Stretcher Trolley Driven Wheel Pivoting Mechanism
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Solution Overview
Problem
Manual operation of stretchers is physically demanding, especially when navigating steep inclines or uneven terrain, and can result in the stretcher losing control or running off course, exacerbated by heavy patients.
Innovation Solution
A stretcher trolley with at least three non-driven wheels and one driven wheel, where the driven wheel is pivotally mounted and can move between driving and non-driving positions, powered by a battery and driven by a mechanism that includes linear or hydraulic actuators, allowing for adjustable wheel configuration to manage inclines and prevent runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manual operation is used, then device complexity is reduced, but operator strain increases and control reliability decreases on inclines
Solution Approach 1:
The stretcher incorporates a driven wheel with motor that can autonomously propel the stretcher up inclines without requiring operator physical effort. The wheel can be selectively engaged or disengaged from the ground to provide powered assistance when needed, allowing the system to serve itself in overcoming gravitational forces during transport.
Solution Approach 2:
The driven wheel is designed to be dynamically adjustable between two states: engaged with the ground to provide powered propulsion, or disengaged to allow manual operation or coasting. This dynamic reconfiguration allows the system to adapt its operational mode based on terrain conditions and operator needs, resolving the contradiction between simplicity and ease of operation.
2Reliability
If driven wheel is engaged on inclines, then control reliability improves, but device complexity increases
Solution Approach 1:
The wheel assembly is segmented into multiple independent components: the driven wheel with motor, the non-driven castor wheels, the pivot mounting mechanism, and the engagement/disengagement system. This segmentation allows each component to perform its specific function independently, improving control reliability on inclines while keeping the overall mechanism manageable through modular design.
Solution Approach 2:
The pivot mounting acts as an intermediary mechanism between the driven wheel and the stretcher frame. It enables controlled movement between engaged and disengaged positions through a simple pivoting action, mediating the transition between powered and manual modes without requiring complex actuation systems. This intermediary mechanism improves reliability while minimizing added complexity.
3Ease of operation
If driven wheel is disengaged, then ease of operation improves for manual maneuvering, but reliability decreases on steep inclines
Solution Approach 1:
The system dynamically switches between powered and manual modes by engaging or disengaging the driven wheel from the ground. When disengaged, the stretcher can be easily maneuvered manually or allowed to coast downhill. When engaged, the motor provides reliable propulsion uphill. This dynamic adaptability allows the system to optimize for either ease of operation or reliability depending on the operational context.
Solution Approach 2:
The operational parameters of the stretcher change based on wheel engagement status. The motor provides torque and propulsion when engaged, enabling reliable incline negotiation. When disengaged, the system reverts to passive manual operation with different force requirements. This parameter change allows the system to meet different operational needs without compromising either ease of operation or reliability in their respective contexts.
4Stability of the object's composition
If non-driven wheels are on ground, then stability improves, but productivity decreases on inclines
Solution Approach 1:
The wheel configuration dynamically changes based on terrain and operational needs. On flat ground, all wheels contact the ground for maximum stability. On inclines, the driven wheel engages with the ground while non-driven wheels may be elevated or cleared to reduce drag and improve propulsion efficiency. This dynamic reconfiguration allows the system to optimize both stability and productivity for different operational conditions.
Solution Approach 2:
The wheel system is segmented into driven and non-driven functions, allowing independent optimization of each. The driven wheel focuses on propulsion and can be positioned to maximize mechanical advantage on inclines. The non-driven wheels focus on stability and support on flat terrain. This functional segmentation enables the system to achieve both stability on flat ground and improved productivity on inclines by having different wheels serve different primary functions.
Data Source
AI summary
A trolley is provided and includes at least one driven wheel and non-driven wheels. The at least one drive wheel may be moved to a position clear of the ground or to a position in which it contacts the ground with the adjacent non-driven wheels being raised off the ground. Movement between these two positions is effected by pivoting a sub-frame to which the driven wheel and the non-driven wheels are connected. During this movement, the region of the trolley above the driven wheel is first lowered and then raised slightly such that the end elevation of the support for a patient remains the same.