1937

Magnetically Levitated Train

When a train is moving at speeds below 100 mph (160 kph), steel wheels work well. They are low cost and efficient without any major downsides. Above 100 mph, wheels start to have problems that become increasingly difficult for engineers to solve. One of those problems is vibration. Another is acceleration and braking. At some level of braking, steel wheels lose their grip on the track and skid. The simple act of keeping the train aligned on the track with wheel flanges causes friction, especially on curves.

The solution to all of these problems is to eliminate the wheels. The best replacement available is magnetic levitation. The concept of a “maglev” train has existed since German engineer Hermann Kemper received a number of patents for the device from 1937 through 1941.

A magnetic levitation train actually implements a package of three magnetic effects: One set of magnets lifts the train off the ground so it is floating. Another set of magnets keeps the train on the track in a left and right sense, especially as the train goes around curves. A third set of magnets (often implemented in conjunction with the lifting magnets) creates a linear motor to accelerate and decelerate the train.

By modulating a set of electromagnets, the train can control its precise height above the ground and its rates of speed, acceleration, and deceleration.

In addition to the benefits of ride smoothness, acceleration, and deceleration, getting rid of the wheels also eliminates the friction that they cause. However, at speeds over 200 mph, most of the energy is consumed overcoming aerodynamic drag. Therefore, engineers pay close attention to aerodynamics, which are as important as they would be in a jet aircraft.

The Shanghai Maglev Train in China, which began service in 2004, was the first public system running at over 200 mph (320 kph). It has seen a top speed of 310 mph (501 kph) and does regular runs (over 100 per day) of its 19-mile (30 km) track in seven minutes.

SEE ALSO Tom Thumb Steam Locomotive (1830), Diesel Locomotive (1897), Anti-Lock Brakes (1971), Vactrains (c. 2020).

Shanghai Maglev Train or Shanghai Transrapid is the first commercially operated high-speed magnetic levitation line in the world.