CDL AIR BRAKES PRACTICE TEST - MISSOURI

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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 Missouri CDL knowledge test. The MO 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 Missouri CDL Manual. Take this MO CDL practice test now to prepare for the actual air brakes test!
1. Most heavy-duty vehicles use:
triple air brake systems.
dual air brake systems.
single air brake systems.
2. During a trip you should check:
pressure gauges.
temperature gauges.
All of the above.
3. Emergency brakes are:
not required on doubles.
required on all vehicles.
not required on buses.
4. In vehicles with air brakes, the two markings on a front brake limiting valve are:
left and right.
high and low.
normal and slippery.
5. Which of the following is not a way to know when to change gears?
Use road speed (mph)
Check that the pressure gauge shows normal oil pressure
Use engine speed (rpm)
6. To check that spring brakes come on automatically, the first thing to do is to:
release the parking brake, move the vehicle forward slowly, and apply the brakes firmly.
continue to step on and off the brake pedal until the air pressure falls to the manufacturer’s specification.
turn off the engine, release the parking brake and time the air pressure drop.
7. Brake lag is:
the amount of air pressure required to stop the vehicle.
the distance your vehicle will travel, in ideal conditions, while you are braking.
the time required for the air brakes to work after the brake pedal is pushed.
8. If are being followed closely, you should:
change lanes quickly.
decrease your following distance.
increase your following distance.
9. Which of the following is NOT a reason for hydraulic brake failure?
Stab braking
Brake fade on long hills
Loss of hydraulic pressure
10. To prevent drowsiness you should:
get adequate sleep before a trip.
never drive with a passenger.
schedule trips for the middle of the night.
 
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Frequently Asked Questions

Teens between 15 and 18 years old must follow the three steps of Missouri's Graduated Driver License Program:
  • Instruction permit ? you must be 15 years old.
  • Intermediate license ? you must be 16 years old and have held the permit for at least 182 days.
  • Full driver license (class F) ? you must be 18 years old.

You can complete the DMV written test at a Missouri State Highway Patrol examination station (no appointment required). After passing the exam, go to a Missouri driver license office to apply and pay for the instruction permit. If you are a minor, your parent/legal guardian must accompany you to the license office.

You must present specific documents when applying for the first time:
  • Proof of identity (provide further proof to verify any name change).
  • Proof of lawful status.
  • Proof of Social Security Number (If you don’t have a SSN, sign the affidavit provided by the license office and present a letter from the Social Security Administration about your situation).
  • Proof of Missouri residency.
  • Driver examination record to prove that you've passed the vision and the DMV written test. You can request it in person at any Missouri license office or by email at the Driver License Record Center.

You can check the list of acceptable documents here.

The DMV written test in Missouri is offered in various languages, including Chinese, French, German, Greek, Italian, Korean, Russian, Spanish, Vietnamese, Japanese, and Bosnian. Although language options are provided, it is advisable to have a basic understanding of English since road signs are always in English.

To prepare for the DMV written test, read the Missouri Driver's Handbook and take our free practice tests. Topics covered on the exam include road signs, parallel parking, turning, passing a vehicle, yielding the right of way, etc. Once your scores are good, you are ready for the real exam.
The Missouri DMV written test comprises 25 questions and is designed to evaluate your knowledge of general traffic laws in preparation for the road test. You should study the manual carefully to ensure success on your first attempt. 

You can make up to 5 mistakes on the Missouri DMV written test. To pass, you need to answer at least 20 questions correctly, achieving an 80% accuracy rate. Take your time to read each question accurately.

For new drivers in Missouri, there are specific restrictions based on their age:

Instruction permit:
  • If you are under 16, you may operate only under the supervision of a parent/legal guardian, a driving instructor, or an adult who is 25 or older with a driver's license for at least 3 years. When you turn 16, you may operate if accompanied by a licensed driver who is at least 21 years old, seated in the front seat.

Intermediate license:
  • For the first 6 months, you cannot transport more than one passenger under 19 (unless they are siblings). After this period, you can drive with a maximum of three passengers under 19.
  • You cannot drive alone from 1 a.m. to 5 a.m., except for school/job activities or emergencies, unless accompanied by a licensed driver who is at least 21 years old.

A Missouri instruction permit is valid for 12 months and can be renewed. To renew, provide proof of identity and Missouri residency at any Missouri license office, and pay for a duplicate permit.

MO CDL Air Brakes Test

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