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The air brakes endorsement applies to applicants who wish to drive a vehicle with air brakes in Class A, B, or C CDL. To drive a vehicle with air brakes, you must pass the air brake component of the Mississippi CDL knowledge test. The MS CDL air brakes test consists of 25 questions, and you'll need at least 20 correct answers to pass (80%). The test covers the information found in the air brakes section of the Mississippi CDL Manual. Take this MS CDL practice test now to prepare for the actual air brakes test!
1. The use of brakes on a steep downgrade is:
the main braking factor.
dangerous, and should be avoided at all costs.
a supplement to the braking effect of the engine.
much more effective than the engine braking effect.
2. You hear a loud "bang" which sounds like a tire blowout. You should:
check the tires at the next stop.
assume you have a tire failure.
keep driving as normal.
inspect your tires with your mirrors.
3. As part of the final air brake check, you should:
Test air leakage rate.
Check air compressor governor cut-in and cut-out pressure.
Test low pressure warning signal.
All of the above.
4. When meeting an oncoming vehicle at night, if the other driver does not put their low beams on, you should:
look slightly to the right to avoid looking directly at the lights of the oncoming vehicle.
flash your high beams at the other driver.
"get back at the other driver" by putting your own high beams on.
slow down and look straight ahead in your lane.
5. In combination vehicles with air brakes, the trailer air supply control should pop out when the air pressure falls within the range of:
10 to 20 psi
50 to 75 psi
100 to 120 psi
20 to 45 psi
6. In vehicles with air brakes, the air compressor governor:
controls when the air storage tanks will pump air into the air compressor.
controls when the air compressor will pump air into the air storage tanks.
controls how much air the air compressor will pump into the air storage tanks.
None of the above.
7. After starting the engine, oil pressure should rise to a normal level:
within 6 minutes.
within seconds.
within 3 miles.
within 2 minutes.
8. To prevent rollover, you should:
keep the cargo as close to the ground as possible.
put the lightest parts of the cargo under the heaviest parts.
place the cargo near the rear of the trailer.
place the cargo near the front of the trailer.
9. How do you test hydraulic brakes for leaks?
Pull forward against parking brake to make sure the hydraulic brakes holds.
Pump the brake pedal three times, then apply firm pressure to the pedal and hold for five seconds. The pedal should not move.
Pump the brake pedal ten times and see if it holds.
None of the above.
10. A broken exhaust system:
poses no threat to the driver.
can let poisonous carbon monoxide to leak into the cab.
does not cause problems.
can improve fuel efficiency.
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MS Air Brakes Test

Number of questions: 25
Correct answers to pass:20
Passing score:80%
Number of questions: 25
Correct answers to pass:20
Passing score:80%
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