Electrodynamic suspension
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Electrodynamic Suspension (EDS) is one method that can be used for maglev trains. Superconductor electromagnets on the train generate a magnetic field. Propulsion coils on the guideway are used to exert a force on these magnets, and make the train move forwards.
The propulsion coils exert a force on the train in the same way that an electric motor works. An alternating current flowing through the coils causes a continuously varying magnetic field, that moves forwards along the track. The magnets on the train line up with this field, and so the train moves.
As the train moves forwards, it induces a current in another set of coils, responsible for guidance and levitation of the train. They have a figure of eight shape, and the current flowing through them induces magnetic poles in both the top and bottom halves. These poles ensure that the magnets on the train are repelled by the bottom half, and attracted by the top half, resulting in the train levitating.
At slow speeds however, the current induced in these coils is not large enough to support the weight of the train. For this reason the train is fitted with a retractable landing gear to support the train until it takes off.