Symmetric 4-Speed Countershaft Gearbox With Reduced Gear Spread

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Solution Overview

Problem

Existing multi-speed power-shift transmissions face issues with increased size, weight, and complexity due to the need for additional shafts, gears, and bearings to achieve more than two speed ratios, leading to inefficient space utilization and higher component loads.

Innovation Solution

A four-speed transmission system with a symmetric layout comprising a first shaft for input speed reduction, a second shaft for a multi-range clutch, a third shaft for a low-speed clutch, and a fourth shaft for a high-speed clutch, allowing for reduced gear spread and smaller gear sizes, thereby optimizing space efficiency and reducing component loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If additional speed clutch shafts, bearings, gears, and fluid pressure systems are added to achieve more than two speed ratios, then the number of selectable speeds increases, but the transmission housing size, weight, and complexity increase significantly

Engineering Contradiction:

Improvenumber of selectable speedsVSAvoidtransmission housing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges multiple clutch operations onto a single speed clutch shaft. Specifically, multiple clutches are assembled on one shaft rather than requiring separate shafts for each clutch, thereby reducing the number of shafts, bearings, and associated components while still achieving multiple speed ratios

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single speed clutch shaft serves multiple functions by supporting multiple clutches that engage different gear sets, allowing one shaft to control multiple speed ratios instead of requiring dedicated shafts for each function

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

Engineering Contradiction:

Improvenumber of selectable speedsVSAvoidtransmission housing weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

Multiple clutches are combined on a single speed clutch shaft, reducing the total number of shafts and bearings required. This consolidation directly reduces the weight of stationary components in the transmission housing

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If pitch diameters of speed ratio gears are chosen differently for two speed clutches to achieve two output shaft speeds, then speed ratio variety increases, but gear spread increases leading to larger and more unequal gear sizes

Engineering Contradiction:

Improvespeed ratio varietyVSAvoidgear size distribution

Core Design Contradiction:

Adaptability or versatilityVSShape

Solution Approach 1:

The transmission system segments the speed ratio achievement into two independent stages: (1) gear ratio selection through different gear pairs, and (2) speed multiplication through clutch engagement. This segmentation allows each stage to be optimized independently, reducing the overall gear spread

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If additional clutches and gears are added to achieve four speed ratios, then speed selection capability improves, but the spread between high-speed clutch and low-speed clutch increases, requiring larger gear sizes

Engineering Contradiction:

Improvespeed selection capabilityVSAvoidgear spread

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The four-speed transmission is achieved through segmented clutch engagement on a single shaft, where different clutch combinations provide different speed ratios. This segmentation avoids the need for a wide gear spread by using multiple clutches with more comparable pitch diameters

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12560221B2Symmetric 4 speed transmission with countershaft power-shift gearbox and input reduction gear set

Publication Date: 2026.02.24 DANA BELGIUM

AI summary

Methods and systems for a multi-ratio gear box and a countershaft power-shift transmission are provided. The system contains one or more electric motors coupled to a transmission housing in such that the electric motor does not exceed the highest point of the transmission. A first shaft may be coupled to one or more input speed reduction gear sets. A second shaft may be coupled to a multi-range clutch allowing two speeds. A third shaft may be coupled to a low-speed clutch and a fourth shaft may be coupled to a high-speed clutch, together doubling the number of speeds. The high and low speed clutches provide a large gear spread that allow the twin range clutches to have a reduced gear spread, overall reducing the required size of the transmission system.