Author(s)

A. Belsak & J. Flasker

Abstract

A crack in the tooth root, which often results in failure of gear unit operation, is the least desirable among damages and faults, which can cause problems in gear unit operation. A fatigue crack in the tooth root brings about important changes in tooth stiffness, whereas other faults are usually associated with changes in other dynamic parameters. In this paper, fault analyses relating to gear units with real damages or faults are presented. Possible damage can be determined by monitoring vibrations. Time signals acquired by experiments are analysed by means of various methods. The Wavelets and Joint Time Frequency Analyses are used to analyse non-stationary signals. Keywords: gear, failure, vibration, signal analysis. 1 Introduction The aim of maintenance is to keep a technical system (e.g. a gear-unit) in the most suitable working condition; its purpose is to discover, to diagnose, to foresee, to prevent and to eliminate damages. The purpose of diagnostics is to define the current condition of the system, and the location, shape and reason of the damage formation. A gear unit has elements that make transmission of rotating movement possible, and as such, it is a complex dynamic model. In spite of this, its movement is usually periodical, and faults and damages represent a disturbing quantity or impulse, which is indicated by local and time changes in vibration signals [1, 2]. As a result, time-frequency changes can be expected [3]. This idea is based on kinematics and operating characteristics. It is possible, by using time-frequency analysis, to describe in what way frequency components of non-stationary signals change with time as well as to define their intensity. Adaptive and wavelet transforms are representatives of

Keywords

gear, failure, vibration, signal analysis