Lift-assisted manhole cover

Abstract

A lift-assisted manhole cover assembly with a flush surface and external pivot shaft. The cover includes a mounting tab that extends beyond the general periphery of the cover. The mounting tab may be connected to a shaft that is threadedly engaged with the frame. A spring may be mounted between the frame and the mounting tab, for example, in a sleeve, to provide a mechanical assist in lifting the cover. The sleeve may be disposed outside the manhole opening where it does not block access to the manhole opening.

1 - 7 . (canceled) 
   
   
       8 . A lift-assisted manhole cover assembly for covering a manhole comprising:
 a manhole frame having a peripheral wall defining an access opening and having a cover flange;   a cover fitted within said peripheral wall upon said cover flange, said cover being substantially flush with said peripheral wall, said cover being pivotally mounted to said frame at a pivot point outside said access opening; and   a lift assist positioned outside said access opening for lifting said cover from within said peripheral wall of said manhole frame, and wherein said lifted cover is rotatable along a plane substantially parallel to said cover flange about said pivot point.   
   
   
       9 . The lift-assisted manhole cover assembly of  claim 8  wherein said frame and said cover are substantially uniform with at least one of a road and walkway. 
   
   
       10 . The lift-assisted manhole cover assembly of  claim 8  wherein said lifting element includes a threaded shaft and said lift-assisted manhole cover further includes a frame supplement outside said peripheral wall having a hole for threadingly securing said shaft to said frame supplement. 
   
   
       11 . The lift-assisted manhole cover assembly of  claim 10  wherein said shaft includes a locking structure for securing said shaft to said cover, whereby tilting of said cover about said shaft is substantially resisted and linear movement of said shaft is substantially translated into linear movement of said cover. 
   
   
       12 . The lift-assisted manhole cover of  claim 10  wherein said shaft includes a mechanical stop, whereby movement of said shaft with respect to said frame is limited. 
   
   
       13 . The lift-assisted manhole cover of  claim 12  wherein position of said mechanical stop may be selected to adjust a maximum cover height. 
   
   
       14 . The lift-assisted manhole cover of  claim 10  wherein said shaft includes a head and a locking structure sandwiching said cover to secure said shaft to said cover, whereby said cover is held substantially perpendicular to said shaft. 
   
   
       15 . The lift-assisted manhole cover of  claim 10  wherein said lifting element further includes a spring. 
   
   
       16 . A manhole cover assembly comprising:
 a manhole frame including an integrally formed boss that defines a threaded opening;   a manhole cover; and   a threaded shaft rotatably mounted to said cover and threadedly engaging said threaded opening in said integrally formed boss of said manhole frame, wherein said threaded shaft moves substantially axially with respect to said manhole frame.   
   
   
       17 . The manhole cover of  claim 16  further comprising:
 a spring disposed between said manhole frame and said manhole cover for biasing said cover away from said frame.   
   
   
       18 . The manhole cover of  claim 16  wherein said threaded opening comprises a counter bored hole to facilitate rotatably mounting said shaft to said cover, whereby said shaft is substantially flush with said manhole cover. 
   
   
       19 . The manhole cover of  claim 16  further comprising:
 an upper pin disposed through said shaft to assist in reducing shaft movement relative to said cover.   a lower pin disposed through said shaft at a selected position, whereby said lower pin prevents said cover from lifting past said selected position.   
   
   
       20 . The manhole cover of  claim 16  wherein said manhole frame includes a frame supplement with said threaded opening, said frame supplement disposed outside said manhole frame.