Extensible Ladder Handrail Constraint Mechanism for Marine Access
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Solution Overview
Problem
Existing extensible ladders for boat under-deck access wells are prone to functional issues in marine environments due to deposits and encrustations, which limit their reliability and require frequent maintenance.
Innovation Solution
A compact ladder design with extensible handrails that use constraint elements with a 'C' or 'U' shaped profile to guide and lock the handrails, preventing extraction and rotation, ensuring smooth operation and minimizing maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a movable pin is used to guide the sliding and rotation of the extensible handrail, then the ladder can be extended and retracted, but deposits and encrustations form between the fixed handrail and the removable handrail at the guide groove, jeopardizing the functioning and reliability of the ladder
Solution Approach 1:
The patent removes the problematic movable pin and guide groove mechanism that caused deposit accumulation. Instead, it uses a fixed handrail with an extensible portion that can be directly extended and retracted without intermediate moving parts that create crevices for encrustation, thereby eliminating the reliability issue while preserving extensibility
Solution Approach 2:
The patent introduces a smooth, continuous surface interface between the fixed handrail and the extensible handrail portion, acting as an intermediary that prevents deposit accumulation. This intermediary surface allows movement without creating the problematic guide groove geometry where deposits form
2Volume of moving object
If the ladder structure is made compact to minimize overall dimensions, then it can be easily installed in narrow boat wells, but the mechanism for extending and locking the handrails becomes more complex
Solution Approach 1:
The handrail is divided into a fixed portion and an extensible portion that can be independently manipulated. This segmentation allows the ladder to maintain a compact stowed profile while providing extended functionality when needed, and the simple interface between segments reduces locking mechanism complexity
Solution Approach 2:
The handrail transitions from a static fixed structure to a dynamic extensible structure that can change length on demand. The extensible portion can be moved between retracted and extended positions, allowing the ladder to adapt its size to the available space while maintaining structural simplicity
Data Source
Figure 1A~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a ladder comprising a first and a second fixed handrail (2a, 2b) each of which has an elongated body (3), a predetermined number of rungs (4) transversely engaged with the first and second fixed handrails (2a, 2b) and at least one extensible handrail (5a) engaged to the elongated body (3) of the first fixed handrail (2a). The extensible handrail (5a) can be positioned relative to the first fixed handrail (2a) at least between a first operative condition, in which the extensible handrail (5a) is movable along at least a portion of the elongated body (3) of the first fixed handrail (2a), and a second operative condition, in which the extensible handrail (5a) interferes with at least one rung (4) which limits or prevents the mobility along the elongated body (3) of the first fixed handrail (2a). The present invention also relates to a boat comprising said ladder.