CDL General Knowledge TestAir Brakes (if applicable)Hard
When inspecting a dual air brake system, a driver should ensure that the air pressure in both the primary and secondary systems builds from 85 psi to 100 psi within how many seconds at normal engine idle?
- A30 seconds.
- B60 seconds.
- C45 seconds.
- D15 seconds.
Show answer & explanationAnswer & explanation
Correct answer: C. 45 seconds.
For a dual air brake system, the air pressure should build from 85 psi to 100 psi within 45 seconds at normal engine idle. This is a critical test to ensure the compressor and system are functioning efficiently.
Why the other options are wrong
- A. 30 seconds is not the standard requirement for this pressure range.
- B. 60 seconds (1 minute) is too slow and would indicate a problem with the compressor or a leak.
- D. 15 seconds is too fast and not the standard requirement.
Air Pressure Build-Up Test
A test to verify that the air compressor can efficiently build and maintain sufficient air pressure in the air brake system.
- Performed at normal engine idle.
- Checks build time from 85 psi to 100 psi.
- Maximum time is typically 45 seconds for dual systems.
Memory trick: 85 to 100? 45 Seconds, Get It Done!