Freewheel
Freewheels are machine elements with particular characteristics:
---In the one direction of rotation
  No driving contact between inner and outer ring; the freewheel is freewheeling.
---In the other direction of rotation
  Driving contact between inner and outer ring; in this direction, it is possible to transmit a high torque.
Freewheels are used as
---Indexing freewheels
---Overrunning clutches
---Backstop