National Repository of Grey Literature 96 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Bearings for large scale applications
Herník, Martin ; Šperka, Petr (referee) ; Michalec, Michal (advisor)
Bearings are currently an indispensable part of industrial machines, that carry out rotational or translational motion. This bachelor's thesis discusses the use cases of bearings for large-scale applications such as wind propellers, space telescopes and many other examples in various areas of industry. At the beginning, individual types and types of bearings are divided. The largest part is devoted to the description of the use of individual types of bearings about their presence in large machines. In the final part, the design and clear division of suitable types of bearings for a specific applications is carried out.
Design of Rubik's Cube Solver
Palán, Petr ; Šperka, Petr (referee) ; Svoboda, Petr (advisor)
The Rubik’s Cube is one of the most famous puzzles in the world, it has evolved into countless variations and in its solving is competed all over the world. However, the record time for its solution is no longer held by a human, but by a robot. This bachelor thesis deals with the structural design and subsequent implementation of the mechanical part of the solver for the Rubik's Cube. A research of existing solvers is carried out and then individual conceptual designs are proposed. The chosen variant is then elaborated in the structural design. It individually controls 5 walls of the cube and thus ensures the possibility of its solving without the need for further positioning and at the same time there is space for comfortable insertion of the cube. The design is then realised by 3D printing. Thereafter an electronic part is connected to the created structure and a simple program written to test the structure is executed using a microcomputer. The result of the testing is that the design is functional but there is room for improvement.
Effect of surface roughness on lubrication of plain bearings
Vaněk, Tomáš ; Hartl, Martin (referee) ; Šperka, Petr (advisor)
This work investigates the influence of surface roughness on the lubrication of axial hydrodynamic bearings with convergent wedge gaps. It focuses on situations where operational conditions allow for full separation of surfaces by the lubricating film, as well as the transition to mixed lubrication. The aim is to understand the impact of surface roughness on the hydrodynamic lubrication process and whether their proper selection can affect the friction and load-carrying capacity of the bearing. Experimental measurements are used to determine the influence of parameters, where the thickness of the lubricating film is captured through fluorescence microscopy, along with the friction force at the contact between the pin and the test sample. The samples form a wedge gap with a rotating saphire disk, and the investigated surface roughness parameters include orientation, height Sq, and skewness Ssk (i.e., the relative ratio of depressions and protrusions). According to the obtained results, the orientation, height, and shape of roughness are key factors influencing hydrodynamic lubrication. However, the orientation alone does not determine the contact behavior, and additional roughness parameters must be considered for a complete understanding of the phenomenon. Increasing surface roughness negatively affects lubrication, but the proper combination of Ssk and orientation can minimize this effect. This work represents one of the first experimental measurements examining the influence of surface roughness on hydrodynamic lubrication. The findings have applications not only in plain bearings, but also in other components such as wet couplings or other sliding interfaces using hydrodynamic lubrication.
Distribution of grease in rolling bearing
Hynek, Jakub ; Čermák, Jan (referee) ; Šperka, Petr (advisor)
The work deals with the issue of grease distribution in a rolling bearing. Grease lubricated ball bearing in this way often experience the problem of starvation, when the contact area is not sufficiently supplied with lubricant, which leads to bearing failure. In general, this is a very complex and comprehensive topic. Specifically, the description of the effect of selected parameters on the distribution of grease in the rolling bearing was solved. The evaluation took place on the contact surfaces of the inner and outer ring and bearing balls. The average film thickness in selected areas at the point of contact and in front of it were evaluated. The method for observation was fluorescence microscopy. The effects of the percentage filling of the bearing with grease, the speed, the material and the design of the cage on the distribution and distribution of the grease on the bearing surfaces are described in the thesis. The result is information about the distribution of the grease on the raceways and balls of the bearing and their immediate surroundings. It was shown that the new experimental approach used makes it possible to evaluate the amount of grease available for bearing lubrication in a real configuration.
Evaluation of machine elements surface topography by optical profilometer
Vrána, Jakub ; Křupka, Ivan (referee) ; Šperka, Petr (advisor)
This thesis deals with the issue of surface texture topography of engineering parts. Research provides general view of surface texture topography evaluation and puts the aforementioned into the context of international standards. In the practical part of this thesis, an experiment is implemented. With help of optical interferometer, parameters are measured and their robustness is evaluated. In the conclusion part of this thesis, acquired information are evaluated and resumed.
An overview of oils and their engineering applications
Kozák, Ondřej ; Frýza, Josef (referee) ; Šperka, Petr (advisor)
This Bachelor´s thesis deals with an overview of current state of knowledge of lubricating oils and their engineering applications. It includes characteristic and division of oils by manufacturing method and division of these oils by chemical structure. Basic compounds of oils including most used types of additives are mentioned and described. Next part of the thesis focuses on lubricant properties. Final part includes resume of applications in which the listed oils are applied and required properties for each type of application are mentioned.
Wear regimes of aluminium alloys
Slivka, Václav ; Zapletal, Tomáš (referee) ; Šperka, Petr (advisor)
This thesis deals with the research of the wear regimes of the selected aluminium alloy in the conditions of dry friction. The aim of this work is the evaluation of the measure of an abrasive and adhesive wear of this alloy. This evaluation is made from the experiments which are made on the base of the knowledge of the research study. The dependence of the wear on the sliding speed and load, the friction on the sliding speed and load and the dependence of the normalised pressure on the normalised speed, so called the map of wear, are given on the base of the results of the measure.
Lubrication of plastic gears
Poledník, Radim ; Vimmr, Jan (referee) ; Šperka, Petr (advisor)
The purpose of this diploma thesis is to describe the influence of input parameters (rolling speed, load, temperature, dynamic viscosity and pressure coefficient of the lubricant) on film thickness in point and elliptical contacts using optical interferometry. Regression based film thickness formula has been obtained using universal form of non-dimensional parameters of entrainment speed U, load W and material G. Equations were also complemented by the function of ellipticity k. New regression formulas for central and minimum film thickness have been compared with existing EHL thickness equations. These film thickness measurement and new regression formulas have applicability to our understanding of the performance and more effective design of lubricated gears from polymeric materials.
The effect of texture geometry on friction and lubricating film formation in radial journal bearing
Katrincová, Tereza ; Čermák, Jan (referee) ; Šperka, Petr (advisor)
The aim of this diploma thesis is to find out how the geometric parameters of circular textures affect the friction and lubrication in a conformal contact. The configuration of a partial, radial, hydrodynamic bearing was investigated on a modified block on-ring device, where the block was replaced by a sapphire section. The device allows simultaneous measurement of friction and optical observation of processes in contact. The light induced fluorescence method was used for the measurement of film thickness. None of the studied texture combinations had a positive effect on the transition from hydrodynamic mode to mixed lubrication mode. Textures in the narrow band of the combination of diameter and depth have a positive effect, outside of them negative effect of texture on friction and film thickness was observed.
Lubrication of flanges of railway vehicles by ecological lubricants
Janovec, Ladislav ; Šperka, Petr (referee) ; Nevrlý, Josef (advisor)
The Aim of this thesis is to search and analytical evaluation of different approaches applied by producers in the field of wheel flanges lubrication of railway vehicles by means of ecological lubricants. The analysis focuses on the cyclical and continuous methods of lubrication of different types of central lubrication systems placed on the railway vehicles.

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