Hinged Table Brake Shoe With Aligned Sleeves
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Solution Overview
Problem
Conventional drum brakes suffer from inconsistent brake dynamics, control, and performance due to their self-energizing characteristic, which results in uneven braking forces and wear, and require heavy, machined webs to support large anchor pins, leading to increased manufacturing costs and weight.
Innovation Solution
The design features an arcuate brake table with aligned sleeves that receive anchor pins, allowing for smaller diameter pins and bushings, reducing the self-energizing effect and distributing loads more efficiently, while also reducing the weight and manufacturing cost of the webs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large anchor pins are used to pivotally couple brake shoes to the brake spider, then the brake shoes can support the required loads, but the radial distance from the brake center to the pivot axis becomes small, which increases the self-energizing characteristic and results in greater variance in braking force between leading and trailing shoes
Solution Approach 1:
The patent transitions from a single-pin configuration to a dual-sleeve configuration where two sleeves are positioned at different radial distances from the brake center. The first sleeve is located at a greater radial distance than the second sleeve, creating a dimensional change in the pivot arrangement. This allows the brake shoe to pivot about an effective axis that is farther from the brake center, reducing the self-energizing effect while maintaining load support capability through the distributed sleeve structure.
Solution Approach 2:
The patent divides the single pivot function into two separate sleeves that work together. Instead of relying on one large anchor pin, the brake shoe is coupled to the brake spider through two sleeves positioned at different locations. This segmentation allows each sleeve to be smaller in diameter while collectively providing the necessary pivot functionality and load support, thereby reducing the self-energizing characteristic.
2Strength
If conventional brake shoe construction with webs supporting both the brake table and anchor pins is used, then the structure can handle loads, but the webs must be made from heavy materials and machined to provide engagement surfaces, increasing manufacturing cost and weight
Solution Approach 1:
The patent extracts the pivot support function from the webs and transfers it to the sleeves. The webs are relieved of the burden of supporting anchor pins, as the sleeves now provide the pivot coupling function. This allows the webs to be designed as simpler, lighter structural elements that only need to support the brake table, eliminating the need for heavy materials and complex machining of engagement surfaces.
Solution Approach 2:
The sleeves act as intermediary elements between the brake shoe and the brake spider, taking over the load-bearing and pivot functions previously handled by the webs. This intermediary structure allows the webs to be optimized for their primary function of supporting the brake table, resulting in weight reduction while maintaining overall structural integrity.
3Volume of moving object
If the radial distance from the brake center to the anchor pin pivot axis is small, then the anchor pin configuration is compact, but the self-energizing characteristic increases, resulting in uneven braking forces and greater variance between leading and trailing shoes
Solution Approach 1:
The patent changes the pivot geometry by positioning the first sleeve at a greater radial distance from the brake center than the second sleeve. This dimensional change in the pivot arrangement effectively moves the pivot axis farther from the brake center, reducing the self-energizing effect without requiring a large single anchor pin, thus maintaining compactness while improving brake force consistency.
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 design enhances brake shoe stiffness, reduces friction, and improves structural integrity by increasing the radial distance between the brake center and anchor pins, resulting in more consistent braking forces and reduced wear, while enabling the use of lighter and less expensive web materials.
Implementation Method 1
a brake lining and a radially inner side opposite the radially outer side... engagement with the braking surface of the brake drum
Implementation Method 2
Each of the first and second sleeves is configured to receive an anchor pin therein... reduces friction
Data Source
AI summary
A brake shoe for a drum brake is provided. The brake shoe includes an arcuate brake table defining a radially outer side configured to receive a brake lining and a radially inner side opposite the radially outer side. The brake table further defines a plurality of sleeves proximate a first end of the brake table. The sleeves are aligned along an axis and axially spaced from one another. Each of the sleeves is configured to receive an anchor pin therein through which the brake shoe may be pivotally coupled to a brake spider. The sleeves are disposed about more than half of a perimeter of the anchor pin.