Spiderless Pinion Arcuate Surface Torque Path
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Solution Overview
Problem
Conventional differentials experience premature wear due to restricted lubrication and mechanical engagement caused by the tilting of spider pinions, which results from the moment created by the engagement of spider pinions with side gears, leading to inefficient torque distribution and reduced lifespan.
Innovation Solution
The design incorporates side pinions with an arcuate outer surface formed by a polynomial curve of third order or higher, which aligns the reaction force gradient with the force direction, preventing tilting and ensuring proper lubrication flow by directing forces normally into cups, eliminating moments and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spider pinions are used with flat tops and bottoms, then the differential can be manufactured with simpler geometry, but the pinions tilt during operation causing restricted lubrication and premature wear
Solution Approach 1:
The patent applies curvature by replacing the flat top and bottom surfaces of conventional spider pinions with arcuate surfaces formed by polynomial curves of third order or higher. This curved geometry aligns the reaction force gradient with the force direction, preventing pinion tilting and ensuring proper lubrication flow, thereby resolving the contradiction between manufacturing simplicity and operational reliability.
2Ease of manufacture
If spider pinions engage side gears with conventional flat geometry, then the manufacturing process is simpler, but moments are created causing pinion tilting and mechanical engagement between bore walls and spider shaft
Solution Approach 1:
The arcuate outer surface with polynomial curve geometry transforms the force distribution during gear engagement. The curved surface ensures that reaction forces are distributed normal to the surface, eliminating moments that cause tilting and preventing harmful mechanical engagement between bore walls and spider shaft, thus resolving the contradiction between manufacturing ease and harmful effects.
3Device complexity
If conventional flat-topped pinions are used, then the design is simpler, but lubrication flow is restricted due to pinion tilting
Solution Approach 1:
The arcuate outer surface geometry oriented at specific angles (e.g., 45 degrees) to the pinion axis creates a surface that naturally guides lubrication flow. The curved geometry prevents tilting during operation, maintaining open lubrication pathways and ensuring consistent lubrication delivery to critical surfaces, thereby resolving the contradiction between design simplicity and lubrication efficiency.
4Device complexity
If spider pinions are allowed to tilt during operation, then the initial design is simpler, but torque distribution becomes inefficient and wear increases
Solution Approach 1:
The polynomial curve geometry of the arcuate outer surface ensures that reaction forces are distributed optimally during gear engagement. This curved surface maintains proper pinion orientation, ensuring efficient torque distribution to the side gears and preventing energy loss through tilting, thus resolving the contradiction between configuration simplicity and torque distribution efficiency.
Data Source
AI summary
A side pinion is disclosed for use with a differential of a mobile machine. The side pinion may have a body with a flat bottom and a flat top located at an end opposite the flat bottom. The side pinion may also have a plurality of gear teeth formed adjacent the flat top, and an arcuate outer surface connecting the plurality of gear teeth to the flat bottom.