Pressure Responsive Locking Latch Arrangement For Manhole Covers

摘要

A manhole cover assembly including a pair of perimeter lugs attached by a mounting to the underside of the manhole cover engaging a feature on a vault frame having an opening receiving the manhole cover upon rising up of the manhole cover in response to development of a pressure condition in the vault in order to relieve the pressure at least one of the lugs mounted to a pivotal member accessible from above the cover to be able to be rotated to rotate a projecting portion to either be aligned with a stop feature on the frame opening which is engaged when the cover rises up or to clear the stop feature allowing removal of the cover.;A resiliently compressible constituent of the mounting generates an increasing resilient force acting on the manhole cover as it rises to cushion the stopping of the cover and to control its height of rise venting the pressure in the chamber.

主权项

1. A manhole cover assembly adapted to be received in an opening in a frame enclosing a vault chamber, comprising:
a manhole cover fit into an opening defined by said frame; a pair of lugs mounted to an underside of said manhole cover on opposite sides thereof each lug having a portion projecting radially out from a perimeter of said manhole cover in at least one position thereof so as to engage a fixed feature of said frame located beneath said cover receiving frame opening so as to prevent said cover from being moved up and free of said frame; at least one of said lugs connected to a lower part of a pivotable member having an upper end projecting up through said manhole cover so that said upper end is engageable to be able to be rotated and cause rotation of said lug therewith to or from said position with said portion projecting radially out, with said portion of said lug not projecting radially out in an alternate position in which said lug radially clears said fixed feature of said frame to allow said manhole cover to be moved up and out of said frame opening.