Lock Nut System with Visual Tamper Detection for Bearing Preload

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Solution Overview

Problem

Existing methods for preloading axle bearings in drive trains, such as truck wheel hubs, face challenges in achieving consistent and repeatable axial compressive deflection, particularly due to resistive drag torque from seals and cumbersome assembly procedures, making it difficult to maintain optimal bearing life and verify adjustments without measurement.

Innovation Solution

A lock nut system with a keeper and retaining member that inhibits rotational movement of the nut relative to the shaft, combined with a cover member that provides a visual indication of tampering, ensuring accurate preload application and verification, and a preload apparatus for monitoring and applying compressive loads to bearings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If specified torques are applied to the bearing assembly by tightening the retaining nut, then preload is created, but it is extremely difficult to achieve consistent and repeatable preload settings under actual in-field conditions

Engineering Contradiction:

Improvepreload setting consistencyVSAvoiddifficulty of achieving preload under in-field conditions

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

A dial indicator is mounted to contact the inner race of the bearing to visually indicate when the desired preload has been achieved. This feedback mechanism allows the mechanic to see real-time information about bearing compression, enabling precise control of preload application without relying solely on torque estimates.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

A preload tool with a pressing member is introduced as an intermediary device between the retaining nut and the bearing assembly. This tool translates rotational motion of the nut into controlled axial compression of the bearing, providing mechanical advantage and precise control over the preload application process.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the wheel hub assembly includes a lip type seal, then sealing is provided, but the seal imposes a resistive drag torque component to the preload torque

Engineering Contradiction:

Improvesealing functionVSAvoidresistive drag torque

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The bearing assembly is preloaded and adjusted to the desired specification before the wheel hub assembly is fully assembled with the seal in place. This preliminary action allows the preload to be established when resistive torques from the seal are minimal or absent, ensuring accurate preload settings are achieved.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The adjustment process accounts for the dynamic nature of seal resistance by establishing preload before the seal is installed, thereby eliminating the variable resistive drag torque that would otherwise complicate the preload adjustment process.

Inventive Principle:

Principle #15Dynamics

3Strength

If the assembly of a heavy truck wheel onto a wheel hub assembly is performed, then the wheel is secured, but the procedure becomes cumbersome and hinders the mechanic

Engineering Contradiction:

Improvewheel securingVSAvoidmechanic accessibility

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The assembly process is segmented into distinct phases: first assembling the bearing assembly and applying preload on the hub, then separately installing the wheel. This segmentation allows the mechanic to work on the bearing adjustment in a more accessible position before final wheel installation, improving ease of operation.

Inventive Principle:

Principle #1Segmentation

4Manufacturing precision

If the lock nut is rotated during bearing preloading, then alignment with the locking member may be achieved, but the degree of rotation is constrained by the compressive force applied

Engineering Contradiction:

Improvelock nut alignmentVSAvoidconstraint on rotation degree

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The lock nut is rotated beyond the exact alignment position during the preloading process, and then back-off adjustments are made to achieve precise alignment with the locking member. This partial excessive action ensures that alignment is achieved without being overly constrained by the compressive force, allowing for fine-tuning of the final position.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS10690174B2Systems and methods for preloading a bearing and aligning a lock nut

Publication Date: 2020.06.23 TEMPER AXLE PRODUCTS CORP

AI summary

A lock nut system includes a nut, a keeper engagement with the nut to inhibit movement of the keeper relative to the nut, and a keeper retaining member. The keeper has a radially inner side configured to engage a shaft to inhibit rotational movement of the nut relative to the shaft when the keeper engages the nut and a radially inner side engages the shaft. The keeper retaining member is secured to the keeper and is engageable with the nut to hold a keeper axially such that keeper is engaged with the nut. A cover member is located on an opposite side of the keeper retaining member relative to the nut and engaged to the keeper retaining member to inhibit a separation of the cover member from the keeper retaining member in such that that the separation of the cover member from the keeper retaining member provides a visual indication to a user.