Self-locking Pulley with Movable Axis for Rope Descending
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Solution Overview
Problem
Existing self-locking pulleys used in mountaineering and emergency situations face issues with inconsistent rope blocking due to varying friction coefficients between the rope and pulley, which affects their performance under different load conditions and temperatures.
Innovation Solution
A self-locking pulley design featuring a movable axis of rotation and a cam system, where the cam is moved by a spring to a blocking position based on the direction of rope rotation, reducing dependence on friction for blocking, and incorporating a toothed wheel and locking spring to ensure secure locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cam system is used to lock the rope, then the locking action is improved, but the locking performance becomes highly dependent on friction between the rope and pulley, causing variability under different conditions
Solution Approach 1:
The patent replaces the friction-dependent cam locking mechanism with a mechanical interlocking system using a toothed wheel and toothed cam. The toothed cam engages with the toothed wheel to provide positive locking action that is independent of friction conditions, thereby resolving the contradiction between reliable locking and adaptability to different friction conditions
Solution Approach 2:
The patent changes the locking mechanism from a friction-based system to a mechanical engagement system. By using toothed elements that physically interlock, the system transforms the locking action from being dependent on friction parameters to being dependent on mechanical geometry, ensuring consistent locking performance across different conditions
2Force
If the pulley rotates freely to allow rope movement, then the pulley can handle loads, but the cam cannot effectively lock the rope when needed
Solution Approach 1:
The patent implements a dynamic system where the pulley can rotate freely in the direction of load movement, but the toothed cam engages with the toothed wheel to prevent reverse rotation and ensure locking. This dynamic interaction allows the pulley to handle loads while maintaining reliable locking capability through mechanical engagement rather than static friction
Solution Approach 2:
The patent separates the functions of load handling and locking into distinct mechanical elements: the pulley handles load movement through free rotation, while the toothed cam and wheel provide locking through mechanical engagement. This segmentation allows each component to optimize its specific function without compromising the other
3Reliability
If friction is increased to improve locking, then the cam can better block the rope, but the pulley experiences excessive heat generation and reduced efficiency
Solution Approach 1:
The patent substitutes the friction-based locking mechanism with a mechanical interlocking system using toothed elements. The toothed cam engages with the toothed wheel to provide locking action through mechanical geometry rather than friction, thereby eliminating excessive heat generation while maintaining strong locking capability
Solution Approach 2:
The patent converts the potential harm of friction (heat generation) into a benefit by using mechanical engagement instead. The toothed cam and wheel system provides locking strength without relying on friction, thereby eliminating the harmful thermal effects while maintaining effective locking
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 design provides consistent and reliable rope blocking independent of friction conditions, enhancing the pulley's ability to handle significant loads and reducing variability in blocking performance across different surfaces and temperatures.
Implementation Method 1
a spring (11) arranged to apply a force that moves the cam (5) toward the rope locking zone
Implementation Method 2
Friction between the rope and the pulley causes the pulley to rotate until the rope is jammed by the cam
Data Source
Figure 1
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AI summary
The self-locking descender (1) with a pulley (2) comprises: • a first flange (3) with a side wall (3a) defining a rope path (4), • a pulley (2) rotating relative to the first flange (3) around a first axis of rotation (A), the pulley (2) rotating only in a first direction of rotation (+) around the first axis of rotation (A). The first axis of rotation (A) is mounted to move relative to the side wall (3a) of the first flange (3) so as to define a first position and a second position at different distances from the side wall (3a) of the first flange (3). Locking the pulley (2) in the second direction of rotation (-) causes the first axis of rotation (A) and the pulley (2) to move towards the side wall of the first flange (3) until a threshold position is reached.