Manhole Cover Latch Mechanism for Pressure Dissipation
Solution Overview
Problem
Manhole covers can be dislodged by sudden pressure increases from events like explosions or flooding, potentially causing damage and safety hazards, and are also vulnerable to vandalism due to their value as scrap metal.
Innovation Solution
A manhole cover assembly with a latch and lug system that allows controlled displacement during pressure events, preventing the cover from being launched and facilitating easy removal and reinstallation, while using extractor rails and a skid pad for safe handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a heavy cast iron manhole cover is used, then it is strong and difficult for unauthorized individuals to remove, but it can be dislodged by explosions or flooding causing safety hazards
Solution Approach 1:
The manhole cover assembly incorporates a latch mechanism with movable components (latch member, latch yoke, spring) that allow the cover to dynamically respond to pressure events. The latch member can transition between locked and unlocked positions, enabling the cover to remain secure during normal conditions while automatically releasing during explosions or flooding events.
Solution Approach 2:
The latch mechanism acts as an intermediary between the manhole cover and the frame. It provides a controlled interface that allows the heavy cover to be securely held in place during normal operation while enabling safe, controlled displacement during pressure events, preventing the cover from being launched into the air.
2Stability of the object's composition
If a heavy cast iron manhole cover is used, then it stays in place during traffic, but it can be launched up to 20 feet into the air during high-intensity explosions
Solution Approach 1:
The latch mechanism transforms the static, stable manhole cover into a dynamic system that can respond to changing conditions. The spring-loaded latch member automatically transitions the cover from a stable locked state to an unlocked state when pressure events occur, controlling the cover's displacement and preventing it from becoming a dangerous projectile.
Solution Approach 2:
The latch mechanism provides beforehand cushioning by being pre-configured in a locked position that secures the cover during normal traffic loads. During pressure events, this pre-configured mechanism activates to control and cushion the cover's displacement, preventing catastrophic launch while allowing safe pressure release.
3Reliability
If the manhole cover is made secure and heavy, then unauthorized access is prevented, but it requires significant effort for legitimate removal and reinstallation
Solution Approach 1:
The latch mechanism introduces dynamic elements (movable latch member, spring, latch yoke) that enable easy operation during legitimate maintenance. The spring-loaded system allows the latch to be easily engaged and disengaged with simple manual manipulation, while maintaining strong security during normal conditions through its automatic locked position.
Data Source
AI summary
A manhole cover assembly includes a manhole cover supportable by a manhole frame. The manhole cover defines a latch bore having a longitudinal axis. A latch housing extends from the manhole cover, and a latch assembly is positioned at least partially therein. A first end of a latch yoke extends through the latch bore and slidably couples the latch yoke to the manhole cover along the longitudinal axis. A latch member is rotatably coupled to the second end of the latch yoke about a first transverse axis perpendicular to the longitudinal axis. The latch member is also rotatably coupled to the latch housing about a second transverse axis spaced from the first transverse axis. The latch member is selectively rotatable relative to the latch housing about the second transverse axis, between a locked position and an unlocked position, via sliding the latch yoke relative to the manhole cover.