Vehicle Gearbox Noise and Vibration

Jiri Tuma graduated from the Brno University of Technology, Czech Republic, in 1970 and completed his doctoral studies in 1977. After graduation, he became a researcher in the field of control systems at a research institute and in 1988 began working in the R&D department of an automotive company (Tatra Trucks). He was a member of the team for the introduction of HCR gears in the transmissions. That time, Tatra entered among the top global manufacturers of this type of gears. In 1995, he joined the VSB - Technical University of Ostrava, Faculty of Mechanical Engineering where he became a full professor in 2001. He gives lectures and does research in the field of control systems, signal processing, active vibration control and machine diagnostics. He is the author of more than 200 publications, including a book on signal processing (in Czech) and a chapter of Crocker’s Handbook on noise and vibration control.

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• Series Preface xiPreface xiiiAcknowledgements xv1 Introduction 11.1 Description of the TATRA Truck Powertrain System 21.2 Test Stands 3References 52 Tools for Gearbox Noise and Vibration Frequency Analysis 72.1 Theory of Digitisation of Analogue Signals 72.2 Nyquist-Shannon Sampling Theorem 162.3 Signal Analysis Based on Fourier Transform 212.3.10 Time and Frequency Scales 352.3.11 Spectral Unit of Autospectrum 362.3.12 Cross-Spectrum 372.3.13 Calculation of the Inverse Discrete Fourier Transform 392.3.14 Fast Fourier Transform 392.3.15 Time Window 402.3.16 Calculation of the Signal Power 432.3.17 Frequency Weighting 462.3.18 Analysis of Random Signals with the Use of Averaging in the Frequency Domain 482.4 Zoom FFT 522.5 Filtration in the Frequency Domain 552.6 Average Power of the Signal 59References 603 Gearbox Frequency Spectrum 613.1 Source of Gearbox Noise and Vibration 613.2 Spectrum Signature 653.3 Low Harmonics of the Shaft Speed 663.4 Harmonics of the Fundamental Toothmeshing Frequency and their Sidebands 673.5 Subharmonic Components 703.6 Ghost (or Strange) Components 713.7 Gear Rattle 723.8 Periodicity in Signals Measured on a Planetary Gearbox 733.9 Spectrum Components Originating from Faults in Rolling Element Bearings 76References 834 Harmonics and Sidebands 854.1 Harmonics 854.2 Sidebands 874.3 Analytic Signal 974.4 Cepstrum 111References 1215 Order Analysis 1235.1 Speed Rotation Measurements 1245.2 Order Analysis Based on External Sampling Frequency 1255.3 Digital Order Tracking 1265.4 Frequency Domain Analysis Methods (Multispectral, Slice Analysis) 1335.5 The Use of Order Spectra for Machine Diagnostics 1375.6 Averaging in the Time Domain 1385.7 Time Domain as a Tool for Gear Mesh Analysis 143References 1606 Tracking Filters 1636.1 Interpolation of the Instantaneous Rotational Speed 1636.2 Quadrature Mixing as a Method for Amplitude and Phase Demodulation 1646.3 Kalman Filter 1686.4 Vold-Kalman Order Tracking Filtration 174References 2067 Reducing Noise of Automobile Transmissions 2097.1 Normal Probability Plot 2097.2 Transmission Error Measurements 2107.3 Case Study 2187.4 Gearbox Improvement Aimed at Noise Reduction 2267.5 Effect of Gear Quality on the Gearbox SPL 2307.6 Effect of Operation Conditions on the Gearbox Vibrations 2317.7 Quality Control in Manufacturing 233References 234Index 237