Pivoting Thrust Washer for Even Wear in Planetary Gears
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Solution Overview
Problem
Thrust washers in planetary gears experience concentrated wear and increased risk of bearing damage due to dry or mixed friction during startup and shutdown, leading to reduced service life and potential damage.
Innovation Solution
A thrust washer with first and second abutments, formed by pins and recesses or surfaces, allows for rotational movement between two positions, distributing wear evenly by alternating contact under changing load conditions, preventing localized wear zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thrust washer is fixed in the planetary carrier, then the mounting is simple and stable, but wear is concentrated in specific areas leading to reduced service life
Solution Approach 1:
The thrust washer is designed to rotate relative to the planetary carrier through a bearing gap, transforming from a static fixed mounting to a dynamic rotating mounting. This rotation distributes wear evenly across the entire thrust washer surface, preventing localized wear concentration and extending service life while maintaining simple mounting through the bearing gap design
2Reliability
If the thrust washer rotates freely, then wear is distributed evenly, but the thrust washer may become unstable under varying load conditions
Solution Approach 1:
The bearing gap dimensions are specifically optimized to allow controlled rotation under varying load conditions. The gap is sized to permit sufficient rotation for wear distribution while maintaining stability through proper clearance control, transforming the thrust washer from a completely fixed or completely free state to a controlled intermediate state
Solution Approach 2:
The thrust washer transitions from a static fixed position to a dynamic rotating position within the bearing gap. This controlled rotation allows the thrust washer to adapt to varying load conditions while distributing wear evenly, achieving both wear distribution and stability through dynamic adjustment
3Productivity
If dry or mixed friction occurs during startup and shutdown, then the gear can operate, but increased wear and bearing damage risk occur
Solution Approach 1:
The thrust washer is designed to rotate dynamically within the bearing gap during operation. This rotation ensures that during startup and shutdown phases, the contact point continuously changes, distributing the high friction wear across the entire thrust washer surface rather than concentrating it at a single location, thereby reducing bearing damage risk while maintaining gear operation capability
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
The solution increases the load capacity and service life of the thrust washer by evenly distributing wear, reducing the risk of wear-related failures and maintaining lubricant efficiency in the bearing gap.
Implementation Method 1
A bearing gap extends between a respective thrust washer and a planetary wheel. It is filled with lubricant so that liquid friction is present under normal operating conditions.
Implementation Method 2
When the gear starts up or comes to a standstill, however, dry or mixed friction cannot be avoided. This is accompanied by increased wear.
Data Source
AI summary
A unit includes a thrust washer having a first abutment and a second abutment. The thrust washer is configured to be moved, by rotation, between a first position in which the thrust washer abuts the first abutment and a second position in which the thrust washer abuts the second abutment. The first abutment and the second abutment are formed by at least one pin and at least one recess. The pin is configured to engage in the recesses, and the recess is designed as a groove that extends tangentially around an axis of rotation of a component that is rotatably mounted by way of the thrust washer.