Compact Fall Arrest Block with Integrated Energy Absorbing Webbing
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Solution Overview
Problem
Existing fall arrest blocks are bulky and complex, particularly in their energy absorption mechanisms, which can fail to effectively arrest severe falls due to the separation of sewn lifeline sections, leading to incomplete energy absorption.
Innovation Solution
A compact fall arrest block with an energy absorbing section of stretchable webbing between the spindle and harness attachment point, utilizing an inertia mechanism to quickly lock the spindle and a ratchet wheel, combined with a non-stretchable webbing section for efficient energy absorption, ensuring the workman is halted before reaching the ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multiple sewn sections of lifeline are used for energy absorption, then energy absorption capability is improved, but device complexity and bulk increase
Solution Approach 1:
The patent combines multiple energy absorbing webbing sections into a single integrated energy absorbing element that is joined in parallel with the non-energy absorbing lifeline section. This merging approach maintains the energy absorption capability of multiple sections while reducing structural complexity and bulk compared to using separate sewn sections.
Solution Approach 2:
The energy absorbing webbing element serves multiple functions: it absorbs energy during fall arrest, maintains tension on the lifeline, and provides a compact integrated structure. This multi-functionality eliminates the need for separate components, reducing overall device complexity while maintaining effective energy absorption.
2Loss of energy
If sewn sections of lifeline are used for energy absorption, then energy absorption is provided, but reliability decreases due to separation of sections
Solution Approach 1:
The energy absorbing webbing sections are merged into a single integrated element joined in parallel with the lifeline, eliminating the separation problem that occurs with multiple sewn sections. This integrated structure ensures reliable energy absorption without the risk of sections becoming fully separated during severe falls.
Solution Approach 2:
The energy absorbing webbing is pre-configured in a parallel joined arrangement with the non-energy absorbing lifeline section, establishing a reliable structural configuration before use. This preliminary arrangement ensures that the energy absorption function remains reliable during severe falls, as the parallel structure prevents complete separation.
3Reliability
If a third elastic section is added in parallel to maintain energy absorption, then energy absorption reliability is improved, but device complexity and bulk increase
Solution Approach 1:
The patent merges the energy absorbing webbing into a single integrated element that provides continuous energy absorption throughout the fall arrest process. This eliminates the need for a third separate elastic section, maintaining energy absorption reliability while reducing structural complexity and bulk.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a compact, efficient, and reliable fall arrest mechanism that effectively absorbs kinetic energy, preventing injury by halting the fall quickly and smoothly, even at relatively short heights above the ground.
Implementation Method 1
The kinetic energy of the fall may be absorbed by an energy absorbing means being an energy absorbing section of the lifeline between the spindle and the harness attachment point
Implementation Method 2
The inertia mechanism comprises an inertia weight positioned around the mounting post, with relative rotational movement of the weight with respect to the spindle and the ratchet wheel upon acceleration of the spindle
Implementation Method 3
a ratchet wheel, combined with a non-stretchable webbing section for efficient energy absorption
Data Source
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AI summary
A fall arrest block (10) has a spindle on which a length of lifeline (14) is wound. In normal use, the lifeline (preferably webbing) retracts onto and extends from a drum housing (12), as the workman moves towards and away from a secure point to which the housing is attached. In the event of a fall, an inertia mechanism (42) sensitive to acceleration of the spindle (34) operates to lock a locking mechanism to hold the spindle (34) against further rotation. An energy absorbing link (18) is built into the webbing, close to a hook (16) to which the workman is attached. The energy absorbing link (18) includes a section (20) of lifeline that is stretchable, but non-elastic. The locking mechanism includes a toothed ratchet wheel that is engaged by a pawl in order to lock the spindle rotation. The tool-bed ratchet wheel (36) is part of a unitary body with the spindle (34).