Folding Step Stool Linkage Assembly Design
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Solution Overview
Problem
Folding step stools require a means to secure the open position without using a separate latch component, as per ANSI specifications, while maintaining stability and ease of use.
Innovation Solution
A folding step stool design featuring a crossbar that fits into notches on the step, utilizing a linkage assembly with a compressible mechanism, such as a bent metal wire or spring, to secure the crossbar in place when the stool is open, using the stool's own structural elements to maintain the open position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate latch component is used to secure the step stool in the open position, then the reliability of securing the open position is improved, but the device complexity increases
Solution Approach 1:
The patent combines the latch function with the existing linkage assembly that connects the step to the rail assembly. The linkage assembly is modified to include a latch mechanism that utilizes the same moving components, eliminating the need for a separate latch component while maintaining the security of the open position.
Solution Approach 2:
The linkage assembly is designed to serve multiple functions: it provides structural support, enables folding motion, and incorporates the latch mechanism to secure the open position. This multi-functionality reduces the overall number of components needed in the step stool.
2Ease of operation
If a compressible linkage assembly is used to allow notches to fit over the crossbar, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The linkage assembly incorporates a compressible element (such as a spring) that allows the assembly to dynamically adjust during operation. This enables the notches to be pushed over the crossbar with reduced force, making operation easier while the spring returns the linkage to its original position after engagement.
3Stability of the object's composition
If the linkage assembly exerts force to maintain the crossbar in the notches, then the stability of the open position is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes the spring force in the linkage assembly to compensate for minor variations in manufacturing tolerances. The elastic properties of the spring allow the system to maintain stable engagement between the notches and crossbar even with slight dimensional variations, reducing the stringency of manufacturing precision requirements.
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 effectively secures the step stool in the open position without additional latches, ensuring stability and ease of use by leveraging the spring force to keep the crossbar engaged within the notches, allowing for secure operation and easy folding.
Implementation Method 1
The linkage assembly compresses to allow the notches to fit over the crossbar and the linkage assembly exerting a force to maintain the crossbar in the notches when the stool is in the open position
Data Source
AI summary
A folding step stool includes a front rail assembly. The step stool includes a rear rail assembly, pivotally connected to the front rail assembly, having a crossbar. The step stool includes a step pivotally attached to the front rail assembly having notches which fit over the crossbar when the stool is in an open position. The step stool includes a linkage assembly pivotally and fixedly attached to the step and pivotally and fixedly attached to the crossbar. The linkage assembly compresses to allow the notches to fit over the crossbar and the linkage assembly exerting a force to maintain the crossbar in the notches when the stool is in the open position. A method for securing a step stool includes the steps of moving the notches of a step against a crossbar of a rear rail assembly pivotally connected to a front rail assembly of the step stool. There is the step of compressing a linkage assembly pivotally and fixedly attached to the step and pivotally and fixedly attached to the crossbar to allow the notches to fit over the crossbar. There is the step of exerting a force with the linkage assembly to maintain the crossbar in the notches when the stool is in the open position.