What component of the service brake system is responsible for applying and releasing the brakes?

The brake pedal is a critical component of the service brake system, as it is the control interface that the driver uses to engage and release the brakes. When the driver presses down on the brake pedal, it physically activates the brake system and signals the other components—like the master cylinder—to initiate braking. This action creates hydraulic pressure, allowing the brakes to clamp down on the wheel components.

Additionally, the functionality of the brake pedal is essential for safe vehicle operation, as it directly determines how quickly the vehicle can be slowed or stopped in response to the driver’s actions. Without the brake pedal, it would be impossible for the driver to control the vehicle's speed or come to a halt when necessary.

The other components, such as the brake drum, brake booster, and master cylinder, each play supportive roles in the braking process but do not directly translate the driver’s input into brake application. The brake drum is where the braking force is applied, the brake booster enhances the force applied by the driver to the master cylinder, and the master cylinder converts the pedal's action into fluid pressure to engage the brakes. However, it is the brake pedal that initiates the entire process.