Abstract: A device for balancing rotating bodies including a sensing arrangement for sensing the out of balance of the rotating body and for generating a control signal of approximately rectangular pulse shape. An electromagnetic transducer response to the control pulse signal is provided and is operated at a frequency in accordance with the speed of the rotating body. A spray valve is combined with the electromagnetic transducer to form a single spray unit and at least one spray disk is mounted on the rotating body to be balanced, the spray disk having at least three chambers or compartments. A spray medium is supplied to the spray unit which injects the spray medium into at least one chamber in response to the control pulse signal with correct phasing during the normal revolution of the rotating body until the amount of spray medium injected compensates for the out of balance of the rotating body.