Pivotally Mounted Cam Rope Guide Distributes Arresting Force
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Solution Overview
Problem
Existing fall arrest devices concentrate the engaging force at a single point on the rope, leading to potential rupture of rope fibers under high loads or when the rope is worn or degraded.
Innovation Solution
A fall arrest device that engages the rope at two separate points through a cam and abutment mechanism, featuring a V-shaped groove on the cam's distal end to grip the rope and a pivotally mounted cam that biases towards the abutment upon load application, distributing the arresting force across a section of the rope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the fall arrest device engages the rope at a single point via the cam and abutment, then the device structure is simple, but the rope fibers may rupture under high loads or when the rope is worn
Solution Approach 1:
The cam is divided into two distinct functional portions: a rope jamming portion that transmits force to the abutment, and a rope engaging surface with a groove that independently grips the rope. This segmentation allows the force to be distributed across two separate engagement points, preventing rope fiber rupture while maintaining structural simplicity
2Ease of operation
If the cam groove is made wider than the rope diameter to allow smooth sliding, then the rope can slide smoothly through the groove, but the rope gripping capability is reduced
Solution Approach 1:
The groove cross-section is designed with non-parallel sides that are spaced apart by a distance less than the rope diameter, creating a localized gripping zone. This local quality change allows the groove to grip the rope effectively at specific points while still permitting smooth sliding motion along the cam surface
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 device effectively distributes the arresting force across a section of the rope, reducing the risk of rupture and ensuring secure arrest of a person's descent by increasing frictional engagement, thereby enhancing safety and reliability.
Implementation Method 1
said cam being pivotally mounted on said body about a pivot axis extending perpendicular to said rope guide path
Implementation Method 2
a rope engaging surface of the rope guide path remote from said rope jamming portion of the cam is adapted to grip the rope when the rope acts thereagainst by virtue of a downward load applied to the attachment means
Implementation Method 3
the sides of the groove or channel being shaped and/or dimensioned to trap or squeeze the rope therein, preferably between opposite sides of the groove or channel, when a downward load is applied to the attachment means
Data Source
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AI summary
A fall arrest device comprising a body having a rope guide path therethrough defined between a cam and a cooperating abutment. The cam is pivotally mounted on the body about a pivot axis extending perpendicular to the rope guide path. The device is provided with an attachment means for attaching the device to a harness, a rope jamming portion of the cam being arranged to be urged towards the abutment to a rope jamming position to arrest movement of the rope through the rope guide path under the action of a load applied to the attachment means. A rope engaging surface of the rope guide path remote from said rope jamming portion of the cam is adapted to grip the rope when the rope acts thereagainst by virtue of a downward load applied to the attachment means.