Michigan CDL - Air Brakes Practice Exam

At what air pressure does an air compressor governor stop the compressor from pumping air?

1. 100 psi

2. 110 psi

3. 125 psi

4. 150 psi

The correct answer is: 125 psi

The air compressor governor in a vehicle is designed to maintain the air pressure in the braking system at an optimal level. The compressor stops pumping air when the pressure reaches approximately 125 psi. This pressure is critical because it ensures that the air brake system has enough air supply to function properly while also preventing overcharging of the system, which could lead to potential damage or failure of components. When the pressure falls below a certain threshold, the governor will activate the compressor to begin pumping air again, ensuring that the brake system remains operational. This cycle of building and releasing pressure helps maintain a safe and effective air brake system. Understanding this operation is essential for CDL drivers, as it allows them to recognize the importance of monitoring air pressure and the role that the governor plays in ensuring safe vehicle operation.