What is the CDL air brakes test? The CDL air brakes test is usually a 25 question multiple choice test that anyone that is going to drive a commercial vehicle with air brakes has to pass. If you are planning on driving a commercial motor vehicle (CMV), then you will have to pass the CDL air brakes test, and once you pass the air brakes test the restriction will be removed from your CDL.
The air brakes test isn’t like the other endorsement tests.
If you haven’t passed the air brakes test, then your CDL will have a restriction on it, and the restriction will not allow you to drive any CMV’s that are equipped with air brakes.
In this article I’m not going to go into all the different endorsements and restrictions that a CDL driver can have. I’m just going to focus on the air brakes test.
To find out more about them I encourage you to go to the FMCSA (Federal Motor Carrier Safety Administration) web page right here about endorsements and restrictions.
To pass the air brakes test you will have to have knowledge about how air is being pumped into the braking system along with understanding how the air will pass through multiple filters, then it will dry, and then it will be stored into a reservoir.
The air brakes test is a very important test and it should not be taken lightly!
Who is Required to Pass the Air Brakes Test?
If you have a CDL and/or you are planning on driving a CMV with air brakes, then you will be required to pass the air brakes test.
The air brakes test is not an endorsement, but it is a restriction on your CDL if you have not passed the air brakes test.
The restriction will prevent you from driving any CMV with air brakes.
For some drivers this is not a big deal, if you have a Class B CDL (in this article I explain the Class B CDL) and never plan on driving a commercial vehicle with air brakes then it doesn’t matter to you.
However, if you are planning on driving a passenger bus (city or school bus) or tractor trailer that has air brakes, then you will need to pass the air brakes test.
Make sure you know whether or not the vehicle you are going to drive has air brakes, if it does then you need to pass the air brakes test.
What is a Passing Score?
The passing score for the air brakes test is 80%.
If you score below 80%, then you will have an air brake restriction on your CDL.
The air brakes test has twenty-five questions, and you have to get twenty of the questions correct to have the air brakes restriction removed from your CDL.
What Kind of Test is the Air Brakes Test?
The air brakes test is a multiple-choice test.
There are twenty-five questions on the air brakes test, and you have to get twenty of the questions correct to pass the air brakes test.
Also, each state may have different amount of numbers for their air brakes tests, but usually there are twenty-five multiple choice questions.
Air Brakes Test Sample Questions
Air brake test sample questions can vary, but they usually include questions like these:
Question: What does the air compressor governor manage?
a) the actual speed of the vehicle
b) the air compressor pumps the air into the air storage tanks
c) how quickly the air is pumped into the air storage tanks
d) the actual temperature of the air that is being pumped into the air storage tanks
The correct answer is: C – How quickly the air is pumped into the air storage tanks. Why C? With an air braking system, the air compressor governor actually controls when and how the air compressor is pumping air into the tanks.
Question: What should be on an air tank when it’s an air braking vehicle?
a) Oxidizer
b) Lock
c) One Way Check Valve
d) A trap door
The correct answer is: C – The check valve. Why C? An air braking vehicle’s air tanks should have a one-way check valve, because it will prevent the air from being leaked out if there happens to be a leak in the tank. The one-way check valve is usually located between the air compressor and the first reservoir tank.
Air Brakes Test: What Is On It?
The air brakes test will cover the following information:
• Air Brake System Parts
• Dual Air Brake System
• Air Brakes Inspecting
• Air Brakes Usage
Before you take the air, brakes test you will want to make sure you know the above information, because the air brakes test will cover all of the above.
What if You Fail the CDL Air Brakes Test?
What happens if you fail the CDL air brake test?
Don’t get upset or be worried if you fail the CDL air brake test, because you can retake the test, but you will have to pay the $15.00 again.
You should make sure you are prepared and have studied all the air brake information before you take the air brake test.
When you feel that you know all the information and you are confident, then you can go retake the test.
How Much Does it Cost to Take the CDL Air Brakes Test?
Usually, the CDL air brakes test is $15.00 for most states, and you want to make sure you have studied and you think you can pass the air brake test, because if you fail, then you will have to pay an additional $15.00 for the retake, and nobody wants to pay twice.
How Many Questions is on the Air Brake Test?
There are usually twenty-five multiple choice questions on the air brake test, but each state is different as some states may only have fifteen multiple choice questions.
CDL Air Brakes Practice Tests
Honestly, don’t spend money on practice tests. You can find a ton of them online for free.
I listed some really good, FREE, practice tests that you can practice with.
The questions are not exactly like they will be on the actual test but they are very similar.
- Test Guide Air Brakes CDL Test Practice (free website)
- CDL Knowledge (free website)
- Trucker Country (free website)
- CDL Career Now (free website)
What is the Air Brake Endorsement?
An air brakes endorsement with a CDL allows the driver to operate a vehicle that has an air brake system.
If you have taken the air brakes test and you have failed it, then you will have a restriction code on your CDL.
The restriction code is “L”, which means you have failed the air brakes test, haven’t identified the air brake components on the system, and you have not conducted an air brake system check properly.
To learn about all the other endorsements you need to check out this article I wrote where I describe each one.
If you have taken the air brakes test in a vehicle that has an air hydraulic braking system, then you will have the restriction “Z” on your CDL, which means you are not able to operate a commercial motor vehicle that has complete air brakes.
Do You Need the Air Brake Endorsement for a Class B CDL?
Yes, you need to have the air brake endorsement for a Class B CDL if the vehicle has an air braking system.
It doesn’t matter that you have a Class B CDL, if the vehicle that you will be driving has an air braking system, then you must have the air brake endorsement as well.
What You Should Study to Pass the Air Brakes Test
If you are wanting to get your air brake endorsement, then you will want to know what information you need to study, so you can pass the air brakes test.
You should have the CDL manual for your state, and you should study the Section 5 thoroughly, which include:
• Air Brakes Usage
• Air Brakes Inspection
• Parts of the Air Brake Parts
• Dual Air Brake System
Before you take your air brake test you will need to understand and know how the air is stored along with having the right pressure needed to drive under.
Usually, the pressure is approximately 125 psi (Pounds Per Square Inch).
If the pressure mounts at approximately 150 psi, then maintenance will need to be done.
You will also need to understand about the parking brake.
The parking brake is a safety function with the air brake system.
The parking brake is a spring actuated brake that will stop any movement with the vehicle.
You will also need to know about other parts of the vehicle that also power the air brakes besides the compressed air.
There are two videos provided below that can help you with CDL air brakes and air brake pre-trip inspection.
CDL Air Brake Pre-trip Inspection YouTube Video (awesome!)
CDL Air Brakes Explained Simply YouTube Video (must see!)
Summary Of The CDL Air Brakes Test
The CDL air brakes test is essential for those individuals that are wanting to be able to drive any commercial motor vehicle that has air brakes.
The CDL air brakes test is usually twenty-five multiple choice questions.
To pass the CDL air brakes test you need to get twenty of the questions correct or 80%.
If you fail the CDL air brakes test, then you can retake the test, but you will have to pay the $15.00 fee again.
If you have a Class B CDL, you will need to have the air brake endorsement if the vehicle that you will be driving has air brakes.
Anyone who is getting their CDL should go ahead and get the air brakes endorsement, because it will only benefit you in the long-run.
You will be able to drive any commercial vehicle that has an air braking system.
You should study Section 5 in the CDL manual in your personal state.
This section will give you all the information that you need to study to pass the air brake test.
The air brakes test isn’t as difficult as you may think, but you want to make sure you are prepared, so you don’t fail and have to pay an additional $15.00 again to retake the test.
