Capture Block Assembly for Wire Rope Sling Shackles
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Solution Overview
Problem
Conventional wire rope sling assemblies face issues with unauthorized swapping or replacement of shackles, which compromises safety and traceability, and existing methods for securing shackles within thimbles require welding before assembly, potentially damaging the wire rope.
Innovation Solution
A capture block assembly comprising two identical half members with concave surfaces and transverse bores, secured by fasteners, is installed within the thimble after shackle installation, preventing shackle removal without observable damage, thus ensuring permanent fixation and maintaining wire rope integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding is used to secure the shackle within the thimble before assembly, then the shackle is permanently fixed and cannot be removed, but the heat from welding damages the wire rope and changes its strength properties
Solution Approach 1:
The capture block is divided into two separate half-members that are installed independently within the thimble. This segmentation allows the capture block to be assembled after the shackle is in place, eliminating the need for pre-assembly welding that would damage the wire rope.
Solution Approach 2:
The capture block half-members are prepared in advance with concave surfaces and fastener holes, but the actual assembly action is delayed until after shackle installation. This preliminary preparation enables post-assembly installation without requiring welding on the wire rope.
2Ease of operation
If the shackle can be easily removed and replaced, then component replacement is simple and quick, but unauthorized swapping compromises safety and traceability
Solution Approach 1:
The capture block half-members are simple, inexpensive components that can be easily installed and removed as a pair. While individual shackles remain secured, the capture block itself can be replaced if needed, providing a cost-effective solution to prevent unauthorized shackle swapping.
3Reliability
If a capture block is installed to prevent shackle removal, then shackle replacement is prevented, but the installation complexity increases
Solution Approach 1:
Dividing the capture block into two simple half-members reduces manufacturing complexity compared to a single complex locking mechanism. Each half-member is a simple block with a concave surface and fastener hole, making them easier to manufacture and install.
Solution Approach 2:
Instead of trying to prevent shackle removal through complex locking mechanisms, the invention inverts the approach by using a simple capture block that physically blocks removal. The simplicity of the block design outweighs the complexity of traditional locking mechanisms.
Data Source
AI summary
A capture block assembly prevents unauthorized removal, swapping, interchanging or replacement of shackle members used with conventional wire rope sling assemblies. A first half member is permanently joined with a second half member within a thimble member of a sling loop, after a wire rope sling has been manufactured or assembled, to prevent removal of a shackle from such loop. No welding or other operations permanently affecting strength properties of the thimble or sling member is required.