Self-Locking Nut Assembly with Spring-Loaded Washer
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Solution Overview
Problem
Conventional nuts are prone to loosening during use, posing a safety concern as they may back off and cause objects, such as truck wheel-ends, to become loose or break apart.
Innovation Solution
A self-locking nut assembly comprising a single piece nut and washer subassembly with spring-loaded holding features that engage only upon contact with the object's surface, preventing rotation and axial movement, and an optional cam-type locking feature for additional security without requiring special tools for installation or removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional nut is used, then the structure is simple and easy to install, but the nut is prone to loosening and backing off during use
Solution Approach 1:
The patent combines the nut and washer into a single integrated unit, merging two separate components into one. The nut body includes an integrated washer portion that forms a unified structure, eliminating the need for separate washer components while maintaining both the fastening and locking functions in a single piece.
Solution Approach 2:
The nut is divided into distinct functional segments: a nut body for threading onto the spindle, a washer portion for load distribution, and integrated locking features (such as teeth or notches) that engage with the washer. This segmentation allows each part to perform its specific function while working together as a unified anti-loosening system.
2Reliability
If multiple components are assembled to create a self-locking nut, then the anti-loosening performance improves, but the installation requires special tools and complex assembly procedures
Solution Approach 1:
The locking mechanism, spring, and washer are integrated into a single pre-assembled unit. The spring-loaded locking features are built into the nut structure itself, eliminating the need for separate locking components and special assembly tools. This unified design allows standard installation procedures to be used while maintaining self-locking functionality.
Solution Approach 2:
The spring-loaded locking features are pre-loaded and positioned within the nut structure during manufacturing. The locking teeth or notches are pre-configured to engage with the washer upon installation, so that the self-locking action occurs automatically during the normal tightening process without requiring additional steps or special tools.
3Reliability
If holding features are engaged continuously, then the nut is prevented from rotating, but the nut cannot be installed without resistance
Solution Approach 1:
The holding features utilize a spring-loaded mechanism that dynamically adjusts its engagement state. During installation, the spring allows the holding features to disengage or move aside, permitting free rotation and easy tightening. Once the nut is tightened against the washer, the spring force engages the holding features to lock the position and prevent rotation during service.
Solution Approach 2:
The spring is pre-loaded in a direction that creates resistance only when the nut attempts to rotate backward (loosening direction). During forward rotation (tightening direction), the spring allows movement, so the holding features do not interfere with installation. The preliminary spring tension creates anti-action only when needed to prevent loosening.
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
The self-locking nut assembly effectively prevents the nut from backing off, ensuring secure attachment and maintaining bearing adjustment over time, while allowing easy installation and removal with standard tools.
Implementation Method 1
The nut and washer are held apart by a spring, such as a wave spring, until the washer contacts the face of the object to which the nut is being secured. At this point the spring is compressed to engage the nut with the washer.
Implementation Method 2
The holding features, in an embodiment, are spring loaded plungers inserted into the nut body and prevent rotation of the nut during service
Data Source
AI summary
Self-locking nuts help prevent the nut from backing off of a spindle or other type of threaded shaft. A single piece nut assembly is provided that is self-locking and comprises a nut subassembly and a washer subassembly. Nut and washer subassemblies are secured together, and do not require any special tools for installation or removal. The washer has an edge which is formed/rolled over a lip extending from the bottom edge of the nut when assembled to provide the unitized assembly. The nut and washer are held apart by a spring, such as a wave spring, until the washer contacts the face of the object to which the nut is being secured. At this point the spring is compressed to engage the nut with the washer, and engage holding elements located in the nut with a holding feature located on the washer and prevent movement between the washer and nut.