Hoist Load Brake Wear-Locking Mechanism Against Unintended Reeling
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Solution Overview
Problem
Rescue hoists face challenges in maintaining effective load control and braking mechanisms, particularly due to wear-induced issues that can lead to unintended cable reeling, especially when the brake disc pack's wear surfaces thin over time, compromising the automatic brake's functionality.
Innovation Solution
The automatic load brake incorporates a wear-induced locking mechanism with radially oriented surfaces at specific angles to ensure self-locking engagement, preventing unintended cable reeling by adjusting the angle between the radially outer and inner surfaces to match or exceed the coefficient of friction, thus maintaining braking efficiency even as wear surfaces thin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brake disc pack wear surfaces are used for braking, then braking function is provided, but wear thinning compromises brake reliability
Solution Approach 1:
The wear indicator surface is positioned to engage the indicator arm before the brake friction surfaces are completely worn, providing advance warning and allowing for maintenance before complete wear occurs, thus maintaining reliability throughout the service life
Solution Approach 2:
The wear indicator surface and indicator arm assembly serve as an intermediary mechanism that monitors the wear state of the friction surfaces and provides visual indication, allowing operators to assess brake condition without disassembly
2Reliability
If conventional brake mechanisms are used, then load control is provided, but wear-induced locking failures cause unintended cable reeling
Solution Approach 1:
The wear indicator mechanism is self-activating, automatically engaging when wear reaches critical levels without requiring external monitoring systems or additional power sources, providing passive safety functionality
Solution Approach 2:
The wear that previously indicated failure is converted into a useful indicator function, where the thinning wear surfaces themselves become the mechanism for triggering the warning system, transforming a harmful condition into a beneficial safety feature
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 solution ensures reliable and consistent braking performance by providing a self-energizing mechanism that locks the cable in place, preventing unintended reeling and maintaining load control even as wear surfaces thin, thereby enhancing the safety and reliability of the hoist's operation.
Implementation Method 1
a tangent of the first angle is equal to or less than a coefficient of friction between the radially outer surface and the radially inner surface when the radially outer surface is engaged with the radially inner surface
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
An automatic load brake having a wear-induced locking mechanism for a hoist is disclosed. In various embodiments, the load brake includes a first shaft (376) defining an annular hollow portion and a radially outer surface; a second shaft (324) defining an engagement portion and a radially inner surface, the radially inner surface configured to engage the radially outer surface; a first reaction plate (304) coupled to the first shaft; a second reaction plate coupled to the second shaft; and a plurality of friction discs (308), with at least one of the plurality of friction discs coupled to a cup and disposed between the first reaction plate and the second reaction plate, the annular hollow portion of the first shaft being configured to lock to the engagement portion of the second shaft upon thinning of the plurality of friction discs.