| Summary: | A high degree of wear has been identified in the hinge between load cube and underframe on one of Kiruna Wagons freight cars. The wagon is mainly used in the transport of iron ore, which means that it operates in a very dusty environment. The excessive wear results in an increased service demand and high downtime of the wagon. To reduce the need for service and thereby increase the availability of the wagon the cause of the high wear is to be determined. The report includes an analysis of the current hinge, load cases have been developed and strength simulations have been performed. The results of the calculations from the current hinge have been compared to studies of the hinge in reality to determine the conditions applied when using the wagon. Subsequently, the load cases have been modified by demands from the company. Several concepts of new hinges have been developed to then undergo a selection process that identifies the concepts that are most likely to be working on large-scale production.After analysis of the current hinge, it was discovered that the contact pressure in the joints is too high. The contact surface is not sealed from the environment, allowing foreign particles to contaminate the contact surfaces. The company wishes that the new hinge will not require continuous lubrication, or require maintenance with short intervals. The life-expectancy on the exchangeable parts are set to half the life-expectancy of the complete wagon. The concept hinges’ contact surfaces are sealed with o-rings, the journal is a thick-walled tube instead of a solid. The axle rotates against a bushing of a polymeric material rather than, as before, directly against the steel in the seat. The separation of the two steel surfaces remedies the problems that have been observed at the existing hinge, such as adhesion and material transfer between the two surfaces. The design of the concept hinge for the outer and inner hinge is now more homogeneous than before. This allows the company to have to stock fewer unique components.
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