| 摘要 |
<p>A frame member for road surface installations has a rectangular frame with a circular opening to receive circular cover members which can be used for catch basins, for manholes, and other road surface aperture covers e.g. valve chamber covers. The circular cover member may be imperforate, or perforate, with openings or with slots. A standardized frame member may be employed with various forms of structurally distinct cover members, so that a stock of standardized frames and various distinct cover members can be provided. An annular seat surface on the frame member and the matching surface on the cover member which is received on the seat surface can be machined surfaces that will fit accurately so that the cover member will not wobble relative to the frame member and is exposed to less risk of fracture.</p> |
