Ace The CDL Air Brakes Test 2025

CDL Air Brakes

An air brake system is a type of friction brake for vehicles where the compressed air presses on a piston to apply pressure to the pad to stop the vehicle. The CDL Test comprises of a general test, one or more endorsement tests, and an air brakes test.

Drivers operating a Commercial Motor Vehicle (CMV) equipped with an air brake system needs to go through specialized training and pass the CDL Air Brakes test to obtain an air brake certification. Not passing your air brakes test will result in a restriction, which means you cannot drive any CMV with air brakes.

CDL Air Brakes Test

The air brake test will determine if you are qualified and authorized to drive CMVs equipped with air brakes. It will also demonstrate the drivers’ knowledge of air brake systems and ensure they are fully aware of the proper inspection of an air brake system and identify problems that may occur when the system malfunctions.

To get your air brake certification, you need to pass the 25-question air brakes test from your state’s Department of Motor Vehicles (DMV). The passing score for this test is 80%, which means you are allowed 5 mistakes. That is why it is highly recommended to study and practice first before going to the DMV to take your air brake test. Your air brake certification will open up doors that been previously closed.

How to pass the CDL air brakes test?

To pass the test, you have to prepare and study adequately by making use of practice tests and study guides available for free. You can also make use of these alternatives to better prepare for your upcoming air brake test:

CDL practice test air brakes
DMV CDL practice test air brakes
CDL air brakes practice test 3
CDL air brakes study guide
CDL air brake test pdf
CDL air brake test answers
Crist CDL air brakes
CDL air brake test questions and answers
CDL air brakes flashcards
CDL air brakes practice test pdf
Class b CDL with air brakes
2019 CDL air brake test
Air brakes CDL quizlet
CDL air brakes questions and answers

CDL Air Brake Test Pre-Trip

Although the manufacturers have already done their best to design and create safe and efficient vehicles, it is the driver’s responsibility to ensure that all of the safety features are functioning properly. To make sure that the vehicle you’ll be driving is safe, you are expected to know how and when to conduct inspections.

If you are operating a vehicle equipped with air brakes or applying for an air brake certification, you are required to conduct a pre-trip inspection of the vehicle’s air brake system. This way, you can prevent en-route delays and lessen the chances of an accident caused by mechanical failures.

If the vehicle is equipped with manual slack adjusters, you’re expected to show how to adjust a brake for proper pushrod travel. If it has automatic slack adjusters, you’ll be asked to explain how to adjust manual slack adjuster brakes for appropriate pushrod travel.

CDL Pre-trip Inspection Air Brake Test Guide

Turn the engine and brakes on. Check gauges to ensure governor cuts compressor off at 120 psi. Pump your brakes until the pressure drops below 100 psi to ensure governor cuts compressor on.
Turn the engine and brakes off. Don’t touch your brakes and check gauges to make sure pressure doesn’t drop more than three psi in one minute.
Press and hold the brake pedal while observing gauges. Make sure the pressure does not drop more than four psi in one minute.
Turn key on and the engine and brakes off. Pump brakes until the pressure drops to 60 psi. Your warning buzzer should signal at or before 60 psi.
Continue pumping the brakes until reaching 20 to 40 psi. The emergency (red) and service (yellow) brake valves should pop out, turning your brakes on.
Rebuild the air pressure in the tank by holding the accelerator at 1500 RPM. Observe air gauges. Take note that the pressure rate of build between 85 psi and 100 psi should not take more than 45 seconds.
Perform tug tests by tugging against Parking Brake only, Emergency Brake only, and Hand Brake only.

Test your service brake by accelerating to 5 mph and pressing the brake pedal. You will know the vehicle has a brake alignment problem if the vehicle pulls to one side. If a problem is encountered while testing the air brakes, do not drive the vehicle. It is your responsibility to make sure a mechanic repairs it. Never drive a vehicle that is unsafe to operate.

Frequently Asked Questions

Do you need a CDL for air brakes?

Depending on the Gross Vehicle Weight Rating (GVWR) of the vehicle you are driving. If you’re operating a non-CDL vehicle (26,000 lbs. or less GVWR), it does not matter if it has air brakes. A regular license works fine.

You will only need a CDL with a GVWR of not more than 26,000 lbs. when:

the vehicle is transporting a number of hazardous materials which needs placards to be presented
the truck you’re driving is a bus meant to transport 16 or more persons, including the driver
the vehicle is being operated in a non-exempt capacity and is towing a trailer with a GVWR of 10,001 lbs. or more, and the GVWR of the truck and the trailer exceeds 26,000 lbs.

Why must you pass the air brakes knowledge test?

The air brakes test will demonstrate your knowledge of the air brake system and your awareness of the proper inspection and identification of problems of the system. Knowledge about the air brakes system will prevent further problems and accidents to happen.

Participate in CDL Air Brake Practice Test: