What function do service brakes serve in an air brake system?

Answer: B — For normal stopping

The service brakes in an air brake system are primarily designed for normal stopping. This function involves the application of braking force to reduce the vehicle's speed and bring it to a complete stop during regular driving conditions. Service brakes are operated by the driver using the brake pedal and are crucial for everyday driving safety, allowing the driver to control the vehicle effectively in response to traffic conditions. In contrast, emergency brakes are specifically for use in situations where the service brakes fail, providing a backup method to stop the vehicle. Similarly, while maintaining speed is managed through vehicle controls and throttle rather than braking, parking brakes are intended to secure the vehicle when it is stationary. This distinction highlights the specific role of service brakes in the overall braking system.