Method of constructing a rotor assembly for homopolar generator
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A homopolar generator (HPG) having the stator and an inner brush mechanism housed within the machine support structure utilizes a rotor separated into halves electrically insulated from each other, so as to fit around the stator and brush mechanism. A shaft is mounted in the support structure to carry the rotor. A first rotor half is thermally shrunk-fit onto the shaft, and the second rotor half is hydraulically expansion fit thereon. To hydraulically fit the second rotor on the shaft, a shaft is provided having a downward taper from its midpoint toward one end. The shaft also has a circumferential groove and a port therethrough from the end of the taper for communicating high pressure oil from an external pump to the shaft-rotor interface. High-pressure seals on each side of the groove prevent leakage. The application of high-pressure oil expands the bore in the rotor half and shrinks the shaft diameter. A hydraulic ram then pushes the rotor half onto the tapered shaft, whereupon the pressure is released and the rotor half bore contracts against the shaft.