Emporio Rossi sells brake cams of the following brands:
Brake cams are mechanical devices that, spun by the brake levers, allow to expand the brake shoes and push the brake linings against the drum: in this way the vehicle can brake down.
Brake cams are inserted with a gear rack system inside the brake lever cavities; the brake lever in its turn spins around the axle, where there are gaps left by the brake cylinder. The brake cylinder in its turn is activated by the compressed-air system.
So, the drum braking system can be seen as a pneumatic-mechanical system: at the start the compressed-air system moves the brake levers via brake cylinders, and brake levers mechanically act on the brakecams to expand the brake shoes.