Latch Knob and Tail Design for Step Stool Safety
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Solution Overview
Problem
Existing latches for ladders and step stools are difficult to use and often require tight manufacturing tolerances, leading to frustration for users when trying to fold them back into storage, as they are not visibly accessible and can result in premature wear or damage if forced.
Innovation Solution
A latch design with a visible and accessible knob, a curved end that engages a cross member, and a weight-enhancing tail, allowing for intuitive operation and reduced manufacturing tolerances, ensuring the latch is easily engaged and disengaged by the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the latch is positioned below the step to prevent collapse, then safety is improved, but the latch becomes invisible and difficult to operate for folding storage
Solution Approach 1:
The latch mechanism is extended along the longitudinal axis of the step, with the engagement portion positioned below the step for safety while the operating knob extends upward to be visible and accessible to the user. This dimensional extension resolves the contradiction by separating the safety function (below step) from the operation function (above step).
2Ease of operation
If the latch is made visible and accessible, then ease of operation is improved, but manufacturing tolerances must be tighter to function properly
Solution Approach 1:
The latch geometry is designed with specific dimensional relationships - the engagement portion extends below the step while the knob extends above, creating a lever arm that provides mechanical advantage. This geometric parameter optimization allows the latch to function reliably with standard manufacturing tolerances while remaining visible and accessible.
3Reliability
If the latch is hidden from view, then safety is improved by preventing accidental engagement, but users cannot easily fold the ladder back into storage
Solution Approach 1:
The latch operates along the longitudinal axis of the step, with the knob positioned above the step for easy visibility and access. This positioning allows users to quickly see and operate the latch for folding storage without accidental engagement during normal use, resolving both the safety and time loss concerns.
4Productivity
If users apply brute force to forcibly fold the ladder, then folding is achieved, but structural integrity is compromised
Solution Approach 1:
The latch is designed with a visible knob that users can easily locate and operate without force. The mechanism provides clear visual feedback and requires minimal operating force, eliminating the need for brute force that would compromise structural integrity while maintaining fast folding capability.
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
The latch design improves usability and structural integrity by being visible and accessible, preventing user frustration and allowing for easier folding and storage while maintaining performance with looser manufacturing tolerances.
Implementation Method 1
The latch is spaced so that it will engage the cross member with a normal gravitational force.
Data Source
AI summary
A step stool or ladder includes a latch that engages a cross member to prevent a step from disengaging from the cross member. The curved end of the latch has a tail that provides additional weight to the end of the latch that engages the cross member and allows for decreased tolerances in manufacturing the latch. The other end of the latch has a knob that extends through an opening in the step so that the latch is accessible and to give visual cues to the user. The knob also maintains the latch in its position in the opening in the step. A bent out portion of the latch midsection serves to limit the amount of travel between the knob and the bent portion. The latch rotates on the portion of the latch between the bent portion and travel limiter and the knob attached to the latch.