Self-locking Rope Belay Device with Segmented Lever Mechanism
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Solution Overview
Problem
Existing self-locking belay devices for ropes are difficult to use, as they require significant force to transition between locked and unlocked positions, leading to jerky progress and difficulty in finding the correct braking position for continuous speed control.
Innovation Solution
A self-locking rope belay device with a cam and lever mechanism, where the lever has a support that contacts an abutment on the flange, allowing reduced effort in the initial unlocking stroke and direct control in the final stroke, enabling precise adjustment of braking force and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional self-locking belay device with a cam and lever mechanism is used, then the device can automatically lock onto the rope under tension, but the user encounters difficulty in finding the correct braking position and must exert significant force to transition between locked and unlocked positions
Solution Approach 1:
The lever stroke is segmented into two distinct phases: an initial phase where the lever support contacts the flange abutment to provide reduced effort for unlocking, and a final phase where direct lever-to-cam contact provides precise control. This segmentation allows the user to easily transition from locked to unlocked state while maintaining reliable locking capability.
Solution Approach 2:
Different portions of the lever stroke provide different mechanical characteristics. The initial portion of the stroke features reduced mechanical advantage through flange abutment contact to minimize unlocking force, while the final portion provides direct lever-to-cam contact for precise braking control. This local differentiation of mechanical properties resolves the contradiction between ease of unlocking and precision of control.
2Ease of operation
If the lever is designed to provide direct control over the cam throughout its entire stroke, then precise adjustment of braking force is possible, but the force required to unlock the rope becomes excessively high
Solution Approach 1:
The flange abutment acts as an intermediary element during the initial phase of lever actuation. When the lever moves from its rest position, the lever support contacts the abutment first, creating a mechanical advantage that reduces the force required to begin unlocking the rope. This intermediary contact allows easy unlocking while the lever gradually transitions to direct contact with the cam for precise control.
3Strength
If the cam is designed to provide strong braking force when locked, then the device can securely hold the rope, but the user experiences jerky progress when attempting to unlock and scroll the rope
Solution Approach 1:
The mechanical advantage of the lever-cam system is dynamically changed during the unlocking process. The flange abutment provides a moving contact point that gradually transitions from supporting the lever (reducing unlocking force) to allowing direct lever-to-cam contact (increasing control precision). This dynamic adjustment of mechanical properties enables smooth transition from locked to unlocked state without jerky motion.
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
Enables easy and precise control over rope speed and braking force, reducing the energy required to unlock the rope and allowing smooth progression at desired speeds.
Implementation Method 1
a cam articulated on the flange to pinch the rope against the braking surface when the rope is under tension
Implementation Method 2
a cam articulated on the flange to pinch the rope against the braking surface when the rope is under tension
Implementation Method 3
the lever comprises a support coming into contact against an abutment of the flange substantially between the axes of articulation of the cam and of the lever when the lever is turned from its rest position to its active position, such that the actuation of the lever on the cam takes place with a reduced effect in an initial part of its unlocking stroke
Data Source
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AI summary
The device has a cam (14) for clamping a rope when the rope is under tension, and a lever (58) acting on the cam to progressively release the rope by manual action on the lever. The lever acts on the cam with a geared-down effect in an initial part of release travel of the lever and with a direct effect in a final part of travel of the lever such that relative displacement of the cam with respect to the lever is smaller in the initial part than in the final part. A support of the lever has a stud (100) placed in a ring (106) having a diameter less than a diameter of the pin.