The Commercial Driver License Air Brakes Practice Test is designed to help you prepare for the state test. With this practice test your knowledge will be challenged. These practice test questions are designed to see where you stand before you take your CDL. These tests will let you know what areas you will need to improve on. Although these practice tests will prepare you for your state Commercial Driver License it is important to refer to your book. Please refer to your state Commercial Drivers License study guide for answers that may differ from the practice test. In the event that your state booklet has a different answer then your practice test please refer to your state booklet for the correct answer.
Brake drums or discs must not have cracks which are longer than what proportion of the width of the friction area?

Question 1 of 30

On older ABS systems, the malfunction lamp may not go out until you exceed...?

Question 2 of 30

If air hoses connected to brake chambers are cut or worn, they should be...?

Question 3 of 30

What is another name for 'squeeze' braking?

Question 4 of 30

In a dual air brake system the 'secondary' system will usually operate the regular brakes on...?

Question 5 of 30

The air loss rate for a straight truck or bus with engine off and brakes on, should not be more than:

Question 6 of 30

In a dual air brake system, the 'primary' system will usually operate the regular brakes on...?

Question 7 of 30

On tractors, trucks and buses, the ABS malfunction lamp will be found...?

Question 8 of 30

Air brake vehicles other than truck tractors will definitely have ABS if built after March 1...?

Question 9 of 30

Before driving a vehicle with a dual air system you should allow the air compressor to build up a minimum of what pressure in both systems?

Question 10 of 30

The proper method of braking while going down long of steep curves after selecting the proper gear is to brake until your speed drops to _____mph below the safe speed then release your brakes?

Question 11 of 30

You should test the low pressure warning signal with...?

Question 12 of 30

A trailer with ABS will have a malfunction lamp...?

Question 13 of 30

The best way to find out if a vehicle built before ABS was a mandatory requirement is equipped with the system is to...?

Question 14 of 30

Under ideal conditions, a truck with air brakes going 55 miles per hour requires stopping distance of:

Question 15 of 30

If the pressure in a dual air system drops below 60 psi for one system but stays normal for another, you should...?

Question 16 of 30

If on an automatic slack adjuster the push rod stroke exceeds the legal brake adjustment limit, it indicates that...?

Question 17 of 30

The most common flaw found in roadside inspections of air brake systems is...?

Question 18 of 30

In dual air brake systems, which of these will be individual to each system?

Question 19 of 30

If your vehicle has ABS, your stopping distance compared to a non-ABS vehicle will be reduced by...?

Question 20 of 30

When you pull hard on a slack adjuster, it probably needs adjustment if it moves more than...?

Question 21 of 30

Vehicles will have automatic slack adjusters if they were built since...?

Question 22 of 30

If you find an automatic adjuster is outside the brake pushrod stroke legal limit, you should...?

Question 23 of 30

If you fan the brake pedal to reduce tank pressure with the engine off, the spring brakes should activate when the air pressure drops to...?

Question 24 of 30

You have fully-charged air system (125). After turning off the engine and releasing the service brake, what is the maximum leakage rates per minute for both single and combination vehicles?

Question 25 of 30

Before you check the slack adjusters on S-cam brakes, you should...?

Question 26 of 30

During the engine compartment check part of your inspection procedure on an air brake equipped vehicle you should check...?

Question 27 of 30

A dual air brake system has how many separate air brake systems?

Question 28 of 30

If the low-pressure warning signal does not work properly, what should you do?

Question 29 of 30

Which of these applies to vehicles with automatic slack adjusters?

Question 30 of 30



Air Brakes Test

Getting a commercial driver’s license (CDL) is no different from getting your regular driver’s license. However, it is important to understand that a CDL has restrictions and one of them is the air brake restriction. This means that you cannot drive a vehicle equipped with this type of brakes unless you have passed a written air brakes test and have your skills tested on the road with a vehicle equipped with these brakes. Here is all you need to know about getting air brakes endorsement on your commercial driver’s license.

There are three types of CDL classes that determine the type of vehicle you may drive and how much you may tow. A Class A CDL class allows you to operate a vehicle with a GCWR of 26,001 if the vehicle you tow weighs more than 10,000 and a Class B CDL allows you to operate a vehicle with a GVWR of 26,001 or more pounds or operate any vehicle towing another vehicle that weighs less than 10,000 GVWR. With a Class C CDL, you can operate a Class C vehicle that transports hazardous materials.