The invention by Dr. Christoph Lehmann from the Siemens Power and Gas Division in Mühlheim an der Ruhr could lead to considerable savings in the manufacture of gas and steam turbines. According to his calculations, the slewing gear drive (turn motor), which drives the turbine-generator shaft train during the cooling phase, becomes superfluous: its task could be taken over by one of the two auxiliary generators, which supply the generator rotor with electricity at operating speed, by switching to motor operation.