Abstract: A drive for a slow-running annular rotor of a processing machine includes a rotor supported on a standing tubular body by two bearings, between which the the electric motor driving the annular rotor is fastened to the annular rotor. The stator of the electric motor is disposed on and is likewise supported by the tubular body. The electric motor is of encapsulated design, and a gaseous coolant required for cooling the motor is conducted by forced circulation in a closed cooling loop which includes a heat exchanger disposed in the interior of the tubular body. The heat exchanger is designed as an air/air cooler. Such a drive is particularly suitable for bucket wheels of large-volume baggers employed for example in dusty areas lacking cooling water, for lignite strip mining.

Abstract: A pressure plate for a liquid-cooled electric machine is disclosed which improves heat removal from the end-face region of the stator lamination stack. The pressure plate is provided with a cooling canal formed by a recess on the surface facing the stator lamination stack which is closed off by a cover plate. The cover plate may be provided with a rib on the surface facing the recess. In one embodiment, a plurality of juxtaposed recesses are provided which extend transversely to the pressure fingers of the pressure plate. The pressure plate is preferably made of stainless, non-magnetic steel, i.e., of austenitic chrome-nickel steel.

Abstract: The invention is directed to a leak indicating apparatus for the closed cooling system of an electric machine. The elevation of the coolant level in the expansion tank of the cooling system as well as the measured average temperature of the coolant are translated into electrical signals which are compared with each other. Only when there is a deviation from the normal volume-temperature proportionality and after a time delay, is replenishing coolant supplied or an indicating device actuated.