An effect achieved by using an electromagnet to provide the magnetic field to support a load containing magnetic material, by repulsion of like magnetic poles. If the electromagnet is a linear structure of several electromagnets-a linear motor-then by switching each electromagnet on in turn the load can be transported by levitation, without friction. An example is the Transrapid train in Shanghai, which transports passengers to and from the airport at speeds of up to 430 km/h (270 mph).

http://science.howstuffworks.com/transport/engines-equipment/maglev-train1.htm How MAGLEV trains work