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The diploma thesis deals with the issue of bearings noisiness. The bearings noisiness appears as a negative phenomenon in all the mechanical devices that generate any kind of movement. Analysis of this phenomenon enables to analyse the technical condition of the bearing and predict its defects as well. The theoretical part of the thesis is devoted to the vibration diagnostics and noisiness diagnostics, which are deeply linked. The practical part of the thesis deals with the real problem of the bearing’s noisiness in the engineering company. The main asset of this thesis is a design and successful implementation of the measures, which reduce noisiness of the selected type of the bearing.

This thesis presents an interactive computer-graphics geometry interface that simplifies the tapered roller bearing selection procedure. An applications program has been developed that links the CADAM data base to SELECT-A-NALYSIS (SAN), Timken's bearing selection and analysis program. The independent modular format of the SAN preprocessor eliminates the ambiguity and difficulty associated with conventional bearing selection routines. Interactive-graphic menu selection allows program logic to be followed while design geometry is selected from a CADAM model. In addition to the discussion of the program development and structure, step-by-step instructions for an example problem are provided. Complete program listings are also supplied to facilitate future additions and modifications to the preprocessor. / M.S.

Vibration signals generated from spalled elements in rolling element bearings (REBs) are investigated in this thesis. A novel signal-processing algorithm to diagnose localized faults in rolling element bearings has been developed and tested on a variety of signals. The algorithm is based on Spectral Kurtosis (SK), which has special qualities for detecting REBs faults. The algorithm includes three steps. It starts by pre-whitening the signal's power spectral density using an autoregressive (AR) model. The impulses, which are contained in the residual of the AR model, are then enhanced using the minimum entropy deconvolution (MED) technique, which effectively deconvolves the effect of the transmission path and clarifies the impulses. Finally the output of the MED filter is decomposed using complex Morlet wavelets and the SK is calculated to select the best filter for the envelope analysis. Results show the superiority of the developed algorithm and its effectiveness in extracting fault features from the raw vibration signal. The problem of modelling the vibration signals from a spalled bearing in a gearbox environment is discussed. This problem has been addressed through the incorporation of a time varying, non-linear stiffness bearing model into a previously developed gear model. It has the new capacity of modeling localized faults and extended faults in the different components of the bearing. The simulated signals were found to have the same basic characteristics as measured signals, and moreover were found to have a characteristic seen in the measured signals, and also referred to in the literature, of double pulses corresponding to entry into and exit from a localized fault, which could be made more evident by the MED technique. The simulation model is useful for producing typical fault signals from gearboxes to test new diagnostic algorithms, and also prognostic algorithms. The thesis provides two main tools (SK algorithm and the gear bearing simulation model), which could be effectively employed to develop a successful prognostic model.

This thesis incorporates an array of Contact Potential Difference (CPD) sensors to measure and monitor the degree of skew in the rolling elements of a spherical roller bearing. Skewing is the motion of a roller as it turns about an axis normal to the roller race interface. Roller skew is generated as part of the kinematic effects of roller bearings. Skew monitoring is important for bearing design as it is an indirect measure of bearing life. For the purpose of this thesis, roller skew was measured utilizing multiple pairs of CPD probes located around the bearings outer raceway at varying points of the loading zone. These CPD probes are not in direct contact with the rollers, but in close proximity to their surface (through the bearing outer ring). The skew angle measured is related to different operating conditions such as applied load, shaft speed, and lubrication. The pair of CPD probes detected a signal as the roller surface passed by and the phase difference between the two distinct signals measured the skew angles in the range of 0.016 to 1.10. The shaft is rotated both clockwise and counterclockwise to capture any probe misalignment which was in the range of 0.5 up to 2.0 . This thesis also provides a model for the probe signal as a spherical roller surface passes the probe surface.

