Spherical electric motors

The history of spherical motors is traced, beginning with the initial research in the mid-1950s. Interest grew in the 1960s in their use in space, due to their light weight compared with that of conventional motors. In the 1970s, the spherical concept was applied to pumps where the impeller is of spherical shape so that no shaft seals are required. The 1980s saw still more activity, this time with a heavy influence on analysis. The complicated geometry of the motor, which results in a high production cost and does not seem to enhance reliability, has prevented commercial success. It may prove useful for large weightless structures to be constructed out in space.<
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