What is a common characteristic of drum brakes?

Drum brakes operate on the principle of expanding shoes, which is a defining characteristic of this braking system. In drum brakes, the brake shoes are positioned inside a cylindrical drum. When the brake pedal is pressed, hydraulic pressure forces the shoes outward against the inner surface of the drum. This action creates friction, effectively slowing down or stopping the vehicle.

This design contrasts with systems like disc brakes, which use friction pads that clamp onto a rotor. The unique mechanism of expanding shoes in drum brakes allows for effective braking force while also often making them suitable for certain types of vehicles and applications.

Other options may discuss properties or behaviors of braking systems but do not capture the specific operational principle that sets drum brakes apart. For instance, while drum brakes can indeed have issues with overheating or carry weight characteristics compared to disc brakes, these points do not embody the fundamental operational principle. Therefore, identifying the aspect of expanding shoes highlights a core part of how drum brake systems function.