How Maglev Trains Work

Magnetic  levitation  system does more than  just  suspend   trains  above  a guideway , or  track . It  also propels   them   forward  while  keeping   them  centered  on  the guideway. Here's how it works:

Levitation . Powerful  superconducting  magnets  located  on the railcars control  levitation and centering. As the superconductors in the train speed past the figure-eight levitation coils attached to the sides of  the guideway , they induce an electric current  in the coils. This turns  the coils  into electromagnets. The poles on the coils simultaneously push and pull the superconducting magnets upward, suspending the train over the track.

Guidance .  The  levitation  coils  are  also  connected under  the guideway to form a loop.As the superconducting magnets move past  this loop , they induce  an  electric current  in the coils. The coils  nearest  the  train   repulse  the  superconducting magnets aboard  the  train , while  those  coils  further attract them. As the train   moves   toward   the center , the    magnetic   forces  grow proportionately  weaker  and  stronger ,  thus   keeping   the  train centered.

Propulsion.     Electromagnetic coils embedded in the guideway walls govern propulsion . These coils switch alternately between north  and  south  poles, alternately  pulling and pushing the train and its superconductors forward.

Acticle from Japan Railway Central's.