Cammed Caster Brake Assembly for Low Actuation Force
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Solution Overview
Problem
Existing patient transport apparatuses require high actuation force to engage brake assemblies, making it difficult for users to activate the foot pedal, especially when multiple caster wheels are involved, due to the need for simultaneous actuation and high braking forces.
Innovation Solution
A caster assembly with a brake assembly that includes a cammed wheel engaging surface and a brake shoe pivotally connected to a wheel support, allowing for deeper engagement with the caster wheel as it rotates, reducing the initial actuation force required and utilizing a cam actuator to move the brake from an unbraked to a braked position, with a return spring to reset the brake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a typical brake assembly is used to provide suitable braking force, then effective braking is achieved, but high actuation force is required making it difficult for users to operate
Solution Approach 1:
The brake assembly incorporates a cammed wheel engaging surface with a cammed profile (curved geometry) that converts the actuation motion into rotational engagement with the caster wheel. This curved surface allows the brake to progressively engage the wheel as it rotates, providing effective braking force while requiring lower initial actuation force compared to flat or rigid engagement surfaces.
Solution Approach 2:
The brake assembly is designed to dynamically engage the caster wheel during rotation rather than requiring full engagement before rotation begins. The cammed profile allows the brake to transition from initial contact to deeper engagement as the wheel rotates, creating a dynamic braking action that reduces the static actuation force requirement while maintaining effective braking force.
2Reliability
If multiple caster wheels are equipped with brake assemblies requiring simultaneous actuation, then all wheels are braked at once, but the required actuation force becomes excessively high
Solution Approach 1:
The cammed wheel engaging surface with its curved profile enables each brake assembly to be actuated with lower force, and when linked together, the cumulative actuation force required remains manageable. The geometry allows progressive engagement that reduces the peak force requirement compared to rigid simultaneous engagement mechanisms.
Solution Approach 2:
The dynamic engagement mechanism allows the linkage connecting multiple brake assemblies to move through a more favorable range of motion, reducing the force transmission requirements through the linkage system while still achieving simultaneous actuation of all brakes for reliable stopping.
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 solution reduces the actuation force needed for braking, allowing for easier operation and effective braking of the caster wheels with reduced effort, as the cammed profile engages the wheel surface upon rotation, enhancing user convenience and operational efficiency.
Implementation Method 1
The cammed wheel engaging surface is arranged to articulate relative to the wheel support upon the caster wheel rotating about the rotational axis after the brake is initially placed in the braked position such that the cammed wheel engaging surface more deeply engages the caster wheel with rotation of the caster wheel about the rotational axis
Implementation Method 2
The brake shoe is pivotally coupled to the wheel support about a second pivot axis such that the brake pivots about the second pivot axis when moving from the unbraked position into the braked position
Implementation Method 3
with a return spring to reset the brake
Data Source
Figure 1
Figure 2
Figure 3~3A
AI summary
A caster assembly comprises a caster wheel having an outer surface. A wheel support is coupled to the wheel to support the wheel for rotation about a rotational axis and for swiveling about a swivel axis. A brake assembly comprises a brake having a cammed wheel engaging surface shaped to engage the outer surface of the wheel and a brake actuator to move the brake relative to the wheel from an un-braked position to a braked position in which the brake limits rotation of the wheel about the rotational axis. The cammed wheel engaging surface is arranged to articulate relative to the wheel support. The cammed wheel engaging surface articulates relative to the wheel support in response to the wheel rotating about the rotational axis after the brake is initially placed in the braked position such that the cammed wheel engaging surface more deeply engages the wheel with rotation of the wheel about the rotational axis.