| 摘要 |
The mechanism for prevention of theft of manhole cover includes two screws (3) passed through openings (1.1) made on the middle axis (1.2) of the cover (1) for the manhole (2). Over the screws (3) are pulled springs (4) so that they are loaded between the screw heads (3.1) and the butterfly nuts (5) that are screwed onto the screws (3) and secured by nuts (6). The butterfly nuts (5) are screwed onto the screws (3) which loads the springs (4) until the butterfly nuts (5) attain the level of the groove (2.1) made below the frame (8). The butterfly nuts (5) have stop screws (7). The cover (1) is placed on the frame (8) of the mancover (2) so that the butterfly screws (5) enter the grooves (2.1) below the frame (8). The eccentric key (9) is placed in the holes (3.2, 3.3) of the head (3.1) of the screw (3) and turned so that butterfly nuts (5) lean via the stop screw (7) against the frame (8). After that the butterfly nuts (5) are moved upwards, exerting pressure inside the groove (2.1) until the spring (4) attains sufficient force and presses fast the cover (1) against the frame (8). |
