Bell Crank Linkage for Wheel Loader Attachment Angle Control
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Solution Overview
Problem
Conventional wheel loaders with Z-bar links suffer from poor angle characteristics when lifting attachments, leading to attachment angle displacement and tilting force inefficiencies, making them unsuitable for both digging and lifting/unloading tasks without requiring separate machines.
Innovation Solution
A working machine design that incorporates a bell crank mechanism with a tilt cylinder connected to a structural body, where the angle between line segments is set between 0 to 180 degrees, allowing for improved angle and tilting force characteristics, enabling the use of either a bucket or a fork without significant displacement or tilting force loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional Z-bar link configuration is used with the tilt cylinder pivoted on the boom, then the structure is simple, but the attachment angle displacement is large when lifting from ground position to top position
Solution Approach 1:
The patent introduces a bell crank as an intermediary mechanism between the tilt cylinder and the connecting link. The bell crank pivots on the boom while its other end connects to the connecting link, serving as a mediator that transforms the motion and force transmission. This intermediary structure enables the tilt cylinder to maintain proper angle characteristics during lifting while keeping the overall configuration relatively simple.
Solution Approach 2:
The patent changes the geometric parameters of the mechanism by positioning the bell crank pivot point at a specific location on the boom and setting the angle between the bell crank and connecting link within 0-180 degrees. This parameter optimization ensures that the attachment angle remains substantially constant from ground position to top position, resolving the angle consistency issue while maintaining structural simplicity.
2Device complexity
If the bell crank is tilted toward the vehicle body side in conventional designs, then the structure is compact, but the tilting force characteristics deteriorate at the top position
Solution Approach 1:
The patent employs asymmetric positioning of the bell crank and connecting link, with the bell crank tilted toward the bucket side rather than the vehicle body side. This asymmetric configuration optimizes the force transmission geometry, ensuring that the tilting force characteristics are improved at the top position while maintaining reasonable structural compactness through careful spatial arrangement.
3Adaptability or versatility
If a single wheel loader is used for both digging and lifting/unloading tasks, then equipment versatility is improved, but angle characteristics cannot be optimized for both functions simultaneously
Solution Approach 1:
The patent designs a universal attachment mechanism that can effectively perform both digging and lifting/unloading tasks. By optimizing the bell crank positioning and connecting link angle within 0-180 degrees, the mechanism achieves substantially constant attachment angle characteristics that are suitable for multiple functions, eliminating the need for separate machines while maintaining angle precision for different operations.
Data Source
AI summary
In a wheel loader 3, an angle formed by a first line segment L1 connecting a pivot position Y on a boom 10 of a bell crank 11 and a pivot position X on a connecting link 13 and a second line segment L2 connecting the pivot position Y on the boom 10 of the bell crank 11 and a pivot position W on a tilt cylinder 12 is set in a range from 0 degree to 180 degrees on the attachment 20, 30 side, the attachment can be selected from a plurality of types such as a bucket 20 and a fork 30 for use, and each of the attachment 20, 30 that is different from each other has a different pivot position on the connecting link 13 relative to the pivot position on the boom 10 as a reference point.