Removable Crank Gear for Gas Turbine Rotor Access
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Solution Overview
Problem
Maintenance and inspection of gas turbine engines require manual rotation of the rotor, which is often facilitated by permanent features in the gearbox that add weight, increase manufacturing and maintenance costs, and are susceptible to wear.
Innovation Solution
A crank gear system with a shaft, bearings, and a gear that is inserted into the gearbox for manual rotation, featuring a removable interface for torque application, reducing the need for permanent gearbox components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If permanent features are built into the gearbox to facilitate manual rotation, then rotor accessibility is improved, but gearbox weight increases
Solution Approach 1:
The manual rotation interface is segmented from the gearbox structure. A separate crank gear assembly with shaft and bearings is inserted through a port in the gearbox housing, allowing the rotation function to be detached from the permanent gearbox structure. This segmentation enables rotor accessibility without adding permanent weight to the gearbox.
Solution Approach 2:
The manual rotation interface is extracted as a removable component. The crank gear assembly can be completely removed from the gearbox through the port after use, eliminating the need for permanent features in the gearbox structure. This extraction resolves the contradiction by providing rotor accessibility only when needed, without permanently increasing gearbox weight.
2Ease of operation
If permanent features are built into the gearbox for manual rotation, then rotor accessibility is improved, but manufacturing cost increases
Solution Approach 1:
The manual rotation function is segmented into a separate insertable assembly rather than being integrated into the gearbox manufacturing process. The crank gear with shaft and bearings is manufactured as a separate component that can be inserted through a pre-formed port, simplifying gearbox manufacturing while providing rotor accessibility functionality.
Solution Approach 2:
The manual rotation interface is extracted as a removable component that does not require permanent integration into the gearbox. This extraction allows the gearbox to be manufactured with simpler, less expensive structures, as the rotation function is provided by the insertable crank gear assembly rather than requiring complex permanent features.
3Ease of operation
If permanent features are built into the gearbox for manual rotation, then rotor accessibility is improved, but maintenance cost increases
Solution Approach 1:
The manual rotation interface is segmented as a separate removable assembly. When wear or damage occurs, only the crank gear assembly needs to be replaced rather than repairing permanent features in the gearbox. This segmentation reduces maintenance cost by isolating the wear-prone components to a replaceable insertable unit.
Solution Approach 2:
The manual rotation function is extracted as a removable component that can be completely removed and replaced. This extraction simplifies maintenance by allowing the entire crank gear assembly to be removed through the port and replaced without disassembling permanent gearbox features, reducing both maintenance time and cost.
4Ease of operation
If permanent features are built into the gearbox for manual rotation, then rotor accessibility is improved, but gearbox complexity increases
Solution Approach 1:
The manual rotation function is segmented into a separate insertable assembly that does not require permanent integration with the gearbox. The crank gear with shaft and bearings forms a self-contained unit that can be inserted through a simple port, reducing gearbox complexity while providing rotor accessibility functionality.
Solution Approach 2:
The manual rotation interface is extracted as a removable component, eliminating the need for permanent structural modifications to the gearbox. This extraction reduces gearbox complexity by avoiding the need for integrated features, while still providing full rotor accessibility functionality through the insertable crank gear assembly.
Data Source
AI summary
A crank gear includes a shaft extending along a centerline. A first bearing, a second bearing, and a gear are mounted to the shaft. An interface at the first end of the shaft for rotating the shaft and the gear about the centerline. The crank gear is reversibly insertable through a port of a gearbox to engage a gear. The gear is rotationally coupled to a rotor of a gas turbine engine.