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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 Montana CDL knowledge test. The MT 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 Montana CDL Manual. Take this MT CDL practice test now to prepare for the actual air brakes test!
1. 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
35 psi
150 psi
100 psi
2. If your vehicle is equipped with air brakes, loss of air pressure in the emergency line causes:
the speed of your vehicle to increase.
the trailer emergency brakes to come on.
the trailer spring brakes to come on.
All of the above.
3. In vehicles with air brakes, the two markings on a front brake limiting valve are:
high and low.
normal and slippery.
left and right.
wet and dry.
4. If you are feeling sleepy, you should:
drive faster.
slow down.
pull off the road and rest.
get some coffee.
5. After a tire has been changed, the driver should stop a short while later to:
decrease tire pressure.
check tread separation.
deflate the tire to 10 psi.
check the tightness of the nuts.
6. Service brakes should:
only be checked by a mechanic.
always be checked before applying the brakes.
be checked before each trip.
All of the above.
7. When the air pressure is built up to governor cutoff, the air leakage rate for combination vehicles with the engine off and the foot brake fully applied should be less than_____ in one minute.
5 psi
4 psi
3 psi
2 psi
8. The posted speed limit:
should never be exceeded.
may only be exceeded when driving in rural areas.
should only be exceeded when passing other vehicles.
is only a suggestion.
9. Brakes out of adjustment can cause the other brakes to:
apply more braking power.
work better.
overheat and fade.
last longer.
10. Your vehicle has hydraulic brakes. When you press the brake pedal while driving and the pedal goes to the floor, remember that:
shifting into neutral may help slow the vehicle.
pumping the brake pedal may generate enough hydraulic pressure to stop the vehicle.
the parking brake should never used to slow the vehicle.
All of the above.
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MT CDL Air Brakes Test

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