The shaft and foil are separated by the air's high pressure, which is generated by the rotation that pulls gas into the bearing via viscosity effects.
The high speed of the shaft with respect to the foil is required to initiate the air gap, and once this has been achieved, no wear occurs.
[3] Garrett AiResearch air cycle machine foil bearings were first installed as original equipment in 1969 in the DC-10's environmental control systems.
[4] Current-generation foil bearings with advanced coatings have greatly exceeded the limitations of earlier designs.
[6] Commercial applications in production include microturbines,[7] fuel cell blowers,[8] and air cycle machines.