CDL General Knowledge TestDriving SafelyEasy
When performing a pre-trip inspection, you notice that your vehicle's air compressor is not building pressure within the specified time. What is the minimum air pressure required for the air compressor to cut out?
- A150 psi
- B80 psi
- C125 psi
- D100 psi
Show answer & explanationAnswer & explanation
Correct answer: C. 125 psi
The air compressor should cut out between 125 psi and 140 psi. If it does not build to at least 125 psi, there is a problem that needs to be addressed before driving.
Why the other options are wrong
- A. 150 psi is generally above the maximum cut-out pressure for most air brake systems.
- B. 80 psi is too low for the air compressor cut-out pressure.
- D. 100 psi is too low for the air compressor cut-out pressure.
Air Compressor Cut-Out Pressure
The pressure at which the air compressor stops pumping air into the air tanks, typically between 125-140 psi.
- Indicates proper air brake system function.
- Ensures sufficient air pressure for braking.
- A lower cut-out pressure needs immediate attention.
Memory trick: Compressor Cuts Out at 125, ready to drive.