Undulating Idler Wheel for Track Link Scalloping

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Solution Overview

Problem

Scalloping of track links in track chains leads to uneven contact with idler wheels and rollers, causing vibration and maintenance issues in track-type vehicles.

Innovation Solution

An idler wheel with an undulating circumferential perimeter that contacts track links at different positions, reducing the likelihood of scalloping by ensuring the apexes and valleys of the perimeter contact various parts of the link, thereby distributing the contact pressure more evenly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional idler wheel with a smooth circumferential perimeter is used, then the structure is simple and easy to manufacture, but it causes scalloping of track links leading to vibration and maintenance issues

Engineering Contradiction:
Improvetrack link uniformityVSAvoididler wheel structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The idler wheel circumferential perimeter is designed with an asymmetric undulating profile featuring multiple apexes and valleys instead of a smooth symmetric shape. This asymmetric geometry ensures that the idler wheel contacts different portions of the track link during rotation, preventing the formation of scallops at fixed positions and thereby improving track link uniformity while accepting increased structural complexity

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The idler wheel circumferential perimeter incorporates curved undulating surfaces with multiple apexes and valleys rather than straight or simple circular contours. These curved profiles allow for continuous variation in contact position along the track link, distributing wear more evenly and eliminating the scalloping effect that occurs with conventional smooth-perimeter idler wheels

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Strength

If an idler wheel contacts the center portion of track link rails more completely than end portions, then the thicker center portion provides stronger support, but it creates deeper primary scallops and secondary scallops at specific positions

Engineering Contradiction:
Improvecenter portion supportVSAvoidscalloping uniformity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The undulating circumferential perimeter creates zones of varying contact pressure around the idler wheel circumference. Apexes concentrate contact force at specific locations while valleys provide relief zones, ensuring that no single location on the track link rail experiences continuous concentrated loading. This local variation in contact quality prevents the formation of deep scallops at fixed positions while maintaining overall support strength

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The undulating profile with regularly spaced apexes and valleys creates a periodic contact pattern as the idler wheel rotates. This periodic action distributes the loading cycles across different portions of the track link, preventing the accumulation of wear at any single location and thereby improving scalloping uniformity while maintaining the necessary support strength through the periodic reinforcement at apex contact points

Inventive Principle:
Principle #19Periodic action

3Area of stationary object

If the radial extremity of the central portion is further away from the axis of rotation than the radial extremity of outside portions, then the center portion provides greater contact area, but it leads to uneven contact distribution and increased vibration

Engineering Contradiction:
Improvecontact areaVSAvoidcontact uniformity
Core Design Contradiction:
Area of stationary objectVSEase of operation

Solution Approach 1:

The idler wheel circumferential perimeter is designed with an asymmetric undulating profile where the radial distance from the axis of rotation varies continuously around the circumference. This creates an asymmetric contact pattern that shifts the contact position with each rotation, ensuring uniform contact distribution across the track link while maintaining adequate contact area through the undulating apex and valley structure

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The undulating circumferential perimeter introduces dynamic variation in the contact position and contact area as the idler wheel rotates. Rather than maintaining a static contact pattern, the dynamic undulating profile continuously changes the effective contact area and location, distributing the contact uniformly across different portions of the track link and eliminating the vibration caused by fixed asymmetric contact zones

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3507174B1Splined idler for scallop resistance
Publication Date: 2021.04.28 CATERPILLAR INC
  • EP3507174B1 patent drawingFigure 1
  • EP3507174B1 patent drawingFigure 2~3
  • EP3507174B1 patent drawingFigure 4

AI summary

An idler wheel (200) for use with a track chain of a vehicle that includes a plurality of track pins and bushings comprises a main body (202) that includes a generally cylindrical configuration defining an axis of rotation (A), a circumferential direction (C) and a radial direction (R), the main body (202) including a central portion (204) disposed along the axis of rotation (A) defining an axial extremity of the radial portion, and at least a first outside portion (208) disposed along the axis of rotation (A) that includes an undulating circumferential perimeter (210).