Abstract: An apparatus for measuring an unbalance of a rotary member, such as an electric motor armature, comprises a rotary member mounting arrangement for rotatably mounting the rotary member for a measurment operation. The mounting arrangement is capable of oscillating movement in a measurement direction. A drive belt for driving the rotary member in rotation bears against the rotor in substantially tangential relationship therewith or passes around the rotor over a small part of the periphery thereof. A measurement transducer detects forces or oscillations produced by the rotation of the rotary member in the measurement direction and outputs a corresponding signal for unbalance measurement. The drive direction of the belt drive in relation to the rotary member is normal to the measurement direction. The measurement direction may be inclined to facilitate fitting the rotary member into and removing it from the mounting arrangement of the apparatus.

Abstract: In a method and apparatus for mass centering of a rotor, the unbalance of the rotor is measured and the result of the unbalance measuring operation and the weight of the rotor are used to determine the position of the axis of inertia which extends through the center of mass of the rotor, with respect to the axis of rotation thereof. The position of the axis of inertia is marked on an end face of the rotor by a marking tool. For that purpose, to bring the position of the axis of inertia and the marking tool into the appropriate relationship, relative displacement is produced by an actuating means as between the rotor and the marking tool in the radial direction with respect to the axis of rotation of the rotor, with the rotor or the marking tool being guided in the direction of displacement by a guide means disposed at an angle with respect to the axis of rotation of the rotor.

Abstract: A clamping ring for clamping a member such as a rotor on a shaft comprises a ring member formed by a plurality of ring segment portions which are displaceable relative to each other in the peripheral direction of the ring member, and spring elements disposed in the respective gaps between adjacent ring segment portions, thereby connecting the ring segment portions together. The clamping ring is fitted into an opening in the member such as a rotor, and the clamping action is produced by a variation in the inside and/or outside diameter of the ring member, by virtue of the ring segment portions being displaced relative to each other in the peripheral direction only in the plane of the ring member.