Gear and Transmission Case Layout for Stable Work Vehicles

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Solution Overview

Problem

Existing work vehicles with communication passages between gear and transmission cases experience heat dissipation of lubricating oil, leading to instability due to uneven distribution of weight and potential hydraulic oil shortages.

Innovation Solution

The design includes a rear port in the transmission case lower than a front port in the gear case, connected by a communication passage, allowing the transmission case to be positioned lower, enhancing stability and preventing hydraulic oil mixtures with a bent metal tube and posture maintaining portions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the transmission case is positioned lower to improve stability, then the center of gravity is lowered and stability improves, but the communication passage becomes harder to attach due to interference with other components

Engineering Contradiction:
Improvevehicle stabilityVSAvoidcommunication passage attachment
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The communication passage is divided into multiple sections: a first communication passage from the gear case to a intermediate position, and a second communication passage from the intermediate position to the transmission case. This segmentation allows each section to be routed independently, avoiding interference with the motor and other components, and enabling the transmission case to be positioned lower without compromising assembly ease.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The communication passage is routed in three-dimensional space, extending in multiple directions rather than a straight line. It goes from the gear case, extends in a first direction to an intermediate position, then extends in a second direction (different from the first) to the transmission case. This spatial routing avoids interference with the motor and other components, allowing the transmission case to be positioned lower while maintaining assembly feasibility.

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

2Temperature

If lubricating oil flows back and forth between gear case and transmission case for heat dissipation, then heat dissipation improves, but hydraulic oil may be consumed leading to supply shortages

Engineering Contradiction:
Improvelubricating oil temperatureVSAvoidhydraulic oil quantity
Core Design Contradiction:
TemperatureVSQuantity of substance

Solution Approach 1:

A communication passage with specific routing (extending in a first direction to an intermediate position, then in a second direction to the transmission case) acts as a controlled intermediary pathway. This allows lubricating oil to flow between the gear case and transmission case for heat dissipation while the passage design and positioning prevent excessive hydraulic oil consumption, ensuring adequate hydraulic oil supply is maintained.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If the communication passage is positioned to avoid motor interference, then ease of attachment improves, but the transmission case position becomes more constrained

Engineering Contradiction:
Improvecommunication passage attachmentVSAvoidtransmission case position
Core Design Contradiction:
Ease of manufactureVSShape

Solution Approach 1:

The communication passage is segmented into two sections with an intermediate position, allowing flexible routing that avoids the motor area. This segmentation enables the first section to be positioned away from motor interference while the second section connects to the transmission case at an optimal lower position, thus achieving both ease of attachment and favorable transmission case positioning.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The communication passage utilizes three-dimensional routing, extending in a first direction to an intermediate position and then in a second direction to the transmission case. This multi-directional routing provides spatial flexibility to avoid motor interference while still allowing the transmission case to be positioned at the desired lower location, thus resolving the constraint conflict.

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

This configuration lowers the overall center of gravity, improves stability, ensures adequate hydraulic oil supply, and simplifies assembly by minimizing interference during attachment of the communication passage.

Implementation Method 1

lubricating oil may travel back and forth between the gear case and the transmission case via the communication passage. This promotes the dissipation of heat from the lubricating oil.

Methodology Applied
Scientific EffectHeat dissipation: Convection

Implementation Method 2

the rear port being disposed at a position lower than the front port... the transmission case can be disposed at a lower position in the work vehicle... lower the overall center of gravity of the work vehicle

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP4644159A1Work vehicle
Publication Date: 2025.11.05 KUBOTA CORP
  • EP4644159A1 patent drawingFigure 1
  • EP4644159A1 patent drawingFigure 2
  • EP4644159A1 patent drawingFigure 3

AI summary

This work vehicle includes a gear case 20 in which lubricating oil is stored, and a transmission case 12 disposed rearward of the gear case 20 and in which lubricating oil is stored. The work vehicle also includes a communication passage 40 that allows lubricating oil to flow back and forth between the gear case 20 and the transmission case 12. A rear port 61, which is in communication with the interior of the transmission case 12 and is for connection to a communication passage 40, is disposed at a position lower than a front port 60 that is in communication with the interior of the gear case 20 and is for connection to the communication passage 40.