Konceptframtagning av testrigg

Godkänd; 1999; 20080524 (ysko

Fullskalig testrigg : förstudie

Godkänd; 1999; 20080524 (ysko

Lubricant replenishment in the vicinity of an EHD contact

Lubricants are subjected to high pressures in many mechanical devices - notably gears, cams, piston rings and rolling element bearings. The contact pressure between the ball and the race in a ball bearing can be as high as 5 GPa. At such high pressures, it is necessary to be able to measure the rheological behaviour of the lubricant in order to obtain input data for computer simulations of rolling and sliding contacts. Lubricant manufacturers are often unable to provide information about the rheology of the lubricant at high pressures, temperatures, shear stresses and shear rates. In paper A, a new Couette rheometer was developed to measure the rheological properties of fluids at pressures up to 500 MPa. The shearrate range covers 0.5 to 20000 1/s and the instrument can operate up to 1O0°C at maximum pressure. The results from the apparatus show excellent agreement with measurements made with a failing ball viscometer on a Newtonian fluid. Criteria for non-laminar flow and viscous heating have been developed for the apparatus to verify that these effects do not significantly influence the measurements. In grease lubricated machine elements the supply of grease to the contact region is very important for long life and maintenance-free operation. For example, in a bearing application the grease is often applied within the housing but outside the bearing. For good lubrication the grease has to move from the storage space into the bearing in order to separate the moving surfaces. One important part of this grease movement is the transport from near the contact region into the rolling track. This transportation mechanism may depend on different phenomena such as: capillary forces, vibrations, drop formation, oil bleeding etc. The papers B-G in this thesis describe investigations of these various phenomena. Papers B-D deal with the drop formation of oils and greases in the outlet of an elastohydrodynamically lubricated contact and how different surface energies can affect the distribution of lubricant between the surfaces. Paper E describes the elongation of grease filaments formed when two surfaces are separating from each other, as a function of time. Measurements of the lift off (adhesion) force acting between the two solid surfaces as a function of time were also made. In paper F a ball and disc apparatus was used to study the replenishment of grease due to side slip. The inlet distance and the 'butterfly' shaped meniscus that surrounds the contact point was studied as a function of the side slip motion of the ball. The filament formation equations from paper E were extended to include the geometry of the butterfly and the inlet distance. Finally, in paper G, four deep groove ball bearings were tested in a SKF R2F test rig to evaluate how lift-off-speed and breakthrough-speed are affected by ball spin. The results are compared to film thickness calculations. The lubricants used were greases, oil bled from the greases and the base oil used for manufacturing the greases.Godkänd; 1996; 20070428 (ysko

Parallellspår, rundspår : Järnvägsteknisk försöksanläggning

Godkänd; 1999; 20080524 (ysko

Knowledge management in a railway network: The case of signalling systems

The railway network is a complex system with several technologies and a multitude of stakeholders working together to solve problems created by the increasing demands on capacity, speed and mobility for the transportation of goods and passengers. However, the presence of many different stakeholders complicates knowledge management and transfer. The purpose of this paper is to analyse the potential for improving inter-organisational knowledge management in the maintenance of railway signalling systems and make concrete suggestions for improvements. Even if information logistics processes can disseminate explicit knowledge on the maintenance of railway signalling systems, they cannot handle the tacit knowledge transfer that often is crucial. The study finds considerable potential for improving the knowledge management process. It suggests possible measures and makes suggestions for future studies.Godkänd; 2014; 20140422 (ampmor

Cloud-based emaintenance solutions for condition-based maintenance of wheels in heavy haul operation

