Steerable Axle Landing Gear One-Way Castoring Lock
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Solution Overview
Problem
Existing large aircraft landing gears with steerable axles face difficulties in accurately locking the rear axle into the landing position, especially in six-wheel bogies, requiring complex mechanisms and additional pilot maneuvers, which can increase take-off runway length and risk axle scuffing during turns.
Innovation Solution
A bogie landing gear with a telescopic strut acting as both a steering actuator and travel limitation means, featuring a deformable one-way locking mechanism that automatically locks the pivotable axle in a stable, fully extended or fully compressed state, simplifying the locking process and allowing one-way castoring, thereby reducing the complexity of locking the axle into the landing position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional lock means are used to lock the axle in the landing position, then the axle can be locked, but the locking is difficult to achieve accurately and requires complex mechanisms
Solution Approach 1:
The telescopic strut automatically locks the axle in the landing position through its own mechanical deformation. When the axle returns to the landing position, the strut deforms and engages a locking mechanism without requiring external control or complex actuation systems. The strut serves both as a structural component and as the locking actuator.
Solution Approach 2:
The locking mechanism utilizes the deformation parameter of the telescopic strut. As the strut extends or compresses during axle movement, it transitions between locked and unlocked states. The locking occurs at specific deformation states (fully extended or fully compressed) that correspond to the landing position, eliminating the need for precise angular positioning control.
2Ease of operation
If the axle is allowed to castor freely, then the aircraft can turn smoothly, but the axle may scuff during turns and require additional pilot maneuvers
Solution Approach 1:
The system dynamically switches between two states: locked state during straight-line landing and castoring state during turns. The telescopic strut automatically transitions from locked to unlocked when the axle deviates from the landing position, allowing controlled castoring during turns while preventing scuffing by maintaining the locked state during straight-line operation.
3Ease of operation
If the aft portion of the bogie is made pivotable for one-way castoring, then the axle can be steered during turns, but the articulation becomes highly loaded and difficult to implement
Solution Approach 1:
The telescopic strut performs multiple functions: it serves as a structural support element, a steering actuator, and a locking mechanism. By combining these functions into a single component, the patent eliminates the need for separate articulation mechanisms that would be highly loaded, thereby reducing complexity while maintaining steering capability.
4Reliability
If the axle is locked in intermediate positions, then the locking can be achieved, but the positioning accuracy is difficult to achieve and requires complex control
Solution Approach 1:
Instead of controlling the axle angle to achieve locking, the system inverts the approach: the telescopic strut deforms to a specific state (fully extended or fully compressed) to achieve locking. This inversion eliminates the need for precise angular positioning control, as the locking occurs at the extreme deformation states of the strut rather than at specific axle angles.
Data Source
Figure 1A~2B
Figure 3~5
AI summary
There is described a landing gear having a bogie including a elongated beam (2) for accommodating at least two axles receiving each a pair of ground engaging wheels, at least one axle (5) being pivotally mounted on the elongated beam. The landing gear further includes axle travel limitation means (10) extending between said pivotable axle and said elongated beam to be hitched up thereto, said travel limitation means being deformable one way starting from an stable and lockable state thereof corresponding to a landing position of said pivotable axle. There are also described independently lockable and actuatable telescopic struts.