Compact PTO Gearbox Layout for Four-Speed Agricultural Drives

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Solution Overview

Problem

Existing power take-off (PTO) shaft transmissions in agricultural vehicles are overly complex and require excessive installation space due to numerous gears and switching elements, making them inefficient and costly.

Innovation Solution

A compact PTO transmission design featuring an input shaft, output shaft, and intermediate shafts with fixed and idler gears, along with switching elements that allow for adaptable gear engagement and disengagement, enabling efficient power transmission through four distinct gear ratios while minimizing space and complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional PTO transmissions use multiple gears and switching elements to provide different speeds, then speed variability is improved, but device complexity increases

Engineering Contradiction:

Improvespeed variabilityVSAvoidnumber of gears and switching elements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The output shaft is arranged at least partially within the input shaft, creating a nested configuration where the output shaft is positioned inside the hollow input shaft. This nesting arrangement allows multiple shafts and gears to occupy the same spatial envelope, reducing the overall transmission size and complexity while maintaining multiple gear ratios through the intermediate shafts and fixed gears.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The transmission is divided into separate functional components: input shaft, output shaft, first intermediate shaft, and second intermediate shaft, each with specific fixed gears (first, second, and third fixed gears). This segmentation allows independent optimization of each component and simplifies the overall design by distributing gear functions across multiple shafts rather than using a single complex gear train.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If traditional PTO transmissions include multiple intermediate gears and switching elements, then gear ratio options are improved, but installation space increases

Engineering Contradiction:

Improvegear ratio optionsVSAvoidinstallation space

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The transmission utilizes the radial dimension by arranging gears and shafts in a compact, multi-layered configuration. The first, second, and third fixed gears are positioned at different radial and axial locations, allowing four distinct gear ratios to be achieved within a compact footprint by exploiting three-dimensional space rather than requiring linear arrangement of all gear components.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Power

If PTO transmissions operate at rated engine speed for all implements, then power availability is improved, but fuel consumption increases

Engineering Contradiction:

Improvepower availabilityVSAvoidfuel consumption

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The transmission provides four switchable gear ratios that allow the engine to operate at optimal speeds for different power and torque requirements. By enabling the vehicle to operate at reduced engine speeds (economy gear ratios) when full power is not needed, the system dynamically adapts engine operating conditions to match actual power demands, reducing fuel consumption while maintaining adequate power availability through the available gear ratios.

Inventive Principle:

Principle #15Dynamics

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 solution provides a structurally simple and efficient PTO transmission that reduces fuel consumption and improves vehicle performance by allowing optimal engine operation at various speeds, while minimizing installation space and material costs.

Implementation Method 1

the input shaft has a first fixed gear, the first intermediate shaft has a second fixed gear, and the second intermediate shaft has a third fixed gear, wherein only the first fixed gear meshes with the second fixed gear and the first fixed gear meshes with the third fixed gear

Methodology Applied

Scientific EffectGear: Gear

Data Source

PatentEP4098908B1Pto shaft transmission and agricultural vehicle

Publication Date: 2024.12.18 DEERE & CO

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AI summary

Power take-off (PTO) gearbox (20) for an agricultural vehicle (10). The PTO gearbox (20) comprises an input shaft (30), an output shaft (32), a first intermediate shaft (34), a second intermediate shaft (36), and a first gear stage (40). The first gear stage (40) is arranged such that the input shaft (30) has a first fixed gear (42), the first intermediate shaft (34) has a second fixed gear (44), and the second intermediate shaft (36) has a third fixed gear (46), wherein only the first fixed gear (42) engages with the second fixed gear (44) and the first fixed gear (42) engages with the third fixed gear (46). The invention further relates to an agricultural vehicle (10).