| 摘要 |
In a manhole/access cover and frame assembly the cover is supported on the frame by pairs of downwardly facing, oppositely inclined support surfaces on the cover which are engageable respectively with corresponding upwardly facing, oppositely inclined support faces on the frame, and the cover has a substantially continuous downwardly facing ridged peripheral sealing surface which, when the cover is supported on the frame, overlies a substantially continuous upwardly facing ridged peripheral sealing surface on the frame. The engagement between the aforesaid support surfaces so locates the cover with respect to the frame that ridges on the sealing surfaces are interleaved but are held out of supporting contact with one another along substantially the whole of their length, so that the tortuous path between the ridges may be packed with grease to provide a gas and water tight seal. |
