Pivoting Planetary Gear Set for Axle Deflection
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Solution Overview
Problem
Conventional axle arrangements in work vehicles, such as tractors, face challenges with axle shaft deflections due to bending forces, which complicates track width adjustments and affects reliability and performance.
Innovation Solution
The implementation of a final drive assembly with a planetary gear set that includes a pivoting sun gear and spherically crowned teeth and bearings, allowing for deflection accommodation within a compact axial length, thereby mitigating bending forces and enhancing adjustability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the axle shafts are elongated to enable a range of positions for adjustments, then the track width adjustability is improved, but the device complexity and reliability deteriorate due to increased bending forces and structural complexity
Solution Approach 1:
The planetary gear set is designed to pivot relative to the input member, allowing dynamic adjustment of the final drive assembly position. This pivoting capability enables track width adjustment without requiring elongated axle shafts, as the gear set can dynamically adapt its position to accommodate different track widths while maintaining structural integrity
Solution Approach 2:
The invention changes the operational parameters of the final drive assembly by introducing pivoting capability and spherically crowned teeth. This allows the system to accommodate deflections and adjust track width through controlled parameter changes in the gear set geometry and positioning, rather than through static elongation of axle shafts
2Adaptability or versatility
If the axle shafts are elongated to enable a range of positions for adjustments, then the track width adjustability is improved, but the reliability deteriorates due to bending forces and subject to reliability issues
Solution Approach 1:
The pivoting planetary gear set dynamically adjusts its position to accommodate track width changes, eliminating the need for elongated axle shafts that are susceptible to bending forces. This dynamic adaptation maintains reliable power transmission while enabling adjustability
Solution Approach 2:
Spherically crowned teeth and bearings are incorporated into the planetary gear set to accommodate deflections and misalignments. The spherical geometry allows the gear set to pivot and adapt to different positions without compromising reliability, as the curved surfaces distribute loads more evenly and tolerate positional variations
3Reliability
If a pivoting planetary gear set with spherically crowned teeth is used, then the reliability and deflection accommodation are improved, but the manufacturing complexity increases
Solution Approach 1:
While spherically crowned teeth do increase manufacturing complexity compared to straight teeth, the patent addresses this by integrating the spherical crowning into the existing planetary gear set design. The curved surfaces are formed during the gear manufacturing process using specialized cutting tools, allowing reliable deflection accommodation without requiring entirely new manufacturing processes
Solution Approach 2:
The pivoting planetary gear set with spherically crowned teeth serves multiple functions: it provides power transmission, accommodates deflections, enables track width adjustment, and maintains reliability. By combining these functions into a single integrated mechanism, the patent reduces overall system complexity despite the increased manufacturing requirements for the gear teeth themselves
Data Source
AI summary
An axle final drive assembly for a work vehicle is provided. The axle final drive assembly includes a final drive housing; an output shaft extending from the final drive housing; a planetary gear set contained in the final drive housing and having an element fixed to the output shaft; and an input member contained in the final drive housing providing rotational input to the planetary gear set for driving the output shaft. The planetary gear set, at least in part, is pivotally coupled to the input member.