Abstract: A device for balancing rotating bodies comprising two inertia masses, which are disposed in a cylindrical housing which can be connected to the body to be balanced such as a grinding disc, and which are mutually connected by means of a self-locking worm gear. The inertia masses may be displaced by means of one single switch shaft having four positions in which the two inertia masses can be displaced either countercurrently in both directions or concurrently. When braking is effected by means of a brake knob disposed on the switch shaft, displacement occurs until the indicated imbalance lies within the low, desirable range. The worm shaft and the worm wheel contained in the inertia masses are in engagement with the worm gear of the switch shaft and the housing.An arrangement of this type permits, on the one hand, a simple mechanical construction and operation, and, on the other hand, a large inertia mass, relative to the volume available, with a wide range of adjustment.