Arizona Air Brakes CDL Practice Test

What warning level must be seen before the air pressure in the service air tanks falls below?

1. A. 80 psi

2. B. 40 psi

3. C. 20 psi

4. D. 60 psi

The correct answer is: D. 60 psi

The correct warning level that must be seen before the air pressure in the service air tanks falls below is 60 psi. This is crucial for the safe operation of vehicles equipped with air brakes. At this pressure level, a warning signal is typically activated to alert the driver that air pressure is decreasing and may soon reach a point that compromises braking effectiveness. Maintaining adequate air pressure is vital, as it ensures the proper function of the brakes, which rely on air pressure to engage. If the pressure drops below this threshold, it can lead to a loss of brake control, making it imperative for drivers to take immediate action, such as finding a safe place to stop and inspecting the air brake system. In practice, drivers should be mindful of their air pressure gauges and understand the importance of the warning levels as they relate to safe driving and avoiding mechanical failure.