Drum brakes have a self servo effect. The most common design is a leading-tailing design.More exotic design had four ,eight or sixteen shoes .Some motorcycles used finned and/or vented housing for additional cooling ,the first of which was AJS.
Hydraulic and mechanical actuation.
Torque reaction arm transfer the torque from the brake to fixed point to relieve the suspension reacting to the braking force i.e. diving.