Lock Ring Nut Assembly for Landing Gear Axial Load Resistance

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Solution Overview

Problem

Landing gear joints in aircraft are susceptible to nut rotation relative to the pin under axial loads, leading to decoupling issues, which existing nut locking assemblies fail to adequately address.

Innovation Solution

A nut locking assembly featuring a lock ring with a greater number of outer diameter protrusions compared to inner diameter protrusions, and a specific configuration of grooves and protrusions that allow the lock ring to secure the nut to the pin, reducing relative torque and enabling secure coupling of landing gear components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional nut locking assembly is used, then the nut can be secured to the pin, but the assembly is susceptible to rotation under axial loads

Engineering Contradiction:
Improveresistance to nut rotationVSAvoidwithstand axial load
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The lock ring is segmented into multiple discrete protrusions (first, second, third protrusions) that engage with corresponding grooves in the nut. This segmentation allows each protrusion to independently resist rotational forces, distributing the locking function across multiple contact points rather than relying on a single continuous structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lock ring features asymmetric positioning of protrusions with varying axial thicknesses (first protrusion has different thickness than second and third protrusions) and varying gap sizes (first gap differs from second and third gaps). This asymmetric configuration creates unequal mechanical leverage against rotational forces, enhancing the overall resistance to nut rotation under axial loads.

Inventive Principle:
Principle #4Asymmetry

2Stability of the object's composition

If the lock ring has more outer diameter protrusions to prevent rotation, then rotational stability improves, but the device complexity increases

Engineering Contradiction:
Improverotational stabilityVSAvoidnumber of protrusions and grooves
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The lock ring serves multiple functions simultaneously: the protrusions provide rotational locking, the varying axial thicknesses provide differential load distribution, and the gap variations provide both structural integrity and access for tool engagement. This multi-functionality reduces the need for additional separate components, maintaining simplicity while achieving enhanced rotational stability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The asymmetric gap configuration allows the lock ring to be self-locating during assembly, where the varying gap sizes naturally guide the alignment between protrusions and nut grooves. The structure also provides self-locking characteristics where the protrusions automatically engage at optimal positions, reducing the need for complex alignment mechanisms or additional fastening steps.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3771839B1Nut locking assembly
Publication Date: 2024.09.11 GOODRICH CORP
  • EP3771839B1 patent drawingFigure 1
  • EP3771839B1 patent drawingFigure 2
  • EP3771839B1 patent drawingFigure 3

AI summary

A nut locking assembly may comprise a pin (112), a nut (116), and a lock ring (118). The pin may include an outer diameter threaded surface (130) and a plurality of radially inward extending grooves (160) formed between the outer diameter threaded surface and an end of the pin. The nut may include an inner diameter threaded surface (132) and a plurality of radially outward extending grooves (138) formed between the inner diameter threaded surface and an axial end of the nut. The lock ring may include a plurality of outer diameter protrusions (140) and a plurality of inner diameter protrusions (142).