Quick-Release Lawnmower Blade Assembly for Toolless Blade Changes
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Solution Overview
Problem
Lawnmower blades require significant effort to remove and replace, posing a risk of bodily harm due to the need for high torque and thread lock, which complicates safe handling and maintenance.
Innovation Solution
A quick release blade assembly with an actuatable member that allows blades to be locked and unlocked parallel to the drive shaft axis, enabling easy attachment and detachment without tools, using an engagement member that interfaces with a locking component to couple and uncouple the blade securely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded fasteners with high torque and thread lock are used to secure the blade, then the blade remains securely attached during operation, but the blade becomes difficult and dangerous to remove
Solution Approach 1:
The fastening system is segmented into modular components: a drive shaft with external threads, a blade with a hub, a retainer with locking lugs, and a toolless fastener. This segmentation allows the blade assembly to be quickly detached by removing the fastener, which simply lifts off the retaining lugs without requiring torque application or thread lock removal.
Solution Approach 2:
The fastening mechanism inverts the traditional approach by using a lift-off fastener that engages with retaining lugs on the retainer rather than threading into the blade hub. The fastener has internal threads that receive a separate bolt, creating a snap-fit engagement that is secured by axial loading during operation but can be easily released by axial displacement.
2Reliability
If high torque is applied to tighten the nut to prevent blade loosening, then the blade remains secure during operation, but the operator risks bodily harm from slipping on sharp objects
Solution Approach 1:
The dangerous elements of traditional blade fastening—high torque application, wrench usage, and thread lock chemicals—are extracted and replaced with a toolless fastening system. The operator simply lifts the fastener off the retaining lugs, eliminating the need for wrenches and the risk of slipping on sharp blade edges or chemical exposure.
Solution Approach 2:
The retainer with locking lugs acts as an intermediary between the blade hub and the fastener. The lugs provide positive mechanical engagement that secures the blade during operation while allowing easy removal by axial displacement of the fastener, mediating between the need for secure attachment and easy removal.
3Reliability
If threaded fasteners are used to secure the blade, then the blade remains attached during operation, but the fastening process becomes time-consuming and complex
Solution Approach 1:
The blade hub is pre-configured with external threads and the retainer is pre-configured with locking lugs during manufacturing. This preliminary preparation allows the operator to simply lift the fastener onto the threads and snap it onto the lugs without any additional assembly steps, significantly reducing blade change time while maintaining secure attachment.
Data Source
AI summary
Quick release blade assemblies for a power tool are provided. A lawnmower includes a base including an engagement interface; a retainer having a locking component; a blade disposed between the base and the retainer; and an actuatable member including an engagement member, the engagement member being selectively displaceable with respect to the engagement interface between a locked configuration and an unlocked configuration when the actuatable member is translated in a direction parallel with the axis of rotation, wherein the engagement member is configured to interface with the locking component to selectively couple the blade to the drive shaft when the engagement member is in the locked configuration.