Lobed Track Pin Reduces Galling Through Segmented Geometry

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Solution Overview

Problem

Current track pins and bushings in track chain assemblies experience galling issues, leading to increased friction, heat, and malfunction, especially under high loads and low rotational speeds, resulting in maintenance and replacement costs.

Innovation Solution

A track pin design featuring a lobed or scalloped geometry with convex and concave arcuate segments, forming an undulating surface, is introduced to reduce galling by creating channels for lubrication and distributing stress effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If track pins with conventional cylindrical surfaces are used, then the structure is simple and manufacturing is easy, but galling occurs between the track pin and bushing leading to increased friction and heat

Engineering Contradiction:
Improvegalling resistanceVSAvoidtrack pin geometry
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The track pin surface is segmented into multiple lobed portions, each containing convex and concave arcuate segments. This segmentation creates distinct regions that facilitate lubricant distribution and reduce continuous contact stress, thereby preventing galling between the track pin and bushing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the track pin surface are given different geometrical properties through the lobed portions with varying convex and concave segments. This local variation in surface quality ensures optimal lubricant retention and stress distribution at specific contact zones, improving galling resistance without requiring complete redesign of the entire surface.

Inventive Principle:
Principle #3Local quality

2Reliability

If track bushings with lobed surfaces are used to reduce galling, then galling is reduced, but manufacturing cost increases

Engineering Contradiction:
Improvegalling reductionVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of applying the complex lobed geometry to the track bushing as in previous designs, the invention inverts the approach by applying the lobed portions to the track pin. This inversion achieves the same galling reduction effect while potentially simplifying the manufacturing process for the bushing and overall assembly.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The invention modifies the geometric parameters of the track pin by adding lobed portions with specific convex and concave arcuate segments. This parameter change in the pin geometry provides the necessary lubricant distribution and stress relief to reduce galling, offering an alternative to modifying the bushing geometry.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If conventional track pins are used under high load and low speed conditions, then the design is simple, but lubrication fails leading to heat and sticking

Engineering Contradiction:
Improvelubrication consistencyVSAvoidtrack pin surface geometry
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The lobed portions with convex and concave segments are pre-formed on the track pin surface to create channels and reservoirs for lubricant. This preliminary geometric configuration ensures that lubrication is maintained before failure can occur, particularly under high load and low speed conditions where lubrication is most critical.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The track pin surface is transformed from a two-dimensional cylindrical surface to a three-dimensional undulating surface with lobed portions. This dimensional change creates additional spatial features that facilitate lubricant flow and retention, improving lubrication consistency without significantly increasing overall device complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 lobed track pin design reduces the likelihood of galling by ensuring consistent lubrication and stress distribution, minimizing the risk of oil starvation and subsequent friction-related issues, even at low rotational speeds and high loads.

Implementation Method 1

The lobed track pin design reduces the likelihood of galling by ensuring consistent lubrication and stress distribution

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 2

track pins that are surrounded by track rotating track bushings produce galling between the track pin and the bushing. This increases the friction that may occur between the track pin and bushing over time

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3645377B1Lobed track pin
Publication Date: 2021.04.21 CATERPILLAR INC
  • EP3645377B1 patent drawingFigure 1~2
  • EP3645377B1 patent drawingFigure 3~4
  • EP3645377B1 patent drawingFigure 5

AI summary

A track pin may comprise a body (316) that includes a generally cylindrical configuration defining an axis of rotation (A), a circumferential direction (C) and a radial direction (R), the body defining a first end (328), a second end (330) and a peripheral surface (318) extending from the first end (328) to the second end (330). The peripheral surface (318) may include a first lobed portion (314) spaced axially away from the first end (328) and the second end (330) and including a series of convex arcuate segments (308) and concave arcuate segments (332) joined to each other tangentially, forming an undulating surface.