Drum brakes are more susceptible to wheel lock-up compared to other types of brakes. This is because, in emergency braking situations, the brakes can apply excessive force that leads to wheel lock-up.

- The **anti-lock braking system (ABS)** is a device that helps prevent the wheels from locking up when braking, allowing the driver to maintain control of the vehicle. However, not all vehicles are equipped with ABS, and in these cases, drum brakes are more prone to locking up.

- When braking, a force is transmitted to the wheels through the **brake fluid**, which acts on the pads or shoes. In drum brakes, the shoes rub against the drum to stop the vehicle. This mechanism can be less efficient in preventing lock-up compared to disc brakes, which usually dissipate heat better and maintain more consistent contact.

- In emergency situations, if a vehicle does not have ABS, it is necessary to press the brake pedal firmly and then adjust the pressure to avoid lock-up. This is especially relevant for drum brakes, which are more prone to locking up under intense braking pressure.

In summary, drum brakes, due to their design and operation, are more susceptible to wheel lock-up, especially in vehicles without an ABS system.