US Patent 7744304 Socket hinged construction casting assembly

A manhole or hatch cover assembly includes a frame defining an opening and a cover having a top surface, a bottom surface and a perimeter sized and dimensioned for receipt in the frame opening. The cover is coupled to the frame through a hinge connection and moveable between a closed positioned resting across the opening in the frame and an open position. A latch is pivotally coupled to the cover adjacent the hinge. The latch is selectively rotated onto the frame to retain the cover in the open position.