Abstract: An exhaust gas turbocharger for a diesel engine, the turbocharger including a compressor, an exhaust gas turbine, and a shaft joining the compressor and turbine. A flywheel is mounted on another shaft, and a device, such as a freewheel, alternatively couples and uncouples the flywheel shaft and turbocharger shaft. The flywheel shaft is in two sections, and a summation mechanism, such as a planetary gear arrangement, is between the two shaft sections. The summation mechanism is controlled by a hydrostatic device and/or an electronic device. A brake is provided for selectively preventing rotation of the flywheel shaft section between the summation mechanism and the turbocharger shaft.