Disk 1 rotates about fixed axis A. Brake shoes 2 and 3 turn about fixed axes B and C. The working surfaces of shoes 2 and 3 are designed so that each shoe allows rotation of disk 1 in one direction and jams to stop rotation in the other direction. Thus disk 1 can rotate in either one or the other direction depending on which shoe, 2 or 3, is in contact with the disk. Shoe 2 allows counterclockwise rotation of disk 1, and shoe 3, clockwise rotation.
$3388$SmF,Br$