Cranking Pad Interlock for Turbomachine Gearbox Sealing

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Solution Overview

Problem

Existing methods for rotating the interior shaft of a turbomachine during maintenance or inspection are inefficient, as they require manual cover replacement to prevent oil leakage, which can lead to damage or failure if not done correctly.

Innovation Solution

A cranking pad assembly with a rotatably secured cranking pad shaft in the gearbox housing, featuring an interlock pin and disconnect spring, allows for manual rotation of the turbine shaft using a cranking tool while maintaining gearbox sealing without the need for a cover, ensuring secure disengagement and preventing oil leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a simple cover is removed from the gearbox to insert a cranking tool, then the cranking operation can be performed, but the gearbox becomes exposed to oil leakage and contamination

Engineering Contradiction:

Improvecranking operationVSAvoidgearbox sealing

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The gearbox sealing system is segmented into a removable cover and a cranking pad assembly with its own sealing mechanism. The cranking pad includes a seal that divides the sealing function from the cover, allowing the cover to be removed for cranking while maintaining gearbox sealing through the cranking pad seal.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cranking pad assembly acts as an intermediary component between the cranking tool and the gearbox drivetrain. It provides a sealed interface that allows mechanical energy transfer during cranking while preventing oil leakage, eliminating the need to remove the gearbox cover.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the cover is not replaced after cranking, then the cranking operation is convenient, but oil leakage can result in damage to and/or failure of the gas turbine

Engineering Contradiction:

Improvemaintenance efficiencyVSAvoidoil leakage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The cranking pad assembly is designed to automatically maintain sealing functionality throughout the cranking operation and remain sealed when the tool is removed. The spring-loaded seal and interlock mechanism ensure the gearbox remains sealed without requiring manual cover reinstallation, making the system self-protecting against oil leakage.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If a cranking tool is inserted into the gearbox to rotate the shaft, then the turbine shaft can be rotated for maintenance, but the gearbox must be opened exposing it to oil leakage

Engineering Contradiction:

Improveshaft rotation capabilityVSAvoidgearbox opening

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The cranking pad assembly serves multiple functions: it provides a sealed interface for cranking tool insertion, transmits rotational force to the drivetrain, and maintains gearbox sealing throughout the operation. This multi-functional design eliminates the need to open the gearbox while maintaining shaft rotation capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If manual cover replacement is required after cranking, then the gearbox can be sealed, but the process becomes inefficient and error-prone

Engineering Contradiction:

Improvegearbox sealingVSAvoidcover reinstallation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The cranking pad assembly is pre-configured with a spring-loaded seal and interlock mechanism that automatically maintains sealing readiness. The spring is pre-compressed to provide immediate sealing force, and the interlock is pre-positioned to engage with the cranking tool, eliminating the need for manual cover reinstallation and reducing time loss.

Inventive Principle:

Principle #10Preliminary action

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

Enables efficient manual rotation of the turbine shaft during maintenance while maintaining the gearbox seal, reducing the risk of oil leakage and subsequent damage, and eliminating the need for manual cover reinstallation.

Implementation Method 1

a disconnect spring operably connected to the gearbox housing to bias the cranking pad shaft outwardly from the gearbox housing

Methodology Applied

Scientific EffectSpring force: Spring

Implementation Method 2

an interlock pin to retain the cranking tool at the cranking pad shaft

Methodology Applied

Scientific EffectMechanical interlocking: Mechanical Fastener

Data Source

PatentUS8845275B2Cranking pad interlock

Publication Date: 2014.09.30 HAMILTON SUNDSTRAND CORP

AI summary

A cranking pad assembly for a gearbox of a turbomachine including a cranking pad shaft rotatably secured in a gearbox housing and engageable with a gearbox drivetrain when urged inwardly into the gearbox housing. The cranking pad shaft includes an interface for a cranking tool. An interlock pin retains the cranking tool at the cranking pad shaft and a disconnect spring is operably connected to the gearbox housing to bias the cranking pad shaft outwardly from the gearbox housing.