CDL Air Brakes Test (2024) - FREE Nebraska CDL Practice Test

1. Why must air tanks be drained?

The low boiling point of water reduces braking power.
To keep from fouling the air compressor oil.
Water can freeze in cold weather and cause brake failure.
Water and oil reduce the air pressure.

2. With air brake vehicles, you should use the parking brakes:

only if your vehicle is equipped with ABS.
only during the vehicle inspection test.
whenever you leave the vehicle unattended.
as little as possible.

3. If your trailer starts to skid, you should:

use the trailer hand brake (if you have one) to straighten out the rig.
accelerate slightly.
keep the rear of your vehicle close to the curb.
release the brakes to get traction back.

4. In some vehicles a modulating control valve may be used to:

apply the spring brakes gradually.
apply the front brakes.
apply the parking brake.
decrease the pressure in the brake system.

5. If your ABS fails:

you will have no brake function, and could lose control.
your tires might grab unexpectedly and you could lose control.
you will still have normal brake functions.
the first step is to get the vehicle off the road and stop.

6. With the controlled braking method, you:

apply the brakes all the way and release brakes when the wheels the lock up.
apply the brakes as hard as you can without locking the wheels.
push down on the brake pedal as hard as you can so that the wheels the lock up.
None of the above.

7. To check slack adjusters on S-cam brakes, you should:

use gloves and pull hard on each slack adjuster you can reach.
press the brake pedal and listen for any strange noises.
check that the spring brakes come on automatically.
All of the above.

8. When the air system is fully-charged, the air loss rate for a single vehicle with the engine off should be less than:

9. Empty trucks have the best braking. True or False?

10. Spring brakes:

will apply the brakes when a leak in the air brake system causes all the air to be lost.
are usually held back by air pressure.
will come fully on when air pressure drops to a certain range, typically 20 to 30 psi.
All of the above.

NEBRASKA CDL AIR BRAKES PRACTICE TEST