Patent ID: 8292540

Claim:
A manhole assembly comprising: a frame and at least a pair of cover plates that are receivable in and disengageable from the frame to permit selective closing and opening of an aperture, the periphery of which is defined by the frame, the cover plates substantially occupying the aperture when received in the frame; a first cover plate of the pair being smaller than a second cover plate of the pair; the first cover plate being hingeable relative to the second cover plate, while the second cover plate is received in the frame, by a hinge system interconnecting the first and second cover plates so as to permit movement of the first cover plate relative to the second cover plate, from a closed position received in the frame to an open position in which a first part of the aperture is open, by a movement of the first cover plate from a first orientation via a second orientation to a third orientation relative to the second cover plate; and the second cover plate being removable from the frame, when the first cover plate is disengaged from the frame, to open a second part of the aperture, wherein the hinge system includes a tongue and a pocket, the tongue being receivable in the pocket, and the hinge system being formed so as to permit: a. rotatable retention of the tongue relative to the pocket when the first cover plate occupies at least the first orientation relative to the second cover plate; and b. separation of the first cover plate from the second cover plate when the first cover plate occupies the second or third orientation relative to the second cover plate.