Abstract: An apparatus for balancing a rotary member such as a grinding wheel has at least one balancing weight which is guided movably for varying its position with respect to the axis of rotation of the rotary member. The balancing position of the balancing weight is adjusted by means of at least one displacement device including an electric motor. The motor is arranged with its axis of rotary oriented radially with respect to the axis of rotation of the rotary member. The rotor of the motor can be supported by way of a thrust bearing against a main body portion.

Abstract: An apparatus for unbalanced compensation of a grinding wheel which is rotatable about an axis of rotation, with compensating weights which are guided rotatably about the axis of rotation of the grinding wheel with symmetrical mass distribution relative to a central plane of the grinding wheel which is perpendicular to the axis of rotation. A positioning mechanism is provided for different angular positionings of the compensating weights. The compensating weights are mounted for rotation through 360.degree. about the axis of rotation at different radii, the product of the mass of each compensating weight and its associated radius being equal to the product of the mass of each other compensating weight and its associated radius.

Abstract: An arrangement for continuously compensating for unbalance of a rotary member such as a grinding wheel comprises an annular container which is adapted to be coaxially secured to the rotary member to be balanced. The container is subdivided in its circumferential direction into a plurality of balancing chambers which are accordingly disposed at different angular positions in relation to the rotary member. A compensating liquid can be introduced into the respective balancing chambers from the exterior thereof to provide an unbalance compensating effect. Associated with each of the balancing chambers is a respective chamber emptying valve which for the purpose of emptying compensating liquid from the respective chamber can be actuated by an actuating piston arranged coaxially with respect to the container and axially displaceable by a drive controlled from the exterior of the arrangement.