The paper presents the evaluation of experiments on the drag and friction forces in an automatic ball balancer, which raceway is embodied by the outer ring of a ball-bearing. Due to the throughout contact between the balls and the raceway while operating the ball balancer, effort has been made to characterise the flow conditions of the surrounding fluid by determining the drag coefficient CD as a function of the Reynolds number Re. By the use of fluids with different viscosities and the

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... ion of continuity in the run of CD.Re/, coefficients for different friction models, e.g. Coulomb friction and rolling friction deduced from Hertzian surface pressure equation can be derived.