This thesis is the result of the investigation and solution of a mechanicalproblem regarding flywheel malfunctions. A flywheel is, in short, a devicethat relies on a rotating object?s moment of inertia to store energy overshort time spans. This project is part of the development of a fourthflywheel prototype at the division for electricity at Uppsala university,which uses magnetic levitation to keep a hollow cylinder rotating at veryhigh speeds inside a vacuum chamber. Should the magnets fail however, orsome other error occur that leads to an uncontrolled state of rotation, thecylinder needs to be stabilized mechanically by a device usually referredto as ?back-up bearing?.