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Adhesion modelling of grease lubricant in wheel-rail contact
Kuchař, Tomáš ; Voltr, Petr (referee) ; Kvarda, Daniel (advisor)
Currently, there are efforts to optimise the coefficient of adhesion in wheel-rail contact to reduce wear, noise and energy consumption. A project to create a digital twin for the Brno–Adamov line is being solved by ŠKODA TRANSPORTATION, a.s., the Jan Perner Transport Faculty of the University of Pardubice and the Institute of Machine and Industrial Design of the Brno University of Technology. In this thesis, within the previously mentioned project, the problem of grease retentivity was addressed, which is the distance or time for which the grease is able to efficiently lubricate the contact and thus maintain the adhesion coefficient at the desired level. The main objective of this work was to develop a model describing the effect of climatic conditions and operating parameters on retentivity of grease. The studied grease was BECHEM EcoRail 2009, which consists of bentonite thickener and a synthetic ester as a base oil. The grease was studied on a commercial Mini-Traction Machine (MTM) device in a ball on disc configuration. The effects of temperature, air humidity, load, slip, speed and lubricant quantity on retentivity were investigated. It was found that increasing load and slip caused a decrease in retentivity and could be described by using the energy absorbed by the lubricant. Increasing velocity caused a decrease in retentivity expressed in time but an increase in retentivity expressed in slip distance or number of cycles. Increasing the amount of lubricant caused a linear increase in retentivity. Increasing temperature caused an increase in retentivity, but only if the temperature was within the operating range of the grease. Air humidity only had an effect if condensation occurred, such that an increase in retentivity was observed. Dimensionless parameters were used in the model, which should make it possible to transfer the model to real scale. However, lubricant deposition to the rail and redistribution to other wheelsets was not included in the model. The model was then verified with a rail tribometer and it was shown that the model prediction was consistent with the measured results.
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Design of universal belt grinder
Skala, Ondřej ; Kvarda, Daniel (referee) ; Valena, Martin (advisor)
This thesis focuses on the design of a universal belt grinder with the capability for both vertical and horizontal grinding, aiming to maximize its usage potential. Several grinding attachments have been designed for the grinder, with attention to high quality, versatility, and user-friendly operation. The theoretical part describes grinding, types of belt grinders, and abrasive belts. Based on the research, specific requirements for the belt grinder are established, and a suitable type of construction is selected from the conceptual solutions. This is followed by a design proposal supported by calculations necessary for the proper and reliable operation of the machine and stress analysis using the finite element method. The final part describes the manufacturing and assembly of the machine, concluding with the verification of the functionality of the entire belt grinder, including all grinding attachments. The result is a fully functional belt grinder that meets the specified requirements.
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Top of rail lubricant development
Skurka, Šimon ; Polach, Pavel (referee) ; Kvarda, Daniel (advisor)
Friction modification within the wheel-rail interface is an important way of achieving ecologically friendly transportation of both persons and goods. This thesis aims to develop a new TOR lubricant, which will be able to maintain suitable frictional conditions while securing minimal adhesion required for traction. All measurements were carried out on tribometer MTM in the ball-on-disc configuration. In the first step, individual components were examined. More complex compositions were measured after that and the three best of them were compared with commercial TOR lubricants. The results show a good ability of developed compositions to maintain required adhesion, reduce wear, and all of them had resistivity against over-lubrication. Lastly, the process of lubricant verification before its application in real traffic was discussed.
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Conceptual design of device for application of anti-icing agents on overhead catenary
Rohánek, Tomáš ; Kvarda, Daniel (referee) ; Omasta, Milan (advisor)
This bachelor’s thesis deals with icing of overhead contact lines. Relevant patents and existing commercial systems for applying anti-icing agents are comprehensively described and evaluated in the thesis. Based on that, two new concepts for public transportation are proposed. Compared to the existing systems, these concepts bring improvement in operational parameters and expand the number of products offered at the market. Afterwards, both concepts are critically assessed.
