Improvements in cover-plates, especially for cable-channels

摘要

269,920. Tutsch, R. April 23, 1926, [Convention date]. Manhole covers. - A cover plate for cable channels or pipe conduits in floors comprises an angle-iron frame 1 closed at the bottom by a corrugated metal sheet 2 and filled with a plastic insulating material 5 such as xylolith, concrete, or asbestos fibres. Embedded plates 4 riveted to the sheet 2 serve to receive lifting keys.