, a spring 13, an engaging claw 14 formed on the inner surface of the cover bearing frame 1, etc. The lock weight 11 is formed of a forked hanging arm 19 with a pair of rocking shafts 18, a lock base 20 and a lock claw 21, and a spring bearing arm 22 projecting diagonally downward. The closing plug 12 is formed of a blocking piece 31 for blocking the claw bar hole 5, a slide shaft 32 projecting from the lower surface of the blocking piece 31, a stopper piece 33, etc. Then a slide shaft 35 is vertically slidably guided and supported in a guide groove 26 formed in the vicinity of the rocking shafts 18, and held by a restriction rod 38 in a manner of being incapable of lifting upward. COPYRIGHT: (C)2008,JPO&INPIT
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