Michigan CDL - Air Brakes Practice Exam

What is the minimum air pressure required in both primary and secondary systems before driving a dual air brake vehicle?

1. 80 psi

2. 90 psi

3. 100 psi

4. 110 psi

The correct answer is: 100 psi

The minimum air pressure required in both the primary and secondary systems before driving a dual air brake vehicle is 100 psi. This pressure is crucial for ensuring that the air brake system can function effectively. At this pressure, the system is adequately charged to engage the brakes safely and reliably. If the air pressure is lower than 100 psi, the air brake system may not work properly, leading to potential safety hazards. For example, the brake system's ability to stop the vehicle could be compromised, increasing the risk of accidents. Also, below this pressure threshold, warning lights may activate, alerting the driver to insufficient air pressure, emphasizing the need for maintaining proper pressure levels before operating the vehicle. Understanding the importance of maintaining this minimum pressure is key to safe driving practices in vehicles equipped with dual air brakes.