Vibration signals generated from spalled elements in rolling element bearings (REBs) are investigated in this thesis. A novel signal-processing algorithm to diagnose localized faults in rolling element bearings has been developed and tested on a variety of signals. The algorithm is based on Spectral Kurtosis (SK), which has special qualities for detecting REBs faults. The algorithm includes three steps. It starts by pre-whitening the signal's power spectral density using an autoregressive (AR) model. The impulses, which are contained in the residual of the AR model, are then enhanced using the minimum entropy deconvolution (MED) technique, which effectively deconvolves the effect of the transmission path and clarifies the impulses. Finally the output of the MED filter is decomposed using complex Morlet wavelets and the SK is calculated to select the best filter for the envelope analysis. Results show the superiority of the developed algorithm and its effectiveness in extracting fault features from the raw vibration signal. The problem of modelling the vibration signals from a spalled bearing in a gearbox environment is discussed. This problem has been addressed through the incorporation of a time varying, non-linear stiffness bearing model into a previously developed gear model. It has the new capacity of modeling localized faults and extended faults in the different components of the bearing. The simulated signals were found to have the same basic characteristics as measured signals, and moreover were found to have a characteristic seen in the measured signals, and also referred to in the literature, of double pulses corresponding to entry into and exit from a localized fault, which could be made more evident by the MED technique. The simulation model is useful for producing typical fault signals from gearboxes to test new diagnostic algorithms, and also prognostic algorithms. The thesis provides two main tools (SK algorithm and the gear bearing simulation model), which could be effectively employed to develop a successful prognostic model.

Continuous design and improvements in performance of roller bearings have resulted in an increased power transmission whilst size and spatial requirements have been reduced. Radial cylindrical roller bearings have followed this trend and due to their high performance characteristics (such as high loading capacity and high rotational speed capabilities), they have obtained a firm place as high performance machine elements. An essential characteristic of a radial cylindrical roller bearing is the minimisation of frictional torque for particular operating conditions. In spite of these improvements in design and operation the bearing frictional torque is still usually calculated according to the Palmgren method first published in 1957. However, as a result of the increased performance of radial cylindrical roller bearings and a corresponding wider range of application this Palmgren method is insufficiently accurate for the prediction of frictional torques in modern bearings. Whilst the literature review in this thesis identified a variety of bearing frictional torque calculation methods, most of these methods are based on various ball bearing designs and are not necessarily applicable to cylindrical roller bearings types. As a result an accurate frictional torque prediction method is required for radial cylindrical roller bearings because of customer's demands. Consequently, the current project is combined with the development of a method of frictional torque prediction (FTP - Method), which enables the frictional torque of purely radially and radially and axially loaded radial cylindrical roller bearings to be calculated accurately. The FTP - Method is based on the physical effects producing the frictional torque in a bearing, such as the EHL - theory and a contact analysis to determine raceway rolling resistance, and in addition takes into account the frictional forces of the rib / rolling element end face rolling and sliding contact. Comprehensive experimental tests have been undertaken on different radial cylindrical roller bearing designs (including cage guided and full complement types) for a minimum of three different sizes to validate the derived equations. Good agreement was obtained between the predictions according to the FTP - Method and the measured test data for the frictional torqye of both radially and combined loaded bearings. Moreover, the thermal reference speed and the thermal limiting speed of a radial cylindrical roller bearing can be readily calculated for any operating condition using an explicit equation in the radial part of the FTP - Method. The thesis also presents a calculation program to illustrate a method of bearing design based on the thermal balance within a bearing. The bearing is initially pre-selected according to its life time requirements using a life time calculation. After the lubrication method has been defined a thermal balance can be used to design the bearing.

Subject of this master's thesis is to design a control screw connection balance mass and shaft. It is the task of the stress - strain analysis balancer shaft in the FEM system, evaluation of the obtained results and possible design modifications.

Subject of this thesis is analysis of friction power losses in rolling bearings and design and implementation of computing program. Thesis is divided into six chapters. At the beginning there is overview of different types of rolling bearings and their system of lubrication. Fundamentals of elastohydrodynamic lubrication are described together with effects that occur in lubricant. Remaining part is focused on friction in rolling bearing its sources and calculation. Other programs for computing friction losses are shown and own program is designed. Designed program is applied on bearings of chosen type and results are compared with existing models.

This master's thesis is concerned with the mechanical efficiency of cranktrain contact pairs in a combustion engine. In the introductory part, the fundamental terminology relating to the cranktrain is presented along with the specification of the areas of mechanical losses, greasing modes and types of wear. The following chapters describe the possibilities of eliminating mechanical losses of the cranktrain and the calculation methods that can be utilized to mathematically solve mechanical losses. The practical part includes the proposal of a calculation model and its use in the analysis of the cranktrain of Skoda 1.2 HTP engine. The last part of this thesis comprises modified alternatives of the standard cranktrain focusing on the elimination of mechanical losses. The evaluation of the results is presented in the conclusion of this thesis.