On August 9, the first tests of a line of suspended maglev operating on permanent magnets were carried out in China. This
Maglev is a train that uses tomovement of the magnetic force. The system lifts the train with passengers from the surface, avoiding friction, and pushes it forward. Thanks to maglev technology, the train runs on rails that control its stability and speed.
Despite the fact that maglev construction technologies have been developed for more than 100 years, at present, small commercial sections of such roads have been created only in Japan, China and South Korea.
What is the peculiarity of the Chinese maglev?
As a rule, when the word "maglev" immediately arisesa picture of a train hovering over the monorail at a short distance. Chinese development is completely different. The line of suspended maglev "Rainbow" works on permanent magnets, and the composition itself is located under the guide, and not above it. The advantage of such a system is that no electricity is required to levitate the train. If left alone, it will be in limbo forever.
Unlike a conventional track on a magneticsuspension, which requires electromagnets, the Rainbow line is based on alloys of rare earth metals. They create magnetic fields with an induction of more than 1.2 Tesla. For a conventional iron or ceramic magnet, for comparison, it ranges from 0.5 to 1 T.
The materials used forline construction are relatively cheap, while such a system does not require energy to maintain the "flight" of the vehicle. The test site is designed for medium speed trains: the maximum design speed of the system is only 80 km/h. This is sufficient for intra-city and suburban transportation in densely populated areas.
The strength of the magnets that were used inline design, enough to serve a train consisting of two cars that can accommodate up to 88 people. Chinese authorities say that if successfully tested, the system could be used as an airport express train, on tourist routes, and even as an internal transport for small towns.
Train on the Rainbow line. Photo: Xinhua Agency
Electromagnetic suspension
Technology for creating maglev on permanentmagnets is the third direction in the development of this type of transport. The other two systems use electric (EML trains) or superconducting magnets (EML trains).
Diagram of a train on an electromagnetic suspension. Image: Stefan_024, Public domain, via Wikimedia Commons
In systems with electromagnetic suspension trainhovering over a steel rail using electromagnets placed at the bottom of the train. Attached to the bottom of the body of such trains are "C"-shaped levers, with the top of the lever attached to the vehicle and the bottom inner edge containing magnets. The rail runs between the inner and outer edges of the lever.
The disadvantage of this technology in largeinstability. Magnetic attraction varies inversely with the square of the distance. Even slight changes in the distance between the magnets and the rail greatly affect the force of attraction and repulsion. Therefore, such a system uses complex systems to "return" the train to the desired position. They constantly monitor and correct the distance between the magnets and the rail.
It was with this technology thatfirst commercial maglev. He earned in 1984 in England and connected the airport and railway station in Birmingham. This train accelerated to a speed of 42 km/h and operated on a monorail section only 600 m long. The system lasted just over 10 years and was closed in 1995 due to outdated technology and reliability problems.
Birmingham Maglev. Photo: MaltaGC, CC BY-SA 3.0, via Wikimedia Commons
Magnetic levitation maglev may not workonly at low but also at high speeds. For example, this is the technology used by Shanghai Line trains. Launched in 2003, the system is the oldest maglev still in operation and the first commercial high-speed magnetic levitation train.
This route connects Shanghai Airport with the localmetro line, and the train can carry 574 passengers. At the same time, at full speed, the trip takes 7 minutes and 20 seconds. During this time, the train covers a distance of 30 km. It can reach 300 km/h in just over 2 minutes, and reaches its maximum normal operating speed of 431 km/h in 4 minutes.
Despite some shortcomings, it ismaglev train technology is central to most of the systems currently in operation. For example, they operate at Incheon Airport in South Korea and Limo Prefecture in Japan.
Electrodynamic suspension
Unlike electromagnetic suspension, trains onelectrodynamic suspension uses magnets that are installed not only in the train, but also on the rail itself. In such a maglev, superconducting magnets suspend the car above a U-shaped concrete track. Like regular magnets, these magnets repel each other when matching poles are facing each other.
The magnets used are superconductive andthis means that when cooled to low temperatures, they can generate magnetic fields 10 times stronger than conventional electromagnets. These magnetic fields interact with simple metal loops installed in the concrete walls of the maglev rail. They are made of conductive materials such as aluminum, and when the train's magnetic field passes by, it generates an electric current that forms another magnetic field.
Diagram of a train on an electrodynamic suspension. Image: Cool Cat, at the English Wikipedia project, CC BY-SA 3.0, via Wikimedia Commons
Three types of hinges are installed on the railat certain intervals to perform three important tasks. First, they create a field that causes the train to hover a few centimeters above the track. Secondly, keep the composition in a vertical position. And thirdly, they move the train forward.
Not a single one has been put into operation yetcommercial train that runs on this technology. But preliminary tests are underway in different countries. For example, such a system is SCMaglev, a Japanese railway line that holds the speed record for maglevs. In 2015, the train of this company was able to accelerate to 603 km/h.
It is expected that the commercial operation of such trains will begin in 2027, when they will link Tokyo and Nagoya.
Despite the fact that magnetic levitation trainshave been in development for many decades, but have not yet become the dominant means of transportation, this technology should not be buried. Such trains have a number of advantages over classic trains. They can reach higher speeds, consume less energy and are less affected by weather conditions such as snow or rain.
Possibilities of building own linesmaglev is considered by many countries. And, perhaps, with the advent of cheap and environmentally friendly permanent magnet technology, such compositions will no longer be a curiosity.
On the cover: L0 series train for SCMaglev. Image: Saruno Hirobano, CC BY-SA 3.0, via Wikimedia Commons
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