【正文】 these three dissertation deals mainly with excitation, but transmission is also discussed in the section of the literature survey concerning dynamic models, and in the modal analysis of the test gearbox in Paper of vibrations is also investigated in Paper D, which deals with the influence of bearing endplay or preload on gearbox in bearing preload influence a bearing’s dynamic properties like stiffness and properties also affect the vibration of the gearbox Objective The objective of this dissertation is to contribute to knowledge about gearbox following specific areas will be the focus of this study: influence of gear finishing method and gear modifications and errors on noise and vibration from a correlation between gear deviations, predicted transmission error, measured transmission error, and gearbox influence of bearing preload on gearbox of gear geometry for low transmission error, taking into consideration robustness with respect to torque and manufacturing AN INDUSTRIAL APPLICATION ? TRANSMISSION NOISE REDUCTION Introduction This section briefly describes the activities involved in reducing gear noise from a wheel loader aim is to show how the optimization of the gear geometry described in Paper E is used in an industrial author was project manager for the “noise work team” and performed the gear of the requirements when developing a new automatic power transmission for a wheel loader was improving the transmission gear existing power transmission was known to be driving at high speed in fourth gear, a high frequency gearwhine could be there were now demands for improved sound transmission is a typical wheel loader power transmission, consisting of a torque converter, a gearbox with four forward speeds and four reverse speeds, and a dropbox partly integrated with the dropbox is a chain of four gears transferring the powerto the output gears are engaged by wet multidisc clutches actuated by the transmission hydraulic and control Gear noise target for the new transmission Experience has shown that the high frequency gear noise should be at least 15 dB below other noise sources such as the engine in order not to be perceived as disturbing or showed that if the gear noise could be decreased by 10 dB, this criterion should be satisfied with some analysis of the noise measured in the driver39。rn Johansen at Volvo author’s contribution was the evaluation of the results of different housing number of measuring points were chosen in areas with high vibration each measuring point the vibration response due to the excitation was evaluated as a power spectral density(PSD) goal of the housing redesign was to decrease the vibrations at all measuring points in the frequency range 1000 to 3000 Results of the noise measurements The noise and vibration measurements described in section were performed after optimizing the gears and transmission total sound power level decreased by 4 Discussion and conclusions It seems to be possible to decrease the gear noise from a transmission bydecreasing the static loaded transmission error and/or optimizing the the present study, it is impossible to say how much of the decrease is due to the gear optimization and how much to the housing this question would have required at least one more noise measurement, but time and cost issues precluded would also have been interesting to perform the noise measurements on a number of transmissions, both before and after optimizing the gears and housing, in order to determine the scatter of the noise of the though the goal of decreasing the gear noise by 10 dB was not reached, the goal of reducing the gear noise in the wheel loader cab to 15 dB below the overall noise was the noise optimization was SUMMARY OF APPENDED PAPERS Paper A: Gear Noise and Vibration – A Literature Survey This paper presents an overview of the literature on gear noise and is divided into three sections dealing with transmission error, dynamic models, and noise and vibration error is an important excitation mechanism for gear noise and is defined as “the difference between the actual position of the output gear and the position it would occupy if the gear drive were perfectly conjugate” [1].The literature survey revealed that while most authors agree that transmission error is an important excitation mechanism for gear noise and vibration, it is not the only possible timevarying noise excitation mechanisms include friction and bending produced by these mechanisms may be of the same order of magnitude as that produced by transmission error, at least in the case of gears with low transmission error [4].The second section of the paper deals with dynamic modeling of models are often used to predict gearinduced vibrations and investigate the effect of changes to the gears, shafts, bearings, and literature survey revealed that dynamic models of a system consisting of gears, shafts, bearings, and gearbox casing can be useful in understanding and predicting the dynamic behavior of a relatively simple gear systems, lumped parameter dynamic models with springs, masses, and viscous damping can be more plex models that include such elements as the gearbox housing, finite element modeling is often third section of the paper deals with noise and vibration measurement and signal analysis, which are used when experimentally investigating gear survey shows that these are useful tools in experimental investigation of gear noise because gears create noise at specific frequencies related to the number of teeth and the rotational speed of the Paper B: Gear Test Rig for Noise and Vibration Testing of Cylindrical Gears Paper B describes a test rig for noise testing of rig is of the recirculating power type and consists of two identical gearboxes, connected to each other with two universal joint is applied by tilting one of the gearboxes around one of its tilting is made possible by bearings between the gearbox and the s