Drums can be resurfaced like rotors but the brake lathe they are turned on is totally different. There are 2 different types of designs of drum brakes, duo-servo and non-servo. They both work pretty much the same way except non-servo drums are non-energized. The difference between them are pretty much the location of the anchor pin. On duo-servo drums, it's located at the top. On non-servo drums it's located on the bottom. The pads in a drum brake are called shoes. The shoe on the left is called the primary shoe when you refer to duo-servo drums and the shoe on the right is called the secondary shoe. On non-servo drums the primary is called the leading shoe and the secondary shoe is called the trailing shoe. Between the primary/leading shoe and the secondary/trailing shoe is a star wheel adjuster. This is the mechanism that adjusts the drum brakes. There is a spring that holds down each shoe. These are called hold-down springs. In duo-servo drum brakes, the springs that go from the shoe to the anchor pin are called return springs. In non-servo drum brakes, the return springs are inbetween the shoes. Drums have a wheel cylinder which acts like a caliper for disc brakes. Basically the wheel cylinder pushes the shoes out against the drum, this is how drums work. In duo-servo drum brakes, when the primary shoe is pushed out, it is also forced to forced against the anchor pin to push out the shoe even harder. This is called self-energizing.