Patent ID: 8206058

Claim:
A manhole cover assembly comprising: a frame having a peripheral wall defining an access opening; first and second frame extensions adjacent said peripheral wall, said first and second frame extensions each including a sidewall and a floor; a first cover mount post extending from said sidewall of said first frame extension and a second cover mount post extending from said sidewall of said second frame extension, said first and second cover mount posts positioned above said floors of said first and second frame extensions such that said posts are sealed from said access opening; a manhole cover including first and second mounting tabs, said first mounting tab defining a recess receiving said first cover mount post, said second mounting tab including a recess receiving said second cover mount post, said first and second mounting tabs rotating about said first and second cover mount posts between a closed position covering said access opening and an open position providing access to said access opening, wherein said first cover mount post extends into said first mounting tab recess in said closed position and said open position, and said second cover mount post extends into said second mounting tab recess in said closed position and said open position; and wherein said first mounting tab recess includes a first portion shaped to allow said first mounting tab to rotate about said first cover mount post, and a locking groove extending from said first portion of said first mounting tab recess, said first cover mount post sliding from said first portion into said locking groove when said cover is moved to said open position to lock said cover in said open position, wherein said first cover mount post includes an outer surface having opposing parallel surfaces extending in a first direction, said first direction being parallel to said cover in said open position, wherein said locking groove includes opposing sides extending generally in said first direction, wherein said second mounting tab recess is shaped differently than said first mounting tab recess, such that said locking groove is exclusive to said first mounting tab recess.