North Dakota CDL — Air Brakes practice
North Dakota CDL — Air Brakes: Handling Emergencies practice test
What to do when things go wrong — brake failure, tire blowouts, skids, and stalling on railroad tracks.
Content reviewed against official driver handbooks · August 12, 2026
9 questions · pass with 7 correct. You get instant feedback and an explanation after every answer.
Study questions with answers
9 sample Handling Emergencies questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.
Show all 9 questions with answers
1. Something has gone wrong, and tank pressure keeps climbing well past the governor's usual cut-out level. At what pressure does the manual say the safety relief valve typically opens?
Correct answer: 150 psi
The safety valve sits in the first tank the compressor feeds and guards the whole system against too much pressure; its usual setting is 150 psi. If it releases air, something is wrong and a mechanic should fix the fault.
Source: North Dakota Commercial Driver License Manual — Section 5.1.6, Safety Valve
2. A bus with dual parking control valves has lost its main air pressure, and the driver pushes in the spring-loaded control to release the spring brakes and move. What happens when the driver lets go of that control?
Correct answer: The spring brakes come back on
That control is held in the out position by a spring. Pushing it in sends air from the separate tank to release the spring brakes, and letting go allows them to apply again. The separate tank holds enough air for only a few such releases.
Source: North Dakota Commercial Driver License Manual — Section 5.1.15, Parking Brake Controls
3. You are making an emergency stop with the controlled braking method. In which situation does the manual say to release the brakes?
Correct answer: When you need a larger steering adjustment or the wheels lock
Controlled braking means braking as hard as possible short of wheel lockup while keeping steering movements very small. A bigger steering correction or a wheel lockup is the cue to let off, then brake again as soon as you can.
Source: North Dakota Commercial Driver License Manual — Section 5.4.3, Emergency Stops
4. In stab braking you release the brakes when the wheels lock and reapply once they roll. After the release, how long does the manual say it can take the wheels to start rolling?
Correct answer: Up to one second
The manual notes that the wheels may need as much as a second to begin rolling again. Braking again before they roll keeps the vehicle from straightening out.
Source: North Dakota Commercial Driver License Manual — Section 5.4.3, Emergency Stops
5. North Dakota's Air Brakes section says a low air pressure warning must come on before tank pressure falls below 60 psi. What kind of signal does it require?
Correct answer: A signal the driver can see, usually a red light
The required warning is one the driver can see, and the manual says a red light is the usual form, with a buzzer possibly sounding too. On older vehicles the threshold may instead be one-half of the governor cut-out pressure.
Source: North Dakota Commercial Driver License Manual — Section 5.1.11, Low Air Pressure Warning
6. Someone pulls out suddenly in front of you, and there is enough distance to stop. How does the manual say you should brake?
Correct answer: So the vehicle stays in a straight line and you can still turn if you have to
Hitting the brakes is a good response when there is room to stop and the brakes are used correctly. The goal is a straight-line stop that still leaves you able to steer, using either controlled braking or stab braking.
Source: North Dakota Commercial Driver License Manual — Section 5.4.3, Emergency Stops
7. The manual tells drivers to brake the same way whether or not the vehicle has ABS, with one exception. What is the exception?
Correct answer: With working ABS on all axles of your straight truck or combination, you can fully apply the brakes in an emergency stop
The normal advice is to use only the braking force needed and to brake the same way regardless of ABS. The single exception is a driver who always runs a straight truck or combination with functioning ABS on every axle: in an emergency stop, that driver can apply the brakes fully.
Source: North Dakota Commercial Driver License Manual — Section 5.4.2, Braking with Antilock Brakes
8. The manual says tractor and straight truck spring brakes come fully on somewhere between 20 and 45 psi. What narrower range does it give as typical?
Correct answer: 20 to 30 psi
The Spring Brakes subsection gives the full range as 20 to 45 psi and adds that 20 to 30 psi is typical. It also says not to wait for that point: stop safely as soon as the low air warning first comes on.
Source: North Dakota Commercial Driver License Manual — Section 5.1.14, Spring Brakes
9. A modulating control valve lets the driver bring the spring brakes on gradually, harder the farther the lever is moved. What does the manual say this is for?
Correct answer: Giving you controlled braking from the spring brakes when the service brakes have failed
The valve is spring-loaded so the driver can feel the braking action, and the brakes come on harder as the lever moves farther. That gives the driver a controllable way to stop on the spring brakes after the service brakes fail.
Source: North Dakota Commercial Driver License Manual — Section 5.1.15, Parking Brake Controls
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Every North Dakota question is written from the official North Dakota driver handbook and checked against its current edition. DMV Test Free is a free, independent study resource — not affiliated with any DMV or government agency. About DMV Test Free