Asymmetric U-Profile Collapsible Ladder for Elevator Shafts
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Solution Overview
Problem
Existing foldable leaning ladders for elevator shaft pits suffer from instability due to sloping step tread surfaces when folded, which can lead to safety risks, especially when used for extended periods, and require significant storage space.
Innovation Solution
The ladder features U-profile side rails with shorter legs on one side and longer legs on the other, allowing for a compact fold and preventing mutual interference and finger bruising, with recesses in the steps to ensure horizontal tread surfaces and safety during use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the ladder is designed with symmetric U-profile side rails for compact folding, then the folded space is reduced, but the step tread surfaces become sloping which impairs stability
Solution Approach 1:
The patent applies asymmetry by making the U-profile side rails have different dimensions - one side rail has taller U-profile legs than the other side rail. This asymmetric design allows the steps to be positioned such that their U-profile base surfaces form substantially horizontal tread surfaces when the ladder is in use, improving stability. The asymmetric configuration also enables compact folding while maintaining safe step geometry.
2Stability of the object's composition
If the U-profile legs of steps are inclined to achieve horizontal tread surfaces, then stability is improved, but the folded ladder requires more space due to mutual interference
Solution Approach 1:
The patent applies local quality by providing recesses at specific locations on the steps - adjacent to the step ends where the U-profile legs are inclined. These local recesses prevent mutual interference between step ends and side rails during folding, enabling compact storage while maintaining the inclined U-profile leg configuration that creates horizontal tread surfaces for stability.
3Stability of the object's composition
If the steps are designed with inclined U-profile legs for horizontal tread surfaces, then user stability is improved, but finger bruising risk increases during folding and unfolding
Solution Approach 1:
The patent applies local quality by creating recesses at the step ends where the inclined U-profile legs are located. These recesses provide local protection by preventing finger bruising during folding and unfolding operations, while maintaining the overall inclined leg configuration that ensures horizontal tread surfaces and user stability during ladder use.
4Ease of manufacture
If symmetric U-profile side rails are used, then manufacturing is simplified, but the folded ladder has larger dimensions requiring more storage space
Solution Approach 1:
The patent applies asymmetry by designing the two U-profile side rails with different dimensions - one side rail has taller U-profile legs than the other. This asymmetric design optimizes the folded ladder dimensions for compact storage in elevator shaft pits, while the standardized U-profile construction maintains ease of manufacture through conventional fabrication processes.
Data Source
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AI summary
Collapsible extension ladder for elevator shaft pits, consisting of - two side rails (1, 2) in the form of U-profiles with U-profile legs (1.1; 2.1) facing each other and - one-piece steps (3) in the form of U-profiles, the U-profile legs (3.2, 3.3) of which are pivotally connected to the side rails at one end and pivotably connected at the other end, wherein - the U-profile legs (2.1) of the side rail (2), into which the steps (3) can be folded, have a height adapted to the step height, while - the U-profile legs (1.1) of the side rail (1) have a lower height than the U-profile legs (2.1) of the first side rail (2) have, characterized in that - the U-profile legs of the steps are pivotally hinged to the side rails on both sides and are inclined parallel to the U-profile base surface of the steps, and - that the pivot points of the steps (3) on the side rails in the area of their U-profile legs (3.2) adjoining the front step side have a smaller distance from the step tread surface than the pivot points of the U-profile legs adjoining the rear step side.