Composite Fire Ladder Tongue-and-Groove Guidance
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Solution Overview
Problem
Fire service extension ladders made of traditional materials like wood and aluminum are heavy, difficult to set up, and lack the necessary stability and load-bearing capacity for efficient use, especially in high-temperature and smoky conditions, while existing composite material ladders lack sufficient guidance and longevity for frequent extension and insertion processes.
Innovation Solution
A pull-out extension ladder composed of carbon fiber laminates with a tongue and groove system and reinforcing ribs, eliminating the need for additional brackets, providing enhanced stability and user-friendliness through a modular design and carbon fiber laminate construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If traditional materials like wood and aluminum are used for extension ladders, then the ladder has sufficient strength and stability, but the weight becomes excessively high making it difficult to handle and set up
Solution Approach 1:
The patent applies composite materials, specifically carbon fiber laminates, to construct the ladder spars and rungs. This replaces traditional materials like wood and aluminum, achieving a weight reduction of approximately 50% while maintaining the required strength and stability for fire service operations.
2Reliability
If metal brackets are used for guidance and connection between ladder parts, then the connection is secure, but the spars break at bracket positions due to unfavorable force application in composite material ladders
Solution Approach 1:
The patent removes the metal bracket connection system entirely from the design. Instead of using brackets that create stress concentration points in the composite spars, the invention uses a bracket-free construction where ladder parts are connected through interlocking geometry and friction-based mechanisms that distribute forces along the spar length rather than at discrete points.
Solution Approach 2:
The patent implements different connection mechanisms at different locations along the spar. The end regions feature specialized geometries for insertion and guidance, while the intermediate regions maintain uniform cross-sections optimized for structural strength. This local differentiation allows the composite material to perform optimally in each zone without requiring metal reinforcement.
3Productivity
If the ladder is designed for frequent extension and insertion operations, then the operational efficiency improves, but the durability and longevity of the ladder decreases
Solution Approach 1:
The patent designs the ladder with dynamic characteristics that accommodate frequent extension and retraction operations. The spars are engineered with optimized moment of inertia distributions and wall thickness variations that provide flexibility during movement while maintaining rigidity during use. The connection interfaces incorporate friction-based locking and damping mechanisms that absorb operational stresses, preventing fatigue failure over time.
Data Source
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AI summary
The aim is to achieve an extendable sliding ladder for fire service use made of composite materials with at least one first and second ladder section (0, 0'), comprising first and second stiles (1, 1') to which several rungs (2, 2') are attached along a longitudinal axis (L) running transversely to the stiles (1, 1'), wherein stiles (1, 1') and rungs (2, 2') comprise carbon fiber laminates (3) consisting of several carbon fiber layers which completely surround the components and are permanently bonded by means of a resin, which is lightweight and robust and ensures improved linear extension and retraction.This is achieved by the arrangement of a tongue-and-groove system extending completely along the stiles (1, 1') in the direction of the longitudinal axis (L), which is formed by molded cranked end regions along the first stiles (1) and molded cranked end regions along the second stiles (1'), so that a secure and guided linear relative movement of the first ladder part (0) to the second ladder part (0') in the direction of the longitudinal axis (L) can be achieved when using a pull rope mechanism.