Magnetic levitation technology of tracked vehicles present status and prospects

There are more than five types of the magnetically levitated tracked vehicles, on which research and development efforts are being made. All of them provide contactless support and guidance to vehicles, and may be able to eliminate technical problems of the conventional railways, which are supported and guided by wheels on rails. Most popular ones among the proposed types are the electrodynamic levitation, which makes use of repulsive force of superconductive electromagnets, and the electromagnetic levitation, which makes use of attracting force of normal-conductive electromagnets. One of the problems of EDL is the stability problem. EDL is a system, which has very small damping and is liable to oscillation. Although test runs have been made on two EDL system of appreciable sizes, it is still premature to make a definite conclusion on the dynamic stability problem. One of the problems of EML is the small gap length between magnets on vehicle and rails on ground. Probability of contact at the small gap will limit the highest speed limit available. A large number of test runs have been made on EML test vehicles of appreciable sizes in various countries. The probability of contact can be determined by analyses based on the power spectral density of the rail roughness. EML has much test data and analytical data, which might predict a bright prospect on its applications in speed range much higher than conventional railways. Present status of R. & D. of magnetic levitation technology in Japan will be explained.