| 摘要 |
The manhole (1) has a closing device (2) including anchoring units with inner sides formed of inclined lower and horizontal upper surfaces co-operated with respective lateral inclined and horizontal upper and lower surfaces of a stop element. A pocket type portable closing/opening tool has lifting units which recover elastic force of hook shaped elastic arms (7) when a tool position is changed, for releasing the device to raise/lower a grid (5) when a lifting unit's upper part contacts with a passage's lower wall. The arms are integrated in a same piece with the grid and a fixed frame (4). |
