Corrosion-Resistant Self-Locking Manhole Cover

A corrosion resistant self-locking manhole cover, comprising:

• a nonmetallic corrosion-resistant cover plate adapted to rest on a manhole cover support surface of a manhole frame so as to be substantially flush with a top portion of said manhole frame and a surrounding surface in which said manhole frame is situated;
• a first nonmetallic corrosion-resistant locking member on said cover plate that is movable between a locked position in which said first locking member is 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, and an unlocked position in which said first locking member is not adapted to engage said manhole frame;
• a second nonmetallic corrosion-resistant locking member on said cover plate that is movable between a locked position in which said second 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 second locking member is not adapted to engage said manhole frame;
• a spring mechanism adapted to bias said first locking member and said second locking member to said extended position;
• an aperture in said cover plate;
• a fitting in said cover plate aperture having a metallic rotatable lock bolt with a nonmetallic corrosion-resistant exterior on a bottom side of said cover plate;
• a first drive arm operatively driven by said rotatable lock bolt, said first drive arm operatively engaging said first locking member and having a locking rotational position wherein said first locking member is in said extended position and an unlocking rotational position wherein said first locking member is in said retracted position;
• a second drive arm operatively driven by said rotatable lock bolt, said second drive arm operatively engaging said second locking member and having a locking rotational position wherein said second locking member is in said extended position and an unlocking rotational position wherein said second locking member is in said retracted position;
• said rotatable lock bolt comprising a security lock disposed in said cover plate aperture and adapted to receive a security key tool that applies a rotational torque to said locking pin actuator;
• a nonmetallic corrosion-resistant latch arm operatively driven by said rotatable lock bolt;
• a nonmetallic corrosion-resistant latch on said cover plate adapted to releasably retain said drive arm in said unlocking rotational position without said security lock being engaged by said security key tool;
• and
• a quick-latch mechanism operable without using a key or other tool to release said locking members from their unlocked position to allow said locking members to return to their locked position.

A corrosion resistant self-locking manhole cover, comprising:

• a nonmetallic corrosion-resistant cover plate adapted to rest on a manhole cover support surface of a manhole frame so as to be substantially flush with a top portion of said manhole frame and a surrounding surface in which said manhole frame is situated;
• a first nonmetallic corrosion-resistant locking member on said cover plate that is movable between a locked position in which said first locking member is 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, and an unlocked position in which said first locking member is not adapted to engage said manhole frame;
• a second nonmetallic corrosion-resistant locking member on said cover plate that is movable between a locked position in which said second 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 second locking member is not adapted to engage said manhole frame;
• a spring mechanism adapted to bias said first locking member and said second locking member to said extended position;
• an aperture in said cover plate;
• a fitting in said cover plate aperture having a metallic rotatable lock bolt with a nonmetallic corrosion-resistant exterior on a bottom side of said cover plate;
• a first drive arm operatively driven by said rotatable lock bolt, said first drive arm operatively engaging said first locking member and having a locking rotational position wherein said first locking member is in said extended position and an unlocking rotational position wherein said first locking member is in said retracted position;
• a second drive arm operatively driven by said rotatable lock bolt, said second drive arm operatively engaging said second locking member and having a locking rotational position wherein said second locking member is in said extended position and an unlocking rotational position wherein said second locking member is in said retracted position;
• said rotatable lock bolt comprising a security lock disposed in said cover plate aperture and adapted to receive a security key tool that applies a rotational torque to said locking pin actuator;
• a nonmetallic corrosion-resistant latch arm operatively driven by said rotatable lock bolt;
• a nonmetallic corrosion-resistant latch on said cover plate adapted to releasably retain said drive arm in said unlocking rotational position without said security lock being engaged by said security key tool;
• and
• said first locking member and said second locking member being respectively carried by first and second locking mechanisms that are secured to said cover plate using flanged anchors that are each mounted in a stepped bore that extends from an upper cover plate surface to the lower cover plate surface.

A self-locking manhole cover, comprising:

• a cover plate adapted to rest on a manhole cover support surface of a manhole frame so as to be substantially flush with a top portion of said manhole frame and a surrounding surface in which said manhole frame is situated;
• an anchor on said cover plate 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 on said cover plate 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;
• and
• quick-latch mechanism operable without using a key or other tool to release said locking member from its unlocked position to allow said locking member to return to its locked position.