Answer :
Final answer:
The low air warning device in a vehicle's brake system must activate before the air pressure drops below 60 psi, ensuring the vehicle can be stopped safely.
Explanation:
The question is related to the safety features of air brake systems on vehicles such as trucks and buses. The low air warning device is essential for alerting the driver about the air pressure in the brake system. According to safety regulations, the low air warning device must activate before the air pressure drops below 60 psi. This is crucial for allowing the driver enough time to safely stop the vehicle before the air pressure becomes too low to effectively engage the brake system.
