Flexible Rope Coupling Structure for Lighter Load Handling and Safe Failure

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Solution Overview

Problem

Existing coupling devices, particularly metal shackles, are heavy, bulky, and difficult to handle manually, posing safety risks and storage challenges, and their failure can result in catastrophic consequences due to stored energy release.

Innovation Solution

A coupling device comprising a flexible elongate member made of multiple windings of rope, secured to a pin, allowing for a smaller and lighter design that distributes load failure to the rope rather than the pin, using materials like UHMWPE and aramid fibers for strength and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal shackles are used for heavy load coupling, then strength and load-bearing capacity are improved, but weight and bulkiness increase significantly

Engineering Contradiction:

Improveload-bearing capacityVSAvoidweight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent employs composite construction by combining steel wire ropes (providing tensile strength) with synthetic materials such as polyethylene or polypropylene sheathing (providing protection and reducing weight). This composite approach allows the coupling device to achieve high load-bearing capacity while significantly reducing weight compared to solid metal shackles

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent replaces rigid metal shell structures with flexible rope constructions that can bend and conform to loading conditions. The steel wire rope core provides structural integrity and strength, while the flexible nature allows for reduced material usage and weight compared to rigid metal equivalents

Inventive Principle:

Principle #30Flexible shells and thin films

2Strength

If metal shackles are designed for heavy loads, then strength is improved, but ease of operation deteriorates due to difficulty in manual handling

Engineering Contradiction:

Improveload-bearing capacityVSAvoidmanual handling

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The flexible rope construction allows the coupling device to be bent, folded, and maneuvered easily by hand, unlike rigid metal shackles that require tools and multiple persons for installation and removal. The flexibility enables single-person operation while maintaining high strength through the steel wire core

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The coupling device transitions from a static rigid structure to a dynamic flexible structure that can adapt its shape during handling and deployment. This dynamic characteristic enables easy manipulation, storage, and installation while the steel wire core maintains structural strength under load

Inventive Principle:

Principle #15Dynamics

3Reliability

If metal shackles are used for heavy duty applications, then reliability is improved through high strength, but harmful factors increase due to catastrophic failure mode

Engineering Contradiction:

ImprovestrengthVSAvoidcatastrophic failure

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the potential harmful effect of sudden catastrophic failure into a beneficial progressive failure mode. The steel wire rope construction allows gradual strand-by-strand failure with visible warning signs, transforming what would be a sudden dangerous failure into a controlled, predictable process that maintains safety

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The flexible rope construction inherently provides energy absorption and shock cushioning before failure occurs. The gradual deformation and strand failure process absorbs energy progressively, preventing the sudden energy release characteristic of metal shackle failure, thereby cushioning against harmful effects before they can manifest

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Reliability

If metal shackles are designed with high strength for safety, then reliability is improved, but volume and storage difficulty increase

Engineering Contradiction:

ImprovesafetyVSAvoidstorage space

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The flexible rope construction can be coiled, folded, and compressed into compact forms for storage, unlike rigid metal shackles that maintain their full volume. The steel wire core maintains strength while the flexible outer structure allows significant volume reduction during storage, solving the storage difficulty while preserving safety

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentEP3980666B1A coupling device

Publication Date: 2025.07.16 RIGGING CONCEPTS LTD

Figure 1~2A
Figure 2B~3
Figure 4~5

AI summary

A coupling device comprising a flexible elongate member of at least one length of an at least twice wound rope and a pin configured to be removably engaged with the flexible elongate member, wherein the flexible elongate member is formed as a loop or a part loop completing the loop with the pin, wherein at least one winding of rope is of disparate length to at least one other winding.