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A Suggested Homopolar Vehicle (Toy?)

G.R.Dixon, 7/16/2006

This article suggests a variation on the Stewart Motor, first called to the authorís attention by his friend, Jorge, at the Fundacion Julio Palacios in Argentina.

Fig. 1 depicts an edge view of a disc-shaped ceramic magnet with a dielectric disc attached. Fig. 2 depicts a top view of the dielectric disc. Embedded in the disc are radial copper bus bars (or rods). The ends of each bar are soldered to a central conducting shaft and to a peripheral copper ring.

Figure 1

Edge View of Magnet/Disc Assembly

Figure 2

Top View of Dielectric Disc with Embedded Copper Bars

If the central shaft is at a higher potential than the peripheral ring, and if a current return is supplied from the rim to the shaft, then current will flow outward in each conducting rod as indicated. As they move radially inward through the magnetic field, the conduction electrons experience tangential forces. The net effect is a clockwise torque on the disc.

Fig. 3 depicts a top view of 4 magnet/disc subassemblies. The copper rings on each side are electrically connected by a braided (flexible) copper cable loop that runs in slots. Optional rubber "tires" protect the rims of the ceramic magnets. A chassis (not shown) holds the batteries/axles at a constant distance from one another. The entire assembly is free to roll along a surface.

Figure 3

Undercarriage for a Homopolar Vehicle

Since disc-shaped ceramic magnets are limited in their diameters, multiple subassemblies could be "daisy chained" together to generate greater mechanical power. Or, larger subassemblies might be realized by replacing the permanent magnets with large coils (electromagnets), perhaps embedded in the tires. The apparatus should still function if the lower battery is replaced by a conducting shaft.

Tesla was first to point out that the circuit might be more efficiently completed by using non-slipping conducting belts (the braided cable in the figure) in lieu of sliding contacts. Note that like poles face each other on either axle, and the wheels accordingly repel one another.