CDL Air Brakes Practice Test 3

Question 1

What is the proper technique to use when braking on downgrades?

Accepted Answer

Apply the brakes just hard enough to slowdown about 5 mph below your safe speed

Answer

Apply the brakes just hard enough to slowdown about 5 mph below your safe speed.  When going down a long/steep downgrade you should use engine braking to slow your vehicle down.  After your vehicle is in the proper gear, you can apply the brakes just hard enough to feel a definite slowdown (usually about three seconds).  When your speed is about 5 MPH below your safe speed, you can release the brakes.

Question 2

If your vehicle does not have automatic air tank drains, how often should you drain the tanks?

Accepted Answer

At the end of each working day

Answer

At the end of each working day.  Draining the air tanks removes oil and moisture.  If you do not drain each working day, you risk brake failure.

Question 3

When is it acceptable to not use parking brakes if you have to leave your vehicle unattended?

Accepted Answer

You should never leave your vehicle without using parking brakes or chocking the wheels

Answer

You should never leave your vehicle without using parking brakes or chocking the wheels.  If you leave your vehicle unattended without the parking brakes on or the wheels chocked, the vehicle might roll away.

Question 4

When should parking brakes NOT be used?

Accepted Answer

All of the above

Answer

All of the above.  The brakes can freeze if they are applied when wet and the temperature is freezing.  The brakes can become damaged if they are applied when they are very hot.

Question 5

Which device is designed to protect the air tank and system from too much pressure?

Accepted Answer

Safety valve

Answer

Safety valve. A safety relief valve is installed in the first tank that the air compressor pumps air into.  A safety valve protects the tank and system from too much pressure by opening up at 150 psi. The governor controls when the air compressor will pump air into the air storage tanks.  An alcohol evaporator puts alcohol into the air system to help reduce the risk of ice in cold weather.

CDL Practice Test

CDL Practice Test

CDL Air Brakes Practice Test 3