National Repository of Grey Literature 81 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Design of a test chamber to study the emission of solid particles from the wheel-rail contact
Rosecký, Vojtěch ; Galas, Radovan (referee) ; Omasta, Milan (advisor)
In order to study dust particles released from the contact of the wheel and as a result of wear and the application of friction-modifying materials in the contact, a two-disk device simulating this contact was developed at the Institute of Design. A test chamber was added to prevent particles from escaping from the twin-disc device into the environment and to allow their analysis. The main goal of the thesis was to construct the test chamber. Sub-goals included the concept design, construction, preparation of the production documentation and implementation. All required objectives have been met and the working chamber is ready for experiments, although some elements of the chamber would be modified in the near future. The benefit of this work is the completion of a twin-disc tribometer, which can be used for solid particle emission research.
Research on the load-carrying capacity of lubricating film in rolling bearings
Šmíd, David ; Čermák, Jan (referee) ; Omasta, Milan (advisor)
This diploma thesis deals with the problem of sudden contamination of the elastohydrodynamic contact by solid particles and their influence on parameters affecting the lubricating film, such as surface texture and real film thickness, especially for line contact. The contact is operated under conditions corresponding to the operation of the main wind turbine bearings, with measurable parameters supported by optical observations. The main effort of this work is to relate the influence of the flow of solid particles in the lubricant to the parameters determining the lubrication regime. For the experiments, a taper-on-disc device was constructed to simulate linear contact. Using this device, the effects of different solid particles on the damage of a sample (roughness parameters Ra and Rq) with linear contact and the influence of this altered structure on the lubricating film thickness (hmin) are experimentally described. These remarks are partially compared with the effect of particles on point contact. The result of this paper is a better understanding of the solid particle flow in the Hertzian contact region and clarification of the influence of this flow on the surface structure and associated lubricating film thickness, especially for linear contact.
Research into the causes of very low friction between wheel and rail
Polnický, Jan ; Hajžman, Michal (referee) ; Omasta, Milan (advisor)
A low traction coefficient causes problems when starting trains, extends the braking distance, and leads to overrunning stations. These problems often occur in conditions of high humidity and low traffic. Oxides on the rail surface form a suspension with water, causing the traction coefficient to drop. This work addresses the mechanisms by which this drop is caused, based on observations using an optical tribometer. Additionally, a study was conducted to map the influence of various parameters on the drop in the traction coefficient. The tested parameters include suspension concentration, the applied amount, the type of base fluid, and others.
Design of dosing unit for sanding of rail vehicles
Szabari, Šimon ; Čížek, Petr (referee) ; Omasta, Milan (advisor)
This master thesis deals with the development of a sanding unit for rail vehicle. The aim is to develop a dosing device capable of applying sand to the contact of a wheel and a rail depending on the speed of the vehicle with the detection of the flow rate of the applied amount. The application of sand or alternative materials to the wheel-rail contact is an effective way to increase the traction of driving rail vehicles. During the development, there was a cooperation with a company engaged in the production of equipment for rail transport. During the work, experimental development was applied, during which a pneumo-mechanical dosing unit with control of the applied amount of sand was designed and tested. Simultaneously with the dosing unit, a sand box was designed that is suitable for the type of rail vehicle for the purpose of tests in real operation. The pre-prototype design has the potential to bring improvements in several areas of sanding systems.
Experimental study of fluid-induced instabilities in journal bearings
Stifter, Jan ; Polach, Pavel (referee) ; Omasta, Milan (advisor)
Presented diploma thesis deals with experimental study of fluid induced instabilities which occur in rotating machinery with journal bearings. The first part describes the oil whirl and oil whip instabilities. It also gives an example of optical methods used for observation of journal bearings. Next part is dedicated to modifications of an existing test rig that were necessary for carrying out experiments. Finally, there are presented results of experiments that define the effect of initial conditions on appearance of instabilities.
Structure and Use of the Measuring System for Research of Lubrication Device
Brhlík, Rostislav ; Omasta, Milan (referee) ; Nevrlý, Josef (advisor)
This work deals with an adaptation of the measuring system for the functional analysis of the lubricant divider. Within the new structural design, there were used manometers, flowmeters and dynamic scales to determine the properties of the lubrication system; data acquisition card and the appropriate software were designed too. The methodology of data measuring and analysis were also elaborated. The methodology is based on the experience from measuring, which was realized with the lubrication system OK - 02 from Tribotec Company. Finally, the cascade lubricant dividing system was designed. This is a newly designed flow divider with an innovative internal layout. The aim of the proposed measurement system is an optimization that will lead to effective dividing of lubricating mixture and applying the necessary amount of lubricant to wheel flange.
Research on the textured journal bearings for engines in automotive
Svoboda, Martin ; Hartl, Martin (referee) ; Omasta, Milan (advisor)
The aim of this thesis is to describe the effect of surface textures of radial journal bearings with polymer coating on friction and damage development using experimental tests. Wear and friction tests of real bearings with different texture geometries and surface materials were performed. It was found that the wear deterioration of the textured aluminum sliding bearing surface and neutral or positive effects on the wear of the textured bearing with polymer coating. The reason for the improvement is the good resistance to high pressures of the polymer coating and the preservation of the texture dimensions throughout the bearing run. The friction test showed an improvement in the frictional properties of the textured surfaces when the amount of lubricant in contact was insufficient. At the same time, a positive effect on tribological properties was demonstrated by reducing the lateral lubricant discharge.
Friction components produced by rapid prototyping
Pečenka, Tomáš ; Škaroupka, David (referee) ; Omasta, Milan (advisor)
The main aim of this bachelor thesis is to make an overview of use of additive technology for production of friction components. The first part is concerned on review of additive methods and type of materials. In the second section are situated applications of this technology for fabrication of friction components. The main goal of last part is research in area of tribology of parts manufactured by additive technology.
Development of a testing system for evaluation of rolling bearings with variable lubrication parameters
Škoviera, Jozef ; Čermák, Jan (referee) ; Omasta, Milan (advisor)
The presented diploma thesis deals with the design of a test system for rolling bearings, which allows the change of the lubrication parameters (e.g. changing of the relubrica-tion interval). In the document, the reader first learns about the meaning of lubrication of rolling bearings, the possibilities of lubricant supply to the bearing (specifically for the supply of grease) and the possibilities of dosing control. Subsequently in the document is described the present state of experimental stations for testing rolling bearings, which is available at the Institute of Machine and Industrial Design. The end of the part about current state of knowledge is also mentioned the possibility of speeding up fatigue tests. In the next part, the author describes his own solution. The result is the design of an experimental station (for option to relubricate with grease), the creation of a lubrication control platform and the creation of a basic program. Part of the work is also verification experiments and drawing documentation.
Design of safety mechanism for hand-operated press
Runštuk, Jiří ; Omasta, Milan (referee) ; Prokeš, František (advisor)
This bachelor´s thesis deals with a design of safety mechanism for hand-operated press. The first part deals with common guidelines for working with hand-operated presses. The second part deals with a protective machine for mechanic presses in accordance with the ČSN EN 692+A1 norm. The third part deals with the design of two safety mechanism. In the last part there is one option chosen out of these mechanisms and for this one a design solution was carried out.

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