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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 Missouri CDL knowledge test. The MO 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 Missouri CDL Manual. Take this MO CDL practice test now to prepare for the actual air brakes test!
1. In newer vehicles with air brakes, you put on the parking brake:
using a diamond-shaped, yellow, push-pull control knob.
placing the transmission in Park.
using a P-shaped, yellow control knob.
2. Combination vehicles have __ air lines.
3. The tractor protection valve:
will close automatically if the air pressure drops to a certain level.
provides the air supply for the brake system.
All of the above.
4. If stopped on a hill, how can you start moving without rolling back?
Release the parking brake before you have applied enough engine power to keep from rolling back.
Partly engage the clutch before you take your right foot off the brake, put on the parking brake if necessary.
Press on the gas pedal, even if you have to roll back a little.
5. You are going down a steep grade. Once the vehicle is in the proper low gear, you should brake just hard enough to feel a slowdown, and then release the brakes when your speed has been reduced to ____ below your safe speed.
5 mph
10 mph
15 mph
6. Vehicles with air brake systems take longer to come to a complete stop than vehicles with hydraulic brakes because of:
reaction distance.
brake lag.
brake fading.
7. The safety relief valve is located:
in the first tank the air compressor pumps air to.
on each end of the vehicle's axles.
in the front brake.
8. A tank endorsement is:
required for both liquids and gases.
only required when transporting gases.
only required when transporting liquids.
9. Front-end header boards:
protect drivers from spilled cargo.
protect drivers from cargo in case of an accident or emergency stop.
should never be used.
10. The air brake lag distance at 55 mph on dry pavement adds about:
32 feet.
60 feet.
75 feet.
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MO CDL Air Brakes Test

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