Cover for a manhole

Abstract

A cover ( 3 ) for mounting on a frame structure ( 1 ) associated with a manhole, the frame structure ( 1 ) having side walls defining a central opening there through, the cover ( 3 ) including: a cover member dimensioned to fit the central opening with a bottom surface of the cover member facing towards an interior of the manhole and a top surface ( 9 ) of the cover member facing away from the manhole, the cover member being moveable with respect to the frame structure ( 1 ) between a closed position, whereby the central opening is covered, and an open position, a lock mechanism for releasably locking the cover member in the closed position, the lock mechanism including one or more locking members ( 13 ) engagable with the frame structure ( 1 ) to thereby retain the cover in the closed position and a lock actuator connected to the locking members ( 13 ) for engaging and disengaging each locking member ( 13 ) with the frame structure ( 1 ), the lock actuator being accessible from the top surface of the cover member, the lock mechanism further including a restraining means for preventing actuation of the locking members ( 13 ) by the lock actuator, and a release actuator accessible from the bottom surface of the cover member for overriding the restraining means such that the locking members ( 13 ) can be disengaged from the frame structure ( 1 ) by operation of the release actuator

1 . A cover for mounting on a frame structure associated with a manhole, the frame structure having side walls defining a central opening there through, the cover including:
 a cover member dimensioned to fit the central opening with a bottom surface of the cover member facing towards an interior of the manhole and a top surface of the cover member facing away from the manhole, the cover member being moveable with respect to the frame structure between a closed position, whereby the central opening is covered, and an open position,   a lock mechanism for releasably locking the cover member in the closed position, the lock mechanism including one or more locking members engagable with the frame structure to thereby retain the cover in the closed position and a lock actuator connected to the locking members for engaging and disengaging each locking member with the frame structure, the lock actuator being accessible from the top surface of the cover member, the lock mechanism further including a restraining means for preventing actuation of the locking members by the lock actuator, and a release actuator accessible from the bottom surface of the cover member for overriding the restraining means such that the locking members can be disengaged from the frame structure by operation of the release actuator.   
   
   
       2 . A cover as claimed in  claim 1  wherein the lock actuator includes a rotatable member pivotally mounted with respect to the bottom surface of the cover member about a first pivot axis. 
   
   
       3 . A cover as claimed in  claim 2  wherein the rotatable member includes a capturing means for selectively engaging with the restraining means to thereby prevent angular movement of the rotatable member. 
   
   
       4 . A cover as claimed in  claim 3  wherein the capturing means is a notch in the rotatable member. 
   
   
       5 . A cover as claimed in  claim 4  wherein the restraining means is locatable in a restraining aperture which extends through the cover. 
   
   
       6 . A cover as claimed in  claim 5  wherein the restraining means is engageable with the notch in the rotatable member to thereby prevent angular movement of the rotatable member in a first direction. 
   
   
       7 . A cover as claimed in  claim 6  wherein the restraining means is engageable with release actuator to thereby prevent angular movement of the rotatable member in a second direction. 
   
   
       8 . A cover as claimed in  claim 2  wherein the release actuator is pivotally mounted to the rotatable member about a second pivot axis which lies perpendicular to the first pivot axis. 
   
   
       9 . A cover as claimed in  claim 8  wherein the release actuator can be pivoted about the second pivot axis in a direction away from the bottom surface of the cover member to thereby enable disengagement with the restraining member. 
   
   
       10 . A cover as claimed in  claim 9  wherein the release actuator can be pivoted about the first pivot axis when disengaged with the restraining member. 
   
   
       11 . A cover as claimed in any one of the preceding claims further including at least one seal breaking device for moving the cover member from the closed position when the locking members are disengaged from the frame structure. 
   
   
       12 . A cover as claimed in  claim 11  wherein the seal breaking device includes a lug for engaging with the frame structure, and a handle operatively connected to the lug. 
   
   
       13 . A cover as claimed in  claim 12  wherein when the cover is in the closed position, movement of the handle in a direction away from the bottom surface of the cover member forces the lug into abutment with the frame structure to thereby lever the cover member away from the frame structure. 
   
   
       14 . A cover assembly for a manhole, the cover assembly including:
 a frame structure having side walls defining a central opening there through, the frame structure being attachable to the manhole; and   a cover as claimed in any one of the preceding claims, the cover being pivotally mounted with respect to the frame structure such that the cover is moveable between the closed position and the open position.