【正文】 ar deviations and varying torque is considered in order to find a gear geometry giving low noise in an appropriate torque range despite deviations from the nominal geometry due to manufacturing tolerances. Static and dynamic transmission error, noise, and housing vibrations were measured. The correlation between dynamic transmission error, housing vibrations and noise was investigated in speed sweeps from 500 to 2500 rpm at constant torque. No correlation was found between dynamic transmission error and noise. Static loaded transmission error seems to be correlated with the ability of the gear pair to excite vibration in the gearbox dynamic system. Keywords: gear, gearbox, noise, vibration, transmission error, bearing preload. ACKNOWLEDGEMENTS This work was carried out at Volvo Construction Equipment in Eskilstuna and at the Department of Machine Design at the Royal Institute of Technology (KTH) in Stockholm. The work was initiated by Professor Jack Samuelsson (Volvo and KTH), Professor S246。Gearbox Noise?Correlation with Transmission Error and Influence of Bearing Preload Doctoral Thesis in Machine Design TRITAMMK 2020:19 ISSN 14001179 ISRN/KTH/MMK/R08/19SE Department of Machine Design Royal institute of Technology SE?100 44 Stockholm, Sweeden 169。 Mats 197。ren Andersson (KTH), and Dr. Lars Br229。ren Andersson is gratefully acknowledged for excellent guidance and also wish to express my appreciation to my colleagues at the Department of Machine Design, and especially to Dr. Ulf Sellgren for performing simulations and contributing to the writing of Paper D, and Dr. Stefan Bj246。rssinen are highly appreciated. All contributionsto this work by colleagues at Volvo are gratefully appreciated. 1 INTRODUCTION Background Noise is increasingly considered an environmental issue. This belief is reflected in demands for lower noise levels in many areas of society, including the working environment. Employees spend a lot of time in this environment and noise can lead not only to hearing impairment but also to decreased ability to concentrate, resulting in decreased productivity and an increased risk of accidents. Quality, too, has bee increasingly important. The quality of a product can be defined as its ability to fulfill customers’ demands. These demands often change over time, and the best petitors in the market will set the concerns are also expressed in relation to construction machinery such as wheel loaders and articulated haulers. The gearbox is sometimes the dominant source of noise in these if the gear noise is not the loudest source, its pure high frequency tone is easily distinguished from other noise sources and is often perceived as unpleasant. The noise creates an impression of poor quality. In order not to be heard, gear noise must be at least 15 dB lower than other noise sources, such as engine noise. Gear noise This dissertation deals with the kind of gearbox noise that is generated by gears under noise is often referred to as “gear whine” and consists mainly of pure tones at high frequencies corresponding to the gear mesh frequency and multiples thereof, which are known as harmonics. A tone with the same frequency as the gear mesh frequency is designated the gear mesh harmonic, a tone with a frequency twice the gear mesh frequency is designated the second harmonic, and so on. The term “gear mesh harmonics” refers to all multiples of the gear mesh error (TE) is considered an important excitation mechanism for gear whine. Welbourn [1] defines transmission error as “the difference between the actual position of the output gear and the position it would occupy if the gear drive were perfectly conjugate.” Transmission error may be expressed as angular displacement or as linear displacement at the pitch point. Transmission error is caused by deflections, geometric errors, and geometric addition to gear whine, other possible noisegenerating mechanisms in gearboxes include gear rattle from gears running against each other without load, and noise generated by the case of automatic gearboxes, noise can also be generated by internal oil pumps and by clutches. None of these mechanisms are dealt with in this work, and from now on “gear noise” or “gearbox noise” refers to “gear whine”. MackAldener [2] d