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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 Illinois CDL knowledge test. The IL 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 Illinois CDL Manual. Take this IL CDL practice test now to prepare for the actual air brakes test!
1.
The low pressure warning signal will generally activate when the air pressure falls between:
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55–75 psi.
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80–85 psi.
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85–100 psi.
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30–35 psi.
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2.
When checking air brakes on combination vehicles, which of the following is NOT part of checking that air flows to all trailers?
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Going to the rear of the rig.
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Using the trailer handbrake to provide air to the service line.
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Opening the emergency line shut-off valve at the rear of the last trailer.
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Pulling tractor forward until the fifth-wheel comes out from under the trailer.
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3.
Air tanks usually hold enough compressed air to allow the brakes to be used _________ even if the compressor stops working.
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for 3 days
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for one stop
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for one day
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several times
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4.
The air storage tanks:
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are connected to the engine through gears or a v-belt.
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are used to hold compressed air.
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stop the compressor from pumping air.
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protects the tank and the rest of the system from too much pressure.
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5.
The application pressure gauge shows:
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how much pressure is in the air tanks.
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how much pressure the relay valves should send to the trailer brakes.
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how much air pressure you are applying to the brakes.
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All of the above.
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6.
When the low air pressure warning light and buzzer first come on, you should:
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bring the vehicle to a safe stop right away.
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immediately put alcohol into the air system.
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speed up to restore pressure.
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downshift and slow down.
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7.
Service brakes should:
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only be checked by a mechanic.
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always be checked before applying the brakes.
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be checked before each trip.
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All of the above.
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8.
In air brake vehicles, the parking brake should be used:
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when the spring brakes are on.
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any time you park (with a few exceptions).
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as little as possible.
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to hold your speed while going downhill.
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9.
The safety valve is usually set to open at:
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150 psi.
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75 psi.
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100 psi.
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200 psi.
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10.
If you are being tailgated, you should:
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flash your brake lights.
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increase your following distance.
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speed up.
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move to the left lane.
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