Progress in Magnetic Suspension Applied to High Speed Ground Transportation Available to Purchase

The Federal Railroad Administration's Office of High Speed Ground Transportation in early 1971 awarded contracts to Ford Motor Company and Stanford Research Institute for analytical and experimental investigations of magnetic levitation. The objective of these studies is to determine whether magnetic fields can be used to support and guide passenger vehicles at speeds up to 500 mph (224 m/sec). In addition, OHSGT exchanges information with Canada, Japan and Germany, each of which have government‐supported programs in magnetic levitation. Both attractive and repulsive techniques are under consideration. In the former category Germany has constructed two vehicles utilizing servo‐controlled electromagnets on the vehicle which maintain a gap of about 15 mm. beneath a pair of ferromagnetic guiderails. In the latter category, permanent magnets or superconducting magnets are used on the vehicle. Repulsive support results from the opposition of like magnetic poles in the guideway. In the case of permanent magnets implanted in the guideway, the lift force is independent of speed and electromagnetic drag is negligible. If instead a conducting guideway is used to take advantage of induced magnetization due to eddy currents, a critical minimum speed is required for lift‐off and lift‐to‐drag ratios must be taken into account. Results on superconducting magnets moving over solid conducting guideways show that this system has no serious dynamic instabilities. Lift to drag ratios in excess of 40 can readily be attained at 300 mph (134 m/sec).