# 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.
The air compressor stops pumping air at what psi?
2.
During normal driving, spring brakes are usually held back by:
3.
A dual air brake system ________.
4.
To test the vehicle's service brakes, move the vehicle:
5.
The 3 individual systems of the air brakes are the service brakes, emergency brake, and:
6.
In a controlled braking emergency:
7.
The ____ shows how much pressure is in the air tanks.
8.
9.
Generally, air governor cut-in should be at:
10.
When the mechanical arm of a wig wag drops into your view that means the pressure in your system has dropped below what psi?
11.
When parking a vehicle with a modulating control valve ________.
12.
If the spring brakes are on, when should you push the brake pedal?
13.
When brakes are applied, the brake shoes will press against the:
14.
The level at which the air compressor stops pumping air is:
15.
In a dual air brake system, the first system, supplying the rear brakes, is commonly known as the "primary" system, and the other as the:
16.
In order to make contact with the brake drum, the brake pads and linings are pushed outward by the _____.
17.
Which of the following helps the stop light switch work?
18.
The air compressor is connected to the engine through ______.
19.
In a dual air brake system, if the air pressure in one part of the system drops enough to set off the low air warning:
20.
The braking power of the spring brakes ______.
21.
Stab braking should only be used:
22.
If the air compressor has its own oil supply you should do what before driving?
23.
During a normal drive, the spring brakes are held back by _____.
24.
What brake system uses part of the service and parking brake systems to stop the vehicle in the event of a brake system failure?
25.
To test the parking brake you should _______.