Free District of Columbia CDL Air Brakes Practice Test 2022

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 2022 DC commercial driver's license manual
Full answers + detailed explanations
Perfect for first-time, renewal applicants
DC CDL Air Brakes Test format:
25 questions
20 correct answers to pass
80% passing score
List of questions
An air compressor can be cooled by _______.
The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than:
When inspecting air brakes:
The reduced stopping power caused by overuse of the service brakes and excessive heat is called:
The most important thing to do when a low air pressure warning comes on is:
Parking or emergency brakes of trucks and buses can be legally held on by ____ pressure.
An air brake system is fully charged at what psi?
Spring brakes will generally come on at:
When the engine is off and the parking brake released, a single vehicle air loss rate should be less than ________ psi in one minute.
When you release the brakes and reduce the air pressure what makes up for that air loss?
When checking the low pressure warning signal, it should turn on before the pressure drops below what psi?
If you must make an emergency stop, you should brake so you:
Spring brakes will come on automatically, but the parking brake can also be applied:
It is not safe to drive a vehicle that has brake drums with cracks that are longer than _____ of the width of the friction area.
Air braking takes more time than hydraulic braking because:
If the low air pressure warning light comes on, you should:
The air compressor governor controls:
Which of these is NOT a proper time to apply the parking brakes?
How should the air leakage rate be tested?
Why should you drain water from compressed air tanks?
On newer vehicles, the parking brake control knob is typically yellow, but on older vehicles, the parking brake might be what color?
What does the air compressor governor control?
The spring brakes of a tractor will come on when the air pressure falls within _______.
Manual air tank drains require:
To prevent too much pressure from building up in the system, what is installed?