Dual-Wedge Cable Chuck for Shorter Strain-Relief Fittings
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Solution Overview
Problem
Conventional electrical cable fittings with single wedge chucks are inefficient in providing strain relief and have a longer length, making them costly and difficult to mount in tight spaces, while increasing the taper angle compromises the alignment and sealing properties.
Innovation Solution
A cable fitting with a dual wedge chuck design, featuring multiple ring-shaped segments with tapered surfaces and a flexible band, which collapses inwardly to secure the cable, reducing the overall length and improving retention force and sealing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single wedge chuck design is used, then the structure is simpler, but the cable retention force is insufficient and the fitting length is longer
Solution Approach 1:
The chuck is divided into multiple segments (typically three) that can move independently relative to each other. Each segment has tapered surfaces that convert axial compression into radial expansion, allowing the segments to collapse inwardly when compressed to secure the cable. This segmentation enables the generation of multiple contact points around the cable circumference, significantly increasing retention force compared to a single wedge design.
2Force
If the taper angle is increased to improve strain relief, then the strain relief capability is enhanced, but the alignment and sealing properties are compromised
Solution Approach 1:
Different regions of the chuck are given different taper angles optimized for their specific functions. The distal end tapered surfaces have angles optimized for cable engagement and strain relief, while the proximal end tapered surfaces have angles optimized for alignment and sealing with the gland nut and body. This local differentiation allows each region to perform its function optimally without compromising the other.
3Manufacturing precision
If a longer fitting length is used, then the alignment and sealing properties are improved, but the mounting difficulty in tight spaces increases and cost increases
Solution Approach 1:
The chuck segments are designed to be dynamically collapsible, transitioning from an expanded state during installation to a compressed state during operation. This dynamic collapse allows the fitting to be installed with adequate length for alignment and sealing, then compressed to a shorter operational length that fits in tight spaces. The segmented design with flexible band connections enables this dynamic transformation.
4Strength
If a single material is used for the chuck, then the manufacturing is simpler, but the cable engagement and sealing performance is insufficient
Solution Approach 1:
The chuck is constructed as a composite structure combining a rigid segmented body with a flexible band material connecting the segments. The rigid segments provide structural integrity and tapered surfaces for mechanical engagement, while the flexible band material (such as elastomer or thermoplastic elastomer) provides elasticity for cable grip and sealing. This composite construction achieves superior cable engagement and sealing performance compared to single-material designs.
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 dual wedge chuck design enhances cable retention force, reduces the fitting length, and provides a weatherproof seal while maintaining predictable alignment and strain relief, meeting international standards for pull-out force and environmental protection.
Implementation Method 1
Each segment of the multiple segments includes a first tapered surface, on a distal end, that slopes from the distal end away from a central axis of the ring, and a second tapered surface, on a proximal end, that slopes from the proximal end away from a central axis
Implementation Method 2
The chuck for the cable fitting also includes a flexible band to hold the multiple segments in the ring shape
Data Source
AI summary
A chuck for a cable fitting includes multiple segments substantially forming a ring shape. Each segment of the multiple segments includes a first tapered surface on a distal end, wherein the first tapered surface slopes from the distal end away from a central axis of the ring, and a second tapered surface on a proximal end, wherein the second tapered surface slopes from the proximal end away from the central axis. The chuck also includes a flexible band to hold the multiple segments in the ring shape. Each segment of the multiple segments is configured to receive compressive forces on the first tapered surface and the second tapered surface to force each segment of the multiple segments inwardly toward the central axis. The multiple segments are configured to engage a cable to secure the cable within the ring shape.