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.An interesting scheme for the conversion of electrical energy to mechanical energy is the so-called ball bearing motor depicted in FIG. 24. It is, indeed, just what its name suggests—ball bearing racers mounted on an axle. Rotation takes place under the influence of a heavy dc or ac current from a very low impedance source. Speeds of several thousand RPM have been observed, but there is little reliable correlation among performance parameters, with the exception that available torque increases with current. Self starting occasionally occurs, but it is not predictable or reliable; an initial spin in either direction is usually needed.
Such a motor is intriguing to the experimentally inclined, but so far its low efficiency and erratic nature preclude it from practical applications. Its operation evidently is not premised on electromagnetic interactions. Rather, it appears to be an electro-thermal device. High localized heat is developed in the region of contact be tween the balls and their racers. This, in turn, tends to distort the spherical shape of the balls and is accompanied by strong physical forces. The affected balls attempt to reduce such “unbearable” stress by repositioning themselves. In so doing, these movements can be translated into continuous rotation between the inner and outer racers.
It is conceivable that a more refined principle of operation followed by focused developmental work could lead to a practical device with a specialized technology of its own. The compelling attributes of such an electric motor might well be its inherent simplicity and its ultimate high reliability and low maintenance. One problem that will have to be dealt with is its behavior as a near short circuit because there is no counter EMF as with conventional electromagnetic motors.
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