Gear Transmission Failures and Failure Based Design

Abstract

Property based design - PBD approach provides improvement of various properties and characteristics. In the area of transmission units', by applyng PBD, significantly are increased service life and reliability, inclouding vibration and noise reduction. Together with these improvements, operating conditions of gear unit components got significantly worst and possible failure relations are changed and needs the new approaches in analysis in comparison to the traditional one. This article has intention to create relation between possible failures of gearbox components, according to mentioned trends. The main trend is significant reduction of dimensions which is in strong contradiction with gear lubrication and cooling. Together with increase of rotation speed, these contradictory effects transforms pitting as the dominant gear failure into the scoring of the teeth contact surfaces. This and similar failure transitions are presented. In order to prevent it, specific cooling and lubrication systems have to be developed. This is the reason that design structure of gear transmission units getting more and more complex. From presented point of view, failures of gear transmission components interaction is important design constraint and it justifies the introduction of the term Failure based Design - FBD of gear transmission units. Presented cases study of transmission units for various applications, contains mentioned analysys and FBD application.