The Swedish ore line, began in 1898 and was completed and operational by 1902. The line was later electrified and remains so to this day. A study on wheel-rail interaction, to optimize wheel and rail profiles on the Malmbanan and Ofoten lines states that there is a need to develop and apply limit values for the allowable length of single and multiple cracks on wheels. Herein, all stakeholders in the railway organization have to be involved. Provisioning of an integrated decision support system for track and vehicle contributes to increased efficiency and improved effectiveness of the maintenance process, which in turn enables achievement of business excellence. However, an integrated decision support process for maintenance is highly dependent on appropriate information logistics which enables information provisioning to various maintenance stakeholders. One emerging approach for development of eMaintenance solutions is utilization of cloud-based technologies. Cloud-based eMaintenance solutions promises smooth information logistics for maintenance decision support. Hence, the purpose of this paper is to propose an approach for condition-based maintenance decision-making relating to railway vehicle wheels, based on a cloud-based eMaintenance solution. The paper also demonstrates how the proposed approach can be implemented for estimation of Remaining Useful Life (RUL) of railway vehicle wheels.Godkänd; 2015; 20150517 (raka)</p

Technical and economic evaluation of maintenance for rail and wheels on Malmbanan

Godkänd; 2003; 20080416 (ysko

Knowledge management in a railway network: The case of signalling systems

The railway network is a complex system with several technologies and a multitude of stakeholders working together to solve problems created by the increasing demands on capacity, speed and mobility for the transportation of goods and passengers. However, the presence of many different stakeholders complicates knowledge management and transfer. The purpose of this paper is to analyse the potential for improving inter-organisational knowledge management in the maintenance of railway signalling systems and make concrete suggestions for improvements. Even if information logistics processes can disseminate explicit knowledge on the maintenance of railway signalling systems, they cannot handle the tacit knowledge transfer that often is crucial. The study finds considerable potential for improving the knowledge management process. It suggests possible measures and makes suggestions for future studies.Godkänd; 2014; 20140422 (ampmor)JVT

Data-driven model for maintenance decision support : A case study of railway signalling systems

Signalling systems ensure the safe operation of the railway network. Their reliability and maintainability directly affect the capacity and availability of the railway network, in terms of both infrastructure and trains, as a line cannot be fully operative until a failure has been repaired. The purpose of this paper is to propose a data-driven decision support model which integrates the various parameters of corrective maintenance data and to study maintenance performance by considering different RAMS parameters. This model is based on failure analysis of historical events in the form of corrective maintenance actions. It has been validated in a case study of railway signalling systems and the results are summarised. The model allows the creation of maintenance policies based on failure characteristics, as it integrates the information recorded in the various parameters of the corrective maintenance work orders. The model shows how the different failures affect the dependability of the system: the critical failures indicate the reliability of the system, the corrective actions give information about the maintainability of the components, and the relationship between the corrective maintenance times measures the efficiency of the corrective maintenance actions. All this information can be used to plan new strategies of preventive maintenance and failure diagnostics, reduce the corrective maintenance, and improve the maintenance performance.Validerad; 2016; Nivå 2; 20140422 (ampmor

Cloud-based emaintenance solutions for condition-based maintenance of wheels in heavy haul operation

The Swedish ore line, began in 1898 and was completed and operational by 1902. The line was later electrified and remains so to this day. A study on wheel-rail interaction, to optimize wheel and rail profiles on the Malmbanan and Ofoten lines states that there is a need to develop and apply limit values for the allowable length of single and multiple cracks on wheels. Herein, all stakeholders in the railway organization have to be involved. Provisioning of an integrated decision support system for track and vehicle contributes to increased efficiency and improved effectiveness of the maintenance process, which in turn enables achievement of business excellence. However, an integrated decision support process for maintenance is highly dependent on appropriate information logistics which enables information provisioning to various maintenance stakeholders. One emerging approach for development of eMaintenance solutions is utilization of cloud-based technologies. Cloud-based eMaintenance solutions promises smooth information logistics for maintenance decision support. Hence, the purpose of this paper is to propose an approach for condition-based maintenance decision-making relating to railway vehicle wheels, based on a cloud-based eMaintenance solution. The paper also demonstrates how the proposed approach can be implemented for estimation of Remaining Useful Life (RUL) of railway vehicle wheels.Godkänd; 2015; 20150517 (raka