Adjustable Belay Device Cam Spring Stiffness
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Solution Overview
Problem
Existing belay devices face challenges in providing rapid and effective rope blocking, especially in top-roping mode, where the opposing torque from the return spring can slow down the blocking effect during a climber's fall.
Innovation Solution
The belay device features a cam return spring directly driven by an integral control part and an adjustable knob that moves along an oblong groove, allowing for two predetermined spring hardness values: maximum for belay mode and minimum for top-rope mode, reducing the spring's action on the cam and enhancing locking speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the return spring maintains constant hardness, then the device provides consistent belay performance, but the locking speed is reduced in top-roping mode due to opposing torque
Solution Approach 1:
The return spring's hardness is made dynamically adjustable through an oblong groove mechanism that allows the spring's attachment point to shift between two positions, changing the spring's effective length and stiffness. This enables the device to adapt its mechanical characteristics based on the operating mode, achieving fast locking in top-roping mode while maintaining adequate performance in belay mode.
Solution Approach 2:
The invention changes the physical parameter of spring hardness by modifying the spring's geometric configuration. By moving the attachment point along the oblong groove, the spring's free length changes, which directly alters its stiffness parameter. This allows optimization of the locking speed parameter for different operational contexts without changing the spring material or overall structure.
2Duration of action of moving object
If the return spring provides strong restoring torque, then the cam returns quickly to blocking position, but the energy consumption increases and the device becomes less efficient
Solution Approach 1:
The spring energy storage parameter is dynamically adjusted by changing the spring's effective length through the oblong groove mechanism. In top-roping mode, the spring is configured with greater length and lower stiffness, reducing energy storage while maintaining adequate return time. In belay mode, the spring is configured with shorter length and higher stiffness, increasing energy storage for more demanding applications.
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
This design enables faster and more effective rope blocking in both belay and top-rope modes, with reduced spring torque in top-rope mode, ensuring quicker locking in case of a fall and safer handling for supervisors.
Implementation Method 1
the return spring is formed by a torsion spring arranged inside the cam
Implementation Method 2
a flange provided with a braking surface, a cam articulated on the flange to block the rope against the braking surface when the rope is under tension
Data Source
Figure 1
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AI summary
A belay device on a rope comprises a position where a first climber can be belayed, and another position where the first climber can be belayed only in a top-rope mode. The belay device comprises a cam 11 cooperating with a reset spring 24 which can be adjusted through an adjusting knob 28, so the hardness of the spring 24 can be adjusted according to two preset values which correspond to a first value of the belay operating mode and a second value of the top-rope operating mode.