Ball and Socket Hinge for Tool-Free Manhole Cover Removal
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Solution Overview
Problem
Existing manhole and hatch covers are difficult to remove and replace due to their weight and design, requiring brute force and often tools, and trench drain grates are cumbersome to access and maintain.
Innovation Solution
A ball and socket joint system that allows covers to be lifted with a lever and removed without tools, featuring a ball-shaped head that fits into a socket with additional features like parallel faces, bosses, and a guiding fin to restrict movement and facilitate easy removal and reinstallation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hinged cover is used to prevent partial unseating, then safety is improved, but the cover becomes difficult to remove and replace due to weight and design
Solution Approach 1:
The hinge connection is segmented into a ball head portion on the cover and a socket portion on the frame, allowing the cover to be detached by rotating it to a specific orientation where the ball head disengages from the socket, rather than requiring complete lifting against the hinge constraint
Solution Approach 2:
The hinge connection transitions from a static locked position to a dynamic removable position through rotational movement. The cover can be rotated to an orientation where the ball head clears the socket, enabling easy removal without lifting the full weight against the hinge constraint
2Ease of operation
If a T-shaped lug hinge is used, then the cover can be hinged to the frame, but the cover cannot be lifted with ordinary levers and requires brute force
Solution Approach 1:
The T-shaped lug is replaced with a spherical ball head that fits into a socket. This curved geometry allows the cover to be pried open with ordinary levers by exploiting the rotational pivot point, distributing the force required and eliminating the need for brute force lifting
3Reliability
If a lock mechanism is used to secure the cover, then security is improved, but the cover requires tools and time to remove
Solution Approach 1:
The complex lock mechanism is extracted and replaced with a simple ball-and-socket geometric constraint. The cover is secured by the interlocking geometry of the ball head and socket, but can be quickly removed by rotating the cover to disengage the ball from the socket, eliminating the need for tools and reducing removal time
4Strength
If bolts are used to fasten the cover to the frame, then the cover is securely attached, but removal is time-consuming and difficult due to damaged bolts and mechanical locking devices
Solution Approach 1:
The bolted mechanical fastening system is replaced with a geometric constraint system using the ball head and socket. The spherical ball fits into the socket to provide secure attachment through shape complementarity, while allowing easy removal by rotating the cover to disengage the ball from the socket, eliminating issues with damaged bolts and complex locking devices
Data Source
AI summary
A manhole or hatch cover assembly includes a frame defining an opening and a cover having a top surface, a bottom surface and a perimeter sized and dimensioned for receipt in the frame opening. The cover is coupled to the frame through a hinge connection and moveable between a closed positioned resting across the opening in the frame and an open position. A latch is pivotally coupled to the cover adjacent the hinge. The latch is selectively rotated onto the frame to retain the cover in the open position.