Lever-Actuated Retractable Wheel Assembly for Inclined Surface Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing movable structures with retractable wheels, such as scaffolding and aerial work platforms, face instability on inclined surfaces due to worn-out brakes and lack of automatic retraction mechanisms that do not exert spring force when loaded, particularly with occupants at height.
Innovation Solution
A retractable wheel assembly with a biasing mechanism and leverage bracket system that automatically retracts the wheel when loaded, using a gas strut for biasing and a lever for manual extension, ensuring stability and secure positioning without exerting spring force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If brakes are added to wheels to prevent movement on inclined surfaces, then stability is improved, but reliability deteriorates due to wear and failure over time
Solution Approach 1:
The patent removes the braking system entirely and replaces it with a retractable wheel mechanism. The wheel is retracted into the platform structure when stationary, eliminating the need for brakes while maintaining stability on inclined surfaces through geometric constraint rather than friction-based stopping.
Solution Approach 2:
Instead of using brakes to prevent movement, the invention inverts the approach by using a retractable wheel that prevents movement through its retracted state. The stability is achieved by removing the wheel from contact with the ground rather than by applying braking force.
2Ease of operation
If spring mounted casters are used for automatic retraction, then ease of operation is improved, but stability deteriorates because the casters exert spring force when loaded
Solution Approach 1:
The patent removes the spring mounting mechanism and associated spring forces from the system. The retraction is achieved through a different mechanism that does not rely on spring force, thereby eliminating the instability caused by spring pressure on the loaded platform.
Solution Approach 2:
The invention replaces the spring-based mechanical retraction system with a lever-actuated mechanism. This substitution eliminates the continuous spring force while maintaining automatic retraction capability through gravitational and lever mechanical advantages.
3Stability of the object's composition
If over center casters are used for stability, then stability is improved, but ease of operation deteriorates because they do not automatically retract when loaded
Solution Approach 1:
The patent merges the stability function of over-center casters with the automatic retraction capability of spring-mounted casters into a single integrated mechanism. The lever system provides both the over-center stability and the automatic retraction response to loading in one unified structure.
Solution Approach 2:
The invention introduces dynamic response to loading conditions through the lever mechanism. When load is applied to the platform, the lever automatically pivots to retract the wheel, providing dynamic adaptation to changing operational conditions rather than a fixed over-center position.
4Ease of operation
If a lever-actuated biasing mechanism is used for wheel extension, then ease of operation is improved with minimum effort, but device complexity increases
Solution Approach 1:
The patent employs curved pivot paths and arc-shaped lever movements to achieve mechanical advantage. The curved geometry of the lever mechanism allows small input forces to generate large output forces for wheel extension, reducing operator effort while maintaining manageable structural complexity.
Solution Approach 2:
The invention uses a pivot bracket assembly that moves through three-dimensional space, utilizing vertical and horizontal components of motion. This multi-dimensional movement allows the lever mechanism to achieve extension with minimal effort by exploiting gravitational and geometric relationships in multiple directions.
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 provides stable and secure positioning of movable structures on inclined surfaces by automatically retracting the wheels when loaded, minimizing effort for extension and maintaining stability during use, thus addressing the limitations of existing technologies.
Implementation Method 1
A biasing mechanism is coupled with the pivot bracket assembly. The biasing mechanism urges the pivot bracket assembly toward the extended position when the pivot bracket assembly is in the extended position and urges the pivot bracket assembly toward the retracted position when the pivot bracket assembly is in the retracted position. The biasing mechanism preferably includes a gas strut having a cylinder and a piston rod
Implementation Method 2
A lever is preferably attached to the pivot bracket assembly. The lever facilitates manual displacement of the pivot bracket assembly to an over center position from the retracted position to the extended position
Implementation Method 3
the pivot bracket assembly includes a pivot bracket pivotably attached to the wheel frame at one end and pivotably attached to the biasing mechanism at an opposite end, the pivot bracket being coupled with the pivot frame
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A retractable wheel assembly (10) includes a wheel frame (20) supporting a wheel (16), and a pivot bracket assembly (22) secured to the wheel frame. The pivot bracket assembly is displaceable between an extended position and a retracted position. A biasing mechanism (23) is coupled with the pivot bracket assembly. The biasing mechanism urges the pivot bracket assembly (22) toward the extended position when the pivot bracket assembly is in the extended position and urges the pivot bracket assembly (22) toward the retracted position when the pivot bracket assembly is in the retracted position.