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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 Oregon CDL knowledge test. The OR 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 Oregon CDL Manual. Take this OR CDL practice test now to prepare for the actual air brakes test!
1. With brake drums, if brakes become too hot:
the air compressor will kick on to cool the brakes.
the brakes will supply too much power to the drive wheels.
your ABS will malfunction.
the brakes may stop working.
2. Truck tractors with air brakes built after March 1, 1997, are required to be equipped with:
hydraulic brakes.
a rear backup camera.
anti-lock brakes.
3. After starting the engine, oil pressure should rise to a normal level:
within 3 miles.
within 2 minutes.
within 6 minutes.
within seconds.
4. You are driving a vehicle with air brakes when the low air pressure warning light and buzzer come on. You should:
slow down and test your brakes.
pull off the road and stop immediately.
apply the brakes as hard as you can.
activate your hazard lights and drive to the nearest place where you can stop.
5. The s-cam:
pulls the brake shoes away from the drum.
forces the brake shoes away from one another and presses them against the inside of the brake drum.
helps ensure that air flows to all trailers.
All of the above.
6. The application pressure gauge:
protects the tank and the rest of the system from too much pressure.
stops the compressor from pumping air.
shows how much air pressure is being applied to the brakes.
tells you how much pressure is in the air tanks.
7. A dual air brake system:
has a single air brake system, which uses two separate sets of brake controls.
has two separate air brake systems, which use a single set of brake controls.
has two separate air brake systems, which use two separate sets of brake controls.
has a single air brake system, which uses a single set of brake controls.
8. Most hydraulic brake failures occur for one of two reasons, one of which is:
driving in cold weather.
relying too much on the engine braking effect.
loss of hydraulic pressure.
excessive downshifting.
9. To test the low pressure warning signal, you should:
shut the engine off when you have enough air pressure, turn the electrical power on and step on and off the brake pedal until the low air pressure warning signal comes on.
check the air hoses connected to the brake chambers to make sure they aren't cut.
pump the brakes while your vehicle is running.
manually let the air out of your brakes and see if the signal comes on.
10. When driving in very hot weather, the heat will increase the chances of:
suspension system defects.
ABS malfunction.
tire failure.
loss of hydraulic pressure.
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OR CDL Air Brakes Test

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