Drum 1 rotates about fixed axis A. Shoes 4 turn about axis B of the inner disk which rotates independently of drum 1. Shoes 4 are forced against drum 1 by turning cam 6 about axis E. Shoes 9 turn about axis C of the inner disk and are forced against drum 1 by turning cam 3 about axis D. This applies the brake. When the brake is released, shoes 4 and 9 are retracted by springs 7 and 8.
$3126$SmC,Br$