Adjustable Stop for Thin-Walled Tube Axle Protector
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Solution Overview
Problem
The challenge in aircraft landing gear is to create an adjustable end stop on a thin tube axle protector without threading the tube itself, due to difficulties in producing threads on thin tubes that can withstand fatigue and space constraints.
Innovation Solution
A threaded ferrule is attached to the tube with pins for immobilization, allowing a nut with an abutment face to preload elements, and a ring is used to lock the nut in rotation, enabling adjustable stop functionality without threading the tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a thread is produced on the thin tube to create an adjustable stop, then the stop functionality is achieved, but the tube thickness is insufficient and fatigue resistance is compromised
Solution Approach 1:
The invention divides the threaded structure into two separate components: the thin tube (axle protector) and a thick-walled ferrule. The ferrule is threaded and attached to the tube, allowing the thread to be formed on a component with sufficient wall thickness to withstand fatigue loads, while the tube itself remains thin and lightweight.
Solution Approach 2:
The ferrule acts as an intermediary component between the thin tube and the nut. It provides the threaded interface for the adjustable stop while being mechanically coupled to the tube through pins, thereby transferring loads without requiring the thin tube to bear the full fatigue stress of the thread.
2Adaptability or versatility
If a threaded structure is added to the thin tube, then the adjustable stop is achieved, but the device complexity increases
Solution Approach 1:
The invention combines multiple functions into the ferrule component: it provides the threaded interface for adjustment, serves as a mechanical coupling between the tube and nut, and acts as a retaining structure for the pins. This consolidation reduces overall system complexity despite adding the adjustable stop functionality.
3Strength
If the tube thickness is increased to accommodate threading, then the thread can withstand fatigue, but the space constraints in the wheel assembly are violated
Solution Approach 1:
The invention separates the structural function (thin tube for space efficiency) from the threaded connection function (thick-walled ferrule for strength). This allows the tube to maintain its thin profile to satisfy space constraints while the ferrule provides the necessary thickness for a fatigue-resistant thread.
Solution Approach 2:
The solution moves the threaded structure from the radial dimension (tube wall thickness) to a separate component (ferrule) that can be attached axially. This dimensional transition allows the thin tube to maintain its compact radial profile while the ferrule provides the necessary thickness for threading in a different spatial arrangement.
Data Source
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AI summary
The invention relates to a method for adapting an adjustable screw-on stop to the end of a thin tube (1), comprising the steps of: - threading onto the end of the tube (5) a ferrule (10) threaded on its external surface and which is immobilized on the end of the tube by means of a plurality of pins (8) engaged in orifices (7,9) opposite the ferrule and the tube; - screwing onto the ferrule a nut (14) having a first end face (15) serving as a stop to preload any element (4,4) mounted on the tube before the ferrule, and a second opposite end face (18) having forms (25) suitable for its rotational driving by a tool, the nut covering the pins in use.