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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 Iowa CDL knowledge test. The IA 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 Iowa CDL Manual. Take this IA CDL practice test now to prepare for the actual air brakes test!
1. Some vehicles have a separate air tank which can be used to:
hold the vehicle or combination of vehicles stationary.
turn on the 4-way emergency flashers.
release the spring brakes.
2. Why must air tanks be drained?
Water and oil reduce the air pressure.
To keep from fouling the air compressor oil.
Water can freeze in cold weather and cause brake failure.
3. Brake fade results from:
excessive wear.
excessive use of the service brakes.
excessive speeding.
4. When backing, you should:
back quickly.
use the mirrors on both sides.
only use mirror on the driver's side.
5. Pressing and releasing the brake pedal unnecessarily can:
causes friction, which slows the vehicle.
let air out faster than the compressor can replace it.
apply more air pressure.
6. Air tanks usually hold enough compressed air to allow the brakes to be used _________ even if the compressor stops working.
for one day
for one stop
several times
7. ABS:
should only be used on dry roads.
is an addition to your normal brakes.
allows you to brake harder.
8. If the low pressure warning signal doesn't work:
this could cause sudden emergency braking in a single-circuit air system.
you could lose air pressure and you would know it.
None of the above.
9. Controlled braking:
must be used when you need to turn sharply while braking.
can be used to keep your vehicle in a straight line and allow you to turn if necessary.
involves locking the wheels and then releasing the brakes.
10. If a load is 10 feet long, the minimum number of tie-downs required is:
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IA CDL Air Brakes Test

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