| 摘要 |
<p>This device is composed of a closure member (3) which comprises at least one, and preferably two, juxtaposable walls (30, 31) which have the general shape of cylindrical arcs of vertical axis and with a (total) arc length of the order of 180 DEG , the height of which corresponds to that of the opening (O), and which can rotate about a vertical axis (ZZ') coinciding with their own axis and corresponding to the axis of vertical symmetry of the opening (O), such that the said walls (30, 31) can, as desired, either be brought by rotation into a position in which they are inscribed in the opening (O), completely closing it and being located in the said outer space (EE), or be brought into the said inner space (EI). Equipment for building. <IMAGE></p> |
