Aircraft Landing Gear Interlock Geometry for Torque Transmission

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Solution Overview

Problem

Existing aircraft landing gear designs face challenges in efficiently transmitting mechanical torques while minimizing mass, manufacturing complexity, and material volume, particularly in areas prone to torsional, shear, and bending stresses, with existing solutions being costly and difficult to produce.

Innovation Solution

The design incorporates a male part with an exclusively convex external contact surface and a female part with a complementary concave internal surface, featuring rounded lobes that prevent pivoting, allowing for effective torque transmission and reduced material usage by minimizing concavities and facilitating maintenance through interchangeable parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a one-piece forged part with axle hands is used to transmit mechanical torques, then mechanical resistance and strength are improved, but manufacturing complexity and material loss increase significantly

Engineering Contradiction:
Improvemechanical resistanceVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The landing gear is divided into separate modular components: a rod and axle hands that can be manufactured independently and assembled together. This segmentation allows each component to be optimized separately for strength and manufacturing efficiency, eliminating the need for complex one-piece forging while maintaining mechanical resistance through precise interlocking interfaces.

Inventive Principle:
Principle #1Segmentation

2Strength

If a one-piece forged part is used to ensure structural integrity, then strength is improved, but volume of material required and manufacturing cost increase

Engineering Contradiction:
Improvestructural integrityVSAvoidvolume of material
Core Design Contradiction:
StrengthVSQuantity of substance

Solution Approach 1:

By segmenting the landing gear into separate components connected through precision interfaces, the design achieves structural integrity at the connection points without requiring excessive material throughout the entire structure. The modular approach allows material to be placed only where structurally necessary.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The axle hands are designed to fit within or alongside the rod structure, with interlocking interfaces that maximize structural efficiency. The nested configuration allows components to support each other, reducing the total material volume needed while maintaining strength.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Strength

If male and female parts with grooves are used to prevent rotation, then torque transmission is improved, but surface treatment quality becomes difficult to ensure due to concavities

Engineering Contradiction:
Improvetorque transmissionVSAvoidsurface treatment quality
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The invention replaces traditional grooves with rounded lobes on the external contact surface of the male part. These curved, convex features are easier to manufacture with consistent dimensions and provide more uniform surface treatment coverage compared to sharp grooves, while still effectively preventing rotation through their geometric interlocking with the female part.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Data Source

PatentEP4419807B1Aircraft landing gear with interlocking male and female parts for the transmission of mechanical torques
Publication Date: 2026.03.18 SAFRAN LANDING SYSTEMS
  • EP4419807B1 patent drawingFigure 1~2b
  • EP4419807B1 patent drawingFigure 3~4b
  • EP4419807B1 patent drawingFigure 5a~5b

AI summary

The invention relates to aircraft landing gear (0) having a male part (M0, M1, M3) interlocked with a female part (F0, F1, F2, F3) along an interlocking direction (D). The external contact surface of the male part (M0, M1, M3), when it is observed along the interlocking direction (D), is an exclusively convex closed surface having external contact surface portions in the form of rounded lobes (L1, L2, L3, L4) that form obstacles to the pivoting of the female part (F0, F1, F2, F3) with respect to the male part (M0, M1, M3) about the interlocking direction (D). The invention also relates to an aircraft having such landing gear.