Once the shaft is spinning quickly enough, the working fluid (usually air) pushes the foil away from the shaft so that there is no more contact.

So, even when the shaft is spinning at, say, 7,500 rpm, the rotors are turning at a much more leisurely 2,500 rpm.

The shaft spins within a cylinder of pressurized fluid, without mechanical contact.

When the rotor spins, the shaft spins as well.

Drizzt saw the quivering, black-feathered shaft as the angry giant spun about.

The shafts spun at twice the engine rpm, forcing the redline to be reduced from 6800 to 6500 rpm.

The rods started right up in their tight little orbit and very quickly the shaft was spinning at its maximum speed.

The shaft then spins together with that gear.

A shaft spins at 2,500 revolutions per minute.

When the central shaft spins fast enough, the springs extend causing the clutch shoes to engage the friction face.