Foreign-Object Trapping in Dump Truck Travel Drive

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Solution Overview

Problem

The existing travel drive devices for dump trucks face issues with overheating and damage due to the accumulation of foreign objects from the wet brake system, which can lead to loss of sealing function and damage to the reduction gear mechanism, making it difficult for the truck to operate safely, especially on long slopes.

Innovation Solution

A foreign-object trapping portion is introduced between the wheel support bearing and the seal mechanism, forming a radial gap between the brake hub and the retainer, which traps foreign objects and prevents them from reaching the reduction gear mechanism, ensuring the dump truck can travel safely even if components like seal rings or O-rings are damaged.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a floating seal is disposed between the bearings and the wet brake to isolate lubricant oil from cooling liquid, then sealing function is improved, but foreign objects from wet brake damage can still reach the reduction gear mechanism

Engineering Contradiction:
Improvesealing functionVSAvoidforeign object damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A foreign object trapping portion is introduced as an intermediary structure between the wet brake and the wheel support bearing. This trapping portion captures foreign objects (such as damaged seal rings or O-rings) from the wet brake side, preventing them from reaching and damaging the reduction gear mechanism and wheel support bearing, thus resolving the contradiction between maintaining sealing function and blocking harmful foreign objects

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The space between the wet brake and wheel support bearing is segmented into two functional zones: a foreign object trapping zone and a clean lubrication zone. The trapping portion creates a physical barrier that segments the potential damage path, allowing the floating seal to maintain its sealing function while the trapping portion handles foreign object containment

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If repeated braking operations are performed on long down-slopes, then braking function is improved, but heat generated exceeds cooling capability causing overheating

Engineering Contradiction:
Improvebraking functionVSAvoidwet brake temperature
Core Design Contradiction:
Ease of operationVSTemperature

Solution Approach 1:

The foreign object trapping portion serves as a protective cushion that anticipates potential damage from high-temperature conditions. When repeated braking causes overheating and component damage, the trapping portion is already in place to capture damaged components before they can reach critical areas, providing beforehand protection against the consequences of thermal stress

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Power

If high temperature conditions occur in wet brake, then braking performance is maintained, but seal components are broken or damaged

Engineering Contradiction:
Improvebraking forceVSAvoidseal component integrity
Core Design Contradiction:
PowerVSStrength

Solution Approach 1:

The foreign object trapping portion acts as an intermediary protective structure that intercepts damaged seal components generated under high-temperature conditions. This allows the wet brake to maintain its braking power while the trapping portion prevents damaged seal parts from causing further damage to the reduction gear mechanism

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This solution effectively prevents foreign objects from entering the wheel support bearings and reduction gear mechanism, enhancing the durability and reliability of the travel drive device, allowing the dump truck to operate safely and maintain functionality even under high-temperature conditions.

Implementation Method 1

a wet brake provided between the axle housing and the wheel mounting cylinder for applying a braking force to rotation of the wheel mounting cylinder

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

a floating seal arranged between the wet brake and the bearings for retaining a cooling liquid of the wet brake in a sealed state

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP2567848B1Travel drive device for dump truck
Publication Date: 2014.12.17 HITACHI CONSTRUCTION MACHINERY CO LTD
  • EP2567848B1 patent drawingFigure 1
  • EP2567848B1 patent drawingFigure 2
  • EP2567848B1 patent drawingFigure 3

AI summary

A wheel mounting cylinder (18) is rotatably provided on an outer peripheral side of an axle housing (12) through wheel support bearings (20, 21). A wet brake (45) is provided between the axle housing (12) and the wheel mounting cylinder (18) for applying a braking force to rotation of the wheel mounting cylinder (18). A seal mechanism (55) is provided between the wet brake (45) and the wheel support bearing (20) for keeping a cooling liquid (50) of the wet brake (45) in a sealed state to lubricant oil (100) in the wheel mounting cylinder (18). A foreign-object trapping portion (58, 62) is provided between the wheel support bearing (20) and the seal mechanism (55) for trapping foreign objects flowing from the seal mechanism (55) toward the wheel support bearing (20).