Highway manhole, has tool with lifting units recovering arm force when tool position is changed, to release device for raising or lowering grid when unit's upper part contacts with wall, and arms integrated in same piece with grid and frame

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).