Segmented Parking Lever for Drum Brake Axle Clearance
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Solution Overview
Problem
The existing vehicle drum brake designs face challenges in ensuring sufficient strength and size reduction of the parking lever, which affects the mounting of the axle tube bearing and the distribution of load during braking.
Innovation Solution
The design incorporates a first and second parking lever, coupled by a coupling pin, which are engaged with a strut member, allowing for reduced size and thickness without bending restrictions, ensuring strength and adequate gap for axle bearing mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the parking lever is bent into a U-shaped cross section to engage with the strut on both sides of the brake shoe, then the brake shoes are restrained from changing posture or lifting, but the parking lever size increases by the amount of the bent portion and plate thickness must be reduced, making it difficult to ensure sufficient strength and gap for axle bearing mounting
Solution Approach 1:
The parking lever is divided into two separate levers (first parking lever and second parking lever) that are coupled together by a coupling pin. This segmentation allows each lever to be thinner and smaller in cross-section, eliminating the need for a thick U-shaped bent structure while still providing bilateral engagement with the strut to restrain brake shoe movement.
2Reliability
If the parking lever is bent into a U-shaped cross section, then the brake shoes are restrained from changing posture or lifting, but the parking lever size increases, making it difficult to ensure adequate gap for axle bearing mounting
Solution Approach 1:
By segmenting the parking lever into two separate coupled levers, the overall volume is reduced compared to a single U-shaped bent lever. Each individual lever has a smaller cross-sectional area, and the coupling pin connects them in a compact arrangement that fits within the available space without requiring the large volume of a bent structure.
Solution Approach 2:
Instead of creating a U-shaped structure by bending in the same plane (which increases volume), the invention uses two separate levers coupled by a pin that extends in a different dimension (perpendicular to the brake shoe surface). This dimensional change allows compact arrangement and reduces the overall volume occupied by the parking lever assembly.
Data Source
AI summary
A vehicle drum brake including: a pair of brake shoes arranged to be expanded on a backing plate; a first parking lever disposed to rotate around a predetermined mounting shaft positioned at one end portion of one of the brake shoes; a second parking lever made up of a member different from the first parking lever, disposed to rotate around the mounting shaft, and coupled to and rotated together with the first parking lever; and a strut including a first strut member engaged with the first and second parking levers, the first and second parking levers are coupled to each other by a coupling pin so as to be engaged with the first strut member at the same time.