Retract Actuator Assembly Enabling Aircraft Landing Gear Kneeling

Solution Overview

Problem

Existing aircraft landing gear systems require additional hydraulic actuators and mechanical linkages for kneeling, which increase cost, complexity, and weight.

Innovation Solution

A retract actuator assembly with a kneel stop assembly that allows the landing gear to assume a third position between extended and retracted positions, using a piston and cylinder bore configuration with a kneel stop position established by inhibiting piston movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If additional hydraulic actuators and mechanical linkages are used for kneeling, then the landing gear can achieve a kneeled position, but the device complexity increases

Engineering Contradiction:

Improvelanding gear position capabilityVSAvoidactuator and linkage system

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The retract actuator is designed to perform multiple functions: it provides both the retraction extension capability and the kneeling capability through a single actuator system. The kneel stop assembly, integrated with the retract actuator, enables the kneeled position without requiring a separate hydraulic actuator, thus making the actuator system universal for both landing gear operations

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The kneel stop assembly is merged with the retract actuator structure, combining the kneeling function with the existing retraction system. This integration eliminates the need for separate mechanical linkages and actuators, as the kneel stop is directly associated with the piston movement within the cylinder bore

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If additional hydraulic actuators and mechanical linkages are used for kneeling, then the landing gear can achieve a kneeled position, but the weight increases

Engineering Contradiction:

Improvelanding gear position capabilityVSAvoidlanding gear assembly

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The retract actuator serves dual purposes by providing both retraction extension and kneeling functions. This multi-functionality eliminates the need for additional actuators and their associated hydraulic systems, thereby reducing the overall weight of the landing gear assembly while maintaining full positional capability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

By merging the kneel stop assembly with the retract actuator structure, the patent eliminates redundant components such as separate actuators and mechanical linkages. This consolidation reduces the total material used and consequently decreases the weight of the moving landing gear assembly

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If additional hydraulic actuators and mechanical linkages are used for kneeling, then the landing gear can achieve a kneeled position, but the cost increases

Engineering Contradiction:

Improvelanding gear position capabilityVSAvoidactuator and linkage system

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The retract actuator is designed to perform multiple functions: it provides both the retraction extension capability and the kneeling capability through a single actuator system. The kneel stop assembly, integrated with the retract actuator, enables the kneeled position without requiring a separate hydraulic actuator, thus making the actuator system universal for both landing gear operations

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The kneel stop assembly is merged with the retract actuator structure, combining the kneeling function with the existing retraction system. This integration eliminates the need for separate mechanical linkages and actuators, as the kneel stop is directly associated with the piston movement within the cylinder bore

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP4517109A1Retract actuator assemblies, landing gear assemblies and methods for kneeling landing gear assembly of aircraft

Publication Date: 2025.03.05 THE BOEING CO

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AI summary

A retract actuator assembly for a landing gear assembly of an aircraft includes a retract actuator and a kneel stop assembly. The retract actuator includes an actuator housing and a piston. The actuator housing includes a cylinder bore along a longitudinal axis. The piston disposed within the cylinder bore and configured to move within the cylinder bore. The cylinder bore defines a piston stroke with an extended piston position and a retracted piston position. The kneel stop assembly secured to the actuator housing. The kneel stop assembly is configured to selectively establish a kneel stop position within the cylinder bore to reduce the piston stroke by inhibiting movement of the piston to the retracted piston position. The landing gear assembly includes the retract actuator, the kneel stop assembly, a trailing arm and a shock absorber. A method for kneeling a landing gear assembly of an aircraft is also provided.