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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:
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hold the vehicle or combination of vehicles stationary.
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turn on the 4-way emergency flashers.
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release the spring brakes.
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2.
Why must air tanks be drained?
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Water and
oil reduce the air pressure.
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To keep from fouling the air compressor oil.
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Water can freeze in cold weather and cause brake failure.
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3.
Brake fade results from:
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excessive wear.
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excessive use of the service brakes.
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excessive speeding.
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4.
When backing, you should:
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back quickly.
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use the mirrors on both sides.
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only use mirror on the driver's side.
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5.
Pressing and releasing the brake pedal unnecessarily can:
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causes friction, which slows the vehicle.
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let air out faster than the compressor can replace it.
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apply more air pressure.
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