Rear Brake Pedal Leverage Adjustment for Shorter Brake Travel
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Solution Overview
Problem
The Yamaha Tenere 700 motorcycle's rear brake system is weak due to an incorrect leverage ratio, requiring excessive pedal travel and ankle deflection to activate the brake effectively, which is inefficient and dangerous, especially when wearing motorcycle boots.
Innovation Solution
The leverage ratio of the rear brake pedal is adjusted by lengthening the short side of the pedal rearward and using an offset clevis to realign the master cylinder pushrod, reducing pedal travel distance and improving braking speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the original brake pedal leverage ratio is used, then the pedal structure is simple, but the brake activation requires excessive pedal travel and ankle deflection
Solution Approach 1:
The pedal assembly incorporates an adjustable leverage ratio mechanism that allows the pivot point position to be modified, enabling the system to adapt its mechanical advantage dynamically. This adjustment capability reduces the required pedal travel distance while maintaining structural feasibility
Solution Approach 2:
A master cylinder adapter is introduced as an intermediary component between the pedal and the braking system. This adapter modifies the force transmission path and enables more efficient force transfer, reducing the pedal travel required for effective brake activation
2Reliability
If the leverage ratio is adjusted to reduce pedal travel, then braking effectiveness improves, but the pedal structure becomes more complex
Solution Approach 1:
The braking system is divided into modular components including the pedal arm, pivot point mechanism, and master cylinder adapter. This segmentation allows independent optimization of each component's function while maintaining overall system reliability and enabling easier maintenance
Solution Approach 2:
The leverage ratio parameter is made adjustable by allowing modification of the pivot point position on the pedal arm. This parameter change directly improves braking effectiveness by increasing mechanical advantage, while the adjustability allows optimization without requiring complete structural redesign
3Force
If a larger bore master cylinder is installed to move more fluid with less lever stroke, then braking power increases, but the system complexity and modification requirements increase
Solution Approach 1:
Instead of changing the master cylinder bore size, the solution modifies the leverage ratio parameter of the pedal mechanism. This parameter change achieves the same effect of increasing braking force by improving mechanical advantage, while avoiding the complexity of replacing the master cylinder
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 adjustment results in a firmer pedal feel and faster braking with reduced ankle deflection, enhancing the overall effectiveness of the rear brake system.
Implementation Method 1
The leverage ratio of the rear brake pedal is adjusted by lengthening the short side of the pedal rearward and using an offset clevis to realign the master cylinder pushrod
Data Source
AI summary
The leverage ratio of the rear brake pedal of the Yamaha Tenere 700 (XTZ690) motorcycle is changed to allow the rear brake to be activated properly with substantially less pedal travel. This leads to firmer pedal feel, faster braking and less ankle deflection to properly apply the brake. The pivot point of the brake pedal is fixed on the bike's frame so it cannot be moved so the short side of a new pedal has been lengthened rearward creating more upward motion to the master cylinder with less movement of the long side of the lever. The master cylinder's pushrod is then out of alignment with the master cylinder due to the lengthened brake pedal. A newly designed offset clevis is added to realign the pushrod with the master cylinder.