What happens if the emergency air line breaks while driving?

If the emergency air line breaks while driving, the correct outcome is that the emergency trailer brakes engage. This system is designed with safety in mind, ensuring that if there is a loss of air pressure in the emergency line, the brakes will automatically activate. This feature is critical for maintaining control of the trailer and preventing an uncontrolled situation, such as the trailer detaching while in motion.

When the emergency air line loses pressure, a spring-loaded mechanism within the trailer's brake system is activated, causing the emergency brakes to deploy. This action effectively brings the vehicle to a stop safely. The purpose of this system is to protect both the driver and other road users in case of an emergency, emphasizing the importance of having functioning air lines and understanding their role in the braking system.

Other answers do not accurately describe the consequences of a broken emergency air line. The truck will not accelerate or experience power steering failure due to this issue, nor will the engine stop, as these are independent systems that function separately from the braking mechanisms.