Caster Brake Linkage Tolerance Compensation
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Solution Overview
Problem
Existing person support apparatuses with braking systems face challenges in simultaneously braking all four wheels due to manufacturing tolerances and play in linkage systems, leading to inconsistent braking performance.
Innovation Solution
A person support apparatus with a linkage system that includes a drive mechanism and over-travel mechanisms to toggle between braking and non-braking positions, using a user-controlled actuator like a foot pedal to move caster brake actuators between their respective positions, compensating for tolerances and absorbing extra force or play, ensuring simultaneous braking or non-braking of all wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a linkage system with cables and linkages is used to brake all four wheels from a single pedal, then a single actuator can control all wheels, but manufacturing tolerances and play in the linkage system make it difficult to brake all four wheels at the same time
Solution Approach 1:
The linkage system is segmented into multiple independent adjustable linkages, each connecting the pedal to a different wheel brake mechanism. This allows each linkage to be independently adjusted to compensate for manufacturing tolerances and ensure simultaneous braking of all four wheels.
Solution Approach 2:
The system incorporates preliminary adjustment mechanisms that allow the linkage geometry to be pre-adjusted during setup or maintenance. This preliminary action compensates for cumulative tolerance errors before operation, ensuring all wheels brake simultaneously when the pedal is actuated.
2Device complexity
If traditional linkage systems are used, then the structure is simple, but tolerances and play in the system lead to inconsistent braking performance
Solution Approach 1:
The linkage system incorporates feedback mechanisms through adjustable connection points and compensating linkages that detect and correct for positional deviations caused by tolerances. This feedback ensures that all wheel brakes are actuated with consistent force and timing.
Solution Approach 2:
The system allows for parameter adjustments in the linkage geometry, such as link lengths and connection angles, to optimize braking consistency. These parameter changes compensate for manufacturing tolerances and ensure reliable simultaneous braking across all wheels.
Data Source
AI summary
A person support apparatus includes a base frame with a plurality of caster wheel assemblies, each of the caster wheel assemblies including a caster brake actuator movable between a total braking position and a non-braking position. A linkage system is coupled to the caster brake actuators for controlling the caster brake actuators and is operable to move the caster brake actuators between their total braking positions and their non-braking positions. The linkage system is configured to compensate for tolerances in the linkage system wherein the linkage system can control the caster brake actuators to simultaneously move between their total braking positions and their non-braking positions.