Electromagnetic wheels

The possibility of using controlled direct-current electromagnets to support large weights was demonstrated by Kemper in 1932. However, it was only in the mid-1960s, with the advent of high-power solid-state devices, the full potential of electromagnetic suspension was realised. The progress that followed was so rapid that, within the next six years, the idea of using magnetic suspension for transportation progressed from `way out' to `a strong contender'. The evolution of several kinds of magnetic suspension is still proceeding with no indication that the ideal compromise to satisfy the many conflicting requirements has been reached. Because of the exciting possibilities, there is a high level of activity in magnetic suspension in Canada, Japan and W. Germany, with lesser efforts in other countries, including the United Kingdom. Some of the basic control problems associated with the electromagnetic suspension system are discussed in this article, and the case for its use in urban and intercity transport systems presented