CDL Air Brake Cut-Out Pressure
Last updated: September 2026
What is the air brake cut-out pressure?
The governor cut-out pressure is about 125 PSI — typically 120–140 PSI (manufacturer-specified). This is the pressure at which the air compressor stops pumping air into the tanks.
Source: California Commercial Driver Handbook (DL-650)
What “cut-out” means
“Cut-out” is the point where the governor tells the air compressor to stop filling the system because it's fully charged. On the CDL test, the standard answer is about 125 PSI.
The typical range
The exact number is manufacturer-specified, so it's normal to see a range of typically 120–140 PSI (manufacturer-specified). For the written test, memorize 125 PSI — not an exact legal fixed value.
How it's tested
During the air brake check, you watch the gauge build to cut-out pressure. The compressor should stop around 125 PSI, confirming the governor is working.
Cut-out vs cut-in
Cut-out (about 125 PSI) is when the compressor stops. Cut-in (about 100 PSI) is when it starts again. Don't mix the two — see the cut-in page.
Related Resources
Frequently Asked Questions
What PSI does the air brake governor cut out?+
About 125 PSI — the compressor stops pumping air once the tanks are fully charged. The manufacturer-specified range is typically 120–140 PSI.
Is cut-out exactly 125 PSI?+
No. 125 PSI is the standard test answer, but the actual value is manufacturer-specified (typically 120–140 PSI).
This page is an independent study resource. It is not affiliated with the California DMV. Verify current requirements against official sources.