A wheel assembly comprising a wheel-shaped stator plate provided between two wheel-shaped rotor plates, all of which being co-axially attached to a rotation shaft. Each rotor includes a plurality of permanent magnets on the side facing the stator. The stator includes a plurality of coils corresponding in position to the permanent magnets of the rotors. Corresponding magnet faces of the different rotors have opposite orientations, and adjacent magnet faces of the same rotor have also opposite orientations. The rotors are attached to each other to maintain this configuration in place as the rotors rotate. The coils are configured so that each coil generates a magnetic field that extends across the surface of the stator plate to react with corresponding permanent magnets in both rotors, thus maximizing use of the magnetic field generated by the coils and causing the rotor plates to rotate simultaneously. A stream of cooling fluid may be run within the stator plate for reducing overheating.