Riding Mower Brake Linkage for Intuitive Control
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Solution Overview
Problem
Riding lawn mowers often have ambiguous and difficult brake application methods, especially as machines age, leading to uncertainty in brake engagement and potential damage from over-torque due to the traditional outboard motion requirement.
Innovation Solution
The introduction of a mechanical brake linkage assembly that allows steering levers to activate the brake assembly by moving them rearward (or forward) while in the outboard position, providing a more intuitive and unambiguous method for applying the parking brake, separate from the traditional outboard motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steering levers are moved to the outboard position to activate the brake assembly, then the brake can be applied, but the steering levers become immovable in the forward and rearward directions creating ambiguity and potential over-torque damage
Solution Approach 1:
The brake activation function is separated from the steering function by introducing a distinct brake pedal. The steering levers remain dedicated to steering operations (movable in forward and rearward directions), while the brake pedal handles brake activation independently. This segmentation eliminates the functional conflict and ambiguity in the original design where steering levers had to serve dual purposes.
Solution Approach 2:
The brake activation function is extracted from the steering lever mechanism and assigned to a separate brake pedal component. This extraction allows the steering levers to maintain their full range of motion for steering purposes without being constrained by brake activation requirements, while the brake pedal provides dedicated brake control.
2Ease of operation
If steering levers are restricted to forward and rearward movement when in the inboard position, then steering control is maintained, but the brake cannot be applied without moving the levers to the outboard position
Solution Approach 1:
The control functions are segmented into two independent components: steering levers for directional control (with forward and rearward movement restricted to inboard position) and a separate brake pedal for brake activation. This segmentation allows each component to perform its dedicated function without interfering with the other, eliminating the need for ambiguous outboard positioning.
Solution Approach 2:
The brake pedal serves as an intermediary component that mediates between the operator's braking intent and the brake assembly activation. Instead of requiring steering levers to perform dual functions, the brake pedal provides a direct, unambiguous interface for brake control while steering levers maintain their steering-only function.
3Reliability
If the brake assembly is activated by moving steering levers outboard, then braking is achieved, but machines age and the motion becomes ambiguous leading to uncertainty in brake engagement
Solution Approach 1:
The brake pedal acts as a dedicated intermediary that provides clear, unambiguous feedback for brake engagement. The pedal's design and linkage to the brake assembly create a direct, observable connection between operator input and brake activation, eliminating the ambiguous outboard motion feedback that degrades over time in the original steering lever-based system.
Solution Approach 2:
While not explicitly using color changes, the brake pedal provides visual and tactile feedback analogous to color change indicators - the pedal position and mechanical feedback clearly indicate when the brake is engaged, providing continuous, unambiguous information feedback that does not degrade with machine age.
Data Source
AI summary
A riding lawn care vehicle (10) may include a frame (60), a steering assembly (30), a brake assembly (110), and a mechanical brake linkage assembly (120). At least a first drive wheel (32) and a second drive wheel (32) of the riding lawn care vehicle (10) may be attachable to the frame (60). The steering assembly (30) may include a first steering lever (34) and a second steering lever (34), where the first and second steering levers (34) are operably coupled to the first and second drive wheels (32) respectively to facilitate turning of the riding lawn care vehicle (10) based on drive speed control of the first and second drive wheels (32) responsive to positioning of the first and second steering levers (34) along a first direction when the first and second steering levers are in an operating position. The brake assembly may be operably coupled to the first and second drive wheels (32) to enable brakes to be selectively applied to the first and second drive wheels (32). The mechanical brake linkage assembly (120) may be configured to activate the brake assembly (110) relative to the first and second drive wheels (32) in response to movement of the first and second steering levers (34) in a direction parallel to the first direction after the first and second steering levers (34) have been moved from the operating position to a non-operating position.