Patent ID: 9115479
Filing Date: 2015-08-25
Classification: E02D

Abstract:
1. A corrosion-resistant self-locking manhole cover, comprising: a cover plate comprising nonmetallic corrosion-resistant material having an upper side and a lower side, said lower side being adapted to rest on a manhole cover support surface of a manhole frame so that said upper side is substantially flush with a top portion of said manhole frame and a surrounding surface in which said manhole frame is situated; an anchor mounted on said cover plate lower side, said anchor comprising nonmetallic corrosion-resistant material, said anchor being adapted to engage said manhole frame at a first location in a manner that resists lifting of said cover plate proximate to said first location; a locking member mounted on said cover plate lower side, said locking member comprising nonmetallic corrosion-resistant material, said locking member being movable between a locked position in which said locking member is adapted to engage said manhole frame at a second location in a manner that resists lifting of said cover plate proximate to said second location, and an unlocked position in which said locking member is not adapted to engage said manhole frame; metallic components associated with said anchor and said locking member to perform mounting functions, rotary drive functions, and biasing functions, each of said metallic components comprising either a corrosion-resistant metal that is exposed to environmental gases or a metal that need not be corrosion-resistant but is sealed against exposure to environmental gases; said metallic components to perform mounting functions comprising fasteners securing said anchor and said locking member to said cover plate lower side, said fasteners being made of metal and having fastener heads sealed within associated counterbores with sealing plugs, said counterbores and said sealing plugs being made of non-metallic corrosion-resistant material in order to seal said fastener heads against exposure to environmental gases, said sealing plugs being removable to allow access to said fastener heads; said metallic components to perform latching functions comprising a rotary drive mechanism operable to move said locking member between said locked position and said unlocked position, said rotary drive mechanism comprising a rotatable security lock bolt made of metal, said security lock bolt having a security lock face on said cover plate upper side to receive a security key, and a shank that extends below said cover plate lower side, said shank receiving a metallic nut to secure said security lock bolt to said locking member and said cover plate lower side, and said shank and said nut being covered by components made of non-metallic corrosion-resistant material in order to seal said shank and said nut against exposure to environmental gases, said components including an end cap that is removable to allow access to said nut; and said metallic components to perform biasing functions comprising a biasing mechanism below said cover plate lower side operable to bias said locking member to said locked position, said biasing mechanism comprising one or more springs made of corrosion-resistant metal and being exposed to environmental gases.