Zigzag Rope Descender Chain for Wear Reduction
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Solution Overview
Problem
Existing rope ascender and descender devices face issues such as premature wear, high release effort, moisture sensitivity, and lack of control over descent speed, particularly in Prusik knots and cam-based systems used by workers at height.
Innovation Solution
A self-locking descender ascender device featuring a chain of metal links with friction elements and connecting rods, where the rope passes in a zig-zag pattern, allowing blocking initiation under user weight and unlocking under load, with mechanisms like springs, U-shaped riders, or articulated blades for efficient and controlled ascent and descent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a Prusik knot is used for rope climbing and descent, then the device is simple and requires no additional components, but the cord experiences premature wear requiring frequent replacement and the device is sensitive to humidity affecting release effort
Solution Approach 1:
The device divides the friction function into multiple segments through a series of blocking elements (at least three) distributed along the rope path. Each blocking element independently contributes to the overall friction and locking capability, distributing the wear and stress across multiple contact points rather than concentrating it on a single cord or knot location.
Solution Approach 2:
The patent introduces blocking elements as intermediary components between the user and the rope. These elements (which can be plates, cams, or other structures) mediate the friction interaction, allowing the user to control descent through the blocking elements rather than directly through cord friction as in a Prusik knot. This intermediary approach protects the main cord from direct abrasive wear.
2Device complexity
If blocking elements are articulated on the same side of the device, then the structure is simplified, but the release effort becomes significant under load requiring substantial hand force
Solution Approach 1:
The patent distributes blocking elements to different sides of the device rather than concentrating them on one side. This spatial distribution creates a more balanced force system where the blocking elements on opposite sides work together to reduce the net force required for release. The geometric arrangement in multiple dimensions allows for more efficient force transmission and reduction of the manual effort needed to overcome the blocking action under load.
3Power
If a cam-based blocking system is used, then the device provides mechanical advantage for blocking, but the aluminum cam experiences premature wear and the device lacks progressiveness on descent
Solution Approach 1:
Instead of relying on a single cam for all blocking function, the patent segments the blocking capability across multiple blocking elements. Each element provides a portion of the total friction and mechanical advantage, distributing the wear and stress. This segmentation eliminates the premature wear issue of a single aluminum cam while maintaining the mechanical advantage through the cumulative effect of multiple blocking points.
Solution Approach 2:
The patent employs blocking elements made from composite or multi-material constructions rather than single-material cams. The blocking elements can combine materials with different properties (such as wear-resistant surfaces with flexible cores, or different metal alloys) to achieve both the necessary mechanical advantage and resistance to premature wear. This composite approach allows optimization of both power transmission and durability.
4Device complexity
If a rope descender with three hinged parts is used, then the device provides simple alignment blocking, but ascending along the rope is not possible and descent speed control is limited
Solution Approach 1:
The patent designs the device with blocking elements and articulation mechanisms that serve multiple functions. The same blocking elements that provide friction for controlled descent can be manipulated to allow upward movement, enabling both ascent and descent capabilities. The articulation joints are designed to accommodate bidirectional motion, making the device universal for both climbing directions rather than limited to descent-only operation.
Solution Approach 2:
The patent employs dynamic, articulated blocking elements that can change their configuration and friction characteristics during operation. The blocking elements can be adjusted between different states (locked for descent, unlocked for ascent) through user manipulation. This dynamic capability allows the device to adapt its function based on the desired direction of movement, providing both ascent and descent capabilities with a single device structure.
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 provides easy maneuvering, moderate release effort, and maintains self-locking functionality regardless of rope moisture, ensuring user immobilization and controlled descent with progressive speed, while automatic relocking occurs under user weight.
Implementation Method 1
a chain of metal links consisting of a succession of friction elements hinged together by connecting rods to form a series of intervals for the zig-zag passage of the rope
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The apparatus has a body comprising an attachment unit connected to a harness of user, and a blocker device unblocked when loaded. The device is placed at outside of the body and includes a chain of metal links (18) formed by a succession of friction elements (19) articulated with each other by connection rods (21) for forming a series of gaps for zigzag passage of rope (23). Upper part of the chain of links cooperates with a blocking initiating unit i.e. torsion spring (25) of the blocking device.