in the low air pressure super light high speed tube 11 at a high speed the maximum cross section of the floating overshoe means 81 is less than 30 60 preferably 40 of the headroom in the tube 11 and the air pressure in the tube 11 is preferably very low for example less than 0 1 air pressure the floating u201c overshoe u201d means 81 is designed as a u201c overshoe u201d comprising a floating power tray a overshoe door 82 and an aerodynamic shroud for regulating air flow the floating overshoe means 81 has a control means inside it rails 44 u2032 and 45 u2032 are laid on the floating power tray and they are connected to rails 44 and 45 in a normal air pressure low speed tube respectively in this way the electric tube car 31 can run into the u201c overshoe u201d means 81 along rails 44 and 45 and is combined with the u201c overshoe u201d means 81 into an integral part this floating u201c overshoe u201d means 81 is controlled by the control means inside it and runs with the car 31 in the low air pressure super light high speed tube 11 as shown in fig2 a pressure transforming stopcock 10 for seamlessly jointing a normal air pressure low speed tube 9 and a low air pressure high speed tube 11 includes a few airtight cabins 86 each for containing one floating u201c overshoe u201d.