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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 Alabama CDL knowledge test. The AL 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 Alabama CDL Manual. Take this AL CDL practice test now to prepare for the actual air brakes test!
1. The air compressor is connected to:
the radiator.
the suspension system.
the engine.
the transmission.
2. Stepping on and off the brake pedal several times:
reduces the air pressure in the tanks.
may cause air leaks.
may result in dangerously thin linings.
All of the above.
3. Front-end header boards:
protect drivers from cargo in case of an accident or emergency stop.
should never be used.
reduce traction.
protect drivers from spilled cargo.
4. A low air pressure warning signal must come on when the air pressure in the tanks falls below:
10 psi.
60 psi.
15 psi.
100 psi.
5. The alcohol evaporator:
shows how much air pressure you are applying to the brakes.
eliminates the need for daily air tank drainage.
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. You are driving on a steep downgrade. If your safe speed is 35 mph, you should apply the brakes when your speed reaches:
25 mph
30 mph
45 mph
35 mph
7. The safety relief valve is located:
on the dashboard.
in the first tank the air compressor pumps air to.
on each end of the vehicle's axles.
in the front brake.
8. You are coming down a long, steep downgrade. Which of the following is a sign that your brakes may have started to fade?
You have to apply your brakes harder and harder to get the same stopping power.
The brake pedal feels spongy or goes to the floor.
You hear a loud "bang".
The steering feels heavy.
9. In a vehicle with a dual air brake system:
both systems typically operate the regular brakes on the rear axle.
each system has its own air tanks.
one system supplies air to the trailer.
All of the above.
10. Before starting down a hill, you should slow down and shift down:
so you can coast downhill.
to a gear that will cause your engine to exceed its redline.
to a speed that you can control without using the brakes hard.
to a gear that will cause your brakes to overheat.
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AL CDL Air Brakes Test

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