# Free District of Columbia CDL Air Brakes Practice Test 2023

Do you need an Air Brakes endorsement or an L endorsement for your commercial driving license? The District of Columbia CDL Air Brake has some differences from other endorsements because your license will receive a mark of restriction if you fail the test. So having good preparation before exam day is very necessary. To ensure that our DC CDL practice test questions are relevant, all of them are based on the DC CDL Manual. Each question has a detailed explanation for you to thoroughly learn the format and the topic. Don't be afraid of having a restriction on your license. Let’s try with our CDL practice test to get ready to pass the District of Columbia CDL Air Brake Test now.

Our CDL practice tests:
Based on 2021 DC commercial driver's license manual
Perfect for first-time, renewal applicants
DC CDL Air Brakes Test format:
25 questions
80% passing score
List of questions
1.
An application pressure gauge shows how much air you are applying to the brakes. Increased application pressure to maintain the same speed indicates that __________.
2.
Modern air brakes combine three different systems. They are the service, the parking, and the _____ brakes.
3.
Your truck has a dual air system and one of the systems loses its pressure. What will happen?
4.
If you must make an emergency stop, you should brake so you:
5.
The low air pressure warning signal indicates:
6.
With air brake vehicles, the parking brake should be used:
7.
To stop the vehicle, air brakes systems use _______.
8.
Where is the modulating control valve located on some vehicles?
9.
The type of brakes that clamp the rotor between the brake shoes is:
10.
Air governor cut-out should be at around:
11.
What is the purpose of an antilock braking system (ABS)?
12.
When your brake's main air pressure is lost ________.
13.
If your truck or bus has dual parking control valves, you can use pressure from a separate tank to:
14.
What is a \"Wig Wag\"
15.
After the initial pressure drop, air leakage for combination vehicles should be less than:
16.
All of the following apply if the low air pressure warning signal does not work EXCEPT:
17.
The use of brakes on a long and steep downgrade under normal conditions is only a supplement to:
18.
You should avoid using the parking brake when _______.
19.
At what level will the low air warning usually take effect?
20.
Pushing the brake pedal down harder __________.
21.