气垫
a layer of air often used to support a machine or vehicle
  A hovercraft travels on a cushion of air. 气垫船悬浮在气垫上行驶。 
 He realised that a heavy boat could be supported by a cushion of air.
 The train will float on a magnetic cushion of air, just above the track.
 The air hockey puck moves so quickly because it's sitting on a cushion of air, so it never touches the table top.
 The iron is a pleasure to use, gliding as it does on a cushion of air.
 Floating on a cushion of air, the vehicle can travel over land or sea.
 See also: cushion noun (SOFT THING)