Crawler Shaft Transmission Layout for Added Gear Ratios
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Solution Overview
Problem
Heavy-duty vehicle transmissions face challenges in providing additional gear ratios without increasing the transmission length, which is necessary for down-speeded engines to maintain startability while avoiding the drawbacks of longer, heavier, and more expensive transmissions.
Innovation Solution
A transmission design that includes an input shaft, a main shaft, a countershaft, and a crawler shaft, with multiple gear planes for torque transfer, allowing for additional gear ratios without lengthening the transmission. The crawler shaft, with gearwheels arranged in parallel, enables both forward and reverse crawler gears without adding to the transmission housing length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional gears are added to the transmission, then gear ratio coverage is improved, but transmission length increases
Solution Approach 1:
The patent introduces a crawler shaft arranged in parallel with the main shaft, creating a new dimensional arrangement for gearwheels. This parallel shaft configuration allows additional gear ratios to be achieved without extending the transmission length in the conventional axial direction, effectively utilizing a different spatial dimension for gear arrangement.
Solution Approach 2:
The patent arranges multiple gearwheels (first and second crawler shaft gearwheels) on the same crawler shaft in a nested-like configuration. These gearwheels are selectively rotationally connectable and can engage with crawler gears, allowing multiple gear ratios to be achieved within a compact space without requiring separate shafts for each gear.
2Adaptability or versatility
If shaft length is increased to accommodate additional gears, then gear ratio coverage is improved, but shaft strength deteriorates
Solution Approach 1:
By arranging gearwheels on a parallel crawler shaft rather than extending the main shaft axially, the patent avoids increasing shaft length in the direction that would compromise strength. The parallel arrangement allows additional gears to be accommodated without subjecting existing shafts to increased bending moments or deflection risks.
3Adaptability or versatility
If transmission length is increased, then gear ratio coverage is improved, but device complexity increases
Solution Approach 1:
The crawler shaft serves multiple functions: it carries both the first and second crawler shaft gearwheels, provides pathways for torque transfer in both forward and reverse directions, and enables engagement with crawler gears. This multi-functional design achieves comprehensive gear ratio coverage without proportionally increasing device complexity.
Data Source
AI summary
A transmission for a vehicle includes: an input shaft, a main shaft, and a countershaft, the main shaft being coaxial with the input shaft and the countershaft being parallel therewith, first and second primary gear planes arranged for torque transfer between the input shaft and the countershaft, and at least one secondary gear plane arranged for torque transfer between the countershaft and the main shaft. The transmission further includes a crawler shaft arranged in parallel with the main shaft, wherein the first primary gear plane comprises a first crawler shaft gearwheel arranged on the crawler shaft, and wherein the second primary gear plane comprises a second crawler shaft gearwheel 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.