Bogie Beam Jacking Dome Fitting Load Transfer
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Solution Overview
Problem
Current jacking dome arrangements in aircraft landing gear, whether integrally formed or separate, lead to high localized stresses in bogie beams during jacking operations, potentially exceeding safe stress loadings, especially in larger aircraft, due to the need to transfer vertical and lateral loads, which can cause deformation and reduce ground clearance.
Innovation Solution
A jacking dome fitting that extends through the sidewall of the bogie beam and is in contact with the axle to directly transfer vertical loads, with a region of increased thickness to react lateral loads, and optional biasing mechanisms such as retaining bolts, wedges, or threaded collars to ensure contact with the axle, reducing stress on the bogie beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate steel jacking dome is bolted through the bogie beam, then the jacking function is achieved, but high localized stresses cause deformation and reduce ground clearance
Solution Approach 1:
The jacking dome fitting is divided into separate components: a jacking dome portion for vertical load application and a fitting portion that extends into the bogie interior. This segmentation allows the vertical load path to be separated from the bogie beam structure, transferring loads directly to the axle through the fitting portion while the bogie beam only handles lateral loads.
Solution Approach 2:
The jacking dome fitting acts as an intermediary element between the jacking dome and the axle. It transfers vertical jacking loads directly to the axle without passing through the bogie beam, thereby protecting the bogie beam from high localized stresses while maintaining the jacking function.
2Strength
If the bogie beam is strengthened to handle jacking loads, then stress capacity increases, but ground clearance is reduced
Solution Approach 1:
The vertical load transfer function is extracted from the bogie beam and assigned to the jacking dome fitting and axle combination. The bogie beam is relieved of vertical jacking loads, maintaining its original dimensions and ground clearance while still providing lateral support through the socket region.
3Ease of manufacture
If a hole is made through the bogie beam for the jacking dome, then the jacking dome can be attached, but the bogie beam becomes weaker and more prone to deformation
Solution Approach 1:
The socket region of the bogie beam is provided with increased thickness specifically at the location where the jacking dome fitting passes through. This local reinforcement provides the necessary strength to handle lateral loads while maintaining the hole for the fitting, without requiring overall strengthening of the bogie beam that would reduce ground clearance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces localized stresses in the bogie beam by transferring loads directly to the axle, minimizing deformation and maintaining ground clearance, while ensuring stable load transfer and reduced risk of fretting or corrosion.
Implementation Method 1
The jacking dome fitting may be secured to one end of an elongate resilient element, the elongate resilient element biasing the jacking dome fitting into contact with the axle
Implementation Method 2
one or more wedge elements may be located between a portion of the jacking dome fitting and the bogie beam sidewall, thereby urging the jacking dome fitting into contact with the axle
Implementation Method 3
the jacking dome fitting may include a threaded collar in engagement with a threaded portion of the jacking dome fitting and in engagement with the bogie beam sidewall, whereby the threaded collar urges the jacking dome fitting into contact with the axle
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
An aircraft landing gear assembly comprising a bogie beam (2), an axle (4) extending through the bogie beam and a jacking dome fitting (6) extending through a sidewall (8) of the bogie beam and arranged to transfer vertical loads applied to the jacking dome fitting to the axle.