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Rail materials and profiles in rail transportation
Svobodová, Anežka ; Kvarda, Daniel (referee) ; Galas, Radovan (advisor)
This bachelor’s thesis is focused on the issue of the choice of rail materials and profiles. The aim is to give a comprehensive overview of the current situation in Czech Republic and some other foreign countries. The first part is dedicated to rail steels with description of structure, current usage and indication of the scopes of consecutive development. In the second part, there are described the most frequent profiles, their history and the current state. This thesis includes also discussion part which compares current problems and requirements that can be significant to some possible research.
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Race car bonnet shape design based on flow analysis
Šnajdr, Petr ; Kvarda, Daniel (referee) ; Michalec, Michal (advisor)
The bachelor’s thesis deals with reducing aerodynamic drag of a pneumobile. The thesis summarizes knowledge in the field of vehicle aerodynamics and the principle of CFD simulations. The essence of the work is bonnet shape design of racing pneumobile Typhoon, developed at FME BUT, for lowest possible air resistance. CFD simulations are used to observe and analyse the influence of the bonnet shape on the aerodynamics properties. The designed shape solution of the bonnet significantly contributes to the reduction of aerodynamic drag compared to the existing bonnet. Thanks to this, the vehicle’s parameters are improved from maximum speed to the range. The acquired knowledge can also help in the further development of pneumobiles and in improving the setting of the computational model described in the work.
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Analysis of contaminants in wheel and rail contact
Straka, Tomáš ; Galas, Radovan (referee) ; Kvarda, Daniel (advisor)
Wheel/rail contact is significantly influenced by so called third body – contaminants. Aim of this bachelor’s thesis is to analyse those contaminants in the contact and to create a brief overview. Short introduction into problem of wheel/rail contact is included, followed by description of main contaminants occurring in the contact. This thesis may be used as introduction into contamination of wheel/rail contact problem.
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Influence of friction modifiers composition on traction in wheel-rail contact
Kvarda, Daniel ; Hartl, Martin (referee) ; Galas, Radovan (advisor)
Friction modifiers are a new effective way to control adhesion in wheel and rail contact. The aim of this diploma thesis is experimental study of the influence of the constituents of water based friction modifier on adhesion. Measurement of the adhesion behavior for different friction modifier compositions is carried out on a ball–on–disc laboratory device creating point contact. The introductory part of the experiments describes the effect of individual components on adhesion. Subsequently, combinations of different friction modifier compositions are tested. In conclusion, selected compositions are used for wear tests. The results obtained show that the performance of friction modifiers is greatly influenced by evaporation of base medium.
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Off-board systems for top-of-rail lubrication
Málek, Jan ; Kvarda, Daniel (referee) ; Galas, Radovan (advisor)
This bachelor’s thesis is focused on rail off-board lubrication system. The main part of this thesis is explaining of function and design few certain lubrication systems. In this thesis are explained aspects of wheel-rail contact, such as types and parts of rail, adhesion, slip, creep–traction diagram. Another part of this thesis is description of few certain lubrication system for top of rail and gauge face application. In this thesis are explained product of major companies of friction management industries such as SKF-Lincoln, Whitmore, Loram. Additional part of this thesis speaks about usage and development of this devices in Czech Republic. Output of this thesis is conclusion about advantages and disadvantages these certain devices.
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Materials for friction modification within wheel-rail contact
Pláněk, Miloslav ; Kvarda, Daniel (referee) ; Galas, Radovan (advisor)
Problematic aspects of wheel-rail contact can be reduced by application of substances for friction modification. The essence of this bachelor’s thesis is compile overview of substances for friction modification applied on Top of Rail with focus on that one, which are applied to decrease excessive wear and noise. In this thesis, the reader will be firstly introduced to the fundamentals of wheel-rail contact, essence of friction management and partition of substances for friction modification. Next part of the thesis is focused only on substances providing intermediate level of friction. These substances are TOR friction modifiers, TOR lubricants and TOR solid compositions. Thesis describes their composition, ways of application, expected benefits and map commercial products available on the market. The output of the bachelor’s thesis is overview of these substances and their comparison based on theoretical assumptions, test´s results and practice experience. The thesis will allow reader to have better market orientation between available products, which could be wrong tagged by their own producers.
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