Toolless Wheel Nut Assembly for Adjustable Garden Tool Deck Height
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Solution Overview
Problem
Existing garden tools, such as robotic lawn mowers, face challenges in easily and securely attaching and detaching wheels without the need for tools, which complicates adjustments for different deck heights and traction requirements.
Innovation Solution
A toolless shaft nut assembly that self-locks using a nut lock with a pawl or lock surface, allowing for manual engagement and disengagement, enabling wheels of different diameters to be easily swapped for adjustable deck heights and traction control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional fastening methods are used for wheels, then secure attachment is achieved, but tool-free installation and removal is compromised
Solution Approach 1:
The fastening mechanism is segmented into modular components: a shaft nut with internal threads, a separate lock surface, and a pawl component. This segmentation allows each element to perform its specific function independently while maintaining overall simplicity, enabling tool-free operation without excessive complexity
Solution Approach 2:
The shaft nut assembly incorporates self-locking features where the pawl automatically engages with the lock surface to secure the wheel in place without requiring additional tools or complex mechanisms. The design allows the components to serve their own fastening and locking functions
2Reliability
If wheels are securely locked in place, then reliability is improved, but ease of adjustment for different deck heights is reduced
Solution Approach 1:
The fastening system transitions from a static locked state to a dynamic adjustable state through manual manipulation of the shaft nut. Users can easily shift between secured operation (for reliability) and adjustment mode (for adaptability) by simply hand-tightening or loosening the nut, allowing both requirements to be met at different operational phases
Solution Approach 2:
The shaft nut assembly serves multiple functions: it secures the wheel to the axle, provides adjustable positioning for different deck heights, and maintains reliable attachment during operation. This multi-functionality allows a single mechanism to address both reliability and adaptability requirements
3Ease of operation
If tool-free fastening is implemented, then ease of operation is improved, but locking reliability may be compromised
Solution Approach 1:
The pawl acts as an intermediary component between the shaft nut and the lock surface, providing automatic engagement that enhances reliability. When the shaft nut is tightened by hand, the pawl automatically snaps into the lock surface groove, ensuring secure attachment without requiring tools while maintaining locking reliability
Data Source
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AI summary
A garden tool includes a deck, a motor, an implement configured to be driven by the motor, a wheel shaft, and a wheel removably coupled to the wheel shaft by way of a toolless shaft nut assembly. The toolless shaft nut assembly configured to self-lock.