Toggle Assembly Bearings for Low-Friction Ejection Jacks

Solution Overview

Problem

The existing ejection jacks used for deploying and retracting ram air turbines in aircraft experience high friction at pivot points, which reduces the available force and stroke, necessitating iterative shim application to maintain adequate performance.

Innovation Solution

A toggle assembly with pivotally connected joint members and rolling elements, such as roller bearings, is used to reduce friction at pivot points, allowing for increased force margins and stroke availability without the need for excessive shim application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If traditional pivot connections are used in the ejection jack, then the structure is simple, but high friction reduces available force and stroke

Engineering Contradiction:

Improveavailable forceVSAvoidstructure complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

Rolling elements (bearings) are introduced as intermediary components between the pivot connections of the toggle assembly members. These rolling elements mediate the relative motion between members, converting high-friction sliding contact into low-friction rolling contact, thereby reducing overall friction in the ejection jack mechanism while maintaining the structural integrity of the toggle assembly

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces traditional sliding pivot connections with rolling element bearings in the toggle assembly. This substitution transforms the mechanical interaction from sliding friction to rolling friction, significantly reducing the frictional forces that oppose the ejection jack's operation and thereby increasing available force and stroke

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Length of moving object

If traditional pivot connections are used in the ejection jack, then the structure is simple, but friction reduces stroke availability

Engineering Contradiction:

Improvestroke availabilityVSAvoidstructure complexity

Core Design Contradiction:

Length of moving objectVSDevice complexity

Solution Approach 1:

Rolling elements (bearings) are introduced as intermediary components between the pivot connections of the toggle assembly members. These rolling elements mediate the relative motion between members, converting high-friction sliding contact into low-friction rolling contact, thereby reducing overall friction in the ejection jack mechanism while maintaining the structural integrity of the toggle assembly

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces traditional sliding pivot connections with rolling element bearings in the toggle assembly. This substitution transforms the mechanical interaction from sliding friction to rolling friction, significantly reducing the frictional forces that oppose the ejection jack's operation and thereby increasing available force and stroke

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Force

If shims are applied to compensate for friction, then force margins are maintained, but the manufacturing and assembly process becomes more complex

Engineering Contradiction:

Improveforce marginsVSAvoidshimming process

Core Design Contradiction:

ForceVSEase of manufacture

Solution Approach 1:

The patent replaces traditional sliding pivot connections with rolling element bearings in the toggle assembly. This substitution transforms the mechanical interaction from sliding friction to rolling friction, significantly reducing the frictional forces that oppose the ejection jack's operation and thereby increasing available force and stroke

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The rolling element bearings inherently provide low-friction operation without requiring external compensation mechanisms. The bearings self-adjust and maintain optimal clearance through their design, eliminating the need for manual shimming operations to compensate for friction losses, thereby simplifying manufacturing and assembly while maintaining force margins

Inventive Principle:

Principle #25Self-service

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

The toggle assembly effectively reduces friction at pivot points, enhancing the force and stroke capabilities of the ejection jack, potentially reducing the size of actuators and solenoids required, and simplifying the shimming process.

Implementation Method 1

A toggle assembly with pivotally connected joint members and rolling elements, such as roller bearings, is used to reduce friction at pivot points

Methodology Applied

Scientific EffectRolling friction: Friction

Data Source

PatentUS11572193B2Ejection jack having a toggle assembly

Publication Date: 2023.02.07 HAMILTON SUNDSTRAND CORP

AI summary

A toggle assembly includes a first joint member having a first lug and a second lug, a second joint member, and a third joint member. The second joint member has a first arm that receives a first rolling element, a second arm that receives a second rolling element, a third arm, and a fourth arm. The second joint member is pivotally connected to the first joint member via a first pin that extends through the first lug, the first rolling element, the second rolling element, and the second lug. The third joint member has a third lug and a fourth lug disposed opposite the third lug. The third joint member is pivotally connected to the second joint member via a cross rod pin that extends through the third lug, the third arm and the fourth arm.