Modular Rail and Segmented Gearbox for Deep-Bore Blind Fastening

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Solution Overview

Problem

The challenge of accessing and torquing screw fasteners in restricted locations within complex mechanical assemblies, such as aircraft engines, due to limited wrench access and narrow bore diameters, is exacerbated by high torque requirements and complex bolted joints, making maintenance and assembly difficult.

Innovation Solution

A deep reach torque system comprising a modular rail assembly with a flexible, segmented gearbox assembly, including an aft, mid, and forward gearbox subassembly, and a telescoping rotatable axle, which allows for extended reach and precise torque application in confined spaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional socket wrench sets and hand operated wrenches are used, then the structure is simple, but wrench access is blocked by installed parts and structure in restricted locations

Engineering Contradiction:
Improvewrench accessVSAvoidtooling complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The tooling system is divided into modular components including a drive shaft with multiple drive sockets, extendable sections, and interchangeable tool heads. This segmentation allows the system to navigate around installed parts and reach fasteners in restricted locations while maintaining operational capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The tooling system incorporates multi-axis positioning capabilities and articulated sections that allow movement in multiple dimensions. This enables the tool to access fasteners from different angles and directions, overcoming the limitations of linear access paths blocked by installed structure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Weight of moving object

If the bore diameter is decreased to optimize rotor mass efficiency, then the rotor mass efficiency is improved, but the access to bolted joints becomes increasingly difficult

Engineering Contradiction:
Improve rotor massVSAvoidaccess to bolted joints
Core Design Contradiction:
Weight of moving objectVSEase of operation

Solution Approach 1:

The tooling system employs nested components where tool heads, drive sockets, and measurement devices are housed within telescoping sections of the drive shaft. This nesting allows the tool to be compact for insertion through narrow bores while extending to reach fasteners at deep axial distances.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The tooling system incorporates telescoping sections, articulating joints, and adjustable components that allow dynamic reconfiguration during operation. This enables the tool to adapt its shape and reach to access fasteners in tight spaces while maintaining the necessary torque application capability.

Inventive Principle:
Principle #15Dynamics

3Strength

If high torque values are applied to bolted joints, then the fastening strength is improved, but the measurement and recording of torque and angle becomes more difficult in restricted access

Engineering Contradiction:
Improvefastening strengthVSAvoidtorque and angle measurement
Core Design Contradiction:
StrengthVSMeasurement precision

Solution Approach 1:

The tooling system incorporates intermediate measurement devices such as encoded shafts, magnetic sensors, and digital torque sensors that are integrated into the tool structure. These intermediaries transmit measurement data from the torque application point to external recording systems, enabling precise measurement even when direct access is restricted.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system replaces traditional mechanical measurement and recording mechanisms with electronic sensors and digital data transmission. This substitution enables accurate torque and angle measurement in restricted spaces where mechanical gauges and direct reading devices would be inaccessible.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Volume of moving object

If the axial web spacing is decreased to improve compactness, then the compactness is improved, but the reach distance for tooling increases

Engineering Contradiction:
Improvecomponent compactnessVSAvoidtooling reach distance
Core Design Contradiction:
Volume of moving objectVSLength of moving object

Solution Approach 1:

The tooling system employs telescoping drive shafts with multiple extendable sections that can be deployed as needed. This dynamic extension allows the tool to reach fasteners at varying depths while maintaining a compact storage and transport configuration when not in use.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The drive shaft is divided into multiple modular sections that can be extended and retracted independently. This segmentation allows the tool to achieve long reach distances when needed while maintaining overall compactness for installation and removal from the rotor assembly.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4703570A1Apparatus and method for assembling and/or repairing machines
Publication Date: 2026.03.04 RTX CORP
  • EP4703570A1 patent drawingFigure 1
  • EP4703570A1 patent drawingFigure 2
  • EP4703570A1 patent drawingFigure 3

AI summary

A deep reach torque system comprises a modular rail assembly (50) designed to receive a flexible, segmented gearbox assembly (10). The flexible segmented, gearbox assembly comprises an aft gearbox subassembly; a mid-gearbox subassembly; and, a forward gearbox subassembly. A method for installing a part at a blind part location within a machine comprises the steps of deploying a modular rail assembly (50) within a bore of a machine at an intended position therein; deploying a flexible, segmented gearbox assembly (10) on a pair of tracks (404; 467) of the modular rail assembly (50); positioning and aligning the flexible, segmented gearbox assembly (10) with a blind part location; dispensing a part through a tubular-shaped part dispenser (445) to a socket of a drive socket of a forward gearbox subassembly of the flexible, segmented gearbox assembly (10); and rotatably engaging the part with a blind part until the part is secured on the blind part.