Adjustable Crank Arm Assembly for Precise Reusable Length Setting
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Solution Overview
Problem
Conventional crank arms are typically customized through match drilling for a single installation, making them non-adjustable and prone to structural weaknesses and debris generation, limiting their reusability and adaptability in mechanical systems like folding aircraft blades.
Innovation Solution
The development of adjustable crank arms using a combination of a threaded rod end, jam nut, and wedge pieces, allowing for infinitesimal adjustments in length while maintaining structural integrity and load-bearing capabilities, utilizing a turnbuckle approach with structural members for linear adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If match drilling is used to customize crank arms for single installation, then precise length matching is achieved, but reusability and adaptability are lost
Solution Approach 1:
The crank arm is divided into multiple components: a first component with a bearing pocket, a second component with a mounting plate, and adjustable positioning elements. This segmentation allows the components to be assembled in different configurations to achieve various lengths while maintaining precision, and the same components can be reused across different installations.
Solution Approach 2:
The crank arm incorporates adjustable positioning elements such as threaded rods, nuts, and washers that allow dynamic adjustment of the overall length. This enables the crank arm to be adapted to different installation requirements while maintaining precise length control, and the same adjustable mechanism can be reused for multiple installations.
2Manufacturing precision
If conventional crank arms are customized through match drilling, then precise fit is achieved, but structural weaknesses and debris generation occur
Solution Approach 1:
By segmenting the crank arm into separate components connected by adjustable elements, the design avoids the need for extensive match drilling into single solid pieces. The connection points are concentrated in specific areas designed to handle loads, preserving the overall structural integrity of each component while achieving precise fit through the adjustable assembly.
Solution Approach 2:
The crank arm components are pre-manufactured with standardized features and connection points. The adjustable positioning elements are pre-configured with threaded features and locking mechanisms. This preliminary preparation allows for precise assembly without requiring extensive on-site drilling and modification, thereby preserving structural strength.
3Adaptability or versatility
If crank arms are made adjustable for reuse, then adaptability improves, but device complexity increases
Solution Approach 1:
The crank arm is segmented into modular components that can be independently manufactured and assembled. This modularity enables adjustability through different component combinations while keeping each individual component relatively simple in design. The standardized interfaces between components simplify the overall assembly process.
Solution Approach 2:
The adjustable crank arm components are designed with universal features that can accommodate different installation configurations. The same set of components can be assembled in multiple ways to achieve different lengths and orientations, reducing the need for multiple specialized parts and thereby limiting the increase in overall device complexity.
Data Source
AI summary
An adjustable length crank arm includes a first component having a longitudinal length, a second component coupled to the first component, the second component having a longitudinal length. A total length of the crank arm can be adjusted by changing an amount of longitudinal overlap that exists between the first component and the second component. The adjustable length crank arm can include a first wedge and a second wedge and at least a portion of each of the first wedge and the second wedge is longitudinally captured between the first component and the second component.