| 摘要 |
PROBLEM TO BE SOLVED: To provide a manhole structure capable of securely preventing a manhole steel cover from opening due to a pressure of flowing water filled in a manhole. SOLUTION: A lock body 10 supported by a shaft part 12 so as to reciprocate and oscillate freely is arranged in a lower face part of the manhole steel cover 2. The lock body 10 is constituted such that a lock arm 16 protrudes onto a locking part 13 side provided on a manhole steel cover seat 1 and is locked in a locking part 13 by oscillating and energizing it onto the locking part 13 side by a weight 17. A pin 15a of a key receive part 15 of the lock body 10 is fitted into a key hole 20 of the manhole steel cover 2 to regulate the oscillation of the lock body 10. On the other hand, a manhole key K is inserted into the key hole 20 and the pin 15a is depressed against an energizing force of a spring 15c so that the pin 15a comes off the key hole 20, the lock body 10 oscillates, and the lock arm 16 comes off the locking part 13.
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