Parallel Crawler Shaft Transmission for Compact Gear Ratio Expansion
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Solution Overview
Problem
Heavy-duty vehicle transmissions face challenges in providing additional gear ratios without increasing length, which can lead to a longer, heavier, and more expensive design, while also risking shaft weakness and deflection under load.
Innovation Solution
A transmission design featuring an input shaft, main shaft, countershaft, and a crawler shaft arranged in parallel, with multiple gear planes for torque transfer, allowing for both forward and reverse crawler gears without lengthening the transmission housing, using a splitter-type configuration with primary and secondary gear planes and gear engaging devices for selective torque path selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional gears are added to increase gear ratio coverage, then the transmission can provide more gear ratios for down-speeded engines, but the transmission becomes longer, heavier, and more expensive
Solution Approach 1:
The patent introduces a crawler shaft arranged in parallel with the main shaft, creating a new dimensional arrangement for gearwheels. By placing first and second crawler shaft gearwheels on this parallel shaft and selectively connecting them, the transmission achieves additional gear ratios without extending the transmission length in the conventional direction.
Solution Approach 2:
The patent integrates the crawler shaft gearwheels into the existing transmission structure by selectively rotationally connecting them to engage crawler gears. This nested arrangement allows the additional gear functionality to be incorporated within the existing transmission housing boundaries rather than requiring external extensions.
2Adaptability or versatility
If shaft length is increased to accommodate additional gears, then more gear ratios can be provided, but the shafts become weaker and more prone to deflection when loaded
Solution Approach 1:
By arranging the crawler shaft in parallel with the main shaft rather than extending it lengthwise, the patent maintains compact shaft lengths while providing additional gear ratios. This parallel arrangement ensures shafts remain short and stiff, avoiding the weakness and deflection issues associated with lengthened shafts.
3Adaptability or versatility
If the transmission design is extended to include additional gears, then gear ratio coverage improves, but the transmission housing must be longer and more expensive
Solution Approach 1:
The patent utilizes a parallel shaft arrangement that fits within the existing transmission housing footprint. By positioning the crawler shaft parallel to the main shaft and using selective rotational connection, the design achieves extended gear ratio coverage without requiring a longer housing.
Solution Approach 2:
The crawler shaft gearwheels serve multiple functions: they can be selectively connected to provide crawler gears for low-speed maneuvers, while the same structural arrangement integrates with the existing main shaft and countershaft system for normal gear operation, eliminating the need for separate housing sections.
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 design achieves a space-efficient transmission that provides additional gear ratios without lengthening the transmission, maintaining strength and reducing the risk of shaft deflection, while allowing for efficient torque transfer and gear selection, including a crawler gear for low-speed maneuvers.
Implementation Method 1
The first crawler shaft gearwheel (41) and the first countershaft gearwheel (31) are in meshing engagement with one another, and the second crawler shaft gearwheel (42) and the second countershaft gearwheel (32) are in meshing engagement with one another
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
A transmission (120) for a vehicle, comprising: - an input shaft (1), a main shaft (2), and a countershaft (3), the main shaft being coaxial with the input shaft and the countershaft being parallel therewith, - first and second primary gear planes (P1, P2) arranged for torque transfer between the input shaft and the countershaft, - at least one secondary gear plane (S1, S2, Sr) arranged for torque transfer between the countershaft and the main shaft. The transmission further comprises a crawler shaft (4) arranged in parallel with the main shaft, wherein the first primary gear plane comprises a first crawler shaft gearwheel (41) arranged on the crawler shaft, and wherein the second primary gear plane comprises a second crawler shaft gearwheel (42) arranged on the crawler shaft, the second crawler shaft gearwheel being selectively rotationally connectable to the first crawler shaft gearwheel so as to engage a crawler gear of the transmission.