Step Stool Latch Mechanism for Foot-Proof Reliability
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Solution Overview
Problem
Existing step stools with latch mechanisms are complex to manufacture, prone to user error due to awkward operation, and suffer from latch overload or malfunction when the user steps on the latch member, leading to reliability issues.
Innovation Solution
A step stool design featuring a metal upper step with a peripheral skirt and a pivotal latch member hinged inside the skirt, where the latch's actuation portion extends underneath the skirt for intuitive operation, allowing easy manual release without requiring the user to perform opposing motions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the latch member is arranged with its major upper face extending as a continuation of the upper surface of the step, then the latch mechanism is simplified in structure, but the user is likely to place a foot on the latch member causing it to be overloaded, worn, or malfunction
Solution Approach 1:
The latch member is repositioned from a horizontal arrangement on the upper step surface to a vertical arrangement hanging down through an opening in the peripheral skirt. This dimensional change moves the latch from a foot-traffic zone to a hand-accessible zone, eliminating the risk of foot overload while maintaining structural simplicity
2Reliability
If the latch member is fitted through an opening in a downward depending skirt of the upper step body, then the latch is protected from foot overload, but the user has to press down the actuation portion requiring two motions in opposite directions which is awkward
Solution Approach 1:
Instead of requiring the user to press down on the actuation portion as in prior art, the latch is designed to be released by pulling upward on the actuation portion. This inverted actuation direction aligns with the natural collapsing motion of the step stool, allowing the user to release the latch in the same direction they are folding the stool, thereby eliminating the need for opposite-direction motions
3Reliability
If the latch mechanism is only accessible via openings in the upper face of the upper step, then the latch is protected from foot overload, but it is awkward for the user of the step stool
Solution Approach 1:
The latch mechanism is moved from a horizontal position on the upper step face to a vertical position hanging through the peripheral skirt. This repositioning allows the latch to be accessible from below the step level, providing a more ergonomic access point that is both protected from foot overload and convenient for user operation
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 design simplifies manufacturing, enhances user safety by preventing latch overload, and ensures reliable operation throughout the stool's lifespan by allowing easy and intuitive collapse while maintaining structural stability.
Implementation Method 1
the pivotal latch member is hinged to the lower side of the step at a position inside the contour of the peripheral skirt
Implementation Method 2
the latch member has a bridge portion extending from said latch face rearward, underneath the peripheral skirt, to an actuation portion of said latch member
Data Source
Figure 1~5
AI summary
A step stool wherein the upper step is provided with a manually releasable latch mechanism including a pivotal latch member (20) having a latch face (20a) that is arranged to catch under a crossbar (9) so as to retain the step stool in a use position. The pivotal latch member is operable manually by a user to disengage the latch member from the crossbar (9) and fold the frame to the storage position. The pivotal latch member is hinged to the lower side of the step body at a position inside the contour of the platform's peripheral skirt (10b), the latch member having a bridge portion (20b) extending from said latch face rearward, underneath the peripheral skirt, to an actuation portion (20c) of said latch member, said actuation portion extending adjacent the outer side of the peripheral skirt so as to be manually engagable by a users hand.