ABB Motors and Generators manufacture large AC machines with oil lubricated plainbearings. The machines have occasional problems with oil leakage from the bearings. aproblem that ABB wants to be solved.In this thesis the cause of this leakage were investigated, with focus on the bearingseals.The purpose of this work was also to suggest amndments for preventing thisproblem. , and to suggest improvements that can prevent this. The first step was todo a literature survey of earlier work on this problem, study the theory ofhydrodynamic bearings and different types of seals and their properties. Severalexperiments and pressure measurements were performed on machines in operation.The results were then analyzed to identify the causes of leakage and to confirm/oreliminate the hypotheses that had been stablished in the earlier stage of this work.Finally, recommendations for problem management was proposed. New designs werealso developed based on the experimental findings, interviews with the technicians inthe company, and observations on the manufacturing and repairing procedures madeduring this work.The experimental and analytical results suggests that the current design of the bearingsystmem is sensitive to oil leakage. It has been discovered that pressure is the mostrelevant parameter, while several other parameters also contribute to the problem.

No description available.

Stora Enso Kvarnsveden är ett pappersbruk lokaliserat vid Dalälven i Kvarnsveden. Bruket har för tillfället två producerande maskiner och detta arbete behandlar en av dem, vilken är PM12. På PM12 har man problem med oljeläckage i maskinens torkparti. Läckagen uppstår genom de lagerhus som finns för att bära upp torkpartiets valsar. I detta arbete har man undersökt vad läckagen beror på med fokus på dess lagertätningar. Syftet och målet med detta arbete har varit att utreda varför läckagen uppstår samt att generera koncept för att minska eller helt eliminera läckagen. Arbetet har innefattat diverse mätningar och utredningar för att komma till rätta med problemet. En litteraturstudie har genomförts för att identifiera felorsaker samt lösningar. Koncept har genererats utifrån studien samt de mätningar som utförts. Man har inte under arbetets gång helt kommit fram till vad läckagen beror på men man har kommit en bra bit på vägen. Förslag till fortsatt arbete har getts där det rekommenderas mer specifikt vilka typer av mätningar som bör genomföras samt de koncept man som bör bygga vidare på. / Stora Enso Kvarnsveden is a paper mill located at Dalälven in Kvarnsveden. The utility currently has two producing machines, and this study deals with one of them, which is PM12. At PM12 there is a problem with oil leaks in the machine's drying section. Leakage occurs through the bearing houses who are there to support the dryer's rollers. In this study, it has been investigated what the leakage is due to focusing on its bearing seals. The purpose of this study has been to investigate why leakage occurs and to generate concepts to reduce or eliminate leaks. The study has included various measurements and investigations to address the problem. A literature study has been conducted to identify causes and solutions. Concepts have been generated from the literature study as well as the measurements that have been taken. After this study it´s not fully realized why the leakage occurs, but it had come a long bit on the way. Proposals for continued work have been given, where it is recommended more specifically what kind of measurements that should be done and the concepts that should be further developed.