What is true about the emergency brakes in a modern air brake system?

What is true about the emergency brakes in a modern air brake system?

• A. They replace the service brakes entirely
• B. They are the primary brake
• C. They automatically engage when parking brake is on
• D. They provide an additional braking mode separate from service and parking brakes

Answer: (D)

In a modern air brake system, braking power comes from distinct functions: the service brakes for normal stopping, parking brakes to hold the vehicle when parked, and an additional emergency braking function. The emergency brakes are a separate mode designed as a backup or fail-safe, not the main way you stop the vehicle and not simply the same as the parking brakes. They provide an extra option to slow or stop the vehicle if the primary air system or service brakes fail, or when activated by the emergency control. Because of that separation from the normal service and from the parking brake system, the correct statement is that the emergency brakes provide an additional braking mode separate from service and parking brakes.

In a modern air brake system, braking power comes from distinct functions: the service brakes for normal stopping, parking brakes to hold the vehicle when parked, and an additional emergency braking function. The emergency brakes are a separate mode designed as a backup or fail-safe, not the main way you stop the vehicle and not simply the same as the parking brakes. They provide an extra option to slow or stop the vehicle if the primary air system or service brakes fail, or when activated by the emergency control. Because of that separation from the normal service and from the parking brake system, the correct statement is that the emergency brakes provide an additional braking mode separate from service and parking brakes.