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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 Minnesota CDL knowledge test. The MN 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 Minnesota CDL Manual. Take this MN CDL practice test now to prepare for the actual air brakes test!
1. If air pressure does not build up fast enough:
the pressure may drop too low during driving.
you should turn the electrical power on and step on and off the brake pedal.
you may be forced to turn off the engine and release the parking brake.
you should put the parking brake on and gently pull against it in a low gear.
2. Your vehicle has air brakes. To stop, you should:
release the accelerator, push in the clutch, and shift to Neutral at the same time.
pull the parking brake control knob out.
push the brake pedal down.
pump the brake pedal 3 times.
3. Trailers built on or after March 1, 1998 are required to be equipped with anti-lock brakes. These trailers will have:
yellow malfunction lamps on the right side.
blue malfunction lamps on the right side.
red malfunction lamps on the left side.
yellow malfunction lamps on the left side.
4. If your truck has automatic transmission, you should downshift:
after entering a curve.
when going down grades.
whenever road conditions allow.
when you need to accelerate.
5. As part of your vehicle inspection, you are checking that air flows to all trailers. After using the trailer handbrake to provide air to the service line, you go to the rear of the rig. When you open the emergency line shut-off valve at the rear of the last trailer, you should hear:
the service line valve close.
a mechanical vibration.
a thumping sound.
air escaping from the open valve.
6. When you use your mirrors while driving on the road, you should:
check them quickly.
only use the driver's side mirror.
stare for a long time at the mirror.
avoid checking them regularly.
7. If your vehicle does not have automatic air tank drains, how often should you drain air tanks to remove moisture and oil?
Once a week.
At least once a month.
At the end of each working day.
Every 4 hours.
8. If your vehicle has dual parking control valves, you can use pressure from a separate tank to:
balance the service brakes while you are parked.
park better.
release the spring brakes so you can move the vehicle in an emergency.
None of the above.
9. Most heavy-duty vehicles use:
air brakes.
solid brakes.
hydraulic brakes.
pressure brakes.
10. ABS:
should only be used on dry roads.
allows you to brake harder.
replaces your normal brakes.
is an addition to your normal brakes.
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MN CDL Air Brakes Test

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