Aircraft Rail Fastener Assembly for High-Load Low-Height Locking
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Solution Overview
Problem
Existing fastening devices for perforated aircraft rails face challenges in transmitting high loads while minimizing space requirements, particularly in the Z-direction, and often require additional components and increased installation height, which is problematic for applications involving containers and pallets on rollers.
Innovation Solution
A fastening device with a non-rotatable shear pin and a rotatable actuating pin mechanism, allowing for a non-circular cross-section design that optimizes structural strength and reduces overall height, combined with a locking bolt made of steel for increased mechanical load capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fastening device uses rotatable tension bolts and immovable shear bolts with spring-loaded locking elements, then the locking reliability is improved, but the device complexity and installation space requirements increase
Solution Approach 1:
The patent extracts and eliminates the spring-loaded locking elements from the fastening device, using only immovable shear pins and a simple actuating mechanism. This removes the complex vibration-resistant locking components while maintaining sufficient reliability for the application
Solution Approach 2:
Instead of using rotatable tension bolts that require vibration-resistant locking, the patent inverts the approach by using immovable shear pins combined with a simple actuating pin mechanism that achieves reliable locking without complex safety features
2Device complexity
If a fastening device uses screw-in fixing pins for shear bolts, then the locking mechanism is simplified, but the overall height and installation space increase
Solution Approach 1:
The patent changes the dimensional approach by using a non-circular cross-section for the shear pin (e.g., rectangular or oval) instead of a circular cross-section. This allows the shear pin to be guided non-rotatably in the housing without requiring additional height for rotation mechanisms, thereby reducing the overall height while maintaining structural integrity
3Ease of manufacture
If the shear pin has a circular cross-section and is rotatable, then the manufacturing is simplified, but the structural strength and load transmission capability decrease
Solution Approach 1:
The patent applies asymmetry by using a non-circular cross-section for the shear pin. This asymmetric shape provides superior structural strength and load transmission capability compared to a circular cross-section, while the non-rotatable guidance in the housing ensures proper orientation during assembly
4Reliability
If additional components are added to prevent tension bolt back-turning, then the vibration-resistant locking is improved, but the additional installation space and costs increase
Solution Approach 1:
The patent extracts and removes the need for additional vibration-resistant locking components by using immovable shear pins that inherently prevent back-turning. The simple actuating pin mechanism provides sufficient reliability without requiring extra space for spring-loaded locking elements
Data Source
AI summary
A fastening device for releasable connection to a perforated rail of an aircraft and a method of assembly for such a fastening device. The fastening device comprises a housing having at least one locking head portion fixedly connected to the housing, at least one shear pin and an actuating pin. The locking head portion is insertable into a rail hole of the perforated rail and slidable along the longitudinal direction of the perforated rail to a locking position in which the locking head portion engages a slot portion of the perforated rail. The shear pin can be engaged with a rail hole of the perforated rail by axial displacement. The actuating pin is rotatably arranged relative to the housing and connected to the shear pin in such a way that a rotation of the actuating pin causes an axial displacement of the shear pin relative to the housing.