Caster Biasing Assembly for Compact Stair Chair Storage
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Solution Overview
Problem
Conventional patient transport apparatuses, such as stair chairs, often require complex and specific sequences for transitioning between use and storage configurations, leading to potential misalignment and increased footprint during storage.
Innovation Solution
A patient transport apparatus with a caster assembly that includes a pin coupled to a support structure, allowing a caster frame to pivot between orientations via a biasing mechanism, automatically adjusting to a stowed position when not in use, ensuring minimal footprint and easy storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional patient transport apparatuses are designed to fold or collapse for storage, then storage footprint is reduced, but the transition process becomes complicated and requires specific predetermined sequences
Solution Approach 1:
The biasing mechanism automatically urges the caster frame toward the stowed caster orientation in response to wheel disengagement, eliminating the need for caregivers to manually manage complex transition sequences. The system self-regulates the caster position based on the operational state of the wheel.
Solution Approach 2:
The biasing mechanism pre-positions the caster frame in the stowed orientation before the transition is complete, ensuring that the caster is already in the correct position for minimal footprint as the support structure moves to the stowed configuration.
2Ease of operation
If caster frames are allowed to pivot freely for ease of operation, then maneuverability is improved, but misalignment during storage increases footprint
Solution Approach 1:
The caster frame is designed to be dynamic during operation, allowing free pivoting for maneuverability, but automatically transitions to a fixed stowed orientation during storage through the biasing mechanism. The system adapts its degree of freedom based on the operational context.
Solution Approach 2:
The biasing mechanism replaces complex mechanical locking systems with a simpler elastic or magnetic biasing system that passively maintains the stowed orientation, reducing mechanical complexity while achieving the same footprint minimization goal.
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
Facilitates seamless transition between configurations by automatically aligning caster wheels for optimal storage, reducing the risk of misalignment and ensuring a consistent, compact footprint.
Implementation Method 1
A biasing mechanism interposed between the caster frame and the pin to urge the caster frame toward the stowed caster orientation in response to disengagement between the wheel and floor surfaces occurring as the support structure moves from the chair configuration to the stowed configuration
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A patient transport apparatus including a support structure movable between a chair configuration for traversing floor surfaces and a stowed configuration for storage. A seat section is pivotably coupled to the support structure. A caster assembly includes a pin coupled to the support structure and defining a swivel axis, a caster frame arranged to pivot about the swivel axis between a plurality of caster orientations, a wheel coupled to the caster frame and arranged for engagement with the floor in the chair configuration, and a biasing mechanism interposed between the caster frame and the pin. The biasing mechanism urges the caster frame toward a stowed caster orientation in response to disengagement between the wheel and floor surfaces occurring as the support structure moves from the chair configuration to the stowed configuration.