Free Missouri CDL Air Brakes Test 2024

Today, you will be taking a practice exam that will prepare you for the real Missouri CDL air brakes exam. Passing this exam will allow you to either receive a CDL without an air brakes restriction or have the restriction removed from your current CDL, opening up new possibilities for your driving career. These questions is based on information directly from the Missouri Commercial Driver License Manual so read each explanation closely, as they may help you answer future questions correctly on the real CDL exam. Practice as often as you desire, and in no time at all, you will be comfortable enough to take the CDL air brakes exam with ease. Good luck and drive safely!

Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements
Triple-checked for accuracy

What you need to know

9 min to complete

Available in EN and ES

Verified by Steven Litvintchouk, M.S., Chief Educational Researcher, Member of ACES. See our detailed commitment to accuracy and quality in our practice tests.

What to expect on the actual MO DOR exam

questions

correct answers to pass

80%

passing score

Helpful links

MO DMV website

List of questions (classic view)

How would you check your truck's slack adjusters?
How can you tell if your vehicle is equipped with an anti-lock braking system (ABS)?
What is the best way to test your vehicle's low air pressure warning signal?
Which of the following will be true about your brake function if your anti-lock braking system (ABS) fails?
How do brakes work on a long, steep downgrade?
Which of the following should you do before leaving your vehicle unattended?
The purpose of a supply pressure gauge is
When should you use the parking brake?
If the air tanks are not drained,
Which of the following are true about a dual air brake system?
Which vehicles must have low air pressure warning signals?
An anti-lock braking system (ABS)
After the initial drop, the maximum acceptable leakage rates per minute are
Which of the following is NOT part of the air brake system?
When should you drain your air tanks?
The tractor protection valve
Why must you pass a knowledge test on air brakes?
Which of the following is NOT part of the drum brake?
Which of the following is NOT part of the braking process when driving a tractor-trailer combination vehicle with an anti-lock braking system (ABS)?
Which of the following can cause brakes to fade or fail?
Under which conditions are front wheel brakes good?
Spring brakes are
At what measurement is the safety valve USUALLY set to open?
Slack adjusters are
What is the best way to test if your vehicle's spring brakes come on automatically?
The low air pressure warning signal will come on before the pressure in the air tanks falls below
A low pressure warning signal is required on
All vehicles equipped with air brakes have
With air brake-equipped vehicles, the parking brakes should be used
The use of air brakes on a downgrade is only a supplement to the

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