D-Shaped Anti-Rotation Washer for Vibration-Locked Nuts
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Solution Overview
Problem
Existing washers fail to effectively prevent rotation and loosening of nuts during secondary tillage, leading to loss of bearing preload and potential damage to hub assemblies due to vibrations and high tilting forces.
Innovation Solution
A circular profiled anti-rotation washer with a D-shaped step profile locking mechanism that engages positively with a machine arm, preventing rotation around its axis and reducing the likelihood of nut loosening through a central axial aperture and optional leaf-shaped grooves or ratchet teeth for secure locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard washers (flat, spring, wedge locking, slotted, tooth lock, or split washer) are used with nuts, then the nut fastening is provided, but the nut still loosens and unlocks under vibrations and high tilting forces during secondary tillage
Solution Approach 1:
The washer features a D-shaped profile with a flat portion and a rounded portion, creating an asymmetric geometry that prevents rotation when engaged with the corresponding D-shaped aperture in the arm. This asymmetric design ensures the washer cannot rotate freely, thereby preventing nut loosening under vibrations and high tilting forces during secondary tillage operations.
Solution Approach 2:
The anti-rotation washer is installed on the bolt before the nut is tightened, establishing a positive locking mechanism in advance. The D-shaped profile engages with the arm's aperture before any loosening can occur, preventing rotational movement that would lead to nut loosening under subsequent vibrations and loads.
2Reliability
If Nyloc nut with nylon collar insert is used, then friction locking is provided, but the nut unlocks when subjected to higher reverse torques and is inefficient for sustaining vibrations
Solution Approach 1:
The anti-rotation washer acts as an intermediary component between the bolt and the arm, providing a mechanical constraint that prevents rotation. This intermediary element with its D-shaped profile engages positively with the arm's aperture, preventing the nut from unlocking under reverse torque and vibrations, unlike the nylon insert which relies solely on friction.
3Reliability
If Wedge-lock nut is used, then higher reliability under extreme vibration is achieved, but the cost increases making it unsuitable for secondary tillage applications
Solution Approach 1:
The solution segments the fastening system into separate functional components: a standard nut for fastening and a separate anti-rotation washer for preventing loosening. This segmentation allows each component to be manufactured independently using conventional processes, reducing overall cost compared to integrated Wedge-lock nuts, while maintaining reliability under extreme vibration through the D-shaped positive locking mechanism.
4Device complexity
If no anti-rotation mechanism is used, then device complexity is low, but the nut loosens leading to loss of bearing preload and potential damage to hub assembly
Solution Approach 1:
The simple D-shaped asymmetric profile on the washer provides an effective anti-rotation mechanism without adding complex moving parts or adjustment mechanisms. This geometric asymmetry engages with the corresponding aperture to prevent nut loosening, thereby protecting hub assembly integrity while maintaining device simplicity.
Data Source
AI summary
Disclosed is a circular profiled anti-rotation washer. The anti-rotation washer includes a step profile locking mechanism on a first surface. The anti-rotation washer provides a central axial aperture for receiving a threaded shaft. The step profile is a D-shaped profile and allows the washer to engage with an arm in a positive locking mechanism.