Spline Coupling Strength in Heavy Dump Truck Travel Drive

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Solution Overview

Problem

The existing travel drive devices for dump trucks face challenges in enhancing the strength of the spline-coupling portion between the spindle and carrier, particularly when the loading weight exceeds 250 tons, due to insufficient strength and the need for complex and labor-intensive modification processes.

Innovation Solution

The introduction of a cylindrical coupling member, which is an independent component with a simple shape, allows for increased tooth width of the spline teeth without increasing the diameter, and facilitates the crowning or relieving process to ensure uniform tooth contact and prevent partial contact issues, thereby enhancing the strength and durability of the spline-coupling portion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the diameter of the spline-coupling portion is increased to enhance strength, then the strength increases, but the device size increases and manufacturing becomes more complex

Engineering Contradiction:
Improvestrength of spline-coupling portionVSAvoidcomplexity of modification process
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The spline-coupling portion is divided into multiple spline teeth (typically 4-6 teeth) along the axial direction, allowing the load to be distributed across multiple contact points. This segmentation enables the coupling to achieve high strength without requiring an excessively large diameter, thus resolving the contradiction between strength and device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of increasing strength by enlarging the diameter (radial dimension), the invention utilizes the axial dimension by increasing the number of spline teeth and optimizing their axial distribution. This dimensional shift allows strength enhancement without proportionally increasing the overall device size or manufacturing complexity.

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

2Strength

If the tooth width of the spline teeth is increased to enhance strength, then the strength increases, but the diameter of the coupling portion must be increased

Engineering Contradiction:
Improvestrength of spline teethVSAvoiddiameter of spline-coupling portion
Core Design Contradiction:
StrengthVSLength of moving object

Solution Approach 1:

The invention optimizes the local geometry of each spline tooth by applying crowning or relieving to the tooth flanks, creating non-uniform surface profiles that improve contact distribution. This local quality enhancement allows the teeth to bear higher loads without requiring an increase in overall tooth width or coupling diameter.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the geometric parameters of the spline teeth by applying surface modifications (crowning or relieving) that alter the contact characteristics. These parameter changes improve the load-bearing capacity and contact uniformity without requiring dimensional increases in the coupling portion.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If crowning or relieving process is applied to ensure uniform tooth contact, then the contact uniformity improves, but the manufacturing time and labor increase significantly

Engineering Contradiction:
Improveuniformity of tooth contactVSAvoidmanufacturing time for modification process
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The crowning or relieving process is applied during the initial manufacturing stage rather than as a post-processing modification. By integrating this surface modification into the primary manufacturing process, the invention achieves uniform tooth contact without requiring separate, time-consuming modification steps, thus reducing overall manufacturing time.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2567849B1Travel drive device for dump truck
Publication Date: 2014.11.19 HITACHI CONSTRUCTION MACHINERY CO LTD
  • EP2567849B1 patent drawingFigure 1
  • EP2567849B1 patent drawingFigure 2
  • EP2567849B1 patent drawingFigure 3

AI summary

There are provided an axle housing (12), a rotational shaft (17) provided to axially extend in a spindle (14) of the axle housing (12), a wheel mounting cylinder (18) which is mounted on an outer peripheral side of the spindle (14) through wheel support bearings (20, 21) and to which wheels (7) are mounted, and a planetary gear reduction mechanism (25, 33) for decelerating rotation of the rotational shaft (17), which is transmitted to the wheel mounting cylinder (18). A carrier (38) forming a part of the planetary gear reduction mechanism (25, 33) is mounted in a non-rotating state on an open end side of the spindle (14). A cylindrical coupling member (51) is provided between the spindle (14) and the carrier (38), and provided with an axial one side outer periphery splined-coupled to an open end inner peripheral side of the spindle (14) and an axial other side outer periphery spline-coupled to an inner peripheral side of the carrier (38).