Quick Change Lawn Mower Blade Assembly with Biasing Pin
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Solution Overview
Problem
Existing lawn mower blades require tools for replacement and are not easily removable, discouraging operators from maintaining or sharpening them due to the need for lifting or tilting the mower.
Innovation Solution
A mower blade assembly with a movable pin plate and biasing member that allows for tool-free attachment and detachment of the cutting blade, using pin apertures and a biasing mechanism to secure the blade to the rotatable spindle or engine crankshaft, enabling easy installation and removal without tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional hardware and tools are used to attach the cutting blade, then the blade is securely retained, but the blade replacement requires tools and is time-consuming
Solution Approach 1:
The retention system is segmented into multiple independent components: a mounting plate with first pin aperture, a retaining plate with second pin aperture, and a movable pin plate with pin and third pin aperture. This segmentation allows the blade to be attached through sequential engagement of pin apertures without requiring traditional tools, enabling quick tool-free replacement while maintaining secure retention.
Solution Approach 2:
The movable pin plate is designed to move between engaged and disengaged positions. When disengaged, the blade can be easily removed; when engaged, the blade is securely retained. This dynamic mechanism allows rapid blade replacement by simply moving the pin plate without requiring tool operations, directly addressing the time loss issue.
2Productivity
If the cutting blade is securely retained to prevent movement, then cutting efficiency is maintained, but the blade becomes difficult to remove for maintenance
Solution Approach 1:
The movable pin plate provides dynamic retention: when moved to the engaged position, it secures the blade firmly through pin engagement with all three apertures, maintaining cutting efficiency; when moved to the disengaged position, it releases the blade for easy removal during maintenance. This single dynamic component resolves the contradiction between secure retention and easy removal.
3Ease of operation
If the mower blade assembly includes multiple plates and pin mechanisms, then tool-free blade replacement is enabled, but the device complexity increases
Solution Approach 1:
Multiple retention functions are merged into the movable pin plate, which simultaneously provides positioning, retention, and release capabilities through its movement between engaged and disengaged positions. The pin aperture alignment mechanism is merged with the retention function, allowing the same components to serve both alignment and securement purposes, thereby reducing overall system complexity despite enabling tool-free operation.
4Reliability
If the pin plate is held in engaged position by biasing member, then blade retention is secure, but the mechanism requires more components
Solution Approach 1:
The biasing member provides self-service by automatically urging the movable pin plate into the engaged position, securing the blade without requiring additional active components or complex control mechanisms. The biasing member's elastic force naturally maintains reliable retention, and the same component structure serves both the retention and the actuation functions, minimizing the increase in component count.
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
Facilitates quick and tool-less replacement of mower blades, providing a secure mounting system that reduces blade movement and improves cutting efficiency while allowing for easy maintenance, such as sharpening, and enhances operational convenience.
Implementation Method 1
a biasing member configured to urge the movable pin plate from a disengaged position to an engaged position
Data Source
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AI summary
A mower blade assembly (20) attaches to a rotatable spindle (24) and includes a mounting plate which defines a first pin aperture. The mounting plate and a retaining plate are attached to the rotatable spindle (24). The retaining plate defines a second pin aperture. A movable pin plate comprises a pin. A blade is selectively attachable to the mounting plate. The blade defines a retaining plate aperture and a third pin aperture. A biasing member (98) urges the movable pin plate from a disengaged position to an engaged position. The pin is engageable with the pin apertures for mounting and retaining the cutting blade (26) to the mounting plate. The blade (26) is attached by moving the blade over the retaining plate aperture, urging the movable pin plate to the disengaged position, rotating the blade, and releasing the movable pin plate. Another embodiment includes a force finger.