Brake Cable Actuation Mechanism for Riding Lawn Mower Steering
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Solution Overview
Problem
Riding lawn mowers with short turning radius and steering levers face limitations in brake system design, where the pivoting action is constrained by component sizes and tolerances, requiring additional components like springs to maintain lever stability, which complicates the structural architecture and user experience.
Innovation Solution
A mechanical brake linkage assembly that amplifies the angular input from the steering lever, allowing a small input angle to translate into a larger angular output, enabling effective brake activation without the need for additional springs, by using a cable tensioner mechanism that provides greater rotation of the cable tensioner than the steering lever, thus simplifying the design and enhancing user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the steering lever is designed with limited pivot angle due to component sizes and tolerances, then the structural architecture remains compact, but the brake activation effectiveness is insufficient
Solution Approach 1:
The cable tensioner redirects the cable force through a different spatial dimension by pivoting perpendicular to the steering lever's movement plane. This dimensional change allows the limited linear movement of the steering lever to be converted into effective rotational motion of the brake assembly, achieving sufficient brake activation without requiring additional components like springs
Solution Approach 2:
The cable tensioner acts as an intermediary mechanism between the steering lever and the brake assembly. It receives the limited movement input from the steering lever and transforms it into the required rotational motion for brake activation, effectively mediating the mismatch between input and output requirements
2Stability of the object's composition
If additional components like springs are added to maintain steering lever stability in outboard position, then the lever stability is improved, but the structural architecture becomes more complex
Solution Approach 1:
The cable tensioner utilizes the existing motion of the steering lever to automatically maintain cable tension and stabilize the lever in the outboard position. The system serves itself by converting the lever's movement into the tensioning force needed, eliminating the need for external springs or additional stabilization components
Solution Approach 2:
The cable tensioner performs multiple functions: it activates the brake assembly, maintains cable tension, and stabilizes the steering lever in the outboard position. This multi-functionality replaces what would otherwise require multiple separate components, simplifying the overall structural architecture
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
This solution improves the operator's ability to apply brakes, facilitating starting, dismounting, and transporting the vehicle by providing a more efficient and effective brake application mechanism that feels 'locked' in both inboard and outboard positions, enhancing user experience without additional structural complexity.
Implementation Method 1
The mechanical linkage assembly may be configured to provide a greater amount of rotation of the cable tensioner than a magnitude of rotation of the steering lever when the steering lever is moved from the inboard position to the outboard position
Data Source
AI summary
A riding lawn care vehicle (10) includes first and second drive wheels (32), a steering lever (34), a brake assembly (110), and a mechanical brake linkage assembly (120) including a cable tensioner (250). The brake assembly (110) may be operably coupled to at least one of the first and second drive wheels (32) to enable brakes to be selectively applied to the first and second drive wheels (32) based on a position of the steering lever (34). The cable tensioner (250) may be configured to activate the brake assembly (110) relative to the at least one of the first and second drive wheels (32) in response to the steering lever (34) being moved outwardly to an outboard position. The mechanical linkage assembly (120) may be configured to provide a greater amount of rotation of the cable tensioner (250) than a magnitude of rotation of the steering lever (34) when the steering lever (34) is moved from the inboard position to the outboard position.