The internal work and parts of a drum brake commonly used in scooters and some motorcycles (as a back brake).
The idea is very simple, there are two halves of “shoes” (yes that’s what they call ‘em.. the orange colored crescents) covered with a high friction braking material. When ever the driver/rider squeezes the brakes, the arm rotates and push the two shoes outside, causing a friction between the braking material (dark gray) and the outside moving drum (outer ring, lighter gray).
PROS of such system is probably simplicity. Its probably heavier too, due to the massive metal drum it needs.
CONS are many…. brakes less efficient than a disk brake, especially in hard usage where it will probably overheat causing drastically reduced braking ability (yes, you can loose brakes if you don’t use them correctly, especially in large TRUCKS that use drum brakes actuated by air pressure). Another thing is dimensions – drum brake is less compact then a disk brake.