Hand-Actuated Stretcher Caster Braking with Bowden Cable
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Solution Overview
Problem
Conventional stretcher caster braking mechanisms are inadequate for smoothly slowing down stretchers during transport, especially on ramps, as they either fail to provide partial braking or require complete wheel stoppage, which is not feasible for safe and efficient patient movement.
Innovation Solution
A patient support apparatus with a hand-actuated caster braking system that uses a Bowden cable and caliper arms to control brake pads, allowing for adjustable braking force to impede wheel rotation without complete stoppage, enabling smoother speed control and safer navigation of ramps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional caster braking mechanisms are used, then the stretcher can be completely stopped, but the stretcher cannot be smoothly slowed down during transport
Solution Approach 1:
The braking force is made dynamically adjustable through a spring mechanism that allows the operator to modulate the pressure applied to the brake shoe. The spring constant and pre-compression can be adjusted to provide different levels of braking force, enabling smooth deceleration rather than abrupt stopping.
Solution Approach 2:
The braking system allows continuous adjustment of the braking parameter (force) through mechanical means. The operator can vary the applied force by adjusting the lever position or spring compression, transforming the binary on/off braking into a continuous parameter control system.
2Force
If conventional caster braking mechanisms are used, then the wheels can be completely blocked, but partial braking force cannot be applied
Solution Approach 1:
The braking force transitions from a static blocked state to a dynamic adjustable state. The spring-loaded mechanism allows the brake shoe to be pressed against the wheel with variable force, enabling the system to adapt to different operational requirements such as gentle deceleration or firm stopping.
Solution Approach 2:
Instead of requiring complete wheel blockage, the system applies partial braking force through the adjustable spring mechanism. This allows the operator to apply just enough braking force to achieve the desired deceleration without completely locking the wheel, providing finer control over the stretcher's motion.
3Reliability
If conventional caster braking mechanisms are used, then the stretcher can be held stationary, but smooth navigation of ramps and corners is compromised
Solution Approach 1:
The braking system provides dynamic control that allows operators to modulate braking force during ramp navigation. The spring mechanism absorbs shocks and allows for smooth, controlled deceleration rather than abrupt stops, making ramp and corner navigation safer and easier.
Solution Approach 2:
The spring-loaded brake mechanism provides cushioning by allowing gradual energy dissipation. When approaching ramps or corners, the operator can apply gradual braking force that is absorbed by the spring, preventing sudden stops and providing a smoother, more controlled deceleration process.
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 system allows caregivers to gradually slow the stretcher, enhancing safety and efficiency, particularly when transporting obese patients or navigating corners and ramps, potentially reducing the number of caregivers needed for patient transport.
Implementation Method 1
a cable having a first end coupled to the brake handle and a second end coupled to the caliper arm
Implementation Method 2
brake pads, allowing for adjustable braking force to impede wheel rotation without complete stoppage
Data Source
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AI summary
A patient support apparatus (20) includes a frame (22), a plurality of casters (24) coupled to the frame (22) and supporting the frame (22) above a floor (50), a wheel (23b), a push handle (66,68) that is coupled to the frame (22) and that is gripable to maneuver the patient support apparatus (20) along the floor (50), and a brake handle (302) coupled to the push handle (66,68) and movable to move a brake (900) to impede rotation of the wheel (236).