Arizona Air Brakes CDL Practice Test

What is a sign that your vehicle's single brake system needs adjustment?

1. Pressure builds from 50 to 75 psi within three minutes

2. Pressure builds from 85 to 100 psi within 45 seconds

3. The compressor cuts out between 70 to 90 psi

4. The governor stops between 75 to 90 psi

The correct answer is: The compressor cuts out between 70 to 90 psi

The situation described in the correct answer is an important indicator of a potential issue with a vehicle's single brake system. If the compressor cuts out between 70 to 90 psi, it suggests that the air supply system might not be operating efficiently. In a properly functioning braking system, the compressor should maintain and regulate the air pressure within a certain range to ensure optimal braking performance. When the cut-out pressure is significantly lower than the recommended operational range, it can lead to insufficient air pressure, which is critical for the effective functioning of air brakes. Knowing when a compressor cuts out is essential, as proper air pressure is vital for maintaining safe braking distances and overall vehicle control. The prescribed pressure levels for air brake systems typically range higher, and any consistent cut-out below this could indicate problems, such as leaks in the air system or malfunctioning components, necessitating an adjustment or maintenance check. Understanding these factors helps ensure that drivers can identify early warning signs of brake system issues, contributing to safer driving practices and vehicle reliability.