Drum Brake Single Spring Automatic Shoe Clearance Adjustment
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Solution Overview
Problem
Conventional drum brakes require two springs, an anti-rattle spring and a quadrant spring, increasing parts and manufacturing costs due to additional assembly processes.
Innovation Solution
A drum brake design utilizing a single spring, the cable return spring, which functions as both the anti-rattle spring and the lever return spring, to automatically adjust shoe clearance, eliminating the need for separate springs and simplifying the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two springs (anti-rattle spring and quadrant spring) are used in the conventional drum brake, then the automatic shoe clearance adjustment and anti-rattle functions are achieved, but the parts cost and manufacturing cost increase due to additional assembly processes
Solution Approach 1:
The patent combines the anti-rattle spring and quadrant spring into a single integrated spring structure. The spring is positioned to simultaneously engage with both the quadrant and the brake shoe, providing both the anti-rattle function and the automatic clearance adjustment function through its dual engagement points, thereby eliminating the need for separate springs and reducing assembly complexity
Solution Approach 2:
The single spring in the invention serves multiple functions: it acts as both the anti-rattle spring (providing radial support and preventing shoe vibration) and the quadrant spring (providing tangential force for automatic clearance adjustment). This multi-functional design allows one component to replace two, reducing parts count and manufacturing cost while maintaining both required functions
2Reliability
If two springs are installed in the conventional drum brake, then both anti-rattle and clearance adjustment functions are provided, but the manufacturing cost increases due to additional assembly processes
Solution Approach 1:
The patent merges the anti-rattle spring and quadrant spring into a single integrated spring that performs both functions simultaneously. This spring is installed in one assembly operation rather than requiring separate installation of two springs, thereby simplifying the manufacturing process and reducing assembly complexity while maintaining brake shoe stability
3Device complexity
If a single spring is used to replace two springs, then the parts cost and assembly complexity are reduced, but the spring must perform multiple functions simultaneously
Solution Approach 1:
The single spring is designed with a specific geometry that enables it to perform multiple functions: its first end engages with the quadrant to provide automatic clearance adjustment, while its second end engages with the brake shoe to provide anti-rattle support. This universal design allows the spring to adapt to multiple functional requirements through its dual engagement configuration
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
Reduces the number of springs and assembly steps, lowering the overall cost of the drum brake while maintaining effective automatic shoe clearance adjustment and anti-rattle functionality.
Implementation Method 1
a spring urging the brake lever in a cable releasing direction
Implementation Method 2
the quadrant rotating to adjust a brake shoe clearance automatically when the amount of brake shoe outward movement exceeds a predetermined value
Data Source
AI summary
To provide the drum brake with the automatic shoe clearance adjustment apparatus to reduce the cost of the drum brake as reducing the number of components. The first engagement portion is provided between the brake lever and the strut body to engage the brake lever and the strut body without operating the service brake, and the second engagement portion is provided also to engage the brake lever and the strut body while automatically adjusting the shoe clearance.