Manhole cover sealing and locking arrangement

A manhole assembly comprising, in combination:

• (a) a centrally apertured frame member (1) upstanding from a base plate (8) and defining a radially inwardly extending support flange (11),
• (b) a cover member (2) seated on said support flange for closing said aperture,
• (c) a compressible sealing ring (G1;
• G3) interposed between the frame member and the cover member,
• (d) a plurality of independent and individual clamping flanges (4) separate and distinct from the frame member and evenly distributed around a periphery thereof, each clamping flange having a generally central aperture, a clamping edge (10) extending radially outwardly from said aperture a first distance and adapted to overhang the frame member support flange and bear directly against the cover member when the clamping flange is in a first position, and a flattened edge angularly displaced from the clamping edge, extending radially outwardly from the aperture a second distance shorter than the first distance, and adapted to lie clear of the cover member when the clamping flange is in a second position, and
• (e) an equal plurality of fixing means (3) separate and distinct from the frame member for individually securing the clamping flanges to the frame member via the apertures such that the clamping flanges may be locked in said first position whereat they bear vertically downwardly against the cover member to urge the cover member against the support flange and thereby prevent any vertical movement of the cover member upon the passage of vehicles over the manhole assembly, and wherein the fixing means may be loosened to unlock the clamping flanges and enable their rotation to said second position whereat the cover member is removable from the frame member without necessitating the removal of the fixing means and the clamping flanges.