Interlocking Snap Hook Gate for Fall Protection
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Solution Overview
Problem
Existing snap-hooks used in personal fall protection systems face issues with the gate opening under extreme loading conditions due to uneven stiffness and loading distribution between the hook body and gate, leading to potential release of the lanyard, especially when attached to structures like I-beams.
Innovation Solution
A snap hook design featuring a J-shaped body with a slide bar and gate mechanism, where the gate's tip includes an aperture and the nose has a male portion that interlocks when closed, allowing the components to move together under load, preventing unwanted opening and distributing forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the hook is made large to provide enough space to retain the lanyard, then the lanyard retention capability is improved, but the hook's ability to resist fall forces is worsened due to increased cantilevered lever length
Solution Approach 1:
The hook is divided into functionally distinct segments: a large J-shaped body for lanyard retention and a separate gate assembly with interlocking nose for strength. This segmentation allows each part to be optimized independently - the body provides space while the gate-nose assembly provides structural strength to resist fall forces.
Solution Approach 2:
The gate and nose are merged into an interlocking assembly where the gate tip engages with the nose feature. This merging creates a unified load-bearing structure that maximizes structural efficiency by ensuring the gate and nose move together under load, preventing gate opening while maintaining strength despite the large hook size.
2Strength
If the gate is made stiff to resist loads, then the gate's load resistance is improved, but the uneven stiffness distribution between hook body and gate causes the gate to open under extreme loading
Solution Approach 1:
The nose feature is designed to engage the gate tip in advance, creating a mechanical interlock that prevents the gate from opening. This preliminary engagement ensures that under extreme loading, the gate and nose move together as a unit, counteracting the tendency for the gate to open due to uneven stiffness distribution.
Solution Approach 2:
The gate and nose are designed to move dynamically together under load through their interlocking engagement. The nose feature allows the gate to flex and move with the hook body under extreme loading conditions while maintaining engagement, accommodating the differential movement caused by uneven stiffness without causing gate opening.
3Reliability
If the gate bears against the edge of the beam to prevent lanyard release, then the prevention of inadvertent release is improved, but the load on the gate is magnified by bearing against the nose portion
Solution Approach 1:
The nose feature acts as an intermediary between the gate and the external environment. Instead of the gate bearing directly against the beam edge with magnified forces, the nose feature mediates the interaction by providing a controlled engagement point that distributes loads more evenly and prevents excessive force concentration on the gate.
Data Source
AI summary
A snap hook that includes gate that includes and aperture that accepts a male portion that protrudes from the nose portion of the hook is disclosed. The coupling of the nose portion and the gate prevents the unwanted opening of the gate while the hook is under extreme loads. Still further, the use of a slide bar that is moved through translation and rotation when opening the gate of the hook is also disclosed. The translation and rotation motion provides improved cooperation of the components and improves the resistance of undesired movement of the slide bar by forces against a protrusion on the slide bar, and thus provides greater resistance to unwanted opening of the gate.