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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. Which of the following is not part of the air brake system?
Air compressor
Air storage tanks
Air filter
Alcohol evaporator
2. Passive railroad crossings:
have at least one traffic control device.
should never be crossed using a CMV.
do not have traffic control devices.
usually have a person directing traffic.
3. Why must air tanks be drained?
There might not be enough antifreeze in the system.
Your transmission fluid may drain out.
The water can freeze in cold weather and cause brake failure.
The alcohol evaporator might stop working.
4. If you are being tailgated, you should:
flash your brake lights.
increase your following distance.
speed up.
move to the left lane.
5. The alcohol evaporator:
eliminates the need for daily air tank drainage.
shows how much air pressure you are applying to the brakes.
ensures the coolant temperature gauge remains in the normal range.
helps to reduce the risk of ice in air brake valves and other parts in cold weather.
6. Under a pressurized system, the radiator cap:
should always be cool.
should never be removed until the system has cooled.
should never be hot.
should be removed when the coolant is hot.
7. The space under a heavily loaded vehicle can be very small. This can cause problems:
on unpaved yards.
when crossing railroad tracks.
on dirt roads.
All of the above.
8. Before driving a vehicle with a dual air brake system, you should allow time for the air compressor to build up a minimum of ____ pressure in both the primary and secondary systems.
50 psi
150 psi
35 psi
100 psi
9. The wig wag is:
a low air pressure warning system.
a noise reduction mechanism.
when your tires might grab unexpectedly and you lose control of your vehicle.
a type of rollover.
10. Spring brakes:
will come fully on when air pressure drops to a certain range, typically 20 to 30 psi.
will apply the brakes when a leak in the air brake system causes all the air to be lost.
are usually held back by air pressure.
All of the above.
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MS CDL 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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