FREE CDL Air Brakes Questions and Answers

Question 1

To check the slack adjusters on S Cam brakes, which of the following procedures should you follow?

Accepted Answer

Use gloves and pull hard on each slack adjuster

Answer

Pull on the slack adjusters after draining the air from the system

Answer

Put the parking brake on and pull on the slack adjuster

Answer

Insure that the slack adjusters move more than 1 inch where the push rod attaches to it

Question 2

What is the normal air pressure in an air brake system that has been fully charged?

Accepted Answer

125 psi

Answer

100 psi

Answer

150 psi

Answer

85 psi

Question 3

How should one go about testing the air leakage rate correctly?

Accepted Answer

Turn off the engine and release the parking brake

Answer

Leave the engine running and release the parking brake

Answer

Depress the brake pedal and monitor the air pressure gauge

Answer

Fully charge the air system and leave the engine running

Question 4

What is brake stab?

Accepted Answer

Applying your brakes until the wheels lock up, releasing, and then reapplying when the wheels start rolling

Answer

Using the parking brake to slow the vehicle in an emergency

Answer

Applying the brakes as hard as possible without locking the wheels

Answer

Applying a constant light pressure on the brakes

Question 5

Why do hydraulic brakes stop more quickly than air brakes?

Accepted Answer

It takes longer for the air to flow through the lines

Answer

The air compressor adds a delay

Answer

The driver has an increased reaction time

Answer

All of the above

Question 6

If your air compressor stops, what will happen?

Accepted Answer

You'll still have air pressure left in the air tanks to stop

Answer

Your brakes will lock up

Answer

You will have an immediate loss of your brakes

Answer

Your brakes will not be affected

Question 7

How should the "cut in" and "cut out" pressures on your air compressor governor be checked?

Accepted Answer

All of the above

Answer

Monitor the air pressure gauge

Answer

Run the engine at a fast idle

Answer

Step on and off the brake to reduce tank pressure

Question 8

In a dual air system, how quickly should the air pressure build up?

Accepted Answer

From 85 to 100 psi in 45 seconds

Answer

From 100 to 150 psi in 45 seconds

Answer

From 70 to 125 psi in 60 seconds

Answer

From 50 to 90 psi in 3 minutes

Question 9

What are the normal cut-in and cut-out pressures for the governor of an air compressor?

Accepted Answer

Cut-in: 100 psi; Cut-out: 125 psi

Answer

Cut-in: 90 psi; Cut-out: 125 psi

Answer

Cut-in: 100 psi; Cut-out: 150 psi

Answer

Cut-in: 60 psi; Cut-out: 125 psi

Question 10

In the event that the air compressor leaks, what mechanism will maintain air in the tanks?

Accepted Answer

The one way check valve

Answer

The treadle valve

Answer

The safety valve

Answer

The tractor protection valve