| 摘要 |
The invention relates to a locking device to be mounted in the space between a cover (11) or grate and a surrounding frame (12) in openings in water and sewage systems and that prevents unauthorised opening. The locking device comprises two first elements (1), identical and put inverted to each other and on one side provided with friction element (5) of resilient material. In their lower edge the metal elements have outwardly bent flanges (3), extending to half the width of the element, which catch under the lower edge of respective elements when they are put together and inserted in the space. The upper part of the elements is bent outwardly to a second flange (4) in the opposite direction to the first flange (3). A second metal element (6) is inserted between the two first elements and expands the device, whereby the friction elements are compressed and cause extensive friction force against the walls of the space (11, 12